Author(s):

Jyh-Ferng Yang, Cheng-Hong Yang, Chi-Chun Wu, Li-Yeh Chuang

Abstract: An indigenous herb, Sophora flavescens, has been widely used as a traditional medicine in Taiwan. The main goal of this study was to determine the antibacterial and antioxidant activities of various extracts, including 95% ethanol crude extracts, ethyl acetate fraction, and aqueous fraction, from Sophora flavescens. Antioxidant activity was determined by the methods of DPPH radical scavenging test, trolox equivalent antioxidant capacity (TEAC), and reduction capacity. In addition, the contents of total phenolics and flavonoids were determined. Antibacterial activity was performed by disk diffusion method, minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC), time-killing curve and synergy effect. The clinical antibiotic isolates, including gram-positive and gram-negative pathogens were used for antimicrobial activity assay. Experimental results showed that the extracts of ethyl acetate exhibited a higher antioxidant activity and antioxidant activity among all the extracts. In vitro, the ethyl acetate extracts presented a significant antibacterial activity against oxacillin-resistant S. aureus with MIC value of 0.025 mg/mL and MBC of 0.04 mg/mL. The extracts of ethyl acetate scavenged DPPH radicals and TEAC with values of 178 ppm (IC50) and 78 g trolox / 100 g DW, respectively. A higher content of both total phenolics and flavonoids were found in the ethyl acetate extracts which correlated with a better biological activities compared with other extracts. These results reveal that the extracts of ethyl acetate from Sophora flavescens could be developed as a potential natural antioxidant and antibacterial agent.

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