Therapeutic Potential of Rare Sesterterpenoids from Aspergillus Variecolor Strain SDG and Docking Studies.

Ethyl acetate extract of the cultures of the soil-derived filamentous fungus, Aspergillus variecolor SDG strain from Nallamala forest resulted in the isolation of extremely rare sesterterpenoids, stellatic acid (1) and andilesin C (2). We report a thorough chemical characterization of these compounds using various spectroscopic techniques and evaluation of their in vitro preclinical therapeutic potential. Stellatic acid exhibits potent antioxidant activity with an IC of 38 μg/mL and significant anticancer activity against HeLa, HepG2, MCF7, and A549 cancer cell lines with an IC of 7-12 μM. On the other hand, andilesin C displayed moderate cytotoxicity against DU145 and B16F10 cancer cell lines but lacked antioxidant activity. Furthermore, the potential hypoglycemic property of stellatic acid was evaluated by measuring its inhibitory effect against α-glucosidase. It exhibited tenfold potency against yeast α-glucosidase (IC 101.73 μg/mL) than mammalian α-glucosidase (IC 1000.00 μg/mL). Docking studies were also performed to suggest the interaction mode of stellatic acid in the α-glucosidase enzyme active site. Notably, yeast α-glucosidase shows a higher affinity towards stellatic acid than mammalian α-glucosidase (3TOP). Thus, the in vitro preclinical study of stellatic acid suggests its potential efficacy in therapeutic drug development.