Journal of Ethnopharmacology 123 (2009) 143–148 Contents lists available at ScienceDirect Journal of Ethnopharmacology journal homepage: www.elsevier.com/locate/jethpharm Antimicrobial activity of Acacia mellifera extracts and lupane triterpenes Charles Mutai a,∗ , Christine Bii a , Constantinos Vagias b , Dennis Abatis b , Vassilios Roussis b a Kenya Medical Research Institute, Centre for Traditional Medicine and Drug Research, PO Box 54840, Nairobi, Kenya b University of Athens, Department of Pharmacy, Division of Pharmacognosy and Chemistry of Natural Products, Panepistimiopolis Zografou, Athens 157 71, Greece article info Article history: Received 3 August 2008 Received in revised form 8 December 2008 Accepted 3 February 2009 Available online 14 February 2009 Keywords: Acacia mellifera Leguminosae Antimicrobial activity Medicinal plants abstract Ethnopharmacological relevance: Acacia mellifera (Vahl) Benth (Leguminosae) is a subtropical medicinal plant that is widely used in traditional African medicines against various diseases such as pneumonia and malaria. Aim of the study: The present study was performed to evaluate the antimicrobial effects of extracts from the stem bark of Acacia mellifera. Materials and methods: The extracts were examined for antibacterial and antifungal activity using the disc-diffusion method against bacterial strains: Streptococcus pneumoniae (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35218), Escherichia coli (ATCC 25922) and Staphylococ- cus aureus (ATCC 25923) and fungal strains Candida albicans (ATCC 90028), Candida krusei (ATCC 6255), Cryptococcus neoformans (ATCC 6603) and clinical isolates of Microsporum gypseum and Trichophyton mentagrophytes. Results: Some of these extracts were found to be active against some bacterial and fungal strains and were further fractionated to give 12 pure compounds. The methanolic and methanol:dichloromethane (1:1) extracts exhibited antibacterial and antifungal activity. The two were active against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, and Trichophyton mentagrophytes. Activity guided fractionation led to isolation of two active compounds: 3-(Z)-cis coumaroylbetulin and 30-hydroxylup-20 (29)-en-3-ol which were against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, Trichophyton mentagro- phytes and Pseudomonas aeruginosa (ATCC 27853). Conclusions: These results may partly explain and support the use of Acacia mellifera stem barks for the treatment of infectious diseases in traditional Kenya medicine. © 2009 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Infectious diseases, particularly those involving the gastro intestinal and respiratory tracts are a serious problem worldwide, mainly among third world children (Dunn et al., 1997). On the other hand, some of the drugs currently in use result in adverse side effects (Covington, 1988). Therefore, the search for new antimi- crobial substances exhibiting minimal side effects is warranted (Covington, 1988; Kandil et al., 1994). Herbal remedies play a fun- damental role in traditional medicine in rural areas of Kenya, where they are often the therapeutic treatment of choice. Depending on the cultural practice, a medicinal plant can be obtained from healers already prepared or from the raw materials according to traditional practices. One of the most promising areas in the search for new bio- logically active compounds is the plant used in traditional medicine (Alonso et al., 1995). ∗ Corresponding author. Tel.: +254 202722541/2713349x3326; fax: +254 202720030. E-mail address: cmutai@kemri.org (C. Mutai). Although, Acacia is the second largest genus in the family Legu- minosae comprising more than 1200 species (Harden, 1991) and occurs in almost all habitat types, little research has been attempted in the context of phytochemical leads for therapeutic use. Aca- cia mellifera is one of the valuable medicinal plants commonly used in Kenyan’s folk medicine. The stem bark parts of the plant are used as a syphilis, and pneumonia agent (Kokwaro, 1993). Triterpenoids of this plant have been isolated and reported to be cytotoxic and antimalarial (Mutai et al., 2004, 2007). The objec- tive of the study was to determine the antimicrobial potential of Acacia mellifera extracts and fractions against infectious disease agents. 2. Materials and methods 2.1. Plant material The stem bark of Acacia mellifera were collected on January 2000, in Machakos, District, Kenya. A voucher specimen (ChM-1) was deposited at the East Africa Herbarium-National Museums of Kenya, Nairobi. 0378-8741/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2009.02.007