title: Aqueous extracts of Roselle (Hibiscus sabdariffa Linn.) varieties inhibit α-amylase and α-glucosidase activities in vitro.
abstract: This study sought to investigate the inhibitory effect of aqueous extracts of two varieties (red and white) of Hibiscus sabdariffa (Roselle) calyces on carbohydrate hydrolyzing enzymes (α-amylase and α-glucosidase), with the aim of providing the possible mechanism for their antidiabetes properties. Aqueous extracts were prepared (1:100 w/v) and the supernatant used for the analysis. The extracts caused inhibition of α-amylase and α-glucosidase activities in vitro.The IC(50) revealed that the red variety (25.2 μg/mL) exhibited higher α-glucosidase inhibitory activity than the white variety (47.4 μg/mL), while the white variety (90.5 μg/mL) exhibited higher α-amylase inhibitory activity than the red variety (187.9 μg/mL). However, the α-glucosidase inhibitory activities of both calyces were higher than that of their α-amylase. In addition, the red variety possessed higher antioxidant capacity as exemplified by the (•)OH scavenging abilities, Fe(2+) chelating ability, and inhibition of Fe(2+)-induced pancreatic lipid peroxidation in vitro. The enzyme inhibitory activities and antioxidant properties of the roselle extracts agreed with their phenolic content. Hence, inhibition of α-amylase and α-glucosidase, coupled with strong antioxidant properties could be the possible underlying mechanism for the antidiabetes properties of H. sabdariffa calyces; however, the red variety appeared to be more potent.
authors.affiliation: Department of Biochemisry, Federal University of Technology, Akure, Nigeria. ademiluyidayo@yahoo.co.uk
authors.forename: Adedayo O
authors.initials: AO
authors.lastname: Ademiluyi
authors.forename: Ganiyu
authors.initials: G
authors.lastname: Oboh
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000737:chemistry* / Q000302:isolation & purification; D065089:Glycoside Hydrolase Inhibitors; D031584:Hibiscus / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry* / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D013552:Swine; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D010936:Plant Extracts; D000516:alpha-Amylases