Endophytic fungi found in association with Smallanthus sonchifolius (Asteraceae) as resourceful producers of cytotoxic bioactive natural products

Abstract

Smallanthus sonchifolius is a traditional Andean plant which has been cultured mainly in Brazil, Japan and New Zealand due to its medicinal properties. A study of the endophytic fungi associated to the plant was carried out in order to characterize new cytotoxic agents. Thirty two fungal strains were isolated and submitted to cultivation and extraction producing 186 extracts. Of these, 12% displayed moderate to high cytotoxic activities and were considered promising anticancer compound sources. The ethyl acetate fractions of Nigrospora sphaerica and Phoma betae liquid fermentations contained the synergistic compounds 8-hydroxy-6-methoxy-3-methylisocoumarin and (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one which are potential compounds for drug discovery. Another isolated compound, pimara-7,15-dien-3-beta-ol diterpene is being characterized for the first time through a detailed spectroscopic analysis including GC/MS, homo- and hetero-nuclear correlated NMR experiments (HMQC, HMBC, COSY and NOEdiff) along with its optical rotation.

Bioactive extracts and chemical constituents of two endophytic strains of Fusarium oxysporum

“…On the other hand, F. oxysporum SS50 produced bioactive compounds of lower polarity only in solid medium, as observed for the high activities of SS50-HxS extract. In our previous investigation, F. oxysporum SS46 had already produced high cytotoxic ethyl acetate extracts; however no cytotoxic activity had been detected for F. oxysporum SS50 (Gallo et al, 2009). This result can be explained by the different extraction methods, because in that previous screening all the fungal solid cultures extracts were partitioned only with ethyl acetate.…”

“…The endophytic fungal strains were isolated from the roots of S. sonchifolius according to the procedure described by Gallo et al (2009). After collection, the plant material was washed with water and surface sterilized by immersion in 70% aqueous ethanol (2.5 min), followed by 2.5% aqueous sodium hypochlorite (30", 60" or 90"), and finally with 70% aqueous ethanol (1 min).…”

Fungal Endophytes: An Amazing and Hidden Source of Cytotoxic Compounds

“…Aphidicolin exhibited cytotoxicity against HCT-8, MDA-MB435, SF295, and HL-60 cell lines with IC 50 values of 0.05, 0.20, 0.16, and 0.09 μg/ml, respectively. Compound 60 exhibited cytotoxicity against HCT-8, MDA-MB435, SF295, and HL-60 cell lines with IC 50 values of 6.24, 14.11, 17.03, and 5.29 μg/ml, respectively (Gallo et al 2009). (22E, 24R)-8,14-epoxyergosta-4,22-diene-3,6-dione (61) was isolated from an endophytic fungus Papulaspora immerse, isolated from S. sonchifolius.…”

Direct MALDI-TOF/TOF analyses of unnatural beauvericins produced by the endophytic fungus Fusarium oxysporum SS46

“…The endophytic fungus Fusarium oxysporum SS46, isolated from the host plant Smallanthus sonchifolius (Gallo et al, 2009), is a producer of the cyclohexadepsipeptide beauvericin (Nascimento et al, 2012). Beauvericin has antibiotic, antifungal, insecticidal, antimycobacterial, antiplasmodial, and nematicidal properties, and also inhibits angiogenesis, cell migration, and cancer cell proliferation (Xu et al, 2007;Zhan et al, 2007;Zhang et al, 2007;Xu et al, 2009;Shimada et al, 2010).…”