Role of plasma lipoproteins in the transport of the soyabean isoflavones daidzein and daidzein-7-O- beta-D-glucoside.

摘要

Isoflavone intake is associated with various properties beneficial to human health which are related to their antioxidative activity, e.g. to their ability to increase LDL oxidation resistance. However, the distribution of isoflavones among plasma lipoproteins has not yet been elucidated in vivo. Therefore, this study examined the association between daidzein (DAI) and lipoproteins in human plasma upon administration of the aglycone and glucoside form. 5 men aged 22-30 yr participated in a randomized, double-blind study in cross-over design. After ingestion of DAI and daidzein-7-O- beta-D-glucoside (DG) (1 mg DAI aglycone equivalents/kg body wt.) blood samples were drawn before isoflavone administration as well as 1, 2, 3, 4.5, 6, 8, 10, 12, 24 and 48 h post-dose. Concn. of DAI in the different lipoprotein fractions (chylomicrons, VLDL, LDL, HDL) and in the non-lipoprotein fraction were analysed using isotope dilution capillary GC/MS. The lipoprotein fraction profiles were similar for all subjects and resembled those obtained for plasma in a previously published study. The lipoprotein distribution based on the area under the concn.-time profiles from 0 h to infinity in the different fractions were irrespective of the administered form: non-lipoprotein fraction (53%) > LDL (20%) > HDL (14%) > VLDL (9.5%) > chylomicrons (2.5%). Of DAI present in plasma, 47% was associated to lipoproteins. Concn. in the different lipoprotein fractions as well as in the non-lipoprotein fraction were always higher after the ingestion of DG than of DAI. Taken together, these results demonstrate an association between isoflavones and plasma lipoproteins in vivo.