Effect of a new acyl-coenzyme A:cholesterol acyltransferase inhibitor, HL-004, on cholesterol esterification and lipid metabolism in hep G2 cells

S-propyl cysteine reduces the secretion of apolipoprotein B100 and triacylglycerol by HepG2 cells

A number of sulfur-containing amino acids and peptides are found in allium plants such as onion and garlic that have physiologic functions. In HepG2 cells, S-propyl cysteine decreased the secretion of apolipoprotein B100. The compound reduced the secretion of newly synthesized triacylglycerol and cholesterols from radiolabeled acetate. We associated the decrease of apolipoprotein B100 secretion to the length of the acyl-chain of the sulfur-containing amino acids. The present study suggests that foods containing S-propyl cysteine including onions have beneficial effects.

Inhibitory effect of TS-962 on the formation of early atherosclerotic lesions in high fat-fed hyperlipidemic hamsters

The hypocholesterolemic and anti-atherosclerotic effect of TS-962, a specific ACAT inhibitor, was investigated in a hamster model fed a high fat diet containing 10% coconut oil and 0.05% cholesterol. Lipid accumulated atherosclerotic lesions were detected by using oil red O staining in the lesion-prone aortic arch. A high dose, estimated to be 15 mg/kg, of TS-962 decreased serum cholesterol to normal levels with reduction of liver cholesterol contents below normal levels, and as a consequence, entirely inhibited the lipid accumulation in the aortic arch. Furthermore, a low dose, estimated to be 1.5 mg/kg, of TS-962 remarkably inhibited aortic lipid accumulation by 73% compared with the control group, without changing either serum cholesterol level or liver cholesterol content. These findings suggest that TS-962 is effective in the primary prevention of atherosclerosis by directly suppressing the formation of foam cells in arteries.

The ACAT inhibitor HL-004 inhibits cholesterol absorption and lowers serum cholesterol in rats

1. HL-004 decreased absorption of cholesteryl ester from the intestine into the lymph in a rat lymph-fistula model. 2. HL-004 reduced serum cholesterol level in acute cholesterol-fed rats. 3. HL-004 simultaneously decreased hepatic cholesteryl ester content and increased free cholesterol in cholesterol-fed rats. 4. These findings suggest that: (1) the hypocholesterolemic effect of HL-004 is principally due to inhibition of cholesterol absorption via inhibition of ACAT in the intestine; and (2) changes in hepatic cholesterol metabolism due to direct inhibition by HL-004 of hepatic ACAT may account in part for reduction of serum cholesterol level by HL-004.

HL-004, the ACAT inhibitor, prevents the progression of atherosclerosis in cholesterol-fed rabbits

HL-004, N-(2,6-diisopropylphenyl) tetradecylthioacetamide, a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, was evaluated concerning the possible prevention of hyperlipidemia and atherosclerosis in 1% cholesterol-fed rabbits. HL-004 (0.2, 5 and 25 mg/kg) was orally administered once a day for 12 weeks. HL-004 inhibited the rise of total serum cholesterol at a dose of 5 mg/kg and over. In the thoracic aorta, HL-004 at the doses of 5 mg/kg and 25 mg/kg reduced the total cholesterol content by 56.3% and 84.2% compared with control, and decreased ACAT activity, dose-dependently. HL-004 also attenuated the development of aortic lesions. The area of atherosclerotic lesions was reduced by 30.3% with 5 mg/kg of HL-004 and 100% with 25 mg/kg. In this study, we suggest that the main reason for HL-004 preventing the progression of atherosclerosis is its hypocholesterolemic effect due to the inhibition of cholesterol absorption in the intestine.

ACAT inhibitor HL-004 accelerates the regression of hypercholesterolemia in stroke-prone spontaneously hypertensive rats (SHRSP): stimulation of bile acid production by HL-004

The effect of the acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor HL-004 on bile acid production was studied during the regression phase of pre-established hypercholesterolemia in stroke-prone spontaneously hypertensive rats (SHRSP). These rats were fed a hypercholesterolemic diet containing 5% cholesterol, 2% cholic acid, and 20% suet for 30 days to induce hypercholesterolemia. The regression phase was started by switching the diet to normal chow, followed by another 30 days of the diet. The decrease in serum cholesterol level was accelerated by treatment with 0.09% HL-004. At the end of regression, hepatic ACAT activity was significantly lower in the HL-004 treated animals, an event concomitant with the significant decrease in cholesteryl ester content in the liver. In contrast hepatic cholesterol 7 alpha-hydroxylase activity was maintained at a higher level in the HL-004 treated animals. HL-004 increased the secretion of bile acid and biliary lipids in bile duct-cannulated SHRSP. In HepG2:cells, HL-004 at 1-30 microM dose-dependently stimulated bile acid synthesis from [3H]cholesterol. When cholesterol 7 alpha-hydroxylase activity of the liver was compared ex vivo in the presence and in the absence of exogenous cholesterol, it was suggested that the higher 7 alpha-hydroxylase activity of the HL-004 group could be attributed not only to expansion of the endogenous cholesterol pool, which may be the result of hepatic ACAT inhibition by HL-004 but to the direct effect of HL-004 on bile acid production. Thus, HL-004 accelerates the regression of hypercholesterolemia, an event which may be related to the stimulation of bile acid production in the liver.

The hypolipidemic action of the ACAT inhibitor HL-004 in hamsters fed normal chow

1. A novel ACAT (acyl-CoA: cholesterol acyltransferase) inhibitor, HL-004, exhibited a strong inhibitory effect on the hepatic and intestinal ACAT, but was less effective on the adrenal ACAT in vitro. 2. HL-004 selectively decreased serum VLDL cholesterol, and inhibited hepatic ACAT activity in hamsters fed normal chow. 3. These results suggest that the cholesterol-lowering effect of HL-004 can be attributed to a decrease in hepatic VLDL secretion via inhibition of ACAT.