Colletotridemin A and Three New Botrydial Sesquiterpenoids From Fungus Colletotrichum dematium

One new bicyclic sesterterpene, colletotridemin A (1), and three new botrydial sesquiterpenoids (3-5), along with 11 identified compounds (2, 6-15) separated from the plant-associated fungus Colletotrichum dematium. Electronic circular dichroism (ECD) and spectroscopic analyses (NMR and HR-ESI-MS) were conducted to characterize the structures and their absolute configurations. All compounds were assessed for their α-glucosides and cytotoxic activities. Notably, compound 1 exhibited remarkable inhibitory effects on α-glucosidase, and the IC₅₀ value was 16.8 µM, which was 118-fold greater than that of the positive control acarbose. The mechanisms underlying α-glucosidase inhibition were investigated through enzyme reaction kinetics and molecular docking. In addition, compound 1 showed potent cytotoxic effects on RKO cells, with an IC₅₀ value of 33.03 ± 6.13 µM, which induced apoptosis in RKO cells.