1 The e ects of an oral daily dose (10 mg kg 71 ) of the¯avonoid quercetin for 5 weeks in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY) were analysed. 2 Quercetin induced a signi®cant reduction in systolic (718%), diastolic (723%) and mean (721%) arterial blood pressure and heart rate (712%) in SHR but not in WKY rats. 3 The left ventricular weight index and the kidney weight index in vehicle-treated SHR were signi®cantly greater than in control WKY and these parameters were signi®cantly reduced in quercetin-treated SHR in parallel with the reduction in systolic blood pressure. 4 Quercetin had no e ect on the vasodilator responses to sodium nitroprusside or to the vasoconstrictor responses to noradrenaline or KCl but enhanced the endothelium-dependent relaxation to acetylcholine (E max =58+5% vs 78+5%, P50.01) in isolated aortae. 5 The 24 h urinary isoprostane F 2a excretion and the plasma malonyldialdehyde (MDA) levels in SHR rats were increased as compared to WKY rats. However, in quercetin-treated SHR rats both parameters were similar to those of vehicle-treated WKY. 6 These data demonstrate that quercetin reduces the elevated blood pressure, the cardiac and renal hypertrophy and the functional vascular changes in SHR rats without e ect on WKY. These e ects were associated with a reduced oxidant status due to the antioxidant properties of the drug.

The antidiarrhoeic activity of the Euphorbia hirta whole plant was investigated. The lyophilized decoction demonstrated antidiarrhoeic activity in experimental models of diarrhoea induced by castor oil, arachidonic acid, and prostaglandin E2. It showed no activity when magnesium sulphate was used to provoke the diarrhoea. The lyophilized decoction delayed small intestinal transit when this was accelerated by castor oil but not in normal conditions. A flavonoid, quercitrin, with antidiarrhoeic activity was isolated from this crude drug.

The intestinal anti-inflammatory activity of two flavonoids, hesperidin and diosmin, was evaluated in the acute stage of the trinitrobenzenesulfonic acid (TNBS) model of rat colitis. The results obtained showed that pretreatment with diosmin (10 mg/kg) or hesperidin (10 and 25 mg/kg) reduced colonic damage compared to TNBS control rats. This effect was confirmed biochemically by a reduction in colonic myeloperoxidase activity compared to non-treated colitic animals. Colonic glutathione levels in colitic animals were significantly increased after hesperidin or diosmin treatment. Diosmin decreased colonic MDA production and inhibited LTB4 synthesis, whereas hesperidin failed to do so. Conversely, only hesperidin improved colonic fluid absorption, which was impaired in colitic animals. In conclusion, both diosmin and hesperidin were able to prevent colonic inflammation, acting via a mechanism in which protection against oxidative insult may play a role.

The essential oil of Bupleurum fruticescens was investigated qualitatively and quantitatively by GC and GC-MS analyses. The anti-inflammatory activity of the whole essential oil and its major components was also investigated in the rat hindpaw edema model induced by carrageenin or by PGE1. The anti-inflammatory activity shown by the essential oil can be attributed to the two major components, alpha-pinene and beta-caryophyllene. In order to know the role of the adrenal glands in the anti-inflammatory activity exerted by the two major components of the essential oil, they were studied against the carrageenin-induced hindpaw edema in adrenolectomized rats. It is concluded that alpha-pinene needs the integrity of the adrenal glands to exert its anti-inflammatory activity, as opposed to beta-caryophyllene which was also active in adrenolectomized animals.

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