Comparative Effects of Vitamin K₂ and Vitamin E on Experimental Arteriosclerosis

The comparative effects of vitamin K₂ and vitamin E on aortic calcium (Ca) and inorganic phosphorus (P) levels in the aorta and the elastin fraction (fr.) were investigated in male rats after experimental arteriosclerosis was induced by vitamin D₂ with atherogenic diet. Both vitamin K₂ (100 mg/kg b.w.) and vitamin E (40 mg/kg b.w.) inhibited the increase of Ca and P in the aorta and the elastin fr. from the arteriosclerotic rats. Vitamin K₂ (50 mg/kg b.w.) also suppressed the deposition of Ca and P in the aorta, but there was no change due to vitamin K₃ or geranylgeraniol (side chain of vitamin K₂) administration. Both vitamin K₂ and vitamin E showed lipid radical scavenging activity in the in vitro experiment. However, neither vitamin K₃ nor geranylgeraniol exhibited anti-arteriosclerotic or radical scavenging activity under the above experimental conditions. It is suggested that vitamin K₂ and vitamin E promoted an antiarteriosclerotic effect by radical scavenging activity. These actions of vitamin K₂ are required in the structure of 2-methylnaphthoquinone and its side chain (geranylgeraniol).