Phytochemical investigation and antimicrobial activity of girardinia diversifolia (link) friis (urticaceae)

Abstract

Girardinia diversifolia (Link) Friis (Urticaceae) is a herb used traditionally for various ailments, including microbial infections. The objective of this study was to carry out phytochemical investigation of its chemical constituents and screen it for in vitro antibacterial and antifungal activities. The plant material was collected from Kamweti Location, Kirinyaga District. Phytochemical studies showed that the roots and stems of Girardinia diversifolia contained saponins, tannins and cardiac glycosides but lacked alkaloids and anthracene glycosides. Extracts of the plant material were prepared by sequential Soxhlet extraction using petroleum ether (60-80 "C), chloroform and methanol. Ethyl acetate extract was prepared by partitioning the methanol extract between water and ethyl acetate. Chromatographic fractionation of the petroleum ether root extract using normal-phase silica gel yielded four crystalline compounds, three of which were identified as ~-sitosterol, 3-hydroxystigrnast-5-en-7-one and 7-hydroxysitosterol. This isthe first time that these compounds are reported from Girardinia diversifolia. Agar diffusion method was used to screen for in vitro antibacterial and antifungal activities. All the tested extracts exhibited varying degrees of antibacterial activity against Bacillus pumilus, Staphylococcus aureus and Escherichia coli. Bioautography using Bacillus pumi/us revealed several components with antibacterial activity in all extracts. Only the ethyl acetate extract exhibited significