BackgroundPrevious study showed that the aqueous extract of the stem bark of Cinnamomum zeylanicum possesses antihypertensive and vasodilatory properties. The present work investigates the acute and chronic antihypertensive effects of the methanol extract of Cinnamomum zeylanicum stem bark (MECZ) in L-NAME-induced hypertensive rats.MethodsThe acute antihypertensive effects of MECZ (5, 10 and 20 mg/kg) administered intravenously were evaluated in rats in which acute arterial hypertension has been induced by intravenous administration of L-NAME (20 mg/kg). For chronic antihypertensive effects, animals were treated with L-NAME (40 mg/kg/day) plus the vehicle or L-NAME (40 mg/kg/day) in combination with captopril (20 mg/kg/day) or MECZ (300 mg/kg/day) and compared with control group receiving only distilled water. All drugs were administered per os and at the end of the experiment that lasted for four consecutive weeks, blood pressure was measured by invasive method and blood samples were collected for the determination of the lipid profile. The heart and aorta were collected, weighed and used for both histological analysis and determination of NO tissue content.ResultsAcute intravenous administration of C. zeylanicum extract (5, 10 and 20 mg/kg) to L-NAME-induced hypertensive rats provoked a long-lasting decrease in blood pressure. Mean arterial blood pressure decreased by 12.5%, 26.6% and 30.6% at the doses of 5, 10 and 20 mg/kg, respectively. In chronic administration, MECZ and captopril significantly prevented the increase in blood pressure and organs’ weights, as well as tissue histological damages and were able to reverse the depletion in NO tissue’s concentration. The MECZ also significantly lower the plasma level of triglycerides (38.1%), total cholesterol (32.1%) and LDL-cholesterol (75.3%) while increasing that of HDL-cholesterol (58.4%) with a significant low atherogenic index (1.4 versus 5.3 for L-NAME group).ConclusionMECZ possesses antihypertensive and organ protective effects that may result from its ability to increase the production of the endogenous NO and/or to regulate dyslipidemia.

Parts of Ceiba pentandra are wildly used in Africa to treat diabetes and previous works have demonstrated their in vivo antidiabetic effects on type 1 diabetes models. In addition, it has been recently shown that the decoction and the methanol extract from the stem bark of C. pentandra potentiate in vitro, the peripheral glucose consumption by the liver and skeletal muscle slices. But nothing is known about its effect on type II diabetes, especially on insulin resistance condition. We investigated herein the antihyperglycemic, insulin-sensitizing potential, and cardioprotective effects of the dried decoction from the stem bark of Ceiba pentandra (DCP) in dexamethasone-induced insulin resistant rats. DCP phytochemical analysis using LC-MS showed the presence of many compounds, including 8-formyl-7-hydroxy-5-isopropyl-2-methoxy-3-methyl-1,4-naphthaquinone, 2,4,6-trimethoxyphenol, and vavain. Wistar rats were given intramuscularly (i.m.) dexamethasone (1 mg/kg/day) alone or concomitantly with oral doses of DCP (75 or 150 mg/kg/day) or metformin (40 mg/kg/day) for 9 days. Parameters such as body weight, glycemia, oral glucose tolerance, plasma triglycerides and cholesterol, blood pressure, and heart rate were evaluated. Moreover, cardiac, hepatic and aortic antioxidants (reduced glutathione, catalase, and superoxide dismutase), malondialdehyde level, and nitric oxide content were determined. DCP decreased glycemia by up to 34% and corrected the impairment of glucose tolerance induced by dexamethasone but has no significant effect on blood pressure and heart rate. DCP reduced the total plasma cholesterol and triglycerides as compared to animals treated only with dexamethasone. DCP also increased catalase, glutathione, and NO levels impaired by dexamethasone, without any effect on SOD and malondialdehyde. In conclusion, the decoction of the stem bark of Ceiba pentandra has insulin sensitive effects as demonstrated by the improvement of glucose tolerance, oxidative status, and plasma lipid profile. This extract may therefore be a good candidate for the treatment of type II diabetes.

Postprandial hyperglycemia and oxidative stress are important factors that worsen the health condition of patients with type 2 diabetes. We recently showed that extracts from Ceiba pentandra mitigate hyperglycemia in dexamethasone- and high diet/streptozotocin-induced diabetes. Herein, we evaluated the postprandial regulatory properties and the antioxidant effects of the aqueous (AE) and methanol (ME) extracts from the stem bark of Ceiba pentandra. The phytochemical analysis of AE and ME was performed using the LC-MS technique and the total phenolic and flavonoid assays. Both extracts were tested for their ability to inhibit superoxide anion (O2•ـ), hydrogen peroxide (H2O2), protein oxidation, alpha-amylase, and alpha-glucosidase activities. The mode of enzyme inhibition was also determined in a kinetic study. AE and ME were both rich in phenolic and flavonoid compounds. ME was 2.13 and 1.91 times more concentrated than AE in phenolic and flavonoid compounds, respectively. LC-MS allowed the identification of 5 compounds in both extracts. ME and AE inhibited O2•ـ with IC50 of 51.81 and 34.26 μg/ml, respectively. On H2O2, they exhibited IC50 of 44.84 and 1.78 μg/ml, respectively. Finally, they exhibited IC50 of 120.60 and 140.40 μg/ml, respectively, in the inhibition of protein oxidation induced by H2O2, while showing IC50 of 39.26 and 97.95 μg/ml on the protein oxidation induced by AAPH. ME and AE inhibited alpha-amylase with IC50 of 6.15 and 54.52 μg/ml, respectively. These extracts also inhibited alpha-glucosidase, demonstrating IC50 of 76.61 and 86.49 μg/ml. AE exhibited a mixed noncompetitive inhibition on both enzymes, whereas ME exhibited a competitive inhibition on α-amylase and a pure noncompetitive inhibition on α-glucosidase. These results demonstrate that ME and AE scavenge reactive oxygen species and prevent their effects on biomolecules. Besides, ME and AE inhibit carbohydrate digestive enzymes. These properties may contribute to reduce postprandial hyperglycemia and regulate glycemia in diabetic patients.

These results suggest that the antidiabetic effect of C. pentandra is due to its ability to increase glucose uptake and to reduce glucose release by target organs. The antioxidant properties of C. pentandra extracts are additional benefit for their antidiabetic effects.

The present work evaluates the cardiovascular activity of the aqueous (AES) and methanol (MES) extracts from S. torvum fruits. The anti-platelet aggregation activity of the AES was also evaluated on platelets isolated from rats. Intravenous administration of AES and MES induced a significant reduction in arterial blood pressure. The intravenous administration of AES at the doses of 1 and 2 mg/kg did not affect the heart rate. In contrast to AES, MES reduced the heart rate at all the doses (1, 2 and 5 mg/kg). Neither atropine (1 mg/kg) nor yohimbine (1 mg/kg) significantly affects the hypotensive activity of AES. Yohimbine almost completely inhibited the cardiac effect of AES. L-NAME (20 mg/kg) significantly potentiated the hypotensive and the cardiac effects of AES. When essayed on the platelet aggregation, induced by either thrombin (0.5 U/ml) or Adenosine diphosphate (5 µM), AES significantly and dose dependently inhibited the aggregation induced by both agents. MES and AES possess hypotensive activity which may partially result from their bradycardic effect. The anti-platelet aggregation effect of AES may be a benefit for its cardiovascular effect. These results support the use of the plant in the treatment of arterial hypertension and haemostatic ailments.