FLAVONOID-INDUCED ABILITY OF MINIMALLY MODIFIED LOW-DENSITY LIPOPROTEINS TO SUPPORT LYMPHOCYTE-PROLIFERATION

Low-density lipoprotein (LDL) peroxidation appears to be involved in a therogenesis. We studied the ability of minimally modified LDL (MM-LDL ) to be used by proliferating lymphocytes and the effects of antioxida nt flavonoids on this lipoprotein. MM-LDL were obtained by storing LDL at 4 degrees for 1 month, which resulted in a decrease in lipophilic antioxidants and an increased susceptibility to oxidation when incubat ed with cells. MM-LDL were not cytotoxic; however, in cells treated wi th lovastatin that require cholesterol for cell growth, they were much less efficient than fresh LDL in sustaining proliferation as determin ed by [H-3]thymidine incorporation into DNA. Pure quercetin and grape- derived beverages restored proliferation in the presence of MM-LDL and prevented the apoptosis otherwise induced by lovastatin. These effect s of flavonoids correlated with their activity in inhibiting LDL perox idation. The results demonstrate that potent antioxidants, such as fla vonoids, protect MM-LDL from lipoperoxidation and preserve their abili ty to efficiently deliver cholesterol to cells. (C) 1998 Elsevier Scie nce Inc.