Letters in Applied Microbiology 2000, 30, 105–108 Antimicrobial activity of Mitracarpus scaber extract and isolated constituents G. Bisignano, R. Sanogo, A. Marino, R. Aquino 1 , V. D’Angelo, M.P. Germano `, R. De Pasquale and C. Pizza 1 Pharmaco-Biological Department, Microbiological Section, School of Pharmacy, University of Messina and 1 Pharmaceutical Science Department, School of Pharmacy, University of Salerno, Italy 2091/99: received 8 February 1999, revised 23 September 1999 and accepted 1 October 1999 G. BISIGNANO, R. SANOGO, A. MARINO, R. AQUINO, V. D’ANGELO, M.P. GERMANO ` , R. DE PASQUALE AND C. PIZZA. 2000. The antimicrobial activity of a methanol extract and isolated constituents of Mitracarpus scaber, a species used in folk medicine by West African native people, was evaluated against Staphylococcus aureus and Candida albicans strains. The mitracarpus methanol extract possesses both antibacterial and antimycotic activities (minimum inhibitory concentration—MIC 31·25 and 62·50 mg ml −1 , respectively). This extract was subsequently fractioned and monitored by bioassays leading to the isolation of seven compounds screened for antibacterial and antimycotic activities. Among these compounds, gallic acid and 3,4,5-trimethoxybenzoic acid inhibited the growth of Staph. aureus (MIC 3·90 and 0·97 mg ml −1 ). 4- Methoxyacetophenone and 3,4,5-trimethoxyacetophenone effectively inhibited C. albicans (MIC 1·95 mg ml −1 ). The other compounds (kaempferol-3-O-rutinoside, rutin and psoralen) which were also isolated showed low antibacterial and antimycotic activities (125–500 mg ml −1 ). INTRODUCTION The research into biologically active compounds from natural sources has always been of great interest for scientists looking for new sources of useful drugs against infectious diseases. Mitracarpus scaber is widely employed in traditional medicine in West Africa for headaches, toothache, amenorrhoea, dys- pepsia, hepatic diseases, venereal diseases and leprosy. Among the folkloric uses, the juice of the plant is applied topically for the treatment of skin diseases (infectious der- matitis, eczema and scabies) (Dalziel 1936; Kerharo and Adam 1974). In the Traditional Medicine Department of Bamako (Mali), a lotion and a skin ointment made with the aerial part of M. scaber are used for skin diseases and infec- tions. Previous studies (Moulis et al. 1992) reported the iso- lation of pentalogin, from fresh aerial parts of mitracarpus, which demonstrated a potent antifungal activity against Can- dida albicans and Trichophytum soudanense. Other investigations (Sanogo et al. 1996) showed that dif- ferent extracts of M. scaber exhibited broad antibacterial and Correspondence to: Prof. G. Bisignano, Pharmaco-Biological Department, Microbiological Section, School of Pharmacy, University of Messina, Vill. SS. Annunziata, 98168 Messina, Italy. © 2000 The Society for Applied Microbiology antifungal activity against standard strains and clinical isolates of Staphylococcus aureus and C. albicans responsible for com- mon skin infections. More recently, Germano ` et al. (1999) reported the hepatoprotective effects of mitracarpus decoc- tion on CCl 4 -induced hepatotoxicity in vivo as well as in vitro using isolated hepatocytes. The purpose of this study was to evaluate the antimycotic and antibacterial activities of a M. scaber methanol extract and isolated constituents. MATERIALS AND METHODS Plant material Mitracarpus scaber (Rubiaceae) aerial parts were collected in Mali and identified by the Traditional Medicine Department; voucher specimens are preserved in the herbarium for future reference. Preparation of the extract and isolated compounds Air-dried and powdered aerial parts of M. scaber (500 g) were extracted at room temperature with MeOH to afford 17·4 g