Int J Pharm Pharm Sci, Vol 8, Issue 8, 35-42Review Article


ENDOPHYTIC FUNGI: TREASURE FOR ANTI-CANCEROUS COMPOUNDS

ANAND DILIP FIRODIYAa*, RAJESH KUMAR TENGURIAb

aCSRD, Peoples University, Bhopal 462037, Madhya Pradesh, India, bDepartment of Botany, Govt. PG College, Rajgarh 496551, Madhya Pradesh, India
Email: anand.bt16@gmail.com

Received: 22 Apr 2016 Revised and Accepted: 20 June 2016

ABSTRACT

Endophytic fungi that live asymptomatically inside the plant tissues have novel bioactive metabolites exhibiting a variety of biological activities, especially against cancer. This review highlights the research progress on the production of anticancer compounds by endophytic fungi from 1990-2015. Anticancer activity is generally associated with the cytotoxicity of the compounds present in the endophytic fungi. The ubiquitous nature of endophytic fungi synthesise diverse chemicals with promising anticancer activity from either their original host or related species. Modification in fermentation parameters and genetic insight of endophytes may produce novel anti-cancerous compounds.

Keywords: Cancer, Medicinal plants, Secondary metabolites

© 2016 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

INTRODUCTION

The interest in the biogenic medicines has revived throughout the world, as the increase in awareness of the health hazards and toxicity associated with the random use of synthetic drugs and antibiotics [1]. As chemotherapy and conventional treatment causes the adverse side effects for the cure of cancer (CA). Hence, there is an urgent necessitate effective and low toxic drugs. Natural products or their derivatives provide a continuous source of novel bioactive metabolites [2]. Microorganisms seem to cover almost all niches of earth and the probability increases of finding novel compounds by investigating the secondary metabolites of microorganisms from unusual or specialized niches.

Endophytes

Endophyte inhabited in internal tissues of plants without causing any immediate, overt adverse effect [3]. Approximately 1.5 million fungal species exist [4]; while 100,000 have been described. Fungal endophytes are diverse group of microorganisms that colonize plants in the Arctic [5] and Antarctic [6] and in geothermal soils [7], rainforest [8], desert [9], ocean [10], mangrove swamps [11] and coastal forests [12]. They had isolated from the root complexes and aerial parts of a range of hosts, including algae [10, 13], bryophytes [14], pteridophytes [15], gymnosperms [16] and angiosperms [17, 18].

Endophytic fungi: alternative source of secondary metabolites

The search for novel secondary metabolites seems to be characteristics of certain biotopes, centered on organisms that inhibit unique biotopes. A fungus producing secondary metabolite may vary with the biotope where it grows and to which it adapts. Genes involved in the production of secondary metabolites appear to cluster in fungi and bacteria [19] and have gained attention because genetic screening methods are rapid, economical and sensible. Fungal endophytes harbored a broad variety of bioactive secondary metabolites with a distinctive structure including, alkaloids, benzopyranones, flavonoides, phenolic acids, quinines, saponins, steroids, terpenoides, xanthones and others [20]. The respective ecological niche and persistent metabolic interaction between fungus and plant may augment the synthesis of secondary metabolites [21].

Data revealed in this review includes the diversity and taxonomy of endophytes of different species and genera and its anticancer compounds between the year 1990 and 2015 have been systematically represented in the table 1. The structure of these anticancer compounds isolated from the endophytes between 2010 and 2015 are represented in fig. 1. The selection criteria of the reference in the study were based on the bioactive components from endophytic fungi detectable by high-performance liquid chromate-graphy, nuclear magnetic resonance, mass spectrophotometer and X-ray crystallography and its cytotoxicity of the bioactive compounds against cancer cell lines. The compounds with potential application were also considered in the selection of antitumor compounds that are produced by endophytes fungi.

Anti-cancerous natural products from fungal endophytes

Long term co-evolution between endophytic fungi and their host plant for making friendly relationship is believed to shape natural product patterns of endophytic fungi. Endophytic fungi residing in the plants biosynthesize important plant secondary metabolites. There are some natural lead compounds isolated from endophytic fungi acting as lead antiCA compounds viz., paclitaxel, podo-phyllotoxin, camptothecin, vincristine and vinblastine.

Endphytic fungi producing paclitaxel

Paclitaxel is the earliest antiCA compound secured from endophytes. It is a highly functionalized diterpenoid quarantined from the endophytes Taxomyces andreanae obtained from Taxus brevifolia plant species familiar as Pacific yew, which belongs to the Taxus family. The Taxol biosynthetic machinery differs specifically in combination of structural and regulatory genes for one Pestalotiopsis microspora isolate to another. Paclitaxel is produced from most commonly isolated endophytic species P. microspora from Taxus wallichiana [22] and Tubercularia sp. from the southern Chinese yew (Taxus mairei) in the Fujian province [23]. Paclitaxel production was manifold from P. microspora isolates quarantined from bald cypress in South Carolina [24], and in Pestalotiopsis guepini isolated from Wollemi pine (Wollemia nobilis) an extremely rare species from Australia [25]. The highest amount of Taxol produced from an endophytic fungus, P. terminaliae isolated from the Terminalia arjuna [26]. More than two dozen of Taxol producing fungi have been acknowledged [27], including mangrove endophytic fungi Fusarium oxysporum from Rhizophora annamalayana [28] and from an endophytic fungus, Fusarium redolens from Himalayan yew of Taxus baccata [29]. The Alternaria sp. isolated from the shells of Corylus avellana also exhibited an extracellular production of paclitaxel in the MID medium [30].

Endophytic fungi producing podophyllotoxin (PDT)

Podophyllotoxin (PDT) and aryl tetralin lignin with antiCA, antiviral, antioxidant, antibacterial, and immunostimulation capacity commonly occurred in genera of Diphylleia, Dysosma, Sabina [31-38]. The first report of an alternative strategy for efficient production of podophyllotoxin was encountered from Sinopodo-phyllum hexandrum, Diphylleia sinensis and Dysosma veitchii [31]. It was found that PDT can produce from an endophytic fungus Alternaria sp. of Sabina vulgaris [34]. The two endophytes, Phialocephala fortinii strains PPE5 and PPE7 was also able to produce PDT from the rhizomes of Sinopodophyllum peltatum with the yield of 0.5-189 μg/l in liquid suspension culture [35]. It was also produced from an endophytic fungus Trametes hirsute of Sinopodophyllum hexandrum in Sabouraud broth culture [36], whereas Alternaria sp. isolated from Sinopodophyllum hexandrum [37] and also from endophytic fungus Fusarium oxysporum recovered from Sabina recurva [38]. A new endophytic PDT-producing fungus of Fusarium solani has been isolated from the roots of Podophyllum hexandrum [39]. Recently, an endophytic fungus, Mucor fragilis (TW5) was isolated from Sinopodophyllum hexandrum which produces podophyllotoxin [40].

Endophytic fungi producing camptothecin (CPT) and its analogues

Camptothecin (CPT), a pentacyclic quinoline alkaloid was first obtained from the wood of Camptotheca acuminata (Nyssaceae) [41]. CPT and its analogue10-hydroxycamptothecin are effective in inhibition of the intranuclear enzyme topoisomerase-1, required for DNA replication and transcription during the molecular events [42]. The first report of an endophytic fungus Entrophospora infrequens obtained from Nothapodytes foetida had the ability to produce camptothecin [43]. The F. solani obtained from Camptotheca acuminata may able to produce CPT, 9-methoxycamptothecin and 10-hydroxycamptothecin [44]. The endophytic fungi, Alternaria alternata, Fomitopsis sp., and Phomposis sp. isolated from Miquelia dentate (Icacinaceae) were produced CPT, 9-methoxy CPT (9-MeO-CPT) and 10-hydroxy CPT (10-OH-CPT), respectively. The fungal extracts are effective against colon and breast CA cell lines [45]. It was also found that an endophytic fungi Trichoderma atroviride LY357 isolated from C. acuminata produces highest yield 142.15 μg l(-1) on subculturing [46].

Endophytic fungi producing Vinblastine/Vincristine

Vinblastine and vincristine, terpenoid indole alkaloids derived by the linking of vindoline and catharanthine monomers are acknowledged as antiCA agents [47, 48]. The primary mechanism of action of vincristine is to interfere with microtubule formation and mitotic spindle dynamics, further interruption of intracellular transport leads to anti-angiogenesis [47, 49]. The endophytic fungus Alternaria sp. and F. oxysporum isolated from the phloem of Catharanthus roseus has the ability to yield vinblastine [50] and Vincristine [51] respectively. Vincristine also isolated from an endophytic fungus of leaves of C. roseus [52]. Vinblastine and Vincristrine have been also isolated from an endophytic fungi F. oxysporum from Catharanthus roseus [53].

