Mechanisms of the antihypertensive effects of Nigella sativa oil in L-NAME-induced hypertensive rats

OBJECTIVES: This study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers. METHODS: Twenty-four adult male Sprague-Dawley rats were divided equally into 4 groups. One group served as the control (group 1), whereas the other three groups (groups 2-4) were administered L-NAME (25 mg/kg, intraperitoneally). Groups 3 and 4 were given oral nicardipine daily at a dose of 3 mg/kg and Nigella sativa oil at a dose of 2.5 mg/kg for 8 weeks, respectively, concomitantly with L-NAME administration. RESULTS: Nigella sativa oil prevented the increase in systolic blood pressure in the L-NAME-treated rats. The blood pressure reduction was associated with a reduction in cardiac lipid peroxidation product, NADPH oxidase, angiotensin-converting enzyme activity and plasma nitric oxide, as well as with an increase in heme oxygenase-1 activity in the heart. The effects of Nigella sativa on blood pressure, lipid peroxidation product, nicotinamide adenine dinucleotide phosphate oxidase and angiotensin-converting enzyme were similar to those of nicardipine. In contrast, L-NAME had opposite effects on lipid peroxidation, angiotensin-converting enzyme and NO. CONCLUSION: The antihypertensive effect of Nigella sativa oil appears to be mediated by a reduction in cardiac oxidative stress and angiotensin-converting enzyme activity, an increase in cardiac heme oxygenase-1 activity and a prevention of plasma nitric oxide loss. Thus, Nigella sativa oil might be beneficial for controlling hypertension.

The Effects of Cosmos caudatus (Ulam Raja) on Detoxifying Enzymes in Extrahepatic Organs in Mice.

‘Ulam Raja’ or Cosmos caudatus is a common appetizer (ulam) consumed by the Malay community in Malaysia. However, in vivo studies pertaining to its antioxidant and chemoprotective properties are lacking. This study was done to determine the effects of Cosmos caudatus on detoxifying enzymes in extrahepatic organs (lungs, kidneys and stomach) in mice. Thirty adult male white mice were treated orally for 21 days with different doses of ‘Ulam Raja’ aqueous extract (UR) (100, 500, 1000mg/kg). The control group was given normal saline by oral gavage. Mice fed with diet containing 0.5% butylated hydroxyanisole (BHA) were used as positive control. After 21 days, the mice were sacrificed and extrahepatic organs were harvested. The activities of several detoxifying enzymes [catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), DT-diaphorase (DTD)] were measured. Lipid peroxidation level was determined by measuring malondialdehyde (MDA) concentration. In lungs, 100, 500 & 1000 mg/kg UR oral supplementation resulted in significant increases in CAT, SOD and GST activities. DTD activity in lungs was significantly increased in mice treated with 1000mg/kg UR. MDA levels in lungs were significantly decreased in mice treated with 100mg/kg & 500 mg/kg UR but was significantly increased in mice treated with 1000mg/kg UR. In kidneys, DTD activity was significantly increased in mice treated with 1000mg/kg UR. In stomach, CAT activity was significantly increased in mice treated with 1000mg/kg UR. The results showed that Cosmos caudatus supplementation in mice could protect extrahepatic organs from xenobiotic and oxidative injury. This indicates that consumption of ‘Ulam Raja’ might be a useful chemoprotective measure.

High C reactive protein associated with increased pulse wave velocity among urban men with metabolic syndrome in Malaysia

To determine the association between carotid femoral pulse wave velocity [PWV[CF]]; augmentation index [AI]; and high-sensitivity C reactive protein [hs-CRP] with metabolic syndrome [MetS], and to determine the influence of ethnicity on PWV[CF] and AI, and the association between high hs-CRP and increased PWV, and AI in MetS. A cross-sectional study was conducted at Universiti Kebangsaan Malaysia Medical Center, Kuala Lumpur, Malaysia from September 2009 to September 2011. Three hundred and eighty men [Chinese and Malays] were recruited from the study. The PWV[CF] and AI were measured by Vicorder [SMT Medical, Wuerzburg, Germany]. The hs-CRP level was also determined. We defined MetS using the International Diabetes Federation [IDF] and harmonized criteria. Malays had higher AI compared to the Malaysian Chinese. Patients with MetS had higher PWV[CF] [IDF criteria: 8.5 [8.3-8.7] versus 8.2 [8.0-8.4] m/s, p=0.03; harmonized criteria: 8.5 [8.4-8.7] versus 8.2 [8.0-8.4] m/s, p=0.007] and hs-CRP [IDF criteria: 0.9 +/- 2.0 versus 0.4 +/- 1.1 mg/L, p=0.0007; harmonized criteria: 0.8 +/- 1.9 versus 0.4 +/- 1.1 mg/L, p=0.002] compared to non-MetS. In subjects with MetS, those with high hs-CRP [>3mg/L] had higher PWV[CF]. Augmentation index values were significantly higher in Malays compared with Malaysian Chinese. Metabolic syndrome was associated with increased PWV[CF] and hs-CRP. Patients with MetS and high hs-CRP were associated with higher PWV[CF]. The measurement of hs-CRP reflects the degree of subclinical vascular damage in MetS

