Comparative phenolic content and antioxidant activity of some medicinal plant extracts prepared by choline chloride based green solvents and methanol

Abstract In the present study, three north-western Himalayan medicinal plants, Ocimum sanctum, Terminalia bellericaand Terminalia chebula were used to evaluate the effectiveness of choline chloride based natural deep eutectic solvents in extracting the polyphenolic compounds. The natural deep eutectic solventsusedin the study were choline chloride:glucose: water, choline chloride:fructose:water, choline chloride: xylose, choline chloride:glycerol:water and choline chloride:malicacid:water.The results of the above study showed all the eutectic solvents were more effective in extracting phenolic compounds than methanol, however, choline chloride:malicacid:waterbased NADES was most effective among all the NADESs tested and methanol. Additionally, profiling of phenolic compounds in extracts obtained bychloride:malicacid:waterand methanol was also carried out using HPLC analysis. It was also observed that extracts possessing higher polyphenolic content also showed higher DPPH radical scavenging activity, ferric reducing antioxidant power, reducing power and α-glucosidase inhibitory activity. Our results suggests that natural deep eutectic solvents offers efficient and safe alternative to methanol for extraction of phenolic compounds from medicinal plants.