New secondary metabolites as an anticancer compound

It includes various chemical entities, including alkaloids and nitrogen-containing heterocycle, benzofluranthenes, chromones, cyclohexanthrone, depsidone, coumarins, ergochromes, esters, lactones, peptides, peroxide, polyketides, pyrans, quinines, steroids, stilbene, diterpenes, sesquiterpenes, triterpenes and xanthones.

Alkaloids and nitrogen-containing heterocycle

Plant-derived alkaloids reveal a wide range of biological activity. Many potential antiCA agents studied are plant alkaloids [54, 55]. A number of alkaloids have been isolated from endophytic fungi. Some alkaloid compounds explored for commercial purpose for clinical use for targeting tumors are Camptothecin (CPT), and Vincristine. In recent years, several new alkaloids isolated from endophytic fungi have shown antitumor activity.

Cytochalasin, is a highly substituted perhydroisoindol moiety usually attached to heterocyclic ring. There are>80 different cytochalasins reported from fungal isolate of different genera, with a wide range of biological activity. The mechanism of action of cytochalasins is to inhibit cell division, induce an apoptotic response and inhibit the polymerization of actin filaments [56]. Cytochalasin 1 showed cytotoxic activity against A2780S (ovarian), HCT-116 (colon) and SW-620 (colon) tumor cell line with IC100 values of 3.91, 15.6 and 3.91 µg/ml, respectively, while 14 showed values of 15.6, 62.5, 15.6 µg/ml respectively. Cytochalasin 3 exhibited an IC100 (inhibitory concentration, 100%) value of 3.91µg/ml against A2780S and 15.6µg/ml against SW-620 [57].

Chaetominine, alkaloidal metabolites, isolated from an endophytic fungus Chaetomium sp. IFB-E015 from healthy leaves of Adenophora axilliflora. Chaetominine 19 showed cytotoxicity against the K562 (human leukemia) and SW1116 (colon cancer) cell lines. Its potency was greater than that of 5-fluorouracil, with IC50 values of 33.0 and 76.0 nM, respectively [58].

The 9-Deacetoxyfumigaclavine C, an alkaloid was isolated from the endophyte Aspergillus fumigatus from a healthy stem of Cynodon dactylon. 9-Deacetoxyfumigaclavine C 2 exhibited selectively potent cytotoxicity against human leukemia cells (K562) with an IC50 value of 3.1 µM, which was similar to that of doxorubicin hydrochloride (1.2 µM) [59].

Novel fungal alkaloids Cytoglobosin C and D, cytochalasan derivatives isolated and identified from a culture of Chaetomium globosum QEN-14, an endophytic fungus of the marine green alga Ulva pertusa. Two cytoglobosins compounds C10 and D11 displayed very similar cytotoxicity profiles with IC50 values of 2.26 and 2.55 µM against the lung CA A549 tumor cell line [60].

Citriquinochroman, a structure consisting of quinolac-tacide and (3S)-6-hydroxy-8-methoxy-3,5-dimethylisochro-man linked by a C-C bond. It was isolated from Penicillium citrinum, an endophytic fungus from a fresh stem of the Moroccan plant Ceratonia siliqua. Citriquinochroman showed cytotoxicity (IC50=6.1 µM) against the murine lymphoma L5178Y [61].

Aspochalasins D and J, two cytochalasans analogues were isolated from Trichoderma gamsii, obtain from the traditional Chinese medicinal plant Panax notoginseng. Compound aspochalasins D and J displayed inhibitory activity against the HeLa cells with an IC50 value of 5.72 and 27.4 µM, respectively [62].

Chaetoglobosin U, an alkaloid belonging to the cytochalasin family had an affinity for actin filaments. It was isolated from Chaetomium globosum IFB-E019 from healthy stem of Imperata cylindrica. It showed cytotoxic activity against the KB cell line with an IC50 value of 16.0 µM comparable to that of 5-fluorouracil as a positive reference (14.0 µM) [63]. Chaetoglobosin X isolated from an endophytic fungus C. globosum of medicinal plant Curcuma wenyujin exhibited potent cytotoxic activity against H22 and MFC CA cell lines [64].

Benzo[j] fluoranthenes

New benzo[j]fluoranthene structures, daldinone C and daldinone D isolated from an endophyte Hypoxylon truncatum IFB-18 reside inside the stem tissue of Artemisia annua. Both compounds exhibited potent cytotoxicity against human colorectal CA cell line SW1116 cells, with IC50 values of 49.5 and 41.0 µM, respectively, as compared to 5-fluorouracil with IC50 value 37.0 µM [65]. One contrasting thing to note is that the value of 5-fluorouracil as a standard was 76.0 nM [58] as compared to another study, eventhough the same researchers used the same cell line (SW1116) and the same MTT colorimetric method.

Chromones

Pestalotiopsone F, is a new chromone, 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone derivative isolated from an endophytic fungus Pestalotiopsis sp. of Chinese Mangrove plant Rhizophora mucronata. Among other chromone derivatives, compound 6 exhibited moderate cytotoxicity against the murine CA cell line L5178Y, with an EC50 value of 8.93µg/ml [66].

Pestaloficiols, novel isoprenylated chromone derivative was isolated from fungal endophyte Pestalotiopsis fici of Camellia sinensis. Four novel derivatives, pestaloficiol I, pestaloficiol J, pestaloficiol K and pestaloficiol L (heterodimer) had IC50 values ranging between 8.7 µM and>136.1 µM for HeLa cells and between 17.4 µM and>153.8 µM for MCF7 cells, compared to the positive control 5-fluorouracil with IC50 values of 10.0 and 15.0 µM, respectively. Pestaloficiol L showed potent cytotoxicity, with IC50 values of 8.7 and 17.4 µM respectively [67].

Coumarins

A new furanocoumarin, 5-methyl-8-(3-methylbut-2-enyl) furano-coumarin was isolated from the mangrove endophytic fungus, Penicillium sp. ZH16, which exhibited in vitro cytotoxicity against CA cell lines with IC50 values KB and KBV200 cells 5 and 10 mg. ml-1, respectively [68].

Arundinone B, a polyoxygenated benzofuran-3 (2H)-one dimer was isolated from a plant endophytic fungus, Microsphaeropsis arundinis. Arundinone B showed cytotoxic activity against T24 and A549 CA cells [69].

Cyclohexanones

Epiepoxydon, a cyclohexanone derivative, was isolated from a marine endophytic fungus Apiospora montagnei of inner tissue of the North Sea alga Polysiphonia violacea. High cytotoxicity of the compound was observed in the brine shrimp assay. The breast adenocarcinoma cell line MCF7 exhibited an LC50 of 3.6µg/ml. The GI50 concentrations for human gastric carcinoma HM02, human liver carcinoma HepG2 an MCF7 were 0.7µg/ml, 0.75µg/ml and 0.8µg/ml respectively. The total growth inhibition (TGI) for HepG2, MCF-7 and HM02 was found to be 4.6µg/ml, 1.5µg/ml and 1.0 µg/ml respectively. The LC50 of compound 27 observed in HM02 and HepG2 cells were>10 µg/ml [70].

Depsidone

Depsidone 1 isolated from order Pleosporales (BCC 8616), an endophytic fungus was isolated from an unidentified leaf of the Hala-Bala evergreen forest. It showed weak cytotoxic activity against KB with IC50 values of 6.5 and 4.1 µg/ml activities for BC cell lines [71].

Ergochromes

Dicerandrol, a dimeric tetrahydroxanthone derivative was isolated from an endophytic fungus Phomopsis longicola of the endangered mint Dicerandra frutescens. The fungal endophyte produced three compounds designated dicerandrols A, B, and C. They have the same tricyclic C15 system with a similar arrangement of substituents, classified as ergochromes. The dicerandrols showed considerable cytotoxicity against lung adenocarcinoma epithelial cell line A549 and colorectal HCT-116. The IC100 value of compound A against both cell lines and the value of compound C against HCT-116 was 7.0µg/ml. The IC100 value of compound C against A549 and of compound B against both cell lines was 1.8µg/ml. The standard antiCA drug etoposide exhibited IC100 values of 30.0µg/ml against A549 and 125.0µg/ml against HCT-116, which were less significant than dicerandrol compound [72].

