The α-glucosidase inhibitory activity of avicularin and 4-O-methyl gallic acid isolated from Syzygium myrtifolium leaves

Abstract

Diabetes Mellitus is the main cause of death on a global scale. In 2019, there were 463 million people with diabetes, and WHO predicts that by 2030, there will be 578 million. As an antidiabetic agent, α-glucosidase inhibitors are one of the methods employed to reduce the prevalence of diabetes. Diabetes is traditionally treated with Syzygium as a primary material, medicine, fruit, ornamental plant, and source of carpentry. This investigation aimed to examine the inhibitory effect of seven species of Syzygium against α-glucosidase enzyme using an in vitro assay and isolate active substances and ascertain their concentrations in each sample. As a solvent, ethanol was used in maceration to extract the substance. Afterward, the extract underwent a series of fractionation techniques, including liquid–liquid extraction, vacuum liquid chromatography, column chromatography, and preparative Thin Layer Chromatography (TLC) for purification and isolation. The compound's structures were elucidated using TLC, UV–Visible spectrophotometry, and nuclear magnetic resonance (NMR) spectroscopy. Based on concentrations of 100 and 200 µg/mL, Syzygium myrtifolium exhibited the most significant inhibitory effect, followed by other species of Syzygium. The proportion of ethyl acetate had the strongest activity (IC50 0.40 ± 0.02 µg/mL) contrasted to positive control acarbose (IC50 55.39 ± 0.67 g/mL) and quercitrin (IC50 6.47 ± 0.40 µg/mL). Avicularin and 4-O-methyl gallic acid were discovered in the ethyl acetate fraction of Syzygium myrtifolium with IC50 values of 17.05 ± 0.75 µg/mL and 25.19 ± 0.21 µg/mL, respectively. As α-glucosidase inhibitory, the results of this study indicate Syzygium myrtifolium can be used as a dietary supplement to manage hyperglycemia.