Chemical Profile, Antioxidant and Alpha-Amylase Inhibitory Activity of Leaves Extracts of Annona muricata: A Combined In vitro and In silico Study

Abstract

Leaves of Annona muricata are commonly used for treating diabetes. This study was conducted to investigate the molecular mechanisms involved in the antidiabetic properties of leaves of Annona muricata. Leaves of Annona muricata were extracted separately with H2O, hydromethanol (50% methanol), methanol, ethylacetate, and n-butanol. Chemical characterization of the extracts was performed by spectrophotometry and Gas chromatography-Mass Spectrometry (GC-MS) techniques. Biological activity was determined by α-amylase inhibition assays and molecular docking. The hydromethanol extract had a total phenolics concentration of 117.00±0.59 µg GAE/mg extract whereas; flavonoids were most abundant in the n-butanol extract accounting for 29.34±8.87 µg QE/mg extract. The n-butanol extract had the best FRAP value of 41.17±0.57 Vit C eqv mM, which was significantly higher than the value of the vitamin C reference. Estimated IC50 for all the extracts did not differ significantly but was significantly higher than the reference compound quercetin. All extracts inhibited α-amylase in vitro albeit significantly lower than acarbose. The hydromethanol extract had the highest inhibitory activity (53.31 ± 0.33%). Furthermore, chemical profiling of the hydromethanol extract revealed the presence of a variety of bioactive compounds. In silico analysis by molecular docking of the compounds identified by GC-MS on α-amylase revealed that the compounds had robust molecular interactions orchestrated by H-bonding and hydrophobic interactions. From the results, it can be concluded that extracts of Annona muricata possess antioxidant phytochemicals that inhibit α-amylase. Therefore, the results justify the use of the plant for the treatment of diabetes.