Belur Ramaswamy Lokesh

Enhanced Hypocholesterolemic Effects of Interesterified Oils Are Mediated by Upregulating LDL Receptor and Cholesterol 7-α- Hydroxylase Gene Expression in Rats

The concentration of LDL cholesterol in plasma is strongly influenced by the amount and type of lipid in the diet. Our studies have shown that positional changes in the fatty acids in blended oil introduced using lipase-catalyzed interesterification differentially modulate circulating LDL levels in rats compared with those observed in rats given a physical blend of oils. To investigate the molecular basis of these differences, transcriptional profiling of genes involved in cholesterol homeostasis was studied after feeding rats with a semipurified diet containing 10% fat from native oils; coconut oil (CNO), rice bran oil (RBO), or sesame oil (SESO); blended (B); CNO+RBO(B) or CNO+SESO(B) and interesterified oil (I); CNO+RBO(I) or CNO+SESO(I) for 60 d. Hepatic LDL receptor (LDL-R) expression significantly increased in rats fed interesterified oils by 100-200% compared with rats fed blended oils and by 400-500% compared with rats fed CNO. Positional alteration in fatty acids of oils used in the diet induced changes in LDL-R expression, which was accompanied by parallel changes in cholesterol-7α-hydroxylase (CYP7A1) and SREBP-2 genes. This suggested that not only the fatty acid type but also its position in the TG of dietary lipids play an important role in maintaining plasma cholesterol levels by suitably modulating gene expression for LDL-R in rat liver.

Modulatory effect of α-linolenic acid-rich garden cress ( Lepidium sativum L.) seed oil on inflammatory mediators in adult albino rats

Vegetable oils containing α-linolenic acid (ALA; 18 : 3n-3) have been shown to modulate the functions of immunocompetent cells. The aim of the present study was to understand the modulatory effect of ALA-rich garden cress (Lepidium sativum L.) seed oil (GCO) on lipid composition, spleen lymphocyte (SL) proliferation and inflammatory mediator production by peritoneal macrophages (PMΦ) in rats. Female Wistar rats were fed diets containing either GCO (2·5, 5·0 and 10 %, w/w) or sunflower oil (SFO, 10 % w/w) for 8 weeks. Ex vivo proliferation of SL was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. IL-2 and TNF-α in SL and PMΦ were analysed by ELISA. Inflammatory mediators such as NO, leukotriene B(4) (LTB(4)) and H(2)O(2) were measured in mitogen-activated PMΦ. GCO significantly increased the levels of ALA, EPA and DHA, but reduced linoleic acid and arachidonic acid in SL and PMΦ lipids. GCO (10 %) significantly decreased the concanavalin A (Con-A)- and phytohaemagglutinin-mediated proliferation of SL by 54 and 38 %, respectively, in comparison with SFO. A marginal decrease in IL-2 and TNF-α was observed in Con-A-stimulated SL and lipopolysaccharide-stimulated PMΦ. LTB(4) levels in Ca ionophore-stimulated PMΦ were reduced by 40 % in GCO-fed rats. NO release in response to various stimuli was significantly decreased in PMΦ of GCO-fed rats. The present study is the first report on the modulatory efficacy of GCO on immunomediators in rats. GCO modulated inflammatory mediators such as NO and LTB(4), and thus may play a role in alleviating inflammatory conditions favourably.

Effect of feeding blended and interesterified vegetable oils on antioxidant enzymes in rats.

The present study was undertaken to evaluate the effect of feeding blended and interesterified oils prepared using coconut oil (CNO) with rice bran oil (RBO) or sesame oil (SESO), with a polyunsaturated/saturated (P/S) ratio of 0.8-1.0, on oxidative stress and endogenous antioxidant system. Feeding blended oils resulted in significantly increased hepatic lipid peroxide levels in rats given blended oil CNO+RBO or CNO+SESO by 1.3 and 1.6-fold, respectively compared to rats fed diet containing CNO. The lipid peroxide level in erythrocyte membrane also increased in rats fed blended oil compared to rats fed with CNO. Rats fed interesterified oils prepared from these blended oils also showed increased lipid peroxide level compared to rats given CNO diet, however it was not significantly different from rats fed with their respective blends. There was a significant increase in the activity of endogenous antioxidant enzymes super oxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase after feeding blended and interesterified oils. The activities of Na(+)/K(+)-ATPase and Ca(2+)/Mg(2+)-ATPase were increased in rats fed blended and interesterified oils. These results indicated that the P/S ratio of dietary fat is an important factor in determining the oxidative stress, activity of endogenous antioxidant enzymes and activity of membrane bound enzymes.

Lipase-Mediated Interesterification of Oils for Improving Rheological, Heat Transfer Properties and Stability During Deep-Fat Frying

This paper deals with the rheological and heat transfer properties and stability of rice bran oil (RBO); refined, bleached and deodorised palm olein (RBDPO) and their blends in terms of viscosity, heat transfer coefficient and thermo-oxidative stability. These values were compared with interesterified oils prepared by subjecting blended oils to 1, 3-specific lipase treatment. Results showed that the apparent viscosities and convective heat transfer coefficients of these oils are within the range of 52.8–61.5xa0mPaxa0s and 229.1–258.0xa0Wu2009m−2xa0°C−1, respectively. The quality parameters, namely free fatty acid (0.12–0.68%), peroxide value (1.47–5.31xa0meq O2/kg), diene value (0.16–2.39%), triene value (0.07–0.7%), polar material (2.4–8.8%) and colour unit (1.0–5.5 red; 7–50 yellow), were significantly (pu2009<u20090.05) different in fresh and fried oils for all the oil systems. The total polar material correlated well (ru2009=u20090.97) with change of viscosity of native, blended and interesterified oils. The interesterified oils are more resistant to degradation during frying in terms of the formation of colour and polar materials in comparison to their blended counterparts. The sensory odour profiles generated by descriptive analysis showed that both RBO and RBDPO had desirable characteristic odour notes and these notes did not alter significantly after frying for ten cycles. Both blended oil and interesterified oil samples exhibited similar sensory notes for the fresh and fried oil samples. The poori fried using blended and interesterified oil have shown desirable and good consumer acceptance score.