In vitro antioxidant properties and inhibitory effect of Plectranthus
glandulosus leaves on human low-density lipoprotein oxidation
Abstract
Background and Purpose : 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. Experimental Approach : 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 CuSO4 inhibition test was also performed. Key
Results : 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
(IC50 13.63µg/ml and 24.59 µg/ml respectively). Ascorbic acid exhibited
an IC50 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%). Conclusion and
Implications : Plectranthus glandulosus is a promising prospect as an
anti-atherosclerotic agent and needs a detailed study to establish the
same.