Evaluation of therapeutic effect of omega-6 linoleic acid and thymoquinone enriched extracts from Nigella sativa oil in the mitigation of lipidemic oxidative stress in rats.

OBJECTIVE: Nigella sativa belongs to the Ranunculaceae family. The therapeutic role of methanolic extract (ME) and volatile oil (VO) fractionated from N. sativa seed oil was investigated for antiperoxidative and antioxidant effects in atherogenic suspension fed rats. METHODS: We examined the protective effects of ME and VO on the enzymatic and nonenzymatic antioxidants status in erythrocytes and the livers of atherogenic suspension fed rats. As a marker of lipid peroxidation, we estimated the conjugated diene, lipid hydroperoxide, and malondialdehyde concentrations in plasma in the following groups of rats: normolipidemic control, hyperlipidemic control, hyperlipidemic methanolic extract, and hyperlipidemic volatile oil. ME 500 mg or VO 100 mg/kg body weight of male rat was orally administrated for 30 d. RESULTS: Pretreatment of hyperlipidemic rats with these test extracts resulted in a significant decrease (P < 0.001) in the level of lipid peroxidation markers, conjugated diene, lipid hydroperoxide, and malondialdehyde (16-50%) compared to the hyperlipidemic control rats. In addition, ME and VO significantly (P < 0.001) elevated the hepatic and erythrocyte superoxide dismutase, catalase, and glutathione reductase activities (19-58%) compared to the hyperlipidemic rats. In liver homogenate of hyperlipidemic-ME and hyperlipidemic-VO, the glutathione-S-transferase activity was protected by 93% and 89%, and in erythrocytes, the glutathione peroxidase activity was protected by 90% and 77%, respectively. Interestingly, reduced glutathione level and activities of ATPases were protected to near normal levels. Pretreatment of rats with the test extracts replenished effectively (P < 0.001) the plasma total antioxidant power by an average of 88% against free radicals. CONCLUSIONS: The lipidemic oxidative stress was effectively mitigated by antiperoxidative activities of ME and VO. Thus, these test extracts, especially ME, may be used as antioxidant as well as hypolipidemic agents in the form of natural food supplement to prevent or treat diseases caused by free radicals.

Mitigating role of thymoquinone rich fractions from Nigella sativa oil and its constituents, thymoquinone and limonene on lipidemic-oxidative injury in rats.

Therapeutic role of Nigella sativa (NS) seed oil fractions, methanolic extract (ME) and volatile oil (VO) and their constituents, thymoquinone (TQ) and limonene (LMN) in relation to lipidemic-oxidative stress in Wistar rats was determined. The total phenolic contents of NS seed oil and their ME and VO extracts were 320.00 ± 3.00, 300.12 ± 0.04 and 288.41 ± 0.01 mg gallic acid equivalents per 100 g of NS oil, respectively. Their Fe(+2) chelating activities were 870.00 ± 2.00, 222.31 ± 5.80 and 38.59 ± 1.43 mg EDTA equivalents per 100 g of NS oil, respectively. These fractions and compounds exhibited strong antioxidant activities against 2,2-diphenyl-1-picryl hydrazyl, 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid, nitric oxide and hydroxyl radicals. Potential antiperoxidative effects of these fractions and compounds were also observed in liposome, and lipidemic-induced lipid peroxidation in atherogenic suspension fed rats, pretreated with 100 mg ME, 20 mg VO, 10 mg pure TQ or 200 mg LMN for 30 days. ME containing ω-6 linoleic acid and palmitic acid natural compounds was highly effective against lipidemic oxidative stress than VO extract possessing thymol and isothymol phenolic natural antioxidant compounds. TQ, principal compound shared to both the extracts. The test fractions and compounds effectively reduced the erythrocyte and liver lipid peroxidation markers, conjugated diene, lipid hydroperoxide and malondialdehyde to near normal levels in the order ME > TQ > VO > LMN, by directly counteracting free radicals as well as suppressing hepatic HMG-CoA reductase activity. Our findings demonstrated that these natural products, preferably ME possess significant antioxidant activities, and may be recommended as new potential sources of natural antioxidants.

Elucidation of mechanisms of actions of thymoquinone-enriched methanolic and volatile oil extracts from Nigella sativa against cardiovascular risk parameters in experimental hyperlipidemia.

BACKGROUND: Nigella sativa belonging to the Ranunculaceae family has been reported to use for thousands of years as protective and curative traditional medicine against a number of diseases. GC-MS analysis of methanolic extract (ME) and volatile oil (VO) extracted from Nigella sativa seed oil was performed by two different mass spectrometry libraries, WIlEY8 and NIST05s. The cholesterol lowering and antioxidant actions of VO and ME fractions were investigated in atherogenic suspension fed rats. METHODS: In this study, four groups of male Wistar rats were used: normolipidemic control (NLP-C), hyperlipidemic control (HLP-C), methanolic extract (HLP-ME) and volatile oil treated (HLP-VO) groups for 30 days of duration. P value < 0.05 was assumed as significant data in groups. RESULTS: Administration of atherogenic suspension to male Wistar rats for 30 days resulted in a marked increase of plasma triglycerides and total cholesterol, and significant change in plasma lipoprotein levels along with a decrease in antioxidant arylesterase activity in hyperlipidemic control (HLP-C) group. The oral feeding of 100 mg ME or 20 mg VO per rat/day effectively reduced the plasma triglycerides to near normal level, while high density lipoprotein cholesterol and its subfraction along with arylesterase activity levels were significantly increased. The test fractions elicited a significant decrease in hepatic HMG-CoA reductase activity. The fractions significantly blocked the ex vivo basal and in vitro maximal formation of conjugated diene and malondialdehyde, and lengthened the lag times of low density lipoprotein, small dense low density lipoprotein and large buoyant low density lipoprotein. ME possessing ω-6 linoleic acid along with palmitic acid active compounds was more effective than VO extract containing thymol and isothymol phenolic antioxidant compounds, thymoquinone phenolic compound common to the both extracts, via reduction in hepatic HMG-CoA reductase activity as well as antioxidant mechanisms. CONCLUSION: The both extracts especially, ME significantly improve cardiovascular risk parameters in treated rats, and can be used in reactive oxygen species disorders such as cardiovascular diseases.

Hypolipidemic and antioxidant activities of thymoquinone and limonene in atherogenic suspension fed rats.

The hypolipidemic and antioxidant actions of thymoquinone (TQ) and limonene (LMN) were investigated by giving 1 ml of 10mg TQ or 200mg LMN suspension, by gavage in two equal doses (morning and evening) of 0.5 ml each for 30 days, in rats, fed an atherogenic suspension. These compounds effectively ameliorated all the altered cardiovascular risk parameters via a reduction in HMG-CoA reductase activity, along with an increase in arylesterase activity. The compounds significantly blocked the shift in buoyancy from less atherogenic lb-LDL to highly atherogenic sd-LDL, restoring the percent distribution of LDL-C and apoB into sd-LDL and lb-LDL to near normal levels. These compounds also blocked basal and maximal formation of CD and malondialdehyde, and lengthened the lag times of LDL, sd-LDL and lb-LDL in the order TQ>LMN. Our results strongly suggest an important therapeutic use of test compounds, especially TQ, in the prevention of cardiovascular disease risks parameters.

The therapeutic impacts of tocotrienols in type 2 diabetic patients with hyperlipidemia.

In type 2 diabetics, the progression of atherosclerosis is more rapid than the general population and 80% of these patients will die of an atherosclerotic event. Since in these patients hyperglycemia per se confers increased risk for cardiovascular disease (CVD), the presence of even borderline-high-risk LDL-C signals the need for more aggressive LDL-lowering therapy. Most of the lipid lowering agents, currently in use in the treatment of dyslipidemia in type 2 diabetics, have a host of side effects. In contrast, dietary tocotrienols are Vitamin E and have effective lipid lowering property in addition to their potent antioxidant activity. In this study, we have investigated the therapeutic impacts of tocotrienols on serum and lipoprotein lipid levels in type 2 diabetic patients. Based on known tocotrienol rich fraction (TRF)-mediated decrease on elevated blood glucose and glycated hemoglobin A(1C) (HbA(1C)) in diabetic rats, we have also investigated the effect of TRF on these parameters. A randomized, double blind, placebo-controlled design involving 19 type 2 diabetic subjects with hyperlipidemia was used. After 60 days of TRF treatment, subjects showed an average decline of 23, 30, and 42% in serum total lipids, TC, and LDL-C, respectively. The goal in type 2 diabetics is to reduce LDL-C levels < or = 100mg/dl. In the present investigation tocotrienols mediated a reduction of LDL-C from an average of 179 mg/dl to 104 mg/dl. However, hypoglycemic effect of TRF was not observed in these patients because they were glycemically stable and their glucose and HbA(1) levels were close to normal values. In conclusion, daily intake of dietary TRF by type 2 diabetics will be useful in the prevention and treatment of hyperlipidemia and atherogenesis.

Hypolipidemic and antioxidant properties of tocotrienol rich fraction isolated from rice bran oil in experimentally induced hyperlipidemic rats.

We investigated a dose-dependent hypolipidemic and antioxidant effect of tocotrienol rich fraction (TRF) isolated from rice bran oil on experimentally induced hyperlipidemic rats. Feeding of atherogenic diet (5% hydrogenated fat, 0.5% cholic acid and 1% cholesterol) for three weeks resulted in a significant increase in plasma triglyceride (3.3-fold) and total cholesterol (2.4-fold) levels. There was a 5-fold increase in the level of LDL cholesterol with only a small increase in HDL cholesterol. On the other hand, HMG-CoA reductase activity was significantly reduced in these animals. The formation of TBARS, thiobarbituric acid reactive substances, (86%) and conjugated dienes (78%) were also significantly higher in these rats compared to normals. After the induction of hyperlipidemia for three weeks, rats were supplemented with different doses of TRF for one week. TRF supplementation decreased the lipid parameters in a dose-dependent manner with an optimum effect at a dose of 8 mg TRF/kg/day. HMG-CoA reductase activity, which was increased after the withdrawal of atherogenic diet, remained significantly decreased during the TRF treatment. Feeding of TRF also decreased TBARS and conjugated dienes significantly. These results suggest that TRF supplementation has significant health benefits through the modulation of physiological functions that include various atherogenic lipid profiles and antioxidants in hypercholesterolemia.