Nicanartine improves in vitro resistance of lipoproteins to oxidation

Purpose. The aim of this study is to investigate the plasma protein binding of nicanartine and to measure its antioxidant effect on lipoproteins. Methods. The blood binding was studied with an erythrocyte partitioning method and the lipoprotein oxidation with the conjugated dienes method. Results. Nicanartine was 24.7% LDL (low density lipoprotein)-bound and 29.2% AAG (alphal-acid glycoprotein)-bound. Nicanartine delayed but did not stop the oxidation of the three density classes of lipoprotein HDL (high density lipoprotein), LDL, VLDL (very low density lipoprotein). The addition of AAG to LDL in the conjugated dienes method decreased the nicanartine fraction bound to LDL and decreased its antioxidant effect. The decrease of nicanartine LDL-bound fraction and the decrease in antioxidant effect were not parallel. Conclusions. This suggested that (a) AAG-bound nicanartine dissociated to equilibrate the decrease in LDL-bound nicanartine consumed by oxidation, or (b) the oxidation conditions could involve chemical modifications of nicanartine and therefore modify its affinity for AAG.