In vitro and in vivo inhibitory effects of Carica papaya seed on α-amylase and α-glucosidase enzymes

The present study was aimed to investigate the in vitro and in vivo inhibitory effects of Carica papaya seeds on α-amylase and α-glucosidase enzymes, as this is known to be an antidiabetic mechanism. Analysis of the extracts of the seeds for phytochemicals revealed the presence of a significant amount of saponins, alkaloids, flavonoids, phenols, terpenoids, and steroids. The seed extracts of Carica papaya exhibited good antioxidant capacity using 2, 2-diphenyl-1-picryl hydroxyl (DPPH), thiobarbituric reactive substance (TBARS) and ferric reducing antioxidant power (FRAP) method. The results of the inhibitory studies of the extracts revealed that the hexane extract followed by the ethyl acetate extract was the most potent inhibitor of α-amylase and α-glucosidase enzyme when compared to other extracts using their IC₅₀ values. In the animal study, different doses (250, 500 and 1000 mg/kg/body weight) of the extracts of Carica papaya seed were administered orally for 120 min, to normal and streptozotocin-induced diabetic rats, and were compared with acarbose 100 mg/kg/body weight and control group for the effect on postprandial hyperglycemia. The extract of ethyl acetate (at doses of 250, 500 and 1000 mg/kg/body weight) significantly reduced postprandial glucose levels in these animals. The characterization of hexane and ethyl acetate extracts by GC-MS analysis revealed 20 bioactive compounds while the FTIR analysis confirmed the presence of this functional groups: -C=C, -C-Cl, -C-O, -O-H, -CH, -C=O, -C=C=C, -N=C=S, -O=C=O and -N-H in Carica papaya seed extracts. It was concluded that the inhibition of α-amylase and α-glucosidase enzymes and the prevention of oxidative stress in postprandial hyperglycemia could be some of the possible mechanisms by which they exert their anti-diabetic properties.