[Mechanisms of action of acetonic and hexanic extracts of leaves of Vernonia colorata (Willd.) Drake (Composeae) on blod glucose regulation]. / Mecanismes d'action des extraits acetonique et hexanique de feuilles de Vernonia colorata dans la regulation de la glycemie.

INTRODUCTION: This study aimed to investigate the mechanism of action of acetonic and hexanic extracts of the leaves of Vernonia colorata on blood glucose regulation. MATERIALS AND METHODS: Experiments were performed in normoglycaemic, type 1 and 2 diabetic rats. The effects of acetonic and hexanic extracts on blood glucose were evaluated. The antagonism effect of hexanic extract on the decrease of blood glucose induced with glibenclamide and metformin was also tested. RESULTS: The hexanic extract of the leaves of V. colorata (HELVC) dose dependently increased the blood glucose in normoglycaemic rats. At the dose of 30 and 100 mg/kg, the glycaemia varied from 0.84 +/- 0.02 to 1.11 +/- 0.10 g/l and 0.68 +/- 0.02 to 1.31 +/- 0.30 g/l (p<0.05, n = 5). Such glibenclamide, the acetonic extract of the leaves of V. colorata (AELVC) induced hypoglycaemia in normoglycaemic rats. The HELVC prevents significantly the AELVC and glibenclamide induced hypoglycaemia. The chronic administration of the AELVC and HELVC as well as glibenclamide in type 1 diabetic rats did not change significantly the level of blood glucose. In type 2 diabetic rats, the single dose administration of metformin (300 mg/kg, per os) decreased the glycaemia which is completely prevented by a HELVC pretreatment. CONCLUSION: These results suggest that: i) The respective hypo- and hyperglycaemic effects of AELVC and HELVC require the presence of the pancreatic beta cells. ii) The AELVC would act by a sulfonylurea-like mechanism as glibenclamide to induce an hypoglycaemic effect.

[Healing activity of methanolic extract of the barks of Spathodea campanulata Beauv (Bignoniaceae) in rat experimental burn model]. / Activite cicatrisante de l'extrait methanolique des ecorces de Spathodea campanulata Beauv (Bagnoniaceae) sur un modele de brulures experimentales chez le rat.

Spathodea campanulata Beauv. (Bignoniaceae) is widely distributed through Africa and found in particular in Cameroon and Senegal. It is used in traditional herbal medicine for the treatment of ulcers, filaria, gonorrhea, diarrhea and fever. S. campanulata was also known in Cameroon traditional medicine to have a healing activity in burn wounds. The aim of the present study was to assess the burn healing effectiveness of the methanolic extract of the barks of S. campanulata ointment (MEBSCO) in comparison to those of Centella asiatica and Peru's balm in experimental burn model in rats. Experimental burn was made in rat under chloral anaesthesia with electric iron (200 degrees C) on the right and left side of the medianus line. Topical applications of MEBSCO (2%, 10% and 49%) dose-dependently decreased the score damage of the burn site. Treatment with 10% and 49% of MEBSCO varied the score damage from 5 to 1 +/- 0.4 and 5 to 0.2 +/- 0.5 (p < 0.05, n = 5) respectively, at day 15 after experimental burn. As well as C. asiatica (1%) and Peru's balm (1%) ointments, MEBSCO (10% and 49%) induced a complete burn healing on the 19-20th post burn day. This study shows for the first time, the burn healing effectiveness of MEBSCO in experimental burn model. It also provides a rational use of the S. campanulata barks in traditional medicine to promote burn healing.

Hypoglycaemic and antidiabetic activity of acetonic extract of Vernonia colorata leaves in normoglycaemic and alloxan-induced diabetic rats.

The aqueous extract of Vernonia colorata (Willd.) Drake (Composeae) leaves is used by African traditional medicine practitioners as a remedy for the treatment of diabetes. Our previous studies have shown the hypoglycaemic activity of the aqueous extract of Vernonia colorata leaves (300 mg/kg, per os) in normoglycaemic rats. The aim of the present study was to investigate the hypoglycaemic and antidiabetic activity of acetonic and hexanic extracts of the leaves of Vernonia colorata in order to further discriminate the type of extract which provides a better antidiabetic activity. Experiments were performed in normoglycaemic and alloxan-induced diabetic rats. The acetonic extract of the leaves of Vernonia colorata (AELVC) (100 mg/kg, per os) induced a significant decrease of blood glucose in normoglycaemic rats. The glycaemia varied from 4.72+/-0.11 to 3.72+/-0.22 mmol/l (p<0.05, n=5) 3 h after AELVC administration per os. In contrast, the hexanic extract of the leaves of Vernonia colorata (HELVC) increased significantly the glycaemia in normoglycaemic rats. Like glibenclamide, AELVC has an antihyperglycaemic effect in oral glucose tolerance test (OGTT) and alloxan-induced diabetic rats. These results have shown that: (i) AELVC and HELVC have an opposite effect on basal blood glucose in normoglycaemic rats, suggesting that the mechanisms of action of both above-mentioned extracts are different; (ii) AELVC has also an antidiabetic activity in hyperglycaemic rat models.

