Therapeutic effect of (Z)-3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl) acrylonitrile (DMMA) against Staphylococcus aureus infection in a murine model Ki-Bong Oh a , Kung-Woo Nam b , Hyunjin Ahn b , Jongheon Shin b , Sanghee Kim b , Woongchon Mar b, * a Department of Agricultural Biotechnology, College of Agriculture & Life Science, Seoul National University, Seoul 151-921, Republic of Korea b Department of Manufacturing Pharmacy & Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea article info Article history: Received 31 March 2010 Available online 28 April 2010 Keywords: (Z)-3-(2,5-dimethoxyphenyl)-2- (4-methoxyphenyl) acrylonitrile DMMA Staphylococcus aureus Sortase A Sortase B abstract Sortase enzymes belong to a family of transpeptidases found in Gram-positive bacteria. Sortase is responsible for the reaction that anchors surface protein virulence factors to the peptidoglycan cell wall of the bacteria. The compound (Z)-3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl) acrylonitrile (DMMA) has previously been reported as a novel sortase inhibitor in vitro, but the in vivo effects of DMMA have not been studied. Here, we evaluated the in vivo effects of DMMA against infection by wild-type and sortase A- and/or sortase B-deficient Staphylococcus aureus in Balb/c mice. With DMMA treatment, survival rates increased and kidney and joint infection rates decreased (p < 0.01) in a dose- dependent manner. The rate of kidney infection was significantly reduced in the mice treated with sortase A knock-out S. aureus (p < 0.01). These results indicate that by acting as a potent inhibitor of sortase A and moderate inhibitor of sortase B, DMMA can decrease kidney and joint infection rates and reduce mortality in mice infected with S. aureus. These findings suggest that DMMA is a promising therapeutic compound against Gram-positive bacteria. Ó 2010 Elsevier Inc. All rights reserved. 1. Introduction Bacterial resistance to antibiotic therapy is an increasing health problem worldwide. Of particular concern is Staphylococcus aureus, a Gram-positive bacterium that is the leading cause of infections in the human bloodstream, skin, respiratory tract, and soft tissues [1,2]. Methicillin-resistant strains of S. aureus are frequently iso- lated (>71.5% of S. aureus) in hospitals throughout the United States [3] and are prevalent in South Korea (>28.1%) [4]. Vancomy- cin has been used as a last-resort therapy for methicillin-resistant S. aureus; however, resistance to vancomycin has reduced its effi- cacy [5,6]. The discovery of new compounds to lessen the virulence of Gram-positive bacteria would provide an alternative treatment to benefit public health. In developing new treatments for S. aureus infection, the iden- tification of potential drug targets is of critical importance. The thick cell wall of bacteria is composed of cellulose, peptidogly- cans, and many cell wall-anchored proteins. Cell wall-anchored proteins at the bacterial surface play crucial roles in the viru- lence of most Gram-positive bacterial pathogens by acting as adhesion and/or invasion sites upon interacting with various host cells [7–9]. These virulence proteins, after being secreted by the cell, are covalently linked to the peptidoglycan layer in a reaction catalyzed by the membrane-associated transpeptidases known as sortases [10,11]. The sortase-dependent anchoring of surface polypeptides to the bacterial cell wall is believed to be an essen- tial strategy for bacterial survival during infection, as mutants deficient in genes for one or more sortase enzymes exhibit atten- uated virulence [12,13]. Two sortase isoforms, SrtA and SrtB, have been identified in S. aureus. Sortase A is constitutively expressed, but the sortase B gene is transcribed only under low-iron conditions [14–16]. In the absence of SrtA, S. aureus has an impaired ability to bind fibrin- ogen in solution [17], suggesting that the deletion of SrtA causes an inability to anchor certain surface proteins such as those responsi- ble for fibrin binding. On the other hand, the absence of only the SrtB gene does not seriously hinder the binding of S. aureus to fibrinogen [17]. Thus, inhibitors of SrtA and SrtB or only SrtA may be promising novel candidates for the treatment of Gram-po- sitive bacterial infections [18,19]. Our group previously reported on the in vitro inhibitory effects of (Z)-3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl) acryloni- trile (DMMA) on SrtA and SrtB activities [2,20]. However, the in vivo effects of DMMA have not been explored. In this study, we extend our knowledge from the in vitro action to the in vivo action of DMMA in Balb/c mice infected with SrtA- and/or SrtB- deleted Gram-positive S. aureus. 0006-291X/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2010.04.113 * Corresponding author at: Department of Manufacturing Pharmacy & Natural Products research Institute, College of Phamacy, Seoul National University, Daehak- dong, Gwanak-gu, Seoul 151-742, Republic of Korea. Fax: +82 2 880 2473. E-mail address: mars@snu.ac.kr (W. Mar). Biochemical and Biophysical Research Communications 396 (2010) 440–444 Contents lists available at ScienceDirect Biochemical and Biophysical Research Communications journal homepage: www.elsevier.com/locate/ybbrc