Influence of extraction methods and solvent system on the chemical composition and antioxidant activity of Centella asiatica L. leaves

Abstract

Abstract Centella asiatica is a valuable medicinal herb widely used in traditional Indian and Chinese system of medicine. However, a suitable extraction method and solvent system to optimize extraction of bioactive compounds and antioxidant capacity in C. asiatica is still lacking. Therefore, the present work was undertaken to screen out an efficient extraction technique on antioxidant capacity and recovery of bioactive compounds in C. asiatica using modern extraction methods (ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and conventional methods like heat reflux extraction (HRE) and maceration (MAC) with methanol, ethanol, acetonitrile, water, 50% aqueous methanol, 50% aqueous ethanol as extracting solvents. Eight major compounds were identified and quantified using a validated High-performance liquid chromatography with diode-array (HPLC-DAD) method. Method validation was done in terms of accuracy, precision, LOD and LOQ. Antioxidant activity of the extracts was evaluated by using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS assay). MAE using methanol was found to be the most effective technique as it showed highest recovery of the eight bioactive compounds viz chlorogenic acid (0.18%), rutin (0.11%), quercetin (0.02%), kaempferol (0.10%), madecassoside (0.76%), asiaticoside (2.66%), madecassic acid (0.32%) and asiatic acid (1.98%) and maximum DPPH (IC50 45.17 μg/ml) and ABTS (IC50 26.38 μg/ml) values were achieved as compared to other conventional methods.