Antioxidant properties and in vitro alpha-amylase and alpha-glucosidase inhibitory properties of phenolics constituents from different varieties of corchorus spp.

This study investigated the phenolic constituents, antioxidant properties and effect of aqueous extracts from some Corchorus species [C. aestuans, C. bougoudo, C. capsularis, C. olitorius and C. urtifolicus] on alpha-amylase and alpha-glucosidase activities in vitro. Gas Chromatography with Flame Ionization Detector [GC-FID] was used to characterize the phenolic constituents. Aqueous extracts were prepared weight/volume [w/v] and their effects on alpha-amylase and alpha-glucosidase activities, Fe[2+] induced lipid peroxidation, and 1,1-diphenyl[-2] picrylhydrazyl [DPPH] radical scavenging properties were determined. Fe[2+] chelating abilities and Ferric Reducing Antioxidant Power [FRAP] properties were also studied. The predominant phenolics detected by GCFID were kaempferol, rutin, apigenin, luteolin, caffeic acid and quercetin. The results showed that all the Corchorus species significantly [P < 0.05] inhibited alpha-amylase and alpha-glucosidase activities dose-dependently [0-8 micro g/ml]. C. olitorius had the highest alpha-amylase inhibitory ability while C. bougoudo demonstrated the maximum alpha-glucosidase inhibition. However, all the Corchorus species inhibited alpha-glucosidase better than alpha-amylase and also exhibited antioxidant properties. The enzyme inhibitory and antioxidant properties exhibited by the Corchorus species could be attributed to their phenolic constituents and vitamin C content; a possible mechanism by which Corchorus species could elicit therapeutic effects on type 2 diabetes mellitus as obtained in folklore medicine

Inhibitory effect of polyphenolic-rich extract from Cola nitida (Kolanut) seed on key enzyme linked to type 2 diabetes and Fe(2+) induced lipid peroxidation in rat pancreas in vitro

<p><b>OBJECTIVE</b>To investigate the inhibitory effect of phenolic-rich extracts from Cola nitida (C. nitida) seeds on key enzymes linked with type-2 diabetes and Fe(2+) induced oxidative stress in rat pancreas.</p><p><b>METHODS</b>The phenolic extract was prepared with 80% acetone (v/v). Subsequently, the antioxidant properties and inhibitory effect of the extract on α - amylase and α - glucosidase as well as on Fe(2+) induced lipid peroxidation in rat pancreas were determined in vitro.</p><p><b>RESULTS</b>The result revealed that C. nitida extract inhibited α-amylase (EC50=0.34 mg/mL) and α-glucosidase (EC50=0.32 mg/mL) activities as well as Fe(2+) induced lipid peroxidation in rat pancreas in a dose dependent manner. In addition, the extract had high DPPH radical scavenging ability (EC50=2.2 mg/mL) and reducing power (8.2 mg AAE/g). Characterization of the main phenolic compounds of the extract using gas chromatography analysis revealed catechin (6.6 mg/100 g), epicatechin (3.6 mg/100 g), apigenin (5.1 mg/100 g) and naringenin (3.6 mg/100 g) were the main compounds in the extract.</p><p><b>CONCLUSIONS</b>This antioxidant and enzyme inhibition could be some of the possible mechanism by which C. nitida is use in folklore for the management/treatment of type-2 diabetes. However, the enzyme inhibitory properties of the extract could be attributed to the presence of catechin, epicatechin, apigenin and naringenin.</p>

Attenuation of oxidative stress and hepatic damage by some fermented tropical legume condiment diets in streptozotocin-induced diabetes in rats

OBJECTIVE@#To investigate the modulatory effect of fermented legume condiments diet on oxidative stress in streptozotocin (STZ) induced diabetic rats.@*METHODS@#Adult male Wistar rats were randomly divided into six groups with six animals in each group. Diabetes was induced by intraperitoneal injection of STZ (35 mg/kg b.w.). After being confirmed diabetic, the rats were fed with fermented Bambara groundnut, Locust bean and Soybean diets for 14 days. The plasma was obtained after 14-day treatment and analyzed for hepatic damage marker enzymes (AST, ALT and ALP) and in vivo antioxidant indices.@*RESULTS@#The diabetic untreated rats showed elevated (P<0.05) levels of AST, ALT, ALP and malondialdehyde with reduced activities of glutathione-S-transferase, catalase as well as plasma reduced glutathione, vitamin C and total protein content. However, treatment of diabetic rats with fermented legume condiments diets for 14 days significantly (P<0.05) reversed the above parameters towards normalcy, suggesting their modulation of oxidative stress, which may be due to their high phenolic content and antioxidant capacity.@*CONCLUSIONS@#The attenuation of oxidative stress and protection of hepatic tissue damage by the legume condiment diets in STZ induced diabetic rats compare favourably with that of metformin, a well known oral hypoglycemic drug.