Etienne Dongo

Leaf methanol extract of Bidens pilosa prevents and attenuates the hypertension induced by high-fructose diet in Wistar rats

Chronic fructose treatment in rats has repeatedly been shown to elevate blood pressure in association with insulin resistance and hyperinsulinemia. The purpose of the current study was to investigate the effect of the leaf methanol extract of Bidens pilosa on systolic blood pressure (SBP) and plasma glucose, insulin, cholesterol, triglycerides and creatinine levels in rats with fructose-induced hypertension. Wistar rats that drank a 10% fructose solution for 3-6 weeks showed significant increase not only in plasma insulin and cholesterol levels but also in SBP. B. pilosa extract was able to prevent the establishment of hypertension and lower elevated blood pressure levels. The extract also reduced the highly elevated plasma insulin levels provoked by the high fructose diet. These results suggest that the leaf methanol extract of B. pilosa exerts its antihypertensive effect in part by improving insulin sensitivity.

Prenylated chalcones and flavones from the leaves of dorstenia kameruniana

Abstract Two novel flavonoids : 6,7-(2,2-dimethylchromano)-5,4′-dihydroxyflavone and 3,4-,4′,5′- bis -(2,2-dimethylchromano)-2′-hydroxychalcone together with the known 6-(3-methylbut-2-enyl)apigenin and two chalcones ( E )-1-[2,4-dihydroxy-3-[3-methylbut-2-enyl]phenyl]-3-4-prop-2-en-1-one and ( E )1 - [ 2 , 4 - d i h y d r o x y - 5 - [ 3 - m e t h y l b u t - 2 - e n y l ] p h e n y l ] - 3 - [ 4 - h y d r o x y - 3 - [ 3 - m e t h y l b u t - 2 - e n y l ] p h e n y l ] - p r o p - 2 - e n - 1 - o n e were characterised from leaf tissue of Dorstenia Kameruniana . The structures were established on the basis of spectroscopic data.

Effects of methanol, cyclohexane and methylene chloride extracts of Bidens pilosa on various gastric ulcer models in rats

Ethnobotanical studies have revealed that Bidens pilosa is used in the traditional management of wounds and chronic gastro-duodenal ulcers. This led us to screen the methanol, cyclohexane and methylene chloride extracts of the plant for anti-ulcerogenic activity using the HCl/ethanol gastric necrotizing solution. The methylene chloride extract, which showed the highest activity (100% inhibition) at a dose of 750 mg/kg compared with the methanol and cyclohexane extracts (41 and 46% inhibition, respectively), was further tested using the indomethacin-HCl/ethanol-, absolute ethanol- and pylorus ligation-induced ulcer methods. Pre-treatment with indomethacin significantly reduced the protective effect of the extract against HCl/ethanol solution to 31%. The extract had very little gastric mucosal protection against absolute ethanol (9.8% inhibition at 750 mg/kg) compared with the controls and neither reduced gastric acid secretion in vivo nor the acidity of gastric juice following in vitro incubation.

Prenylated flavones and phenylpropanoid derivatives from roots of Dorstenia psilurus

Abstract Two new flavones, dorsilurins A and B, and a new benzofuran derivative have been isolated from Dorstenia psilurus , together with three known phenylpropanoid derivatives, stearyl- p -coumarate[octadecanyl 3-(4-hydroxyphenyl)prop-2-enoate], stearyl ferulate [octadecanyl 3-(4-hydroxy-3-methoxyphenyl)prop-2-enoate] and psoralen. The structures of new compounds were determined from spectroscopic data.

Antihypertensive effects of Dorstenia psilurus extract in fructose-fed hyperinsulinemic, hypertensive rats

We examined the effect of methanol/methylene chloride extract of Dorstenia psilurus given by gastric intubation on systolic blood pressure, plasma glucose, insulin, cholesterol, triglycerides and creatinine in rats with fructose-induced hypertension. Male Wistar rats in groups of 6 animals each were fed fructose-rich diets or standard chow for 3 weeks and treated with 100 mg/kg/day or 200 mg/kg/day of plant extract or vehicle for 3 subsequent weeks. Systolic blood pressure was measured every three days using the indirect tail cuff method. Systolic blood pressure was higher in fructose-fed rats (142+/-2 mm Hg, p < 0.01) compared with the controls (112+/-2 mm Hg), and was lower in Dorstenia psilurus-treated groups (127+/-2 and 119+/-1 mm Hg for the dose of 100 and 200 mg/kg, respectively) compared with the fructose-fed rats. Plasma insulin, cholesterol and triglycerides were higher on the fructose-rich diet compared with the controls. Plasma insulin and cholesterol were lower in the Dorstenia psilurus-treated groups. These results suggest that, Dorstenia psilurus treatment could prevent and reverse high blood pressure induced by a diet rich in fructose probably by improvement of plasma insulin levels. The plant extract might prove useful in the treatment and/or prevention of hypertension.

