Kinetics of α-amylase and α-glucosidase Inhibitory Potential of Hermannia geniculata Eckl. & Zehl root Extracts Used in Basotho Traditional Medicine.

Abstract

The scientific investigation of the folkloric use of Hermannia geniculata roots in the management of diabetes mellitus was conducted. Phytochemical analyses, in vitro antioxidant and hyperglycaemic studies were carried out on the crude extracts of H. geniculata. Qualitative phytochemical analysis revealed the presence of saponins, phenols, flavonoids, alkaloids, tannins, phytosterols, triterpenes and anthraquinones. The ethanol extract exhibited the highest free radical scavenging capability with the lowest IC values (0.52, 0.38, 0.59, 0.63, 0.39) mg/mL for 50 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-Azino-bis(3-ethylbenzothiazoline-6-Sulphonic acid (ABTS), hydroxyl radical, superoxide anion radical and metal chelating ability which is significantly different (p<0.05) from the standard (silymarin). In antidiabetic studies, ethanol extract is a potent inhibitor of α-glucosidase (IC : 0.15 mg/mL) which is lower and significantly 50 different (p<0.05) from the standard (acarbose) IC value of (0.52 mg/mL). Ethanol extract 50 exhibited a milder inhibition of α-amylase enzyme with IC (0.57mg/mL) which is higher and 50 significantly different (p<0.05) from acarbose with IC (0.47 mg/mL). Kinetic studies revealed H. 50 geniculata ethanol extract exhibited competitive inhibition of α-amylase and uncompetitive inhibition of α-glucosidase enzymes. All these findings provided the scientific basis which support the use of the root extract of H. geniculata in the management of diabetes mellitus and oxidative stress induced ailments like colitis and ulcers by the Basotho traditional medicine of South Africa.