Polyphenolics in leaves of Paris polyphylla: An important high value Himalayan medicinal herb

Abstract

Paris polyphylla, a source of saponins has not been much studied for polyphenolics and its antioxidant potential. In this investigation, optimization of extraction conditions for polyphenolics compounds using Response Surface Methodology (RSM) in P. polyphylla leaf samples was conducted for the first time to look for alternate and renewable source of such compounds. A total of 32 experiments were conducted for screening of variables (i.e. ethanol concentration, sample-to-solvent ratio, HCl concentration, extraction temperature and time) using Plackett-Burman and central composite design. Among all the tested independent factors, ethanol concentration (X1), sample-to-solvent ratio (X2), and extraction temperature (X3) showed significant variations in polyphenolic content total phenol (TP), total flavonoids (TF) and total tannin (TT) and in vitro antioxidant activity (ABTS, DPPH and FRAP). All the response models showed significant model fitness and a non-significant lack of fit. Under optimal extraction condition, which includes 60% ethanol, 1:40 sample-to-solvent ratio, 45 °C of extraction temperature for 45 min, maximum content of polyphenolics, namely TP (5.36 mg GAE/g dw), TF (44.27 mg QE/g dw), TT (65.41 mg TAE/g dw), ABTS (2.28 mM AAE/g dw), DPPH (12.30 mM AAE/g dw) and FRAP (0.31 mM AAE/g dw) were found. Response values were found to be closer to the model predicted value. Further, High Performance Liquid Chromatography (HPLC) analysis of extract obtained under optimal condition, revealed the presence of 5 phenolic compounds. The present study was found useful in exploring P. polyphylla species for polyphenolics and antioxidant potential under optimal extraction condition, which can be of use for pharmaceutical and nutraceutical industries.