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International audience; Despite long traditional utilization and some reports on the antihyperglycemic and antihyperlipidemic action of Cassia siamea, the mechanisms involved have not been investigated yet. Thus, the objective of the present study was to investigate whether and how oral administration of the ethanolic extract of Cassia siamea Lam leaves (LECS) improves glucose and insulin homoeostasis, liver damage, and endothelial dysfunction in an experimental model of type 2 diabetes, the leptin-deficient ob/ob mice. Oxidative stress and protein expression of insulin-dependent and insulin -independent signaling pathways were studied. Obese ( ob/ob) vs. control (ob/+) mice were treated daily with intragastric administration of either vehicle or LECS (200 mg/kg, per day) for 4 weeks. Fasting blood glucose, body weight, food intake, glucose and insulin tolerance, oxidative stress, and liver damage as well as vascular complications with respect to endothelial dysfunction were examined. Administration of LECS in obese mice significantly reduced blood glucose and insulin levels, improved glucose tolerance and insulin sensitivity, and restored the increase of circulating AST and ALT without modification of body weight and food intake. These effects were associated with increased activity of both insulin and AMPK pathways in the liver and skeletal muscles. Of particular interest, administration of LECS in obese mice completely prevented the endothelial dysfunction resulting from an increased NO· and decreased reactive oxygen species (ROS) production in the aorta. Altogether, oral administration of LECS remarkably attenuates features of type 2 diabetes on glucose, hepatic inflammation, insulin resistance, endothelial function, and vascular oxidative stress, being as most of these effects are related to insulin-dependent and insulin-independent mechanisms. Therefore, this study points for the therapeutic potential of Cassia siamea in correcting both metabolic and vascular alterations linked to type 2 diabetes.

Traditional remedies prepared from Lannea microcarpa leaves, barks, roots, and fruits are used to treat many diseases including hypertension. This study investigated whether oral administration of the ethyl acetate fraction of Lannea microcarpa trunk barks (LMAE) corrects angiotensin (Ang) II-induced hypertension in mice. Its effects on vascular function were specifically investigated. Experiments explored hemodynamic and echocardiographic parameters in vivo and vascular reactivity to acetylcholine (ACh) and CaCl2 ex vivo on isolated aortas. Mice received LMAE for 3 weeks (50 mg/kg/day) by oral gavage. In the last two weeks of treatment, mice were implanted with osmotic minipumps delivering NaCl (0.9%) or Ang II (0.5 mg/kg/day). LMAE completely prevented the increase in systolic and diastolic blood pressure induced by Ang II. Echocardiographic and kidney parameters were not affected by the different conditions. LMAE abrogated Ang II-induced impairment of ACh-induced relaxation without affecting that of sodium nitroprusside. LMAE also completely prevented CaCl2-induced contraction in KCl-exposed aorta ex vivo. The extract alone did not modify superoxide (O2 −) and nitric oxide (NO·) production in femoral arteries from control mice but significantly limited Ang II-induced O2 − production. These effects were associated with reduced expression of inducible isoform of cyclooxygenase- (COX-) 2 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase isoform NOX-2 in aortas. Finally, phytochemical analysis showed that LMAE contains sterols, triterpenes, coumarins, and anthraquinone. These results showed that LMAE prevents Ang II-induced hypertension and vascular dysfunction through a reduction of oxidative stress linked to COX-2 and NOX-2 pathway and inhibition of calcium entry. This study provides pharmacological basis of the empirical use of Lannea microcarpa trunk bark extract against hypertension.