This study evaluates the vasorelaxant and antihypertensive effects of the aqueous extract from the stem bark of M. africana (AEMA). AEMA was tested in vitro on intact or endothelium-denuded rats' aorta rings precontracted with KCl or norepinephrine in absence or in presence of L-NAME or glibenclamide. The effect of a single concentration (300 μg/mL) of AEMA was also examined on the concentration-response curve of KCl. In vivo, the antihypertensive effects of AEMA (200 mg/kg/day) were evaluated in male Wistar rats treated with L-NAME (40 mg/kg/day) for 4 weeks. AEMA relaxed aorta rings precontracted with NE or KCl with respective EC50 values of 0.36 μg/mL and 197.60 μg/mL. The destruction of endothelium or pretreatment of aorta rings with L-NAME shifted the EC50 of AEMA from 0.36 μg/mL to 40.65 μg/mL and 20.20 μg/mL, respectively. The vasorelaxant activity of M. africana was significantly inhibited in presence of glibenclamide. AEMA also significantly inhibited the concentration-response curve of KCl. Administered orally, AEMA induced acute and chronic antihypertensive effects and normalized renal NO level. These results show that the vasorelaxant activity of AEMA might be mediated by the activation of the NO-cGMP-ATP-dependent potassium channels pathway and might predominantly account for its antihypertensive effect.

Millettia thonningii, Ocinum sanctum and Securitaca longepedunculaca are used in traditional medicine in Cameroon to treat epilepsy, insomnia and headaches. Animal models of epilepsy (maximal electroshock (MES), n-methyl-d-aspartate (NMDA), pentylenetetrazol (PTZ), isonicotinic hydrazide acid (INH), picrotoxine (PIC) and strychnine (STR)-induced convulsions or turning behavior were used to evaluate anticonvulsant activity while diazepam-induced sleep test was used to evaluate sedative activity of the plants. Four doses of extracts were used for each plant (100, 200, 500 and 1000 mg/kg). At a dose of 1000 mg/kg, Millettia thonningii protected 60 and 90% of mice against MES and PTZ-induced convulsions, respectively. At the same dose, Millettia thonningii also protected 80% of mice against NMDA-induced turning behavior. At a dose of 1000 mg/kg, Ocinum sanctum provided complete protection against MES, PIC and STR- induced convulsions and 83.3% of protection in PTZ test. Securitaca longepedunculata completely protected (100%) mice in PIC test at a dose of 200 mg/kg, in MES test at a dose of 500 mg/kg and in PTZ test at a dose of 1000 mg/kg. 66.7% of mice were protected against STR-induced convulsions. All the three plants showed also sedative properties for they increased significantly and in a dose dependent manner the total sleep time induced by diazepam. The total sleep time of the control groups was multiplied by a factor of 3 at least by each extract. The presence of sedative and anticonvulsant activity in the three plants could explain their use in traditional medicine in the treatment of epilepsy and insomnia in Cameroon.

Context

Nauclea latifolia Smith (Rubiacea) is a small tree, found in tropical areas in Africa. It is used in traditional medicine to treat malaria, epilepsy, anxiety, pain, fever etc.

Objective

The aim of this study was to investigate the effects of Nauclea latifolia roots decoction on the peripheral and central nervous systems and its possible mechanisms of action.

Materials and methods

The analgesic investigation was carried out against acetic acid-induced writhing, formalin-induced pain, hot-plate and tail immersion tests. The antipyretic activity was studied in Brewer’s yeast-induced pyrexia in mice. Rota-rod test and bicuculline-induced hyperactivity were used for the assessment of locomotor activity.

Results

Nauclea latifolia induced hypothermia and had antipyretic effects in mice. The plant decoction produced significant antinociceptive activity in all analgesia animal models used. The antinociceptive effect exhibited by the decoction in the formalin test was reversed by the systemic administration of naloxone, Nω-L-nitro-arginine methyl ester or glibenclamide. In contrast, theophylline did not reverse this effect. Nauclea latifolia (antinociceptive doses) did not exhibit significant effect on motor coordination of the mice in rota-rod performance. Nauclea latifolia protected mice against bicuculline-induced behavioural excitation.

