Determination of Phenolic Compounds and Bioactive Potential of Plum (Prunus salicina) Peel Extract Obtained by Ultrasound-Assisted Extraction

Abstract

Ultrasound-assisted extraction (UAE) of bioactive compounds from black plum peels was optimized by response surface methodology (RSM). Temperature (35-55°C), time (15-45 min), and ethanol concentration (50-90%) were selected as independent extraction parameters, whereas total anthocyanin content (TAC), total phenolic content (TPC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition were kept as response variables. The optimized extraction conditions were determined by RSM as extraction at 49°C for 37 min with 68% ethanol, which corresponded to TAC, TPC, and DPPH inhibition values of $5.42\pm 0.61$  mg/g, $6.217\pm 0.76$  mg GAE/g, and $89\pm 2.13\%$ , respectively. Fourier-transform infrared spectrometer (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography mass spectrometer (GCMS) were used for chemical characterization of optimized plum peel extract (PPE). Optimized PPE was further evaluated for antibacterial, antioxidant, anticancer, and food preservation potential. PPE showed 92.31% DPPH inhibition with IC50 value of 360.6 μg/ml. Optimized PPE extract was effective in the inhibition of cancer cell proliferation and migration, and IC50 values were in the range 1.85-3.96 mg/ml for different human cancer cell lines. Major phenolics identified in PPE were ferulic acid (47.87 mg/kg), sinapic acid (9.15 mg/kg), quercetin (7.44 mg/kg), gallic acid (3.24 mg/kg), m-coumaric acid (2.59 mg/kg), and vanillic acid (1.12 mg/kg). PPE extract inhibited the growth of various foodborne bacterial pathogens and increased the shelf life of PPE coated fresh grapes. PPE due to antibacterial, anticancer, antioxidant, and food preservation potential can be used in developing functional food and pharmaceutical products.