A preliminary study of the mechanism of hypoglycaemic activity of Nauclea latifolia leaf ethanolic extract.

The aim of this study was to determine the possible underlying mechanism of the hypoglycaemic activity of the ethanolic extract of Nauclea latifolia leaves in rats. The extract, glibenclamide or water was administered orally in a glucose, sucrose and maltose tolerance tests. In addition, the effect of the extract on α-glucosidase enzymes was also studied. The ethanolic extract at 200mg/kg body weight inhibited the increase in glucose level after both oral and intraperitoneal glucose loads as did glibenclamide. The extract also dose dependently inhibited both maltase and sucrase activities in vitro but not in vivo. The hypoglycaemic effect of N. latifolia leaf ethanolic extract thus appears to be most probably exerted through a mechanism similar to that of glibenclamide which is related to increased insulin release from pancreatic ß-cells.

Antioxidant, hepatoprotective, and ameliorative effects of methanolic extract of leaves of Grewia mollis Juss. on carbon tetrachloride-treated albino rats.

The methanolic extract of Grewia mollis leaves was evaluated in vivo for its antioxidant and hepatoprotective properties. Oxidative stress was induced in rats by administering carbon tetrachloride (CCl(4)) intraperitoneally at a dose of 0.6 mL/kg, whereas the crude plant extract and standard antioxidant (vitamin E) were administered at a dose of 5 mg/kg and 50 mg/kg, respectively. The effect of G. mollis crude extracts and vitamin E on malondialdehyde (MDA) and liver function parameters such as protein, bilirubin, aspartate aminotransferase, and alanine aminotransferase were measured spectrophotometrically. The methanolic extract of G. mollis leaves and vitamin E showed a significant (P<.05) hepatoprotective potential by lowering the serum levels of bilirubin, aspartate aminotransferase, and alanine aminotransferase and decreasing MDA levels in rats pretreated or post-treated with CCl(4). Based on these results, it is concluded that G. mollis leaves contain potent antioxidant compounds that could offer protection against hepatotoxicity as well as ameliorate preexisting liver damage and oxidative stress conditions.

Evaluation of the polyphenol content and antioxidant properties of methanol extracts of the leaves, stem, and root barks of Moringa oleifera Lam.

Medicinal plants have been shown to have both chemopreventive and/or therapeutic effects on cancer and other diseases related to oxidative damage. Moringa oleifera Lam., known in the Hausa and Igala languages of Nigeria as "Zogale" and "Gergedi," respectively, and drumstick in English, is a plant that is used both as food and in folkloric medicine in Nigeria and elsewhere. Different parts of the plant were analyzed for polyphenol content as well as in vitro antioxidant potential. The methanol extract of the leaves of M. oleifera contained chlorogenic acid, rutin, quercetin glucoside, and kaempferol rhamnoglucoside, whereas in the root and stem barks, several procyanidin peaks were detected. With the xanthine oxidase model system, all the extracts exhibited strong in vitro antioxidant activity, with 50% inhibitory concentration (IC(50)) values of 16, 30, and 38 microL for the roots, leaves, and stem bark, respectively. Similarly, potent radical scavenging capacity was observed when extracts were evaluated with the 2-deoxyguanosine assay model system, with IC(50) values of 40, 58, and 72 microL for methanol extracts of the leaves, stem, and root barks, respectively. The high antioxidant/radical scavenging effects observed for different parts of M. oleifera appear to provide justification for their widespread therapeutic use in traditional medicine in different continents. The possibility that this high antioxidant/radical scavenging capacity may impact on the cancer chemopreventive potential of the plant must be considered.

Hypoglycaemic activity of Nauclea latifolia Sm. (Rubiaceae) in experimental animals.

Aqueous, ethanolic and hexane extracts of the leaves of Nauclea latifolia (Rubiaceae) were assessed for their fasting blood glucose lowering effect in normoglycaemic and streptozotocin-diabetic rats. Wistar strain albino rats were given different doses of the extracts after 18 hrs fast and their blood glucose measured at 0, 1, 2, 4 and 6 hours after treatment. The aqueous and ethanolic extracts significantly lowered the fasting blood glucose levels of the STZ-diabetic rats in a dose-dependent manner. The highest dose administered (400 mg/kg) lowered the fasting blood glucose of the diabetic rats by 31.7% (aqueous) and 36.1% (ethanolic) extracts. The aqueous extract did not significantly lower the glucose levels of normoglycaemic rats (maximum 6.6%), nor was any significant decrease seen in the rats administered with the hexane (maximum of 4.0% for normoglycaemic and 2.4% for diabetics) extract. The hypoglycaemic and antihyperglycaemic potentials of the aqueous and ethanolic extracts were comparable to that of glibenclamide (1 mg/kg).These results further support the traditional use of the plant in the treatment of diabetes mellitus.