ABSTRACT
Retinoic acid, a derivative of vitamin A, is known to possess in vivo anti-inflammatory, anti-platelet and fibrinolytic activities. We have investigated the in vitro thrombin and platelet aggregation inhibitory activities of vitamin A (retinol) and its derivatives, retinoic acid and retinaldehyde. The thrombin enzymatic assay was performed fluorimetrically to assess the inhibition of thrombin (Sigma and plasma). Retinoic acid, retinaldehyde and retinol exhibited potent inhibition of thrombin, with IC50 values of 67µg/ml, 74µg/ml and 152µg/ml, respectively for the inhibition of thrombin (Sigma); and 49µg/ml, 74µg/ml and 178µg/ml, respectively for the inhibition of thrombin (plasma). Amongst vitamin A and its derivatives, retinoic acid showed the highest inhibition of both the forms of thrombin. Vitamin A and its derivatives also displayed remarkable inhibition of platelet aggregation. This is the first report of vitamin A and its derivatives showing inhibition of thrombin and platelet aggregation in vitro.
ABSTRACT
Fish oil (FO) rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is known to reduce the risk of cardiovascular diseases (CVDs). Little information is known regarding the influence of lipid composition in the background diet on the modulatory effect of FO supplementation on CVDs. The present study was designed to investigate the influence of various background dietary lipids and FO on selected cardiovascular risk factors in rats. Adult Wistar rats were fed semisynthetic diet with FO at 1.0% or 2.0% along with other lipids, namely, medium-chain triacylglycerols (MCTs), monounsaturated fatty acids (MUFAs), n-6 polyunsaturated fatty acids (PUFAs) and n-3 PUFAs, for 5 weeks. Some of the potent CVD risk factors were estimated in the rats. FO at 1.0% and 2.0% has significantly reduced serum lipid peroxides, total cholesterol, triglycerides (TAGs), tumor necrosis factor-α, interleukin-6 and C-reactive protein; liver and adipose TAG and cholesterol levels in MCT, MUFA and n-6 PUFA diet groups. Notably, these alterations were comparatively higher in 1.0% FO-substituted MCT and MUFA diet groups. Interestingly, feeding of FO along with n-3 PUFAs did not show additive effect in attenuation of these factors. Serum liver EPA and DHA levels were remarkably elevated in rats fed FO-enriched MCT or MUFA diets. Our results suggest that MCTs or MUFAs in the background diet might promote the beneficial effects of FO on CVDs.
