Garlic reduces plasma lipids by inhibiting hepatic cholesterol and triacylglycerol synthesis

Abstract

Prompted by the reported hypolipidemic activity of garlic, the present study was undertaken to elucidate the mechanism(s) underlying the cholesterol-lowering effects of garlic. Rat hepatocytes in primary culture were used to determine the short-term effects of garlic preparations on [1-14C]acetate and |2-3H]glycerol incorporation into cholesterol, fatty acids and glycerol lipids. When compared with the control group, cells treated with a high concentration of garlic extracts [i.e., petroleum ether-(PEF), methanol-(MEF) and water-extractable (WEF) fractions from fresh garlic] showed decreased rates of [1-14C]acetate incorporation into cholesterol (by 37-4i4%) and into fatty acids (by 28-64%). Kyolic containing S-allyl cysteine and organosulfur compounds inhibited cholesterogenesis in a concentration dependent manner with a mn~dmum inhibition of87% at 0.4 raM. At this concentration, Kyolic decreased [1-14C]acetate incorporation into fatty acids by 67%. Sallyl cysteine at 2.0 and 4.0 mM inhibited cholesterogenesis by 20-25%. PEF, MEF and WEF depressed the rates of [2-3H]glyeerol incorporation into triacylglycerol, diacylglycerol and phospholipids in the presence of acetate, but not in the presence of oleate. The results suggest that the hypocholesterolemic effect of garlic stems, in part, from decreased hepatic cholesterogenesis, whereas the triacylglycerol-lowering effect appears to be due to inhibition of fatty acid synthesis. Primary hepatocyte cultures as used in the present study have been proven useful as tools for screening the anticholesterogenie properties of garlic principles.Lipids 29, 189-193 (1994).Aside from its general use as a condiment, garlic (A1lium sativum) is known for its pharmacological and nutritional properties (1). Among the potential therapeutic applications of garlic, its antilipidemic effects have been demonstrated in studies on humans (2-6), as well as on animals, including rats (7-13), rabbits (14,15), chicken (16-17) and swine (18). Garlic is known to contain a variety of sulfur compounds, in addition to amino acids, vitamins and minerals (19). Although some of these sulfur compounds, such as S-methylcysteine sulfoxide and Sallyl cysteine sulfoxide, are known to reduce cholesterol levels in the liver and plasma (10), the principle(s) foremost responsible for the hypolipidemic action of garlic is presently not known. Likewise, the mechanism(s) underlying the hypocholesterolemic effects of garlic constituents(s) have not been fully elucidated (20).

Effects of turmeric and garlic on blood cholesterol level

“…This finding is supported by the previous work (Chi et al, 1982;Yeh and Yeh, 1994). According to these authors, the reduced cholesterol level in these animals might be attributed to the capacity of garlic to reduce lipid content in arterial wall.…”

Alliin obtained from leaf extract of garlic grown underin situconditions possess higher therapeutic potency as analyzed in alloxan-induced diabetic rats

“…However, HDL-cholesterol value increased by about 6.5%. Epidemiological studies showed that supplementation of leaf extract decreases serum cholesterol, hepatic cholesterol, and/or triglyceride levels in animals (Yeh & Yeh, 1994), though the mechanism by which garlic does so is not fully elucidated. Studies have demonstrated that garlic-supplemented diets decreased activities of various lipogenic enzymes such as FAS, G6PDH, and the cholesterogenic enzyme, HMG-CoA reductase (Sheela & Augusti, 1995); therefore, it is speculated that the lipidlowering effects of leaf extracts may result from decreased lipogenesis and cholesterogenesis.…”

Scavenging Activity of Different Garlic Extracts and Garlic Powder and their Antioxidant Effect on Heated Sunflower Oil

“…Garlic is known in history as treatment for cold, cough and asthma and is reported to strengthen immune system (Lawrence and Lawrence, 2011). It has many medicinal effects such as lowering of blood cholesterol level (Yeh and Yeh, 1994), antiplatelet aggregation (Steiner et al, 1996), anti-inflammatory activity (Baek et al, 2001) and inhibition of cholesterol synthesis (Piscitelli et al, 2002). Garlic has been long known to have antibacterial (Rees et al, 1993;Sasaki et al, 1999;Shobana et al, 2009), antifungal (Pai and Platt, 1995), anticancer (Unnikrishnan and Kuttan, 1990;Kaschula et al, 2010), antioxidant (Galano and Francisco-Marquez, 2009) and antiviral (Weber et al, 1992).…”