Antibacterial Activity of Thai Medicinal Plants against Methicillin-resistant Staphylococcus aureus Mullika Traidej Chomnawang a, ⁎, Suvimol Surassmo a , Karn Wongsariya a , Nuntavan Bunyapraphatsara b a Department of Microbiology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand b Department of Pharmacognosy, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand article info abstract Article history: Received 20 August 2008 Accepted in revised form 15 October 2008 Available online 5 November 2008 Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen which causes severe morbidity and mortality worldwide. Seventeen Thai medicinal plants were investigated for their activity against MRSA. Garcinia mangostana was identified as the most potent plant, and its activity was traced to the prenylated xanthone, α-mangostin (MIC and MBC values of 1.95 and 3.91 μg/ml, respectively). © 2008 Elsevier B.V. All rights reserved. Keywords: Methicillin-resistant S. aureus Medicinal plants Antibacterial activity Bioautography Garcinia mangostana α-mangostin 1. Introduction Staphylococcus is part of the human indigenous microflora, and is carried asymptomatically in a number of body sites. Transmission from these sites causes both endemic and epidemic diseases. Staphylococcus aureus, a member of the Micrococcaceae family, appears as Gram-positive cocci in clusters [1]. S. aureus infection is a major cause of skin, soft- tissue, respiratory, bone, joint, and endovascular disorders. Many strains of S. aureus are developing resistance to available antibacterial agents, creating a serious problem in medical microbiology [2]. The ß-lactam antibiotics are the drugs of choice for the treatment of S. aureus infections. Resistance to ß- lactam compounds has been reported for methicillin, oxacillin, nafcillin, cloxacillin, and dicloxacillin. Methicillin-resistant S. aureus (MRSA) infections can cause a broad range of symptoms depending on parts of the body that are infected. These may include surgical wounds, burns, catheter sites, eyes, skin and blood. Infections often result in redness, swelling and tender- ness at the site of infection and possibly progress to severe diseases. Methicillin resistance is most commonly mediated by the mecA gene, which encodes for a single additional penicillin binding protein, PBP2a, with low affinity for all ß- lactams [3]. S. aureus is also resistant to other commonly used antimicrobial agents including aminoglycosides, macrolides, chloramphenicol, tetracycline, andfluoroquinolones [4]. Medicinal plants have been used as remedies for infectious diseases in many tropical countries, providing a rationale for investigating natural products for the treatment of MRSA infection. To this purpose, we have assessed the antimicrobial activity of 17 Thai medicinal plants, identifying Garcinia mangostana and its constituent α-mangostin as interesting anti-MRSA leads. 2. Experimentals 2.1. Collection and preparation of plant materials Plants were collected wild from various locations in Thailand. A voucher specimen is held for each species at Fitoterapia 80 (2009) 102–104 ⁎ Corresponding author. Department of Microbiology, Faculty of Pharmacy, Mahidol University, 447 Sri Ayudthaya Road, Rachathevi, Bangkok 10400, Thailand. Tel.: +662 644 8677 90x5507; fax: +662 644 8692. E-mail address: scmtd@mahidol.ac.th (M.T. Chomnawang). 0367-326X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.fitote.2008.10.007 Contents lists available at ScienceDirect Fitoterapia journal homepage: www.elsevier.com/locate/fitote