Phytochemical screening, total phenolics, total flavonoids, total tannins, antioxidant activities, and α-glucosidase inhibition of ethanolic leaf extracts from 37 cultivars of Antidesma puncticulatum Miq.

Introduction: Antidesma puncticulatum Miq., commonly known as Mao-Luang in Thailand, is a medicinal plant widely renowned for its abundance of bioactive compounds with diverse pharmacological properties. This study investigated the phytochemical components, antioxidant potentials, and α-glucosidase inhibitory activity of ethanolic leaf extracts from 37 cultivars of A. puncticulatum. Methods: The leaves of 37 different varieties of A. puncticulatum were dried, finely ground, and then extracted using ethanol. The phytochemical screening, total amounts of phenolics, flavonoids, and tannins of the extracts were assessed. To evaluate their antioxidant potential, the extracts were subjected to the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and the ferric reducing antioxidant power (FRAP) Assays. In addition, standard in vitro methods were used to determine the α-glucosidase-inhibitory activity of the extracts. Results: Five phytochemical classes were detected in high concentrations in all of the extracts. Total phenolics, flavonoids, and tannins contents were in the range of 9.86-26.75 mg gallic acid equivalent (GAE)/g dry extract, 8.10-16.18 mg catechin equivalent (CE)/g dry extract, and 14.83-33.67 mg CE/g dry extract, respectively. According to DPPH, ABTS, and FRAP assay results, the antioxidant activities of the extracts were 5.10-9.07, 0.73-2.12, and 2.06- 4.01 mg ascorbic acid equivalent antioxidative capacity (AEAC)/g crude extract, respectively. Interestingly, the crude extracts from A. puncticulatum were more effective as α-glucosidase inhibitors than acarbose, with IC50 values ranging from 1.26 to 25.07 µg/mL. Conclusion: The ethanolic leaf extracts of A. puncticulatum were potent sources of phytochemicals with antioxidant and antidiabetic properties. Therefore, more research is needed to substantiate their potential applications as therapeutic remedies for diabetes.