Ergoflavin, a dimeric xanthene, linked in position 2 classes of ergochrome compounds, were first isolated from the ergot fungus Claviceps purpurea, as well as Aspergillus sp., Penicillium oxalicum, Phoma terrestris and Pyrenochaeta terrestris. It has been isolated from ascomycetous endophyte of a leaf, Mimosops elengi (‘bakul’) designated PM0651480. Ergoflavin showed cytotoxicity against renal ACHN with IC50 value1.2±0.20, for lung H460 IC50 4.0±0.08, for pancreatic Panc IC50 12.4±0.02, for colorectal HCT116 IC50 8.0±0.45 and 1.5±0.21 µM IC50 values for lung Calu1 cell lines. Flavopiridol has been used as standard for assessing the cytotoxicity of ergoflavin with the IC50 values in ACHN (0.84±0.03 µM); H460 (0.38±0.01µM); Panc-1 (0.23±0.07 µM); HCT116 (0.25±0.03 µM); and Calu1 (0.41±0.09 µM) CA cell lines [73].

Secalonic acid D, an ergochrome group of compounds isolated from the mangrove endophytic fungus no. ZSU44 [74], was first isolated from Penicillium oxalicum [75] with highly toxic and teratogenic properties. Secalonic acid D showed potent cytotoxicity to HL60 with IC50 values of 0.38 µM and 0.43 µM in K562 cells. It induced apoptosis in HL60 and K562 cells, confirmed by Annexin V-FITC/PI assay and Western blot. Secalonic acid D also downregulated c-Myc and cell cycle arrest of G(1) phase through activation of GSK-3beta followed by degradation of beta-catenin [74].

Esters

Globosumone, orsellinic acid ester, was isolated from endophytic fungus, Chaetomium globosum of Mormon tea, Ephedra fasciculate. Two isolated compounds Globosumone A and B exhibited moderate cytotoxic activity with IC50 for compound A 21.30 and 21.90 µM for compound B against MCF-7, IC50 values for compound A 10.60 and 30.20 µM for compound B against MIA Pa Ca-2 with IC50 values for compound A 6.50 and 24.80 µM for compound B against NCI-H460. The IC50 value for compound A 8.80 and 29.10 µM for compound B against SF-268, and against WI-38 with IC50 for compound A was 13 and 14.20 µM for compound B [9].

Lactones

Brefeldin A, a lactone antibiotic, was isolated from endophytic fungi Aspergillus clavatus and Paecilomyces sp. isolated from Taxus mairei and Torreya grandis. Brefeldin A has antifungal, antiCA and antiviral activities. It showed good cytotoxic activity against HeLa, HL-60, KB, MCF-7 and Spc-A-1 cell lines with IC50 values of 9.0, 10.0, 1.8, 2.0 and 1.0 ng/ml, whereas standard paclitaxel drug with IC50 values of 0.16, 1.2, 1.8, 5.0 and 0.8 ng/ml respectively. It has been also isolated from numerous fungal species, including Alternaria, Ascochyta, Curvularia, Cercospora, Phyllosticta and Penicillium [76]. Brefeldin A was also isolated from Acremonium species of a healthy twig of Knema laurina with potent activity against BC-1 (breast cancer), KB (epidermoid cancer of the mouth), and NCI-H187 (small-cell lung cancer), with IC50 values of 0.04, 0.18 and 0.11 µM, respectively [77].

Eutypellin A, a gamma-lactone isolated from Eutypella sp. BCC 13199, an endophytic fungus was isolated from Etlingera littoralis (Earth ginger). It showed cytotoxic activity against MCF-7, NCI-H187 (human small-cell lung cancer cells), KB and non-malignant Vero cells with IC50 values of 84, 12, 38 and 88 mM compared to the standard ellipticine, which exhibited IC50 values of 2.5, 3.6 and 5.5 µM respectively [78].

Cytospolide P, a nonanolide isolated from an endophytic fungus Cytospora sp. of Ilex canariensis. In vitro cytotoxicity assay showed the gamma lactone 17 with a potent growth inhibitory activity toward the cell line A-549, while nonanolide (Cytospolides P) with (2S) configuration showed potent activity against cell lines A-549, QGY and U973. It has significantly arbitrated G1 arrest in A549 tumor cells, as the role of C-2 methyl in the growth inhibition toward the tumor line [79].

Azalomycin F analogs including 25-malonyl demalony-lazalomycin F5a monoester, 23-valine demalonylazalo-mycin F5a ester, 23-(6-methyl)heptanoic acid demalonylazalomycins F3a ester, F4a ester and F5a ester, 23-(9-methyl) decanoic acid demalonylazalo-mycin F4a ester and 23-(10-methyl)undecanoic acid demalonylazalomycin F4a ester were isolated from endophytic fungus Streptomyces sp. 211726. All seven compounds exhibited good antimicrobial and anti HCT-116 activities (IC50 values of 1.81–5.00 µg/ml) [80].

Peptides

Leucinostatin A, a peptide was isolated from cultures of Penicillium lilacum, having potent biological activity against several different cell lines [81]. It inhibited prostate CA growth through reduced insulin-like growth factor-I expression in prostate stromal cells [82]. Leucinostatin A was also isolated from an endophytic fungus Acremonium sp. of European yew, Taxus baccata. The fungal endophyte also produced leucinostatin A beta di-O-glucoside from leucinostatin A which had an LD50 (50% lethal dose) of>25 nM against breast CA cell line BT-20, compared to leucinostatin A, which had an LD50 of 2 nM [83].

Verticillin D, depsipeptides pullularin A, C was isolated from endophytic fungus Bionectria ochroleuca of the inner leaf tissues of Sonneratia caseolaris (Sonneratiaceae). It showed good cytotoxic activity against the L5178Y cell line. Pullularin A, C and E showed EC50 values ranging between 0.1 and 6.7 µg/ml [84].

Beauvericin is depsipeptide, was isolated from Aspergillus terreus (No. GX7-3B), an endophytic fungus of Bruguiera gymnoihiza [85]. It was previously isolated from several other fungi [54]. The compound showed moderate cytotoxic activities with IC50 values 2.02 (MCF-7), 0.82 (A549), 1.14 (HeLa) and 1.10 µm (KB). It was also isolated from endophytic fungus Fusarium oxysporum EPH2RAA of the Sonoran desert plant Ephedra fasciculata. It inhibited migration of PC-3M and MDA-MB-231 cells and antiangiogenic activity against HUVEC-2 cells in sublethal concentrations. It showed cytotoxic activity against four different cell lines, human CNS CA glioma (SF-268), human breast CA (MCF-7), human pancreatic CA (MIA Pa Ca-2) and human non-small-cell lung CA (NCI-H460) with IC50 values of 2.29, 1.81, 1.66 and 1.41 µM, respectively [86]. It was also isolated from mangrove endophytic fungi Fusarium sp. (DZ27), which inhibited growth of KB and KBv200 cells potently with IC50 values of 5.76 and 5.34 µM respectively [87].

Peroxides

Talaperoxides B and D, are norsesquiterpene peroxides isolated from an endophytic fungus, Talaromyces flavus collected from mangrove plant Sonneratia apetala. It showed in vitro cytotoxic activities against MCF-7, MDA-MB-435, HepG2, HeLa and PC-3 cell lines with IC50 values ranging between 0.70 and 2.78 µg/ml [88].

Polyketides

Sequoiatone A and B are novel polyketides isolated from fungus Aspergillus parasiticus, an endophyte of the bark of Sequoia sempervirens. The test results from the NCI human tumor 60 cell-line screen exhibited moderate activity and greatest efficacy against breast CA cell lines. The GI50 values of the compounds were between 4–10 µM and LC50 values>100 µM [89].

Sequoiamonascin A and B were isolated from Aspergillus parasiticus of a redwood tree bark, Sequoia sempervirens. The compound A and B exhibited cytotoxic activity against MCF-7, NCIH460, and SF-268 cell lines. In the 60-human cell line assay, compound A showed a median log GI50 of-5.00, below the potency threshold established by NCI [90].

Bikaverin, a polyketide was isolated from endophytic fungus Fusarium oxysporum strain CECIS of Cylindropuntia echinocarpus. It showed cytotoxicity against a panel of four sentinel CA cell lines, MCF-7 (breast), MIAPa Ca-2 (pancreatic), NCI-H460 (non-small-cell lung) and SF-268 (CNS glioma) with IC50 values of 0.42, 0.26, 0.43, and 0.38 µM, respectively. Doxorubicin was standard compound with IC50 values 0.07, 0.05, 0.01, and 0.04 µM respectively. The cytotoxic activity of bikaverin was due to its C−6 hydroxy group [86].