[Antidiabetic activity of the leaves of Vemonia colorata (Wilid.) Drake (Composees) in alloxan-induced diabetic rats]. / Activité antidiabétique des feuilles de Vernonia colorata (Willd.) Drake (Composees) sur un modèle de diabète alloxanique chez le rat.

Vemonia colorata is distributed through Africa (Benin, Cameroon, Senegal, Togo etc...). Its leaves are commonly used by african tradipractitioners for treating diabetes. However, the antidiabetic activity of the leaves of V. colorata had never been investigated in experimental conditions. The present study aimed to test the aqueous extract of the leaves of V. colorata for its effects in normoglycaemic and alloxan-induced diabetic rats in comparison to glibenclamide antidiabetic activity. Such glibenclamide, the aqueous extract of V. colorata (300 mg/kg, per os) induced a significant hypoglycaemic effect in normoglycaemic rats. The blood glucose varied from 0.77 +/- 0.01 to 0.58 +/- 0.01 g/l (p < 0.05, n = 5). It also reduced significantly the fasting glucose level of the hyperglycaemic rats induced with oral administration of glucose (4 g/kg). In alloxan-induced diabetic rats, glibenclamide (0.2 mg/kg, per os) lowered significantly the blood glucose from 2.40 +/- 0.30 to 0.70 +/- 0.40 g/l (p < 0.05, n = 5). As well as glibenclamide, the aqueous extract of V. colorata (300 mg/kg, per os) decreased the blood glucose in alloxanic rats from 2.80 +/- 0.10 to 1.00 +/- 0.20 g/l (p < 0.05, n = 5). The aqueous extract of the leaves of V. colorata possesses both hypoglycaemic and antidiabetic effect in normoglycaemic and alloxan-induced diabetic rats. This may indicate the ethnopharmacological basis of the use of V. colorata leaves in traditional medicine for treating diabetes.

[Effectiveness of syndromic approach for management of urethral discharge in Senegal]. / Evaluation de l'efficacité du traitement des écoulements urétraux au Sénégal selon l'approche syndromique.

The World Health Organization has proposed the syndromic approach for management of sexually transmissible diseases (STD) in countries where diagnostic laboratory tests are not consistently available. The purpose of this study was to evaluate the effectiveness of this approach for treatment of ureteral discharge in Senegal. Twenty seven men presenting ureteral discharge underwent two-week treatment using a combination of cotrimoxazole plus tetracycline for suspected gonococcal and a chlamydial infections. Ureteral samples were collected before and after treatment to detect Neisseria gonorrhoeae by culture and Chlamydia trachomatis by direct immunofluorescence and ELISA. Results demonstrated successful treatment of all patients presenting gonococcal and chlamydial infections i.e. 84.6% of cases. Neither germ was detected in 15.4% of cases. Before treatment, Neisseria gonorrhoeae, Chlamydia trachomatis or both were found respectively in 53.9%, 5.1% and 25.6% of samples respectively. Based on these findings we conclude that the syndromic approach was effective in 84.6% of cases but treatment was in adequation with STD biologically documented only with 25.6% of cases.

Nitric oxide and central antihypertensive drugs: one more difference between catecholamines and imidazolines.

NO is known to be involved in the peripheral and central regulation of the cardiovascular function. It plays a neuromodulatory role via a direct action on presynaptic nerve terminals, stimulating the release of gamma-aminobutyric acid, glutamate, and norepinephrine. Our aim was to study the possible role of NO in the cardiovascular effects of the central antihypertensive drugs clonidine, rilmenidine, and alpha-methyl-norepinephrine (alpha-MNA). Sites and mechanisms of the hypotensive action of these drugs were different; clonidine and rilmenidine acted on imidazoline receptors in the nucleus reticularis lateralis, whereas alpha-MNA acted upon alpha(2)-adrenoceptors in the nucleus tractus solitarius. The influence of N:(G)-nitro-L-arginine, an NO synthase inhibitor, on the central hypotensive effects of these drugs was investigated in pentobarbital-anesthetized rabbits. The intracisternal (IC) administration of alpha-MNA (30 microg/kg) induced hypotension (79+/-2 versus 103+/-4 mm Hg) and bradycardia (222+/-8 versus 278+/-4 bpm) (P:<0.05) (n=5). Clonidine (0.07 microg/kg IC) also induced hypotension (69+/-5 versus 99+/-4 mm Hg) and bradycardia (266+/-7 versus 306+/-10 bpm) (P:<0.05) (n=5). In addition to clonidine, rilmenidine (1 microg/kg IC) induced hypotension (64+/-4 versus 97+/-4 mm Hg) and bradycardia (264+/-11 versus 310+/-4 bpm) (P:<0.05) (n=5). Pretreatment with N:(G)-nitro-L-arginine (900 microg/kg IC) completely prevented the hypotensive effect of alpha-MNA but influenced the cardiovascular effects of neither clonidine nor rilmenidine. These results confirm that imidazoline drugs, such as clonidine, rilmenidine, and the catecholamine alpha(2)-adrenoceptor agonist alpha-MNA, have distinct mechanisms of action.