Phytoconstituents of Terminalia catappa linn fruits extract exhibit promising antidiabetic activities against α-amylase and α-glucosidase in vitro and in silico

Abstract

Terminalia Catappa fruits are recognized for their use in diabetes treatment, yet the mechanism by which they inhibit diabetes-related enzymes remain largely undefined. This study aimed to elucidate the therapeutic potential and interactions of T. catappa fruit extract through in vitro and in silico approaches. The compounds from T. catappa fruit were extracted using microwave-assisted extraction techniques, followed by qualitative phytochemical screening and quantitative analysis via GC-MS. The physicochemical properties were evaluated according to the Lipinski rule and ADMET criteria. Antidiabetic analyses, both in vitro and in silico, were performed on the secondary metabolites found in T. catappa fruit, targeting α-amylase and α-glucosidase enzymes. The methanol and ethyl acetate extracts of T. catappa fruit contained alkaloids, flavonoids, saponins, steroids, and terpenoids. These extracts inhibited α-glucosidase and α-amylase in a dose-dependent manner, with the methanol extract of T. catappa showing significantly higher inhibitory activity than pure acarbose (by two- and five-fold, respectively) and the ethyl acetate extract. Furthermore, the antioxidant activity of the methanolic extract was seven times greater than that of the ethyl acetate extract. Molecular docking studies supported these findings, revealing that the ΔG values of gibberellic acid, rescinnamine, and digoxin were comparable to those of acarbose. Notably, digoxin has higher ΔG values against α-amylase than acarbose, while gibberellic acid, rescinnamine, and nerolidol showed ΔG values similar to acarbose. Gibberellic acid, unique to the methanol extract, demonstrated high ΔG values, suggesting its significant role in the extract's enhanced glucosidase and amylase inhibitory activities. This study identifies specific compounds (digitoxin, rescinnamine, gibberellic acid, and nerolidol) and proposes the potential of multi-target drugs in diabetes treatment. Understanding these phytochemical constituents and their effects on diabetes-involved enzymes could benefit individuals with type 2 diabetes, particularly those at higher risk of complications.