Antimicrobial activities of extracts and decussatin from Ficus congensis (Engl)
Decoctions prepared from the stembark and leaves of Ficus congensis, Fc (Engl) are used by the Southwestern Egun people of Nigeria in the management of„fevers“(translated in local language as iba) arising from infections. This has served as the driving impetus for the present investigational work on this plant. Hexane (stembark) and Methanol (leaf) extracts of Fc were evaluated for antifungal and antibacterial activities using Disk Agar diffusion (DAD) and Brothmicrodilution (MHB) respectively. Hexane stembark extracts subjected to chromatographic separation, followed by spectral analysis, afforded the xanthone:1-hydroxy3,7,8-trimethoxyxanthone (Decussatin)1as main constituent. The extracts and Decussatin, were screened for antifungal and antibacterial activities. Methanol leaf and Hexane stembark extracts were active against Candida albicans alone (zone of inhibition-20.00mm &18.9mm) at MIC of 2mgml-1 and 1mgml-1 respectively, out of the strains of fungi tested-Aspergillus fumigatus, Trichophyton mentagrophytes, Trichophyton rubrum. Methanol leaf extract showed Antibacterial activity against E. coli and B. substilis at MIC(3mgml-1,2mgml-1) respectively. Hexane stembark extract showed Antibacterial activity against E.coli only at MIC of 5mgml-1. No activity was observed in K. pneumonia and S. aureus. However, Decussatin showed little activity at the maximum concentration used;10 and 8 mgml-1for antifungal and antibacterial activities respectively. Spectral analysis were carried with the aid of IR&UV (Perkin Elmer), GC – MS (Agilent 5973 Network Plus),1D&2D NMR (600MHz, TopsinBruker). At this point, is possible to infer a link between the observed biological activities and folkloric claim of decoctions of Fc. We are reporting the existence of a known xanthone, Decussatin, in Fc which could be of great importance to the chemotaxonomy of this family. This is the first time it is reported in this plant species habiting in a swampy area in Lagos, Nigeria.
Acknowledgements: The authors are grateful to School of Chemistry and School of Biological Sciences, University of Kwazulu-Natal, Westville Durban, South Africa for their laboratory services.
References: 1. Dalal, S.R., Sethna, and Shan, R.C.(1953)J.Indian Chem.Soc. 30, 457–463.