In vitro antioxidant properties and inhibitory effect of extracts and fractions of Plectranthus glandulosus leaves on copper sulfate (CuSO4)-induced oxidation in human low-density lipoprotein

摘要

Oxidation of LDL has been suggested to be an initial step in the development of atherosclerosis. This research work deals with the evaluation of antioxidant potential of Plectranthus glandulosus leaves extracts and fractions as well as its protective effects against human LDL oxidation. A preliminary quantitative phytochemical screening was carried out. Antioxidant potential was evaluated employing in vitro hydrogen peroxide, nitric oxide scavenging assays and TAOC test. The human LDL oxidation induced by CuSOsub4/sub inhibition test was also performed. Plectranthus glandulosus leaves exhibited the presence of 18.3% of saponines, 25.6% of terpenoids and 36.2% of flavonoids. EAF exhibited highest hydrogen peroxide and nitric oxide scavenger activity (ICsub50/sub 13.63μg/ml and 24.59 μg/ml respectively). Ascorbic acid exhibited an ICsub50/sub value of 15.39μg/ml in hydrogen peroxide assay and 22.96 μg/ml in nitric oxide scavenging activity. EAF exhibited a higher TAOC (optical density 0.186±0.00) than that of ascorbic acid (0.162±0.001) at the concentration of 25μg/ml while at 200μg/ml N-BUTF exhibited a higher optical density (1.261±0.001) than that of ascorbic acid (1.065±0.001). EAF lengthened the lag time of the CD formation up to 150mins at the concentration 1mg/ml. TBARS formation inhibition at the concentration 0.5mg/ml, were no significant different between n-butanol (68.55%) ethyl acetate fraction (68.21%) and quercetin 67.69%). Plectranthus glandulosus is a promising prospect as an anti-atherosclerotic agent and needs a detailed study to establish the same.