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 IC₅₀ of 38 μg/mL and significant anticancer activity against HeLa, HepG2, MCF7, and A549 cancer cell lines with an IC₅₀ 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 (IC₅₀ 101.73 μg/mL) than mammalian α-glucosidase (IC₅₀ 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.