Extraction, thin layer chromatography isolation and antioxidant activity determination of flavonoids from phytolacca dioica l. berries

Abstract

Phytolacca dioica L. is a medicinal plant known to have various bioactive phytochemicals. This research aimed to extract, isolate, quantify and evaluate the antioxidant activity of the flavonoids obtained from ripe and unripe berries of Phytolacca dioica using ethanol and ethyl acetate as solvents. Dried berry powders were extracted by solvent extraction and the crude extracts were concentrated using a water bath at 40 ºC. Extraction yields were determined and flavonoid compounds were isolated using analytical and preparative thin-layer chromatography (TLC) in a n-butanol: acetic acid: water (2:2:6 v/v/v) solvent system. Flavonoid bands were visualized under the UV lamp after being sprayed with 1% aluminium chloride reagent. Total flavonoid content (TFC) was measured using the aluminium chloride colorimetric method with quercetin as a reference standard and the antioxidant activity was assessed using the hydrogen peroxide (H2O2). The highest extraction yield was obtained from ripe ethanol berry extract (10.6%), while the lowest was for unripe ethyl acetate berry extract (2.35%). TLC analysis confirmed the presence of flavonoids in all extracts by their characteristic yellow and yellow green fluorescent bands. The ripe berry ethanol extract showed the highest total flavonoid content, 658.55 mg QE/g, followed by ripe berry ethyl acetate with 499.24 mg QE/g, unripe berry ethanol extract with 426.87 mg QE/g and the lowest was recorded for unripe ethyl acetate berry extract (311.45 mg QE/g). At 100 µg/mL, ripe berry ethanol extract showed the highest scavenging activity (96.8%), followed by ripe ethyl acetate (88.8%), unripe ethyl acetate (72.9%) and unripe ethanol (61.7%). The ripe berry ethanol extract showed the strongest antioxidant activity, whilst the unripe berry ethanol extract showed the lowest activity.