A new polyketide, 2-(7’-hydroxyoxooctyl)-3-hydroxy-5-methoxy-benzene acetic acid ethyl ester was isolated from mangrove endophyte Phomopsis sp. ZSU-H76 of the stem of Excoecaria agallocha from Dong Zai, Hainan, China. Compound A exhibited cytotoxicity against HEp-2 with IC50 values of 25 and 30 µg/ml for HepG2 cell lines [91].

Oblongolide, a polyketide was isolated from fungus Phomopsis sp. BCC 9789 associated with Musa acuminata (wild banana). Two compounds, oblongolide Y and Z showed cytotoxic activity against CA cell lines. Compound Y showed cytotoxic activity against BC cell line with an IC50 value of 48 µM. Compound Z exhibited cytotoxicity against BC, KB (human oral epidermoid CA), and NCI-H187 (small-cell lung CA), and non-malignant (Vero) cell lines with IC50 values of 26, 37, 32 and 60 µM, compared to doxorubicin as a positive control, which had IC50 values of 0.30 µM (BC), 0.24 µM (KB), and 0.08 µM (NCI-H187) [92].

Kasanosins A and B are novel azaphilones, isolated from cultures of Talaromyces sp. of seaweed. These compounds selectively inhibited specific DNA polymerases. Compound A was more potent than B, with IC50 values of 27.3 (DNA pol β) and 35.0 mM (DNA pol γ). The specificity of compounds toward DNA polymerase families might be useful in the development of anti-CA chemotherapy agents [93].

Hypericin, a naphthodianthrone derivative, is a plant derived isolate from the herb Hypericum perforatum (St. John’s Wort). Hypericin had been reported effective in the treatment of depression, potent MAO inhibitor [94] and potent antiviral against a plethora of enveloped viruses [95]. In India, harvesting was done for the first time for isolation of hypericin and emodin from an endophyte Thielavia subthermophila from stem of H. perforatum [96].

Rubrofusarin B, naphtha-g-pyrone was isolated from an endophyte Aspergillus niger IFB-E003 of Cynodon dactylon. It showed cytotoxicity against colon cancer cell line SW1116, with an IC50 value of 4.5 µg/ml compared to the positive control 5-fluorouracil at 5 µg/ml [97].

The new S-containing benzophenone dimer guigna-sulfide was isolated from an endophytic fungus Guignardia sp. IFB-E028 of Hopea hainanensis. It exhibited cytotoxic activity (IC50-5.2±0.4 µm) against the human liver cancer cell line HepG2 [98].

Penicitide A, polyketide derivative isolated from endophytic fungus Penicillium chrysogenum QEN-24S from Laurencia, an unidentified marine red alga. It showed cytotoxic effect against human hepatocellular liver carcinoma cell line with moderate cytotoxic activity [99].

Sclerotiorin is azaphilone polyketide obtained from an endophytic fungus Cephalotheca faveolata of Eugenia jambolana. It was found to be potent anti-proliferative against different CA cells, which caused apoptosis of colon CA (HCT-116) cells through the activation of BAX and down-regulation of BCL-2 [100].

Polyketide and benzopyran compounds isolated from Phoma sp., endophytic fungi of Cinnamomum mollissimum. 4-hydroxymellein (polyketide) showed high inhibitory activity (94.6%) whereas 4,8-dihydroxy-6-methoxy-3-methyl-3,4-dihydro-1H-isochromen-1-one (benzopyran) exhibited moderate inhibitory activity (48.8%) against P388 murine leukemic cell [101].

Pyrans and pyrones

(2R*, 4R*)-3, 4-dihydro-4-methoxy-2-methyl-2H-1-benzopyran-5-ol, a new benzopyran was isolated from an endophytic fungus Nodulisporium sp. A4, of Aquilaria sinensis. The compound showed less cytoxicity (57.9% inhibition rate) against the SF-268 cell line at 100 µg/ml concentration, compared with the positive control, cisplatin [102].

The genus Aspergillus is the main genus from which compounds pyrone or its derivatives have been produced. Three a pyrone derivatives nigerapyrones B, D, E and one known congener, asnipyrone A have been isolated from Aspergillus niger MA-132, an endophytic fungus isolated from Avicennia marina. The four compounds showed less cytotoxicity against some of the tested (Du145, HepG2, MCF-7, MDA-MB-231and NCI-H460) tumor cell lines [103].

A monomeric naphtho-g-pyrones, TMC 256 A1 isolated from the mangrove endophytic fungus Aspergillus tubingensis (GX1-5E) exhibited in vitro cytotoxicity activities against tumor cell lines of MCF-7, MDA-MB-435, Hep3B, Huh7, SNB19 and U87 MG (IC50 values 19.92-47.98 µM) [104].

Quinones

Torreyanic acid, dimeric quinine isolated from an endophyte Pestalotiopsis microspora of Torreya taxifolia, causes cell death by apoptosis. It showed cytotoxicity with IC50 values were between 3.5µg/ml for human colorectal neuroendocrine cell CA (NEC) to 45µg/ml for human adenocarcinoma alveolar basal epithelial cells (A549), with a mean value of 9.4µg/ml for 25 different cell lines. It also showed G1 arrest of G0 synchronized cells at the 1–5 µg/ml level depending on the cell line [105].

Anti CA compounds have been isolated from Stemphylium globuliferum, an endophyte of the Egyptian medicinal plant Mentha pulegium. Among compounds unresolved mixture of alterporriol G and its atropisomer alterporriol H exhibit cytotoxicity against L5178Y mouse lymphoma cells, with an EC50 value of 2.7µg/ml. The compound 6-O-methylalaternin also exhibited potent cytotoxicity, with an EC50 value of 4.2µg/ml. Kahalalide F tested as a positive control and exhibited an EC50 value of 6.3µg/ml. The atropisomers and 6-O-methylalaternin compounds were the most potent kinase inhibitors, displaying EC50 values between 0.64 and 1.4µg/ml towards each kinase [106].

Cochliodinol and isocochliodinol are compounds isolated from an endophytic fungus Chaetomium sp. which separated from the stem of Salvia officinalis. These exhibited cytotoxicity against L5178Y mouse lymphoma cells. Cochliodinol was in order of magnitude more potent than its isomer, with an EC50 of 7.0µg/ml, compared to 71.5µg/ml for compound [107].

2-chloro-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione, a novel benzoquinone derivative isolated from Xylaria sp., an endophytic fungus of Sandoricum koetjape exhibited potent cytotoxicity against Vero cells with an IC50 value of 1.35 µM compared to the positive control ellipticine, with an IC50 value of 2.03 µM [108].

Alterporriol K and L, anthraquinone compounds were separated from extracts of the endophytic fungus Alternaria sp. ZJ9-6B of Aegiceras corniculatum. It showed moderate cytotoxic activity against breast CA cell line MDA-MB-435 and MCF-7 with IC50 values ranging from 13.1 to 29.1 µM [109].

Altersolanol A a natural product isolated from the endophytic fungus Stemphylium globuliferum of the medicinal plant, Mentha pulegium (Lamiaceae) showed cytotoxic activity against K562 leukemia and A549 CA cells. It induced cell death by apoptosis through the cleavage of caspase-3 and-9 and decrease of anti-apoptotic protein expression [110].

Steroids

Penicisteroids A and B are polyoxygenated steroids obtained from Penicillium chrysogenum QEN-24S, an endophytic fungus isolated from Laurencia, marine red alga. Penicisteroid A displayed potent cytotoxic activity [99].

Nigerasterols A and B are new 6,8 (14),22-hexadehydro-5a,9a-epidioxy-3,15-dihydroxy sterols isolated from an endophytic fungus Aspergillus niger MA-132 of the plant Avicennia marina. Nigerasterol B displayed potent activity against the tumor cell line and A541 with an IC50 value of 1.50 and 1.82 µm respectively, while nigerasterol A displayed stronger activity against HL60 with an IC50 value of 0.30 µM [111]. Another compound 3b, 5a-dihydroxy-(22E, 24R)-ergosta-7, 22-dien-6-one is a phytoecdysteroids isolated from mangrove endophytic fungus Aspergillus terreus of Bruguiera gymnoihiza. The compound exhibited potent cytotoxic activities against cancer cell lines with IC50 values 4.98 (MCF-7), 1.95 (A549), 0.68 (HeLa) and 1.50 µM (KB) [112].

Stilbene

Resveratrodehydes A–C was isolated from the mangrove endophytic fungus Alternaria sp. R6. It showed inhibitory activity against MDA-MB-435, HepG2, and HCT-116 (IC50<50 μM) by MTT assay. Compounds A and B exhibited potent cytotoxic activities (IC50<10 μM) against MDA-MB-435 and HCT-116 cell lines [113].

