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The argan tree plays an important socioeconomic and ecologic role in South Morocco. Moreover, there is much evidence for the beneficial effects of virgin argan oil (VAO) on human health. Thus, this study investigated whether administering VAO to rats can prevent the development of diabetes. VAO extracted by a traditional method from the almonds of Argania spinosa (2 mL/kg) was administered orally (for 7 consecutive days) to rats before and during intraperitoneal alloxan administration (75 mg/kg for 5 consecutive days). An alloxan diabetic-induced untreated group and treated by table oil were used as control groups. Body mass, blood glucose and hepatic glycogen were evaluated. In the present study, subchronic treatment with VAO at a dose of 2 mL/kg, before the experimental induction of diabetes, prevented the body mass loss, induced a significant reduction of blood glucose and a significant increase of hepatic glycogen level (p < 0.001) compared with the untreated diabetic group. In conclusion, the present study shows that argan oil should be further investigated in a human study to clarify its possible role in reducing weight loss in diabetics, and even in inhibiting the development or progression of diabetes. This antidiabetic effect could be due to the richness of VAO in tocopherols, phenolic compounds and unsaturated fatty acids.

Many cardiovascular diseases such as arterial hypertension are associated with an increase in blood platelet activity. Arbutus unedo (Ericaceae) is a medicinal plant reputed to treat arterial hypertension, so the present study was undertaken in order to determine the antiaggregant effect. The crude aqueous extract showed an inhibition of thrombin-induced platelet aggregation (IC50 = 1.8 ± 0.09 g/L, n = 10). The subsequent extraction of Arbutus unedo leaves by successive solvents showed that the methanol and ethyl acetate extracts accounted for most of the antiaggregant activity (IC50 = 0.7 ± 0.08, n = 9; 0.6 ± 0.05; n = 9, respectively). The tannins isolated from the methanol extract exhibited a strong antiplatelet effect (% of inhibition = 75.3 ± 1.4, n = 8) and may be the major chemical compounds responsible for this action. Our results support the traditional use of this plant in the preventive or therapeutic treatment of platelet aggregation linked to arterial hypertension. Copyright © 2006 John Wiley & Sons, Ltd.

This study examined the vascular effect of Arbutus leaves (aqueous extract) and described the isolation of several fractions responsible for their vasorelaxant activity. The aqueous extract (AE) of leaves was tested on rat aortic rings precontracted with 0.1 µm noradrenaline. At 10−2 g/L, AE produced an endothelium dependent relaxation of 66% ± 5%, (n = 8). The leaves of Arbutus were then extracted successively with different solvents and the methanol extract was the most active. When tannins (primarily condensed tannins) were precipitated from the methanol extract, they showed a strong vasorelaxant activity (87% ± 4%, n = 5), whereas the elimination of tannins in the methanol extract reduced significantly its vasorelaxant activity (42% ± 8%, n = 8, p < 0.005). The methanol extract was further separated semi-preparatively by reversed-phase HPLC. Four fractions (Fr2, Fr3, Fr4 and Fr6) were the most active and produced 88% ± 2% (n = 5), 75% ± 6% (n = 5), 76% ± 3% (n = 7) and 77% ± 3% (n = 10) relaxation, respectively. These four fractions mainly correspond to polyphenol compounds. Analysis of Fr6 indicated that this fraction contained catechin gallate. In conclusion, the vasorelaxant activity of Arbutus is likely to be due to polyphenol compounds, primarily condensed tannins and catechin gallate. Copyright © 2004 John Wiley & Sons, Ltd.

International audience; Urtica dioica L. or Nettle (Urticaceae) is widely used in oriental Morocco to treat hypertension. Aqueous extract of Nettle (AEN) also exerts a hypotensive action in the rat in vivo. The aim of this work was to characterize the specific cardiac and vascular effects of AEN. In the isolated Langendorff perfused rat heart, AEN (1 and 2 g/l) markedly decreased heart rate and increased left ventricular pressure. Higher concentration (5 g/l) even led to cardiac arrest. Although carbachol mimicked the bradycardiac effect of AEN, atropine (a muscarinic receptor antagonist, 1 • M) did not modify the response. Beside its action on myocardium, AEN also affected vascular contractility. Indeed, AEN (0.1-5 g/l) produced a dose-dependent increase in basal tone of isolated rat aorta. This effect was endothelium independent and was abolished by 1 • M prazosin (an • 1-adrenergic antagonist). AEN had little additional effects when the aorta was precontracted by noradrenaline (1 • M) or KCl (40 mM). Our data indicate that AEN produces a vasoconstriction of the aorta which is due to activation of • 1-adrenergic receptors. However, AEN also induces a strong bradycardia through non-cholinergic and non-adrenergic pathways which might compensate for its vascular effect and account for the hypotensive action of Urtica dioica L described in vivo.

In order to examine the effect of Arbutus unedo extract on the development of genetic hypertension, three groups of six male spontaneously hypertensive rats (SHR) from 4 to 10 weeks of age, received orally an aqueous extract of the root of this Ericaceae plant at doses of 5, 50 and 250 mg/kg/24 h. The fourth group (n = 6) received tap water only and served as a control. A significant (p < 0.01) reduction of indirect systolic blood pressure (BP) was observed after 4 weeks of treatment with the two highest doses but this effect attenuated 2 weeks later. The continuous measurement of direct BP in conscious 10-week-old rats indicated that chronic treatment with Arbutus did not significantly alter the BP level, the heart rate (HR), the cardiac baroreflex sensitivity and the sympathetic nervous and renin- angiotensin system activities. In contrast, Arbutus (50mg/kg/24 h) attenuated the pressor responses to phenylephrine and angiotensin I. Finally, a diuretic effect was evidenced in the group receiving the highest dose. It is concluded that chronic oral administration of Arbutus unedo slowly delayed the development of hypertension but did not alter the final level of BP and HR in the SHR. The vascular and renal effects of this plant, which may account for its use in folk medicine, require a more detailed analysis.