To investigate and compare the inhibitory properties of free and bound phenolic extracts of clove bud against carbohydrate hydrolyzing enzymes (alpha-amylase & alpha-glucosidase) and Fe2+-induced lipid peroxidation in rat pancreas in vitro. Methods: The free phenolics were extracted with 80% (v/v) acetone, while bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. Then, the interaction of the extracts with alpha-amylase and alpha-glucosidase was subsequently assessed. Thereafter, the total phenolic contents and antioxidant activities of the extracts were determined. Results: The result revealed that both extracts inhibited alpha-amylase and alpha-glucosidase in a dose-dependent manner. However, the alpha-glucosidase inhibitory activity of the extracts were significantly (P<0.05) higher than their alpha-amylase inhibitory activity. The free phenolics (31.67 mg/g) and flavonoid (17.28 mg/g) contents were significantly (P<0.05) higher than bound phenolic (23.52 mg/g) and flavonoid (13.70 mg/g) contents. Both extracts also exhibited high antioxidant activities as typified by their high reducing power, 1,1 diphenyl-2- picrylhydrazyl (DPPH) and 2, 2-azinobis-3-ethylbenzo-thiazoline-6-sulfonate (ABTS) radical scavenging abilities, as well as inhibition of Fe2+-induced lipid peroxidation in rat pancreas in vitro. Conclusions: This study provides a biochemical rationale by which clove elicits therapeutic effect on type 2 diabetes.

OBJECTIVETo investigate and compare the inhibitory properties of free and bound phenolic extracts of clove bud against carbohydrate hydrolyzing enzymes (alpha-amylase & alpha-glucosidase) and Fe(2+)-induced lipid peroxidation in rat pancreas in vitro.

METHODSThe free phenolics were extracted with 80% (v/v) acetone, while bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. Then, the interaction of the extracts with alpha-amylase and alpha-glucosidase was subsequently assessed. Thereafter, the total phenolic contents and antioxidant activities of the extracts were determined.

RESULTSThe result revealed that both extracts inhibited alpha-amylase and alpha-glucosidase in a dose-dependent manner. However, the alpha-glucosidase inhibitory activity of the extracts were significantly (P<0.05) higher than their alpha-amylase inhibitory activity. The free phenolics (31.67 mg/g) and flavonoid (17.28 mg/g) contents were significantly (P<0.05) higher than bound phenolic (23.52 mg/g) and flavonoid (13.70 mg/g) contents. Both extracts also exhibited high antioxidant activities as typified by their high reducing power, 1,1 diphenyl-2- picrylhydrazyl (DPPH) and 2, 2-azinobis-3-ethylbenzo-thiazoline-6-sulfonate (ABTS) radical scavenging abilities, as well as inhibition of Fe(2+)-induced lipid peroxidation in rat pancreas in vitro.

CONCLUSIONSThis study provides a biochemical rationale by which clove elicits therapeutic effect on type 2 diabetes.

Animals ; Antioxidants ; chemistry ; Carbohydrate Metabolism ; drug effects ; Diabetes Mellitus, Type 2 ; metabolism ; Dose-Response Relationship, Drug ; Enzyme Inhibitors ; chemistry ; pharmacology ; Ferrous Compounds ; pharmacology ; Flavonoids ; chemistry ; Glycoside Hydrolase Inhibitors ; chemistry ; pharmacology ; Inhibitory Concentration 50 ; Lipid Peroxidation ; drug effects ; Pancreas ; drug effects ; metabolism ; Phenols ; chemistry ; Plant Extracts ; chemistry ; pharmacology ; Polyphenols ; chemistry ; pharmacology ; Rats ; Syzygium ; chemistry ; alpha-Amylases ; antagonists & inhibitors ; alpha-Glucosidases