Discussion and conclusion

Overall, these results demonstrate that the central and peripheral effects of Nauclea latifolia roots decoction might partially or wholly be due to the stimulation of peripheric opioid receptors through the action of the nitric oxide-cyclic GMP-ATP-sensitive K+ (NO/cGMP/ATP)-channel pathway and/or facilitation of the GABAergic transmission.

Objective:

The present study aims at evaluating the effects of methanol/methylene chloride extract of the stem bark of Mammea africana on the renal function of L-NAME treated rats.

Material and Methods:

Normotensive male Wistar rats were divided into five groups respectively treated with distilled water, L-NAME (40 mg/kg/day), L-NAME + L-arginine (100 mg/kg/day), L-NAME + captopril (20 mg/kg/day) or L-NAME + M. africana extract (200 mg/kg/day) for 30 days. Systolic blood pressure was measured before and at the end of treatment. Body weight was measured at the end of each week. Urine was collected 6 and 24 h after the first administration and further on day 15 and 30 of treatment for creatinine, sodium and potassium quantification, while plasma was collected at the end of treatment for the creatinine assay. ANOVA two way followed by Bonferonni or one way followed by Tukey were used for statistical analysis.

Results:

M. africana successfully prevented the rise in blood pressure and the acute natriuresis and diuresis induced by L-NAME. When given chronically, the extract produced a sustained antinatriuretic effect, a non-significant increase in urine excretion and reduced the glomerular hyperfiltration induced by L-NAME.

Conclusions:

The above results suggest that the methanol/methylene chloride extract of the stem bark of M. africana may protect kidney against renal dysfunction and further demonstrate that its antihypertensive effect does not depend on a diuretic or natriuretic activity.

These studies focus on the toxicity leaf hexane extract of A. occidentale L (Anacardiaceae) used in Cameroon traditional medicine for the treatment of diabetes and hypertension. Previous findings on antidiabetic and anti-inflammatory have given support to the ethnopharmacological applications of the plant. After acute oral administration, it was found that doses of the extract less than 6 g/kg are not toxic. Signs of toxicity at high doses were asthenia, anorexia, diarrhoea, and syncope. The LD50 of the extract, determined in mice of both sexes after oral administration was 16 g/kg. In the subchronic study, mice received A. occidentale at doses of 6, 10 and 14 g/kg (by oral route) for 56 days. At doses of 2, 6 and 10 g/kg of extract, repeated oral administration to mice produced a reduction in food intake, weight gain, and behavioural effects. Liver or the kidney function tests were assessed by determining serum parameters like, creatinine, transaminases, and urea. All these parameters were significantly (p<0.01) abnormal. Histopatological studies revealed evidence of microcopic lesions either in the liver or in the kidney which may be correlated with biochemical disturbances. We conclude that toxic effects of A. occidentale L hexane leaf extract occurred at higher doses than those used in Cameroon folk medicine.

The aim of this work was to investigate the effect of daily oral administration of root bark methylene chloride/methanol extract of Ceiba pentandra (Linn) in streptozotocin-induced type-2 diabetic rats, and the effect of this treatment on the physiological and metabolic parameters that are related in diabetic animals. The diabetic rats were separated into four groups and each given the following samples by gavage, daily for 28 days: vehicle (diabetic control), Ceiba pentandra extract at the dose of 40 mg/kg, Ceiba pentandra extract at the dose of 75 mg/kg and glibenclamide (5 mg/kg). All the parameters were also determined in healthy (non diabetic) rats for comparison. The methylene chloride/methanol extract of Ceiba pentandra treatment significantly reduced the intake of both food and water as well as the levels of blood glucose, serum cholesterol, triglyceride, creatinine and urea, in comparison with diabetic controls. The treatment also improves impaired glucose tolerance but no effect was observed in the level of hepatic glycogen. The effect of Ceiba pentandra (40 mg/kg) was more prominent when compared to glibenclamide in lowering blood glucose, with the added benefit of considerably reducing serum cholesterol and triglyceride concentrations. The results of this experimental animal study indicated that Ceiba pentandra possesses antidiabetic activity; and thus is capable of ameliorating hyperglycaemia in streptozotocin-induced type-2 diabetic rats and is a potential source for isolation of new orally active agent(s) for anti-diabetic therapy.