Antioxidant Activities of Ulmi cortex Extracts According to Ethanol Contents

Objectives : This study was performed to find best extraction solvent for application of Ulmi cortex to food or herbal medicine as an antioxidant only using water, ethanol and their mixtures. Methods : The Ulmi cortex extracts were prepared using water and 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% (v/v) ethanol, and were evaluated yields, total polyphenol contents, DPPH and ABTS radical scavenging activities, lipid peroxidation activities, and catechin and epicatechin contents. Results : Among the Ulmi cortex extracts, the yield was highest in water extract (8.9%) and lowest in ethanol extract (3.8%). The yield of 30% ethanol extract (8.5%) also was very high to similar with water extract. The total polyphenol content was highest in the 30% ethanol extract ($253.6{\mu}g/mg$ extract) and lowest in water extract ($109.0{\mu}g/mg$ extract). The DPPH radical scavenging activity was highest in ethanol extract (IC50, $8.53{\mu}g/ml$), ABTS radical scavenging activity was highest in 60% ethanol extract (IC50, $3.08{\mu}g/ml$), and the inhibition of lipid peroxidation was highest in 70% ethanol extract (IC50, $7.96{\mu}g/ml$). As ethanol content of extraction solvent increased from 0% to 30%, the antioxidant activities were remarkably increased whereas from 30% to 100%, the antioxidant activities were increased or decreased a little. Conclusions : The findings of the present study suggest that 30% ethanol is best solvent for extraction of Ulmi cortex, considering yield, polyphenol content, and antioxidant activities with extraction cost.

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