Evaluation of bioative compounds and antioxidant activity of extracts of black mulberry leaves (Morus nigra L.) using experimental design

Abstract

Extracts of black mulberry leaves present phytochemicals such as phenolic compounds and minerals. These substances have been studied because they show several health benefits. In this work we report the influence of drying temperature, infusion temperature and extraction time by means of factorial design monitoring the total phenolic content (CFT) of aqueous extracts of leaves of Morus nigra L. The concentrations of CFT, flavonoids, flavonols and antioxidant activity of the extracts were determined by spectrophotometry. The identification and quantification of phenolic compounds were performed by LC-ESI-MS / MS. The determination of the mineral concentration in the black mulberry leaves was performed by ICP-MS. The Pareto and surface response graphs suggested that the most efficient extractions occurred for leaves drying at lower temperatures and using higher infusion temperatures, extraction time did not show significant influence. The extracts presented concentration of CFT from 16.96 ± 0.15 to 5.73 ± 0.33 mg GAE g-1. The analyzes by LC-ESI-MS / MS allowed to identify phenolic substances not yet reported in the literature to date. In addition 10 mineral elements were determined in the black mulberry leaves at mg kg-1 concentrations range.