Characterization Of The Function And Mechanism Of Okra In The Management Of Hyperlipidemia

Hyperlipidemia is one of the major risk factor for the development of cardiovasculardisease. Hypolipidemic nutraceuticals and functional foods help improve serum lipid profilesas reducing total cholesterol, triglyceride, and low-density lipoprotein cholesterol, whileelevating high-density lipoprotein cholesterol.Okra is an annual vegetable of Malvaceae family. Despite extensive investigation on itsbeneficial potential and chemical composition, little is known about the hypolipidemicactivity of okra. Therefore we investigated the hypolipidemic activity of okra and itsinteraction with gene expression of several key components involved in lipid homeostasis.Male C57BL/6mice were randomly divided into three groups and fed with hyperlipidemicdiet or two hyperlipidemic diets supplemented with1%or2%okra powder for eight weeks.Results demonstrated that okra dose-dependently decreased serum and hepatic totalcholesterol and triglyceride, and enhanced fecal excretion of bile acids. Quantitative real-timeRT-PCR analysis of gene expression revealed that okra upregulated cholesterol7-hydroxylase (CYP7A1) expression, downregulated expression of sterol regulatoryelement-binding protein1c (SREBP1c) and fatty acid synthase (FAS), with no effect on sterolregulatory element-binding protein2(SREBP2),3-hydroxy-3-methylglutaryl-CoA reductase(HMGR), low-density lipoprotein receptor (LDLR) and carnitine palmitoyltransferase-1A(CPT1A). It was suggested that hypolipidemic activity of okra was mediated most likely byupregulation of cholesterol degradation through CYP7A1and by inhibition of lipogenesisthrough SREBP1c and FAS. Okra raw and fractionated polysaccharide showed strong bileacid binding capacity in vitro, which may contribute to the hypolipidemic activity observed.Then we investigated the bioactive components in okra and their related mechanismthrough3T3-L1preadipocytes and HepG2cells. Okra polysaccharide could inhibit cellproliferation in3T3-L1preadipocytes and TG accumulation in mature adipocytes. And the E2fraction, eluted by0.5M PBS, exhibited as the effective components. Okra rawpolysaccharides showed strong antioxidant activities in preventing hemolysis induced by2.2’-azobis (2-amidinopropane) dihydrochloride (AAPH). Phenolic acid is claimed aseffective hypolipidemic nutraceuticals. And phenolic acid was extracted from okra powder as10.46±0.40mg gallic acid equivalents/g. Salicylic acid, one of the abundant phenolic acidin vegetables and fruits, was chosen for further investigation. Results in cell experimentsshowed that salicylic acid was capable of blocking proliferation of3T3-L1preadipocytes andsuppressed lipid accumulation in3T3-L1adipocytes and oleic acid-induced TG accumulation in HepG2cells.In conclusion, okra has potential application in the management of hyperlipidemia andits associated metabolic disorders, which will dramatically facilitate the development of okraas nutraceuticals and functional foods in the management of hyperlipidemia.