Centaurium erythrea (Gentianaceae) leaf extract alleviates streptozotocin-induced oxidative stress and ß-cell damage in rat pancreas.

ETHNOPHARMACOLOGICAL RELEVANCE: Centaurium erytrea is used in traditional medicine for treat urine retention, abdominal colic and diabetes mellitus. The aim of the present study was to evaluate the possible protective effects of Centaurium erythrea leaf extract (CE) against pancreas ß-cells' damage and antioxidant defense systems in streptozotocin induced diabetes rats. MATERIALS AND METHODS: Experimental diabetes was induced by a single dose of STZ (65 mg/kg) administered by intraperitoneal way. The oxidative stress was measured by tissue MDA levels, protein carbonyl (PCO) content, reduced glutathione (GSH) content and by enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in pancreas. Biochemical observations were further substantiated with histological examination of pancreas. RESULTS: The increase in blood glucose and MDA levels with the decrease in GSH content and in enzymatic activities were the salient features observed in diabetic rats. Administration of CE (200mg/kg bw/day, i.p) for 30 days caused a significant reduction in blood glucose and MDA levels in STZ treated rats when compared with diabetic rats. Furthermore, diabetic rats treated with CE leaf extract showed a significant increase in the activities of both enzymatic and non-enzymatic antioxidants when compared to those of diabetic rats. Degenerative changes of pancreatic ß-cells in STZ treated rats were minimized to near normal morphology by administration of CE leaf extract as evidenced by histopathological examination. CONCLUSION: Results clearly indicate that Centaurium erythrea treatment exerts a therapeutic protective nature in diabetes by decreasing oxidative stress and pancreatic ß-cells' damage which may be attributed to its antioxidative potential.

Acute hypoglycemic, hypocholesterolemic and hypotriglyceridemic effects of continuous intravenous infusion of a lyophilised aqueous extract of Ajuga iva L. Schreber whole plant in streptozotocin-induced diabetic rats.

The hypoglycemic and hypolipidemic effect of continuous intravenous infusion of a lyophilised aqueous extract of the whole plant Ajuga iva (L.) Schreber (Labiatae) (AI-extract) was investigated in anesthetized normal and streptozotocin (STZ)-induced diabetic rats. The AI-extract was administered to a group of rats by continuous intravenous infusion for 4 h at a dose of 4.2 microg/min/100 g body weight; another group was infused with taurine, the reference compound, at the same dose. In normal rats, AI-extract infusion had no effect on plasma glucose or triglycerides, but plasma cholesterol levels were significantly decreased (22%; P<0.05). However, taurine infusion produced significant hypoglycemic, hypocholesterolemic and hypotriglyceridemic effects (all changes, P<0.05). In STZ-diabetic rats, AI-extract infusion reduced plasma levels of glucose by 24 % (P<0.05), cholesterol by 35% (P<0.01) and triglycerides by 13% (P<0.05). Infusion with taurine produced a greater fall in plasma glucose (72%, P<0.01), cholesterol (54%; P<0.001) and triglyceride (24%; P<0.001) levels. Our results indicate that intravenously administered AI-extract exerts hypoglycemic and hypolipidemic effects in diabetic rats by mechanism(s) which appear to be similar to that of taurine, which involve insulin sensitization or an insulin-like effect. The identity and the exact mechanism(s) of action of the active component(s) of the AI-extract are not known. Ajuga iva appears to be a useful plant in the therapy of diabetes, a condition in which hyperglycemia and dyslipidemia coexist quite often.

Diuretic activity of the aqueous extracts of Carum carvi and Tanacetum vulgare in normal rats.

In the Moroccan traditional medicine, the ripe fruits of Carum carvi L. (Apiaceae) and the leaves of Tanacetum vulgare L. (Asteraceae/Compositae), two widely available plant materials, are used as diuretics. Since, the diuretic activity of these substances has not been investigated in scientifically controlled studies, the aim of the present study was to evaluate the diuretic potential of aqueous extracts of Carum carvi fruit (caraway) and the leaves of Tanacetum vulgare (tansy) in normal rats after acute and sub-chronic oral administration. Water extracts of Carum carvi and Tanacetum vulgare (100 mg/kg) or the reference drug, furosemide (10 mg/kg) were administrated orally to male Wistar rats and their urine output was quantitated at several intervals of time after the dose. After single doses of the extracts of both caraway seeds and tansy leaves, urine output was significantly increased at all time points, and at 24 h after the dose, the total volume of urine excreted was similar for the plant extracts and furosemide. Both extracts increased urinary levels of Na(+) and K(+), to about the same extent, while furosemide increased urinary levels of only Na(+) and decreased urinary K(+). Despite changes in urinary excretion of the electrolytes, plasma Na(+) and K(+) levels were not affected by any of the three substances. In the 8-day sub-chronic study, all three substances induced significant diuresis and natriuresis; only tansy increased urinary potassium excretion. The plant extracts did not appear to have renal toxicity or any other adverse effects during the study period. In conclusion, water extracts of both Carum carvi and Tanacetum vulgare have strong diuretic action confirming their ethnopharmacological use. From the pattern of excretion of water, sodium and potassium, it may be deduced that there are atleast two types of active principals present in these extracts, one having a furosemide-like activity and the other a thiazide-like activity.

Hypolipidemic effects of acute and sub-chronic administration of an aqueous extract of Ajuga iva L. whole plant in normal and diabetic rats.

Diabetes is often accompanied by lipid abnormalities, which contribute significantly to cardiovascular (CV) morbidity and mortality in diabetic patients. The plant Ajuga iva (L.) Schreiber (Labiatea) is used in the treatment of diabetes in Moroccan folk medicine. Previously, we have demonstrated potent hypoglycemic activity and relatively non-toxic nature of a lyophilized aqueous extract of the whole plant (AI-extract) in normal (normoglycemic) and streptozotocin (STZ)-diabetic rats. In this study, we examined the AI-extract for its possible lipid-lowering activity in normal and STZ-diabetic rats. Taurine (TR) and glibenclamide (GLB) were used as reference substances. As shown previously, the AI-extract (10 mg/kg; oral) reduced plasma glucose levels after acute (single) and sub-chronic (3 weeks) dosing both in normal and diabetic rats. In normal rats, single and repeated oral administration of the AI-extract, at a dose of 10 mg/kg produced a small but significant decrease in plasma CHL levels (P<0.05). A single dose of the AI-extract did not produce a significant change in plasma TG, but sub-chronic dosing (for up to 21 days) caused a significant decrease in plasma TG (P<0.05). In STZ-diabetic rats, a single dose as well as repeated (3 weeks) treatment with the AI-extract produced a significant decrease in plasma CHL (P<0.01), and triglyceride (P<0.01) levels. The AI-extract also prevented weight loss in the diabetic animals. In summary, an aqueous extract of the Ajuga iva whole plant showed hypolipidemic activity, in addition to its hypoglycemic effect in normoglycemic and diabetic rats. In view of the hypoglycemic and hypolipidemic activity, and its relatively non-toxic nature (shown previously), Ajuga iva may be a candidate for development as an anti-diabetic agent in humans. Further studies are warranted to confirm our results and fractionate the AI-extract to isolate and identify the active principle(s), and to determine the exact mechanism(s) of action.