Prenylated flavanones from the twigs of Dorstenia mannii

Investigation of the twigs of Dorstenia mannii gave 6,8-diprenyl-5,7,3′4′-tetrahydroxyflavanone and four new prenylated flavanones, named dorsmanins E-H and characterized as 5,6-7,8-bis-(2,2-dimethylchromano)-3′,4′-dihydroxyflavanone, 7,8-[2″-(1-hydroxy-1-methylethyl)-dihydrofurano]-6-prenyl-5,3′,4′-trihydroxyflavanone, 6,7-[2″-(1-hydroxy-1-methylethyl)dihydrofurano]-8-prenyl-5,3′,4′-trihydroxyflavanone and 6-prenyl-8-(2-hydroxy-3-methylbut-3-enyl)-5,7,3′,4′-tetrahydroxyflavanone, respectively, on the basis of spectral analysis and chemical evidence for the chromano derivative.

Effets hypotensifs de l'extrait au méthanol de Bidens pilosa Linn chez les rats hypertendus

Abstract Bidens pilosa Linn is highly regarded in some parts of Cameroon in traditional folk medical pratices. The hypotensive effects of the leaf methanol extract from Bidens pilosa Linn (Asteraceae) were evaluated in spontaneously hypertensive rats (SHR), salt-loading hypertensive rats (SLHR) and normotensive Wistar rats (NTR) using the indirect (tail-cuff) method. Acute changes in urine volume and urinary excretion of Na + and K + were also studied. The hypotensive effect of the extract was more remarkable in hypertensive than in normotensive rats. Bidens pilosa did not provoke significant changes in the heart rate and urine volume. Urinary excretion of Na + was decreased by 36 % in spontaneously hypertensive rats and the excretion of K + increased by 35 % in normotensive rats but the effects were not statistically significant. These results suggest that the extract is a useful antihypertensive drug which has no effect on the heart frequency. The hypotensive effects of the extract may be induced by vasodilation.

Crotonadiol, a labdane diterpenoid from the stem barkof Croton zambesicus

Abstract A new labdane diterpenoid, crotonadiol, was isolated from an extract of the stembark of Croton zambesicus together with the known clerodane crotocorylifuran and twotrachylobanes: 7 β -acetoxytrachyloban-18-oic acid and trachyloban-7 β ,18-diol. Lupeol, β -sitosterol and its 3- β -glucopyranosyl derivative were also isolated. The structure of crotonadiolwas determined as 8 (17),13-labdadiene-6a,15-diol, by spectral analysis.

Chemical Constituents from Stem Bark and Roots of Clausena anisata

Phytochemical investigations on the stem bark and roots of the tropical shrub Clausena anisata led to the isolation and characterization three carbazole alkaloids: girinimbine, murrayamine-A and ekeberginine; two peptide derivatives: aurantiamide acetate and N-benzoyl-l-phenylalaninyl-N-benzoyl-l-phenylalaninate; and a mixture of two phytosterols: sitosterol and stigmasterol. The structures of these compounds were established by nuclear magnetic resonance (1H-NMR, 13C-NMR, COSY, HSQC, HMQC, HMBC and NOESY) spectroscopy and electrospray ionization mass spectrometry (MS).

Antidiabetic and hypolipidaemic effects of a methanol/methylene-chloride extract of Laportea ovalifolia (Urticaceae), measured in rats with alloxan-induced diabetes

Abstract A decoction of the leaves of Laportea ovalifolia is widely used in Cameroon for the treatment of several illnesses, including diabetes mellitus. The antidiabetic and hypolipidaemic effects of a methanol/methylene-chloride extract of the aerial parts of L. ovalifolia have now been investigated, in normal rats and rats with diabetes induced by the intraperitoneal injection of alloxan (at 150 mg/kg bodyweight). In the diabetic rats, 2 weeks of daily, intragastric treatment with the L. ovalifolia extract not only produced a significant reduction in the fasting serum glucose concentrations but also lowered the serum concentrations of total cholesterol, triglycerides, and low-density-lipoprotein cholesterol, lowered the ratio of total cholesterol to high-density-lipoprotein (HDL) cholesterol, and increased the serum concentration of HDL cholesterol. At least in rats with alloxan-induced diabetes, the methanol/methylene-chloride extract of L. ovalifolia therefore appears to possess antidiabetic and hypolipidaemic properties.