Leaves extracts of selected crops as potential source of antioxidants

Abstract

Objective — to evaluate the antioxidant potential of leaves extracts of four selected forage plants in conditions of M.M. Gryshko National Botanical Garden of the NAS of Ukraine. Material and methods. In this study used dried raw of Brassica campestris L. f. annua DC., cv. Chanita (Brassicaceae Burnett), Desmodium canadensis DC. (Fabaceae Lindl.), Rhaponticum carthamoides (Willd.) Iljin. (Asteraceae Bercht. & J. Presl.), Sinapis alba L. cv. Karolina (Brassicaceae Burnett) harvested from collections of the M.M. Gryshko National Botanical Garden of the NAS of Ukraine. 0.2 g of dried plant raw material was extracted with 20 mL of 80 % ethanol for 2 hours. The total polyphenol content of extracts was measured by the method described by Singleton and Rossi (1965) using Folin–Chiocalteu reagent and results were expressed in mg of gallic acid equivalent per one gram of dry matter (mg GAE/g). Determination of total flavonoids content was conducted using the modified method described in Shafii et al. (2017) and results expressed in mg quercetin equivalent per one gram of dry matter (mg QE/g). Detection of total phenolic acids content of extracts was carried out using the method described in Farmakopea Polska (1999) and results expressed in mg caffeic acid per one gram of dry matter (mg CAE/g). The antioxidant activity of samples was measured using 2.2-diphenyl-1-picrylhydrazyl (DPPH method) according to Sanchez-Moreno et al. (1998). Also, the antioxidant activity of extracts was determined by the phosphomolybdenum method described by Prieto et al. (1999) with slight modifications. Results of these parameters expressed in mg Trolox equivalent per one gram of dry matter (mg TE/g). Experimental data were evaluated by using Excel 2010. Results. Total content of polyphenol compounds of investigated leaves extracts was from 32.43 to 73.58 mg GAE/g, total content of phenolic acids – from 4.87 to 9.15 mg CAE/g, total content of flavonoids – from 10.16 to 92.61 mg QE/g. Determination of antioxidant activity by DPPH method demonstrated results from 7.15 to 9.00 mg TE/g and by phosphomolybdenum method – from 77.87 to 190.64 mg TE/g. Conclusions. Investigation of ethanol leaves extracts of four forage plants identified high content of polyphenol compounds and flavonoids what characterizes these plants as a valuable source of biologically active compounds. Obtained results can be of interest for deep pharmacological investigations.