Triacontanol inhibits both enzymatic and nonenzymatic lipid peroxidation

Abstract

The effect of the plant growth regulator, triacontanol (TRIA) on lipid peroxidation was studied in three different systems: (i) isolated chloroplasts of spinach (Spinacea oleracea L.) leaves; (ii) egg lecithin liposomes; and (iii) soybean lipoxygenase (LOX) system. The nonenzymatic lipid peroxidation in isolated chloroplasts and egg lecithin liposomes was measured as the amount of thiobarbituric acid reactive substances (TBARS) formed. Inhibition of Fe²⁺ and/or light-induced lipid peroxidation by TRIA was observed in both isolated chloroplasts and egg lecithin liposomes. The kinetics of soybean lipoxygenase-I (LOX-1) was studied using linoleic acid as the substrate. The enzyme was competitively inhibited by TRIA. The K_i for TRIA inhibition of the enzyme was estimated to be 3.2-5.0 μ M according to different methods of estimation. TRIA has been known to exhibit anti-inflammatory action in animals and this anti-inflammatory effect of TRIA might be mediated through inhibition of lipid peroxidation. Since LOX inhibitors have been extensively used as therapeutic agents, TRIA, being a natural compound has been suggested to be an effective anti-inflammatory drug.