Antimicrobial activity of Kielmeyera variabilis

Kielmeyera variabilis Mart. (Clusiaceae), a tree commonly known in Brazil as „malva-do-campo“, is used in Brazilian folk medicine to treat several tropical diseases such as schistosomiasis, leishmaniasis, malaria, fungal and bacterial infections [1]. Multidrug-resistant Staphylococcus aureus (MRSA) have been a major threat to public health in hospitals and the community in the past decade [2]. As part of our on-going project to isolated bioactive compounds from Brazilian species, the anti-staphylococcal properties of the K. variabilis was investigated. The MICs were obtained using the methodology described by Gibbons and Udo [3]. The EtOH extracts from leaves (EFK) and stems (EGK) were tested against S. aureus strain (SA 1199B) with the MIC values of 128 and 32µg/mL, respectively. The EGK was partitioned between hexane (EHGK), EtOAc (EAGK) and n-BuOH (EBGK). The EHGK showed strong activity against SA 1199B (MIC=16µg/mL, compared to the control Norfloxacin MIC=32µg/mL). The EHGK was bioassay-guided fractionated using chromatographic techniques (Sephadex® LH-20, silica gel column, SPE and PTLC) leading to the isolation of the bioactive compound 1. The compound 1 (a phloroglucinol derivate) was tested against six S. aureus strains and showed a strong activity with MIC values of 0.25–2µg/mL (Table 1).

Table 1: MICs of compound 1 and standard antibiotic in µg/mL

	SA 1199B	RN 4220	EMRSA 15	EMRSA 16	Xu 212	ATCC 25943
Compound 1	2	0.25	1	0.5	0.25	2
Norfloxacin	32	0.5	0.5	128	8	0.5

Acknowledgements: 1 FAPESP 2 School of Pharmacy, University of London, London, UK.

References: 1. Alves, T. M. A. et al. (2000) Men. Inst. Oswaldo Cruz. 95:367–373.

2. White, C. (2004) BMJ 329:131.

3. Gibbons, S., Udo, E. E. (2000) Phytother. Res. 14:139–140.