THE EFFECT OF THE AGED GARLIC EXTRACT, KYOLIC, ON THE DEVELOPMENT OF EXPERIMENTAL ATHEROSCLEROSIS

The aged garlic extract 'Kyolic' lowers serum cholesterol levels in hu mans and experimental animals and thus is presumed to have a protectiv e effect against atherosclerosis. However, to date no studies have exa mined the effect of this substance on the actual development of the di sease. In the present study, the right carotid artery of 24 rabbits wa s de-endothelialized by balloon catheterisation in order to produce a myointimal thickening. After 2 weeks the rabbits were randomly assigne d to four groups: Group I received a standard diet; Group II received the standard diet supplemented with 800 mu 1/kg body weight/day 'Kyoli c'; Group III received a 1% cholesterol supplemented standard diet; an d Group IV received a 1% cholesterol supplemented standard diet plus ' Kyolic'. After 6 weeks, the cholesterol diet caused a 6-fold increase in serum cholesterol level (Group III; 6.4 +/- 0.6 mmol/1) compared to normal diet (Group I; 1.2 +/- 0.4 mmol/1) (P < 0.05) with only a mino r, non-significant reduction seen by the addition of 'Kyolic' (Group I V; 6.2 +/- 0.7 mmol/l). Group III rabbits developed fatty streak lesio ns covering approximately 70 +/- 8% of the surface area of the thoraci c aorta, which was significantly reduced to 25 +/- 3% in the 'Kyolic'- treated Group IV. No lesions were present in Groups I and II. The hype rcholesterolaemic diet caused an increase in aortic arch cholesterol ( 2.1 +/- 0.1 mg cholesterol/g tissue) which was significantly reduced b y 'Kyolic' supplementation (1.7 +/- 0.2 mg cholesterol/g tissue) (P < 0.05). 'Kyolic' significantly inhibited the development of thickened, lipid-filled lesions in the pre-formed neointimas produced by balloon- catheter injury of the right carotid artery in cholesterol-fed rabbits (intima as percent of artery wall, Group III 42.6 +/- 6.5% versus Gro up IV 23.8 +/- 2.3%, P < 0.01), but had little effect in rabbits on a standard diet (Group II 18.4 +/- 5.0% versus Group I 16.7 +/- 2.0%). I n vitro studies showed that 'Kyolic' has a direct effect on inhibition of smooth muscle proliferation. In conclusion,'Kyolic' treatment redu ces fatty streak development, vessel wall cholesterol accumulation and the development of fibro fatty plaques in neointimas of cholesterol-f ed rabbits, thus providing protection against the onset of atheroscler osis. (C) 1997 Elsevier Science Ireland Ltd.