Diterpenes

Periconicin B, a fusicoccane diterpene from the endophytic fungus Periconia atropurpurea of Xylopia aromatica showed potent cytotoxic activity against HeLa and CHO (Chinese hamster ovary), with an IC50 of 8.0 µM. It exhibited potency similar to that of antineoplastic agent cisplatin (IC50 5.0 µM) used as a cytotoxic positive control [114].

19-(2-acetamido-2-deoxy-a-Dglucopyranosyloxy)isopimara-7,15-dien-3b-ol and 19-(a-D-glucopyranosyloxy) isopimara-7, 15-dien-3-one, isopimarane diterpenes isolated from the endophytic fungus Paraconiothyrium sp. MY-42 showed moderate cytotoxicities against HL60 cell line [115].

Sphaeropsidins A and D, diterpenes isolated from Smardaea sp. AZ0432 of the moss Ceratodon purpureus. Together with one sphaeropsidins A derivative, 6-O-acetylsphaeropsidin A showed significant cytotoxic activity. Sphaeropsidin A showed cell-type selectivity in the cytotoxicity assay, while it inhibited migration of MDA-MB-231 cells at subcytotoxic concentrations [116, 117].

Sesquiterpenes

Merulin A, and merulin C are the two new sesquiterpenes produced by the endophytic fungus XG8D isolated from Xylocarpus granatum (Meliaceae). Compound A exhibited cytotoxicity against BT474 and SW620 cell lines with IC50 values of 4.98 and 4.84 µg/ml, while compound C exhibited IC50 values of 1.57 and 4.11 µg/ml, respectively. The standard compared to doxorubicin as a positive control with IC50 values of 0.53 and 0.09µg/ml against BT474 and SW620 cell lines, respectively [118].

Eremophilanolide is an eremophilane-type sesquiterpenes isolated from the endophyte Xylaria sp. BCC 21097 of Licuala spinosa. Its three novel compounds possess an alpha-methylene-gamma-lactone, eremophilanolide 1, 2 and 3 exhibited moderate cytotoxic activity with IC50 values of 3.8–21 µM against CA cell lines KB, MCF-7, and NCI-H187 [119].

Ceriponols F, G and K, are tremulane sesquiterpenes isolated from endophytic fungus Ceriporia lacerate of Huperzia serrata. Ceriponols F and K revealed moderate cytotoxicity against HeLa, HepG2 and SGC 7901 (IC50=32.3±0.4 to 173.2±1.5 µM), while slightly better cytotoxicity was observed with ceriponol G against a HeLa cell line [120].

Triterpenes

Xylariacins A, B, C three new triterpenes were isolated from the fermentation extract from Xylarialean sp. A45, an endophytic fungus from Annona squamosa L. Their structures were determined by NMR and mass spectrometry. Xylariacin A-C showed modest cytotoxic activity against human tumor cell line HepG2 [121].

(+)-(3S, 6S, 7R, 8S)-periconone A and (-)-1R, 4R, 6S, 7S)-2-caren-4, 8-olide, new terpenoids isolated from an endophytic fungus Periconia sp. of plant Annona muricata. The in vitro assays of these two compounds showed low cytotoxic activities against six human tumor cell lines (A549, A2780, Bel-7402, BGC-823, HCT-8 and MCF-7) [122].

Xanthones

Phomoxanthones A and B were isolated from an endophytic fungus Phomopsis sp. BCC 1323 of Tectona grandis. Phomoxanthones A showed cytotoxic activity against KB cells, BC-1 cells and non-malignant Vero cells with IC50 values of 0.99, 0.51 and 1.4 mg/ml, respectively, while Phomoxanthones B had IC50 values of 4.1, 0.70 and 1.8 mg/ml, compared to the standard compound ellipticine, which had IC50 values of 0.46 mg/ml of KB cells and 0.60 mg/ml of BC-1 cells respectively [123].

CONCLUSION

This review highlights the role of natural products in drug discovery, endophytic fungi–their occurrence and importance as an alternative source of secondary metabolites with potential antiCA activity. Escalating cancer patient death rate, poor availability to chemotherapy and their side effects, high cost and multi-drug-resistance worsen the scenario of CA treatment. Fungal endophyte, which resides in specialized niche are constantly in a state of ‘metabolic aggressiveness’, thereby synthesizing an inimitable array of metabolites, exhibiting a plethora of antiCA efforts with different chemical classes.

In the near future, the search for isolation and identification of new endophytic fungi producing antiCA agents, their cultivation and improvement in fermentation conditions and study on molecular insight will endow us with a greater opportunity in combating the battle against CA. There are good prospects for understanding molecular mechanisms into drug discovery and clinical efficacy by the continued study of endophytes, which will pave the path for effective prevention and treatment of CA.

ACKNOWLEDGEMENT

The authors are thankful to Ms. Megha Vijayawargiaya, Director HR, and Dr. Vijay Thawani Director CSRD for providing laboratory facilities and Sarvajanik Jankalyan Parmarthik Nyas, People’s Group for granting financial assistance to carry out the present research work.

