An Anti-MRSA(Methicillin Resistant Staphylococcus aureus) Activity and Antioxidant Activity of Poncirus trifoliata Extract

Abstract

Poncirus trifoliata (L.) Raf. (Rutaceae) is widely used as traditional folk medicine in East Asia as a remedy for gastritis, dysentery, inflammation, and digestive ulcers. It has been studied for their potential uses as alternative remedies for the treatment of many infectious diseases and the preservation of the foods from the toxic effects of the oxidants. Particularly, the antimicrobial activities of plant and extract have formed the basis of many applications, including raw and processed food preservation, pharmaceuticals, alternative medicine and natural therapies. In an effort to discover an alternative therapeutic agent against methicillin resistance Staphylococcus aureus (MRSA), several medicinal plants were evaluated for its antibacterial activity against MRSA. A methanolic extract of Poncirus trifoliata exhibited significant antibacterial activity against MRSA. To perform more detailed investigation on antibacterial activity, the methanol extract of P. trifoliata was further fractionated with organic solvents such as n-hexane, dichloromethane, ethyl acetate, and n-butanol. Among them, the ethyl acetate fraction showed the highest antibacterial activity against 9 MRSA strains with minimum inhibitory concentration (MIC) from 256 to 1,024 μg/㎖. Also, the each fraction was subjected to investigate an antioxidant activity. The antioxidant activity was investigated using an electron spin resonance (ESR) spectroscopy. The antiradical activities of P. trifoliata were tested by measuring their ability to scavenge DPPH, superoxide, alkyl, and hydroxyl radicals. In case of hydroxyl radical activity, ethyl acetate fraction exhibited the highest scavenge activity and the IC50 value was 0.28±0.02 ㎎/㎖. In the ethyl acetate fraction, the content of flavonoids was superior than that of other phytochemicals such as lutein, phytic acid, isoflavones anthocyanins limonene, quercitin, lycopene, vitamin C, catechins, and tartaric acid, which often contributed to biological activity such as anti-inflammatory, antibacterial, antioxidant, and anti-anaphylactic activity. These results strongly suggested that the antibacterial and the hydroxyl scavenging activity from P. trifoliata were mainly originated from the flavonoid compounds contained in the ethyl acetate fraction.