Journal of Environmental Biology

Studies on antimicrobial activity of Poncirus trifoliata ethyl extract fraction against methicillin-resistant Staphylococcus aureus and to elucidate its antibacterial mechanism 

Sung-Hwan Eom¹, Yeoun-Joong Jung², Dae-Sung Lee³, Mi-Jin Yim³, Hye Seon Kim³, Sang-Hoon Lee^1,4, Jeong-In Myeong⁵, Jinhwan Lee⁵, Hyun-Woo Kim⁶, Kyoung-Ho Kim⁷, Myung-Suk Lee⁷, and Young-Mog Kim²*

¹Korea Food Research Institute, Sungnam 463-746, Republic of Korea

²Department of Food Science and Technology, Pukyong National University, Busan 608-737, Republic of Korea

³National Marine Biodiversity Institutes of Korea, Seocheon 325-902, Republic of Korea

⁴University of Science and Technology, Daejeon 305-350, Republic of Korea.

⁵Aquaculture Management Division, National Fisheries Research and Development Institute, Busan 619-705, Republic of Korea

⁶Department of Marine Biology, Pukyong National University, Busan 608-737, Republic of Korea

⁷Department of Microbiology, Pukyong National University, Busan 608-737, Republic of Korea

*Corresponding Author E-mail: ymkim@pknu.ac.kr

Publication Data

Paper received:

11 November 2014

Revised received:

08 May 2015

Accepted:

07 June 2015

Abstract

Traditional medicinal plants contain a wide variety of chemicals that have potent antibacterial activity. To find an alternative agent of overcoming the problems of methicillin-resistant Staphylococcus aureus (MRSA), the antibacterial mechanism of Ponciruss trifoliata against MRSA was investigated. Ethyl acetate (EtOAc)-soluble extract of P. trifoliata methanolic extract was evaluated for antibacterial activity using minimum inhibitory concentration (MIC). An EtOAc sub-fraction 08 (EA08) from silica-gel open column chromatography exhibited strong anti-MRSA activity. Apart from the study to isolate single compound from EA08, a synergistic antibacterial effect between the sub-fraction and β-lactam antibiotics against MRSA was determined. In order to elucidate the antibacterial restoring mechanism of EA08 on MRSA, mRNA expression of mecA gene and production penicillin-binding protein 2a (PBP2a) encoded by mecA gene were monitored. EA 08 showed the strongest antibacterial activity with MIC value of 256 μg ml^-1. MIC of oxacillin against MRSA was dramatically reduced from 512 to 16 μg ml^-1 in combination with 256 μg ml^-1 of EA08. The fractional inhibitory concentration index of oxacillin was measured at 0.53 in combination with EA08 against MRSA, suggesting that EA08-oxacillin combinations exert synergetic effect against MRSA. The analysis of RT-PCR and Western blotting profiles revealed that EA08 inhibited mRNA expression of mecA gene and production PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. These results indicated that EA08 eventually led to the reduction or inhibition of PBP2a production through translational inhibition in MRSA. ???  

 Key words

Antibacterial activity, MecA gene, Poncirus trifoliata, Staphylococcus aureus, Synergy effect

Copyright ? 2016 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).