The effects of heated vegetable oils on blood pressure in rats

OBJECTIVES: The goal of this study was to determine the possible mechanism that is involved in the blood pressureraising effect of heated vegetable oils. METHODS: Adult male Sprague-Dawley rats were divided into 11 groups; the control group was fed with rat chow, and the other groups were fed with chow that was mixed with 15 percent weight/weight palm or soy oils, which were either in a fresh form or heated once, twice, five, or ten times. Blood pressures were measured at the baseline and throughout the 24-week study. Plasma nitric oxide levels were assessed prior to treatment and at the end of the study. Following 24 weeks, the rats were sacrificed to investigate their vascular reactivity using the thoracic aorta. RESULTS: Palm and soy oils had no detrimental effects on blood pressure, and they significantly elevated the nitric oxide contents and reduced the contractile responses to phenylephrine. However, trials using palm and soy oils that were repeatedly heated showed an increase in blood pressure, enhanced phenylephrine-induced contractions, reduced acetylcholine- and sodium nitroprusside-induced relaxations relative to the control and rats that were fed fresh vegetable oils. CONCLUSIONS: The blood pressure-raising effect of the heated vegetable cooking oils is associated with increased vascular reactivity and a reduction in nitric oxide levels. The chronic consumption of heated vegetable oils leads to disturbances in endogenous vascular regulatory substances, such as nitric oxide. The thermal oxidation of the cooking oils promotes the generation of free radicals and may play an important contributory role in the pathogenesis of hypertension in rats.

Fresh soy oil protects against vascular changes in an estrogen-deficient rat model: an electron microscopy study

OBJECTIVE: To observe the effects of consuming repeatedly heated soy oil on the aortic tissues of estrogen-deficient rats. METHODS: Thirty female Sprague Dawley rats (200- 250 g) were divided equally into five groups. One group served as the normal control (NC) group. The four treated groups were ovariectomized and were fed as follows: 2 percent cholesterol diet (OVXC); 2 percent cholesterol diet + fresh soy oil (FSO); 2 percent cholesterol diet + once-heated soy oil (1HSO); and 2 percent cholesterol diet + five-times-heated soy oil (5HSO). After four months, the rats were sacrificed, and the aortic tissues were obtained for histological studies. RESULTS: After four months of feeding, the NC, FSO and 1HSO groups had a lower body weight gain compared to the OVXC and 5HSO groups. The tunica intima/media ratio in the 5HSO group was significantly thicker (p < 0.05) compared to the NC, OVXC and FSO groups. Electron microscopy showed that endothelial cells were normally shaped in the FSO and NC groups but irregular in the 1HSO and 5HSO groups. A greater number of collagen fibers and vacuoles were observed in the 5HSO group compared to the other treatment groups. CONCLUSIONS: Fresh soy oil offered protection in the estrogen-deficient state, as these rats had similar features to those of the NC group. The damage to the tunica intima and the increase in the ratio of tunica intima/media thickness showed the deleterious effect of consuming repeatedly heated soy oil in castrated female rats.

Changes in serum lipid profile and malondialdehyde following consumption of fresh or heated red palm oil

The effect of chronic consumption of fresh and heated red palm oil [RO] on lipid profile and lipid peroxidation was investigated. Thirty male rats were divided into 3 groups, each treated with the following prescribed food: [i] basal diet fortified with 15% weight/weight [w/w] fresh red palm oil [FRO], or [ii] heated once red palm oil [1H-RO] or [iii] heated 5 times red palm oil [5H-RO] for 20 weeks. There was a significant increase [p<0.05] in MDA concentration in all 3 groups compared to their respective baseline concentrations and a significant decrease [p<0.05] in total cholesterol [TC] concentration. However, the transient changes observed in serum triglyceride and HDL-cholesterol concentration did not attain significant values. The LDL-cholesterol concentration in 5H-RO group increased significantly [p<0.05] compared to pretreatment value, FRO and 1H-RO groups. Ratio of TC/HDL in 5H-RO group initially increased, but dropped to baseline level at the end of the study. There was no significant difference in the ratio of TC/HDL between the groups. In conclusion, both fresh and heated RO appeared comparable in their effect on serum cholesterol and lipid peroxidation. It appears that long term feeding with fresh and heated RO did not have an adverse effect on serum TG, HDL and TC/HDL ratio. However, it appears that prolonged heating increases LDL-cholesterol level. Further studies are required to ascertain whether the increase in LDLcholesterol and MDA with heated oil would render it more atherogenic