Enzyme inhibitory, antioxidant, antimicrobial activities, and phenolic profiles of the methanol extract of Gelasia sericea an endemic species

Abstract

This study aimed to investigate, for the first time, the phytochemical composition, antioxidant, antimicrobial, and enzyme inhibitory properties of the methanolic extract of Gelasia sericea (Aucher ex DC.) Zaika, Sukhor. & N.Kilian. The extract demonstrated a moderate yield (6.55 g/100 g dry plant material) and was found to be rich in phenolic acids, particularly ferulic acid (17182.97 mu g g-1), followed by caffeic acid, protocatechuic acid, and p-coumaric acid. Antioxidant analyses revealed high total phenolic (388.86 mg GA eq./100 g), total flavonoid (74.03 mg QE eq./100 g), and total antioxidant capacity (503.33 mg AA eq./100 g). The extract exhibited remarkable ABTS radical scavenging activity (95.99%, IC50 = 37.59 mg ml-1) and considerable ferric-ion reducing power (974.78 mg FeSO4 eq./100 g). Antimicrobial assays indicated moderate inhibitory effects, with stronger activity against Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis) and the yeast Candida albicans, whereas Gram-negative bacteria were less susceptible. The extract's MIC values ranged between 0.20-3.25 mg ml-1, and MLC values between 0.41-6.50 mg ml-1, which were higher than those of standard antibiotics. Enzyme inhibition assays revealed moderate activity against carbonic anhydrase II (IC50 = 0.0136 mu g ml-1) and weak inhibition of cholinesterases and alpha-glucosidase, while alpha-amylase inhibition was relatively more pronounced (IC50 = 13350.00 mu g ml-1). Overall, these findings highlight G. sericea as a valuable natural source of phenolic acids and antioxidants, with promising potential for applications in functional foods, nutraceuticals, and phytopharmaceuticals. However, the relatively limited antimicrobial and enzyme inhibitory activities suggest the need for further studies on bioavailability, in vivo efficacy, and compound isolation to optimize its practical applications.