CONFLICT OF INTERESTS

The authors declare no conflict of interest

REFERENCES

  1. Nalawade SM, Sagare AP, Lee CY, Kao CL, Tsay HS. Studies on tissue culture of Chinese medicinal plant resources in Taiwan and their sustainable utilization. Bot Bull Acad Sin 2003;44:79-98.
  2. Newman DJ, Cragg GM. Natural products as sources of new drugs over the last 25 y. J Nat Prod 2007;70:461-77.
  3. Bacon CW, White JFJ. Physiological adaptations in the evolution of endophytism in the Clavicipitaceae. In: Bacon CW, White JFJ. eds. Microbial endophytes. New York, NY, USA: Marcel Dekker Inc.; 2002. p. 237–63.
  4. Hawksworth DL. The magnitude of fungal diversity: the 1.5 million species estimate revisited. Mycol Res 2001;105:1422-31.
  5. Fisher PJ, Graf F, Petrini LE, Sutton BC, Wookey PA. Fungal endophytes of Dryas octopetala from a high arctic polar semidesert and from the Swiss Alps. Mycologia 1995;87:319–23.
  6. Rosa LH, Vaz ABM, Caligiorne RB, Campolina S, Rosa CA. Endophytic fungi associated with the antarctic grass Deschampsia antarctica Desv. (Poaceae). Polar Biol 2009;32:161–7.
  7. Redman RS, Sheehan KB, Stout RG, Rodriguez RJ, Henson JM. Thermotolerance generated by plant/fungal symbiosis. Science 2002;298:1581.
  8. Strobel GA. Rainforest endophytes and bioactive products. Crit Rev Biotechnol 2002;22:315-33.
  9. Bashyal BP, Wijeratne EMK, Faeth SH, Gunatilaka AAL. Globosumones A-C, cytotoxic orsellinic acid esters from the Sonoran desert endophytic fungus Chaetomium globosum. J Nat Prod 2005;68:724–8.
  10. Wang S, Li X, Teuscher MF, Li D, Diesel A, Ebel R, et al. Chaetopyranin, a benzaldehyde derivative, and other related metabolites from Chaetomium globosum, an endophytic fungus derived from the marine red alga Polysiphonia urceolata. J Nat Prod 2006;69:1622–5.
  11. Lin Z, Zhu T, Fang Y, Gu Q, Zhu W. Polyketides from Penicillium sp. JP-1, an endophytic fungus associated with the mangrove plant Aegiceras corniculatum. Phytochemistry 2008;69:1273–8.
  12. Suryanarayanan TS, Wittlinger SK, Stanley HF. Endophytic fungi associated with cacti in Arizona. Mycol Res 2005;109:635–9.
  13. Kralj A, Kehraus S, Krick A, Eguereva E, Kelter G, Maurer M, et al. Arugosins G and H: prenylated polyketides from the marine-derived fungus Emericella nidulans var. acristata. J Nat Prod 2006;69:995–1000.
  14. Silvia P, Roberto L, Duckett JG, Davis EC. A novel ascomycetous endophytic association in the rhizoides of the leafy liverwort family, schistochilaceae. Am J Bot 2008;95:531–41.
  15. Swatzell LJ, Powell MJ, Kiss JZ. The relationship of endophytic fungi to the gametophyte of the fern Schizaea pusilla. Int J Plant Sci 1996;157:53–62.
  16. Hoffman MT, Arnold AE. Geographic locality and host identity shape fungal endophyte communities in cupressaceous trees. Mycol Res 2008;112:331–44.
  17. Gond SK, Verma VC, Kumar A, Kumar V, Kharwar RN. Study of endophytic fungal community from different parts of Aegle marmelos Correa (Rutaceae) form Varanasi (India). World J Microbiol Biotechnol 2007;23:1371–5.
  18. Kharwar RN, Verma VC, Strobel G, Ezra D. Endophytic fungal complexes of Catharanthus roseus (L.) G. Don. Curr Sci 2008;95:228–33.
  19. Keller NP, Turner G, Bennett JW. Fungal secondary metabolism-from biochemistry to genomics. Nat Rev Microbiol 2005;3:937–47.
  20. Tan R, Zou W. Endophytes: a rich source of functional metabolites. Nat Prod Rep 2001;18:448-59.
  21. Rakshith D, Sreedharamurthy S. Endophytic fungi: ‘Trapped’ or ‘hidden’ store houses of bioactive compounds within plants: a review. J Pharm Res 2010;3:2986-9.
  22. Strobel G, Yang X, Sears J, Kramer R, Sidhu RS, Hess WM. Taxol from Pestalotiopsis microspora, an endophytic fungus of Taxus wallichiana. Microbiology 1996;142:435-40.
  23. Wang J, Li G, Lu H, Zheng Z, Huang Y, Su W. Taxol from Tubercularia sp. strain TF5, an endophytic fungus of Taxus mairei. FEMS Microbiol Lett 2000;193:249-53.
  24. Li JY, Strobel GA, Sidhu R, Hess WM, Ford E. Endophytic taxol producing fungi from bald cypress Taxodium distichum. Microbiology 1996;142:2223-6.
  25. Strobel GA, Hess WM, Li JY, Ford E, Sears J, Sidhu RS, et al. Pestalotiopsis guepinii, a taxol producing endophyte of the Wollemi Pine, Wollemia nobilis. Aust J Bot 1997;45:1073-82.
  26. Gangadevi V, Muthumary J. Taxol production by Pestalotiopsis terminaliae, an endophytic fungus of Terminalia arjuna (arjun tree). Biotechnol Appl Biochem 2009;52:9–15.
  27. Zou Z, Zou L, Wang W, Shan T, Zhong L, Liu X, et al. Endophytic fungi for producing bioactive compounds originally from their host plants. Curr Res Technol 2010;2:567-76.
  28. Elavarasi A, Sathiya Rathna G, Kalaiselvam M. Taxol producing mangrove endophytic fungi Fusarium oxysporum from Rhizophora annamalayana. Asian Pac J Trop Biomed 2012;2:S1081-S1085.
  29. Garyali S, Kumar A, Reddy MS. Taxol production by an endophytic fungus, Fusarium redolens, isolated from Himalayan yew. J Microbiol Biotechnol 2013;23:1372-80.
  30. Michalczyk A, Cieniecka-Rosłonkiewicz A, Cholewińska M. Plant endophytic fungi as a source of paclitaxel. Herba Pol 2015;60:22-33.
  31. Yang X, Guo S, Zhang L, Shao H. Selection of producing podophyllotoxin endophytic fungi from podophyllin plant. Nat Prod Res Dev 2013;15:419-22.
  32. Zeng S, Shao H, Zhang L. An endophytic fungus producing a substance analogous to podophyllotoxin isolated from Diphylleia sinensis. J Microbiol 2004;24:1-2.
  33. Guo S, Jiang B, Su Y, Liu S, Zhang L. Podophyllotoxin and its analogues from the endophytic fungi drrivativd from Dysosma Veitchii. Biotechnology 2004;14:55-7.
  34. Lu L, He J, Yu X, Li G, Zhang X. Studies on isolation and identification of endophytic fungi strain SC13 from pharmaceutical plant Sabina vulgaris. Ant. and metabolites. Acta Agric Boreali-Occident Sin 2006;15:85-9.
  35. Eyberger A, Dondapati R, Porter J. Endophyte fungal isolates from Podophyllum peltatum produce podophyllotoxin. J Nat Prod 2006;69:1121-4.
  36. Puri S, Nazir A, Chawla R, Arora R, Riyaz–ul-Hasan S, Amna T, et al. The endophytic fungus Trametes hirsuta as a novel alternative source of podophyllotoxin and related aryl tetralin ligans. J Biotechnol 2006;122:494-510.
  37. Cao L, Huang J, Li J. Fermentation conditions of Sinopodophyllum hexandrum endophytic fungus on production of podophyllotoxin. Food Ferment Ind 2007;33:28-32.
  38. Kour A, Shawl A, Rehman S, Sultan P, Qazi P, Suden P, et al. Isolation and identification of an endophytic strain of Fusarium oxysporum producing podophyllotoxin from Juniperus recurva. World J Microbiol Biotechnol 2008;24:1115-21.
  39. Nadeem M, Ram M, Alam P, Ahmad MM, Mohammad A, Al-Qurainy F, et al. Fusarium solani, P1, a new endophytic podophyllotoxin-producing fungus from roots of Podophyllum hexandrum. Afr J Microbiol Res 2012;6:2493-9.
  40. Huang JX, Zhang XR, Zhang K, Zhang X, He XR. Mucor fragilis as a novel source of the key pharmaceutical agents podophyllotoxin and kaempferol. Pharm Biol 2014;52:1237-43.
  41. Wall M, Wani M, Cook C, Palmer K, McPhail A, Sim G. The isolation and structure of camptothecin, a novel alkaloidal leukemia and tumor inhibitor from Camptotheca acuminata. J Am Chem Soc 1996;88:3888-90.
  42. Hsiang YH, Hertzberg R, Hecht S, Liu LF. Camptothecin induces protein-linked DNA breaks via mammalian DNA topoisomerase I. J Biol Chem 1985;260:14873–8.
  43. Puri S, Verma V, Amna T, Qazi G, Spiteller M. An endophytic fungus from Nothapodytes foetida that produces camptothecin. J Nat Prod 2005;68:1717-9.
  44. Kusari S, Zuhlke S, Spiteller M. An endophytic fungus from Camptotheca acuminata that produces camptothecin and analogues. J Nat Prod 2009;72:2-7.
