Extraction, purification, characterization and antioxidant activities of heat-resistance phenolic compounds from lemon pulp

Lemon as a citrus species is widely cultivated in the Mediterranean region, Turkey. The lemon pulp has been characterized as a rich source of phenolic and flavonoid compounds, phenolic acid as well as novel coumarin derivatives. It is usually obtained within the juice production in the food industries. In the current report, lemon pulp was initially dried and immediately after subjected to extraction with hot water and ethyl acetate. This study deals with the isolation of secondary metabolites along with the determination of 32 phenolic contents. After isolation of major components using Sephadex LH-20 column and silica gel, 11 phenolic components were totally characterized using the 1D and 2D NMR techniques. Lemon pulp known as citrus peel has been recognized as a potential source of coumarin, limonoids, and methoxylated flavones. The antioxidant activities of the limonin (LMN) and lemon pulp ethyl acetate extract (LPEA) were evaluated using in vitro methods involving total antioxidant activity, reducing power, inhibition of lipid peroxidation, scavenging activities of DPPH∙ , H₂O₂ and ABTS+. and compared with standards at 10, 25, 50 and 100 μg.mL-1. According to the finding of this research, LMN and LPEA showed strong in vitro antioxidant activities and also significantly exhibited an increase to be in a dose-dependent manner (p<0.05).