In vitro anti-hypercholesterolemic activity of Calotropis procera (Aiton) using human erythrocytes

This study evaluates in vitro hypocholesterolemic and antioxidant potential of Calotropis procera root extracts and its diterpenoid rich fraction. In vitro hypocholesterolemic activity was determined by measuring cholesterol concentration in the normal and hypercholesterolemic human red blood cells (hRBCs) after incubating with the test extracts (1, 10 and 100 µg/mL) for 24 h. The bioactivity guided fractionation of crude acetone root extract yielded a fraction with EC50 63.03±1.10 µg/mL in relation to ascorbic acid standard (EC50 39.95±1.25 µg/mL). In case of isolated erythrocytes of diseased donors, the purified fraction reduced the membrane cholesterol up to 1.62±0.22 µmole CH/mL (52%), whereas it was 1.01±0.75 µmole CH/mL (35%) in case of quercetin standard. The whole blood, when incubated with purified fraction and quercetin standard at 10 µg/mL for 24 h, it showed significant decrease in the cholesterol level of hRBCs of both, healthy (P<0.001) as well as diseased (P<0.05) donors. GC-HRMS analysis of the bioactive diterpenoid rich fraction revealed cyclic diterpenoids - Phenol, 2,4 bis (1,1-dimethylethyl) ester and 1,2 benzedenedicarboxylic acid, bis(2-methylpropyl) ester. In conclusion, C. procera root extract and its diterpenoid rich fraction exhibited potential hypocholesterolemic effect possibly by inhibiting membrane cholesterol synthesis and improving antioxidant levels in hypercholesterolemic hRBCs.