  45. Singh S, Gurumurthy BR, Ravikanth G, Ramanan US, Shivanna MB. Endophytic fungi from Miquelia dentata Bedd., produce the anti-cancer alkaloid, camptothecine. Phytomedicine 2013;20:337-42.
  46. Pu X, Qu X, Chen F, Bao J, Zhang G, Luo Y. Camptothecin-producing endophytic fungus Trichoderma atroviride LY357:Isolation, identification, and fermentation conditions optimization for camptothecin production. Appl Microbiol Biotechnol 2013;97:9365–75.
  47. Perez J, Pardo J, Gomez C. Vincristine: an effective treatment of corticoid-resistant life-threatening infantile hemangiomas. Acta Oncol 2002;41:197-9.
  48. Wang Q, Yuan F, Pan Q, Li M, Wang G, Zhao J, et al. Isolation and functional analysis of the Catharanthus roseus deacetylvindoline-4-O-acetyltransferase gene promoter. Plant Cell Report 2010;29:185-92.
  49. Moore A, Pinkerton R. Vincristine: can its therapeutic index be enhanced? Pediatric Blood Cancer 2009;53:1180-7.
  50. Guo B, Li H, Zhang L. Isolation of the fungus producing vinblastine. J Yunnan University Nat Sci Edition 1998;20:214-5.
  51. Zhang L, Guo B, Li H, Zeng S, Shao H, Gu S, Wei R. Preliminary study on the isolation of endophytic fungus of Catharanthus roseus and its fermentation to produce products of therapeutic value. Chin Tradit Herb Drugs 2000;31:805-7.
  52. Yang X, Zhang L, Guo B, Guo S. Preliminary study of a vincristine-producing endophytic fungus isolated from leaves of Catharanthus roseus. Chin Tradit Herb Drugs 2004;35:79-81.
  53. Kumar A, Patil D, Rajamohanan PR, Ahmad A. Isolation, purification and characterization of from endophytic fungus Fusarium oxysporum isolated from Catharanthus roseus. PLoS One 2013;8:e71805. Doi.org/10.1371/journal.pone.0071805. [Article in Press]
  54. Kharwar RN, Mishra A, Gond S, Stierle A, Stierle D. Anticancer compounds derived from fungal endophytes: their importance and future challenges. Nat Prod Rep 2011;28:1208–28.
  55. Chen L, Zhang Q, Jia M, Ming QL, Yue W, Rahman K, et al. Endophytic fungi with antitumor activities: their occurrence and anticancer compounds. Crit Rev Microbiol 2016;42:454-73.
  56. Haidle AM, Myers AG. An enantioselective, modular, and general route to the cytochalasins: synthesis of L-696,474 and cytochalasin B. Proc Natl Acad Sci USA 2004;101:12048–53.
  57. Wagenaar MM, Corwin J, Strobel G, Clardy J. Three new cytochalasins produced by an endophytic fungus in the genus Rhinocladiella. J Nat Prod 2000;63:1692–5.
  58. Jiao RH, Xu S, Lin JY, Ge HM, Ding H, Xu C, et al. Chaetominine, a cytotoxic alkaloid produced by endophytic Chaetomonium sp. IFB-E015. Org Lett 2006;8:5709–12.
  59. Ge HM, Yu ZG, Zhang J, Wu JH, Tan RX. Bioactive alkaloids from endophytic Aspergillus fumigatus. J Nat Prod 2009;72:753–5.
  60. Cui CM, Li XM, Li CS, Proksch P, Wang BG. Cytoglobosins A-G, cytochalasans from a marine-derived endophytic fungus, Chaetomium globosum QEN-14. J Nat Prod 2010;73:729-33.
  61. El-Neketi M, Ebrahim W, Lin W, Gedara S, Badria F, Saad HE, et al. Alkaloids and polyketides from Penicillium citrinum, an endophyte isolated from the Moroccan plant Ceratonia siliqua. J Nat Prod 2013;76:1099–104.
  62. Ding G, Wang H, Li L, Chen AJ, Chen L, Chen H, et al. Trichoderones A and B: Two pentacyclic cytochalasans from the plant endophytic fungus Trichoderma gamsii. Eur J Org Chem 2012;2012:2516-9.
  63. Ding G, Song YC, Chen JR, Xu C, Ge HM, Wang XT, et al. Chaetoglobosin U, a cytochalasan alkaloid from endophytic Chaetomium globosum IFB-E019. J Nat Prod 2006;69:302-4.
  64. Wang Y, Xu L, Ren W, Zhao D, Zhu Y, Wu X. Bioactive metabolites from Chaetomium globosum L18, an endophytic fungus in the medicinal plant Curcuma wenyujin. Phytomedicine 2012;19:364–8.
  65. Gu W, Ge HM, Song YC, Ding H, Zhu HL, Zhao XA, et al. Cytotoxic benzo[j] fluoranthene metabolites from Hypoxylon truncatum IFB-18, an endophyte of Artemisia annua. J Nat Prod 2007;70:114–7.
  66. Xu J, Kjer J, Sendker J, Wray V, Guan H, Edrada RA, et al. Chromones from the endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove plant Rhizophora mucronata. J Nat Prod 2009;72:662–5.
  67. Ling L, Liu S, Niu S, Guo L, Chen X, Che Y. Isoprenylated chromone derivatives from the plant endophytic fungus Pestalotiopsis fici. J Nat Prod 2009;72:1482–6.
  68. Huang Z, Yang J, Cai X, She Z, Lin Y. A new furanocoumarin from the mangrove endophytic fungus Penicillium sp. (ZH16). Nat Prod Res 2012;26:1291–5.
  69. Luo J, Liu X, Li E, Guo L, Che Y. Arundinols A–C and arundinones A and B from the plant endophytic fungus Microsphaeropsis arundinis. J Nat Prod 2013;76:107–12.
  70. Klemke C, Kehraus S, Wright AD, Konig GM. New secondary metabolites from the marine endophytic fungus Apiospora montagnei. J Nat Prod 2004;67:1058–63.
  71. Pittayakhajonwut P, Dramae A, Madla S, Lartpornmatulee N, Boonyuen N, Tanticharoen M. Depsidones from the endophytic fungus BCC 8616. J Nat Prod 2006;69:1361–3.
  72. Wagenaar MM, Clardy J. Dicerandrols, new antibiotic and cytotoxic dimers produced by the fungus Phomopsis longicolla isolated from an endangered mint. J Nat Prod 2001;64:1006–9.
  73. Deshmukh SK, Mishra PD, Kulkarni-Almeida A, Verekar S, Sahoo MR, Periyasamy G, et al. Anti-inflammatory and anticancer activity of ergoflavin isolated from an endophytic fungus. Chem Biodiversity 2009;6:784–9.
  74. Steyn PS. The isolation, structure and absolute configuration of secalonic acid D, the toxic metabolite of Penicillium oxalicum. Tetrahedron 1970;26:51-7.
  75. Zhang JY, Tao LY, Liang YJ, Yan YY, Dai CL, Xia XK, et al. Secalonic acid D induced leukemia cell apoptosis and cell cycle arrest of G with involvement of GSK-3beta/beta-catenin/c-Myc pathway. Cell Cycle 2009;8:2444–50.
  76. Wang J, Huang Y, Fang M, Zhang Y, Zheng Z, Zhao Y, et al. Brefeldin A, a cytotoxin produced by Paecilomyces sp. and Aspergillus clavatus isolated from Taxus mairei and Torreya grandis. FEMS Immunol Med Microbiol 2012;34:51–7.
  77. Chinworrungsee M, Wiyakrutta S, Sriubolmas N, Chuailua P, Suksamrarn A. Cytotoxic activities of trichothecenes isolated from an endophytic fungus belonging to order hypocreales. Arch Pharmacal Res 2008;31:611–6.
  78. Isaka M, Palasarn S, Lapanun S, Chanthaket R, Boonyuen N, Lumyong S. Gamma-lactones and ent-eudesmane sesquiterpenes from the endophytic fungus Eutypella sp. BCC 13199. J Nat Prod 2009;72:1720–2.
  79. Lu S, Sun P, Li T, Kurtan T, Mandi A, Antus S, et al. Bioactive nonanolide derivatives isolated from the endophytic fungus Cytospora sp. J Org Chem 2011;76:9699–710.
  80. Yuan G, Hong K, Lin H, She Z, Li J. New azalomycin F analogs from mangrove Streptomyces sp. 211726 with activity against microbes and cancer cells. Mar Drugs 2013;11:817–9.
  81. Arai T, Mikami Y, Fukushima K, Utsumi T, Yazawa K. A new antibiotic, leucinostatin, derived from Penicillium lilacinum. J Antibiot Tokyo 1973;26:157–61.
  82. Kawada M, Inoue H, Ohba S, Masuda T, Ikeda D. Leucinostatin A inhibits prostate cancer growth through reduction of insulin-like growth factor-I expression in prostate stromal cells. Int J Cancer 2010;126:810-8.
  83. Strobel GA, Hess WM. Glucosylation of the peptide leucinostatin A, produced by an endophytic fungus of European yew, may protect the host from leucinostatin toxicity. Chem Biol 1997;4:529–36.
  84. Ebrahim W, Kjer J, El Amrani M, Wray V, Lin W, Ebel R, et al. Pullularins E and F, two new peptides from the endophytic fungus Bionectria ochroleuca isolated from the mangrove plant Sonneratia caseolaris. Mar Drugs 2012;10:1081–91.
  85. Deng CM, Liu SX, Huang CH, Pang JY, Lin YC. Secondary metabolites of a mangrove endophytic fungus Aspergillus terreus (No. GX7-3B) from the South China Sea. Mar Drugs 2013;11:2616-24.
  86. Zhan J, Burns AM, Liu MX, Faeth SH, Gunatilaka AAL. Search for cell motility and angiogenesis inhibitors with potential anticancer activity: beauvericin and other constituents of two endophytic strains of Fusarium oxysporum. J Nat Prod 2007;70:227–32.
  87. Tao YW, Lin TC, She ZG, Lin MT, Chen PX, Zhang JY. Anticancer activity and mechanism investigation of beauvericin isolated from secondary metabolites of the mangrove endophytic fungi. Adv Anticancer Agents Med Chem 2015;15:258-66.
  88. Li H, Huang H, Shao C, Huang H, Jiang J, Zhu X, et al. Cytotoxic norsesquiterpene peroxides from the endophytic fungus Talaromyces flavus isolated from the mangrove plant Sonneratia apetala. J Nat Prod 2011;74:1230–5.
  89. Stierle AA, Stierle DB, Bugni T. Sequoiatones A and B: novel antitumor metabolites isolated from a Redwood endophyte. J Org Chem 1999;64:5479–84.
  90. Stierle DB, Stierle AA, Bugni T. Sequoiamonascins a-d: novel anticancer metabolites isolated from a redwood endophyte. J Org Chem 2003;68:4966–9.
  91. Huang Z, Guo Z, Yang R, Yin X, Li X, Luo W, et al. Chemistry and cytotoxic activities of polyketides produced by the mangrove endophytic fungus Phomopsis spp. ZSU-H76. Chem Nat Compd 2009;45:625–8.
  92. Taridaporn B, Seangaroon Y, Prasert S, Kitlada S, Saisamorn L. Oblongolides from the endophytic fungus Phomopsis sp. BCC 9789. J Nat Prod 2010;73:55–9.
  93. Kimura T, Nishida M, Kuramochi K, Sugawara F, Yoshidab H, Mizushinab Y. Novel azaphilones, kasanosins A and B, which are specific inhibitors of eukaryotic DNA polymerases beta and lambda from Talaromyces sp. Bioorg Med Chem 2008;16:4594–9.
  94. Nahrstedt A, Butterwick V. Biologically active and other chemical constituents of the herb Hypericum perforatum L. Pharmacopsychiatry 1997;30 Suppl 2:129–34.
  95. Kubin A, Wierrani F, Burner U, Alth G, Grunberger W. Hypericin--the facts about a controversial agent. Curr Pharm Des 2005;11:233–53.
  96. Kusari S, Zuhlke S, Kosuth J, Cellarova E, Spiteller M. Light-independent metabolomics of endophytic Thielavia subthermophila provides insight into microbial hypericin biosynthesis. J Nat Prod 2009b;72:1825-35.
  97. Song YC, Li H, Ye YH, Shan CY, Yang YM, Tan RX. Endophytic naphthopyrone metabolites are co-inhibitors of xanthine oxidase, SW1116 cell and some microbial growths. FEMS Microbiol Lett 2004;241:67–72.
  98. Wang FW, Ye YH, Ding H, Chen YX, Tan RX, Song YC. Benzophenones from Guignardia sp. IFB-E028, an Endophyte on Hopea hainanensis. Chem Biodiversity 2010;7:216–20.
  99. Gao SS, Li XM, Li CS, Proksch P, Wang BG. Penicisteroids A and B, antifungal and cytotoxic polyoxygenated steroids from the marine alga-derived endophytic fungus Penicillium chrysogenum QEN-24S. Bioorg Med Chem Lett 2011;21:2894–7.
  100. Giridharan P, Verekar SA, Khanna A, Mishra PD, Deshmukh SK. Anticancer activity of sclerotiorin, isolated from an endophytic fungus Cephalotheca faveolata Yaguchi, Nishim. and Udagawa. Indian J Exp Biol 2012;50:464-8.
  101. Santiago C, Sun L, Munro MH, Santhanam J. Polyketide and benzopyran compounds of an endophytic fungus isolated from Cinnamomum mollissimum: biological activity and structure. Asian Pac J Trop Biomed 2014;4:627-32.
  102. Wu ZC, Li DL, Chen YC, Zhang WM. A new Isofuranonaphthalenone and benzopyrans from the endophytic fungus Nodulisporium sp. A4 from Aquilaria sinensis. Helv Chim Acta 2010;93:920–4.
  103. Liu D, Li XM, Meng L, Li CS, Gao SS, Shang Z, et al. Nigerapyrones A–H, a-pyrone derivatives from the marine mangrove-derived endophytic fungus Aspergillus niger MA-132. J Nat Prod 2011;74:1787–91.
  104. Huang HB, Xiao ZE, Feng XJ, Huang CH, Zhu X, Ju JH, et al. Cytotoxic naphtho-g-pyrones from the mangrove endophytic fungus Aspergillus tubingensis (GX1-5E). Helv Chim Acta 2011;94:1732–40.
  105. Lee JC, Strobel GA, Lobkovsky E, Clardy JC. Torreyanic acid: a selectively cytotoxic quinone dimer from the endophytic fungus Pestalotiopsis microspora. J Org Chem 1996;61:3232-3.
  106. Debbab A, Aly AH, Edrada-Ebel RA, Wray V, Muller WEG, Totzke F, et al. Bioactive metabolites from the endophytic fungus Stemphylium globuliferum isolated from Mentha pulegium. J Nat Prod 2009;72:626–31.
  107. Debbab A, Aly AH, Edrada-Ebel RA, Müller WE, Mosaddak M, Hakiki A, et al. Bioactive secondary metabolites from the endophytic fungus Chaetomium sp. isolated from Salvia officinalis growing in Morocco. Biotechnol Agron Soc Environ 2009;13:229–34.
  108. Tansuwan S, Pornpakakul S, Roengsumran S, Petsom A, Muangsin N, Sihanonta P, et al. Antimalarial benzoquinones from an endophytic fungus, Xylaria sp. J Nat Prod 2007;70:1620–3.
  109. Huang CH, Pan JH, Chen B, Yu M, Huang HB, Zhu X, et al. Three bianthraquinone derivatives from the mangrove endophytic fungus Alternaria sp. ZJ9-6B from the South China Sea. Mar Drugs 2011;9:832–43.
  110. Teiten MH, Mack F, Debbab A, Aly AH, Dicato M, Proksch P, et al. Anticancer effect of altersolanol A, a metabolite produced by the endophytic fungus Stemphylium globuliferum, mediated by its pro-apoptotic and antiinvasive potential via the inhibition of NF-kB activity. Bioorgan Med Chem 2013;21:3850–8.
  111. Liu D, Li XM, Li CS, Wang BG. Nigerasterols A and B, antiproliferative sterols from the mangrove-derived endophytic fungus Aspergillus niger MA-132. Helv Chim Acta 2013;96:1055–61.
  112. Deng CM, Liu SX, Huang CH, Pang JY, Lin YC. Secondary metabolites of a mangrove endophytic fungus Aspergillus terreus (No. GX7-3B) from the South China Sea. Mar Drugs 2013;11:2616–24.
  113. Wang J, Cox D, Ding W, Huang G, Lin Y, Li C. Three new resveratrol derivatives from the mangrove endophytic fungus Alternaria sp. Mar Drugs 2014;12:2840–50.
  114. Teles HL, Sordi R, Silva GH, Castro-Gamboa I, da Silva BV, Pfenning, LH, et al. Aromatic compounds produced by Periconia atropurpurea, an endophytic fungus associated with Xylopia aromatica. Phytochemistry 2006;67:2686–90.
  115. Shiono Y, Kikuchi M, Koseki T, Murayama T, Ewon E, Aburan N, et al. Isopimarane diterpene gycosides, isolated from endophytic fungus Paraconiothyrium sp. MY-42. Phytochemistry 2011;72:1400–5.
  116. Wang QX, Li SF, Zhao F, Dai HQ, Bao L, Ding R, et al. Chemical constituents from endophytic fungus Fusarium oxysporum. Fitoterapia 2011;82:777–81.
  117. Wang XN, Bashyal BP, Wijeratne EK, U’Ren JM, Liu MX, Guantilaka MK, et al. Smardaesidins A–G, Isopimarane and 20-nor-isopimarane diterpenoids from Smardaea sp., a fungal endophyte of the moss Ceratodon purpureus. J Nat Prod 2011;74:2052–61.
  118. Chokpaiboon S, Sommit D, Teerawatananond T, Muangsin N, Bunyapaiboonsri T, Pudhom K. Cytotoxic nor-chamigrane and chamigrane endoperoxides from a basidiomycetous fungus. J Nat Prod 2010;73:1005–7.
  119. Isaka M, Chinthanom P, Boonruangprapa T, Rungjindamai N, Pinruan U. Eremophilane-type sesquiterpenes from the fungus Xylaria sp. BCC 21097. J Nat Prod 2010;73:683–7.
  120. Ying YM, Shan WG, Zhang LW, Zhan ZJ. Ceriponols A–K, tremulane sesquitepenes from Ceriporia lacerate HS-ZJUTC13A, a fungal endophyte of Huperzia serrata. Phytochemistry 2013;95:360–7.
  121. Lin T, Lin X, Lu CH, Shen YM. Three new triterpenes from Xylarialean sp. A45, an endophytic fungus from Annona squamosa L. Helv Chim Acta 2011;94:301–5.
  122. Ge HL, Zhang DW, Li L, Xie D, Zou JH, Si YK, et al. Two new terpenoids from endophytic fungus Periconia sp. F-31. Chem Pharm Bull 2011;59:1541–4.
  123. Isaka M, Jaturapat A, Rukseree K, Danwisetkanjana K, Tanticharoen M, Thebtaranonth Y. Phomoxanthone A and B, novel xanthone dimmers from the endophytic fungus Phomopsis species. J Nat Prod 2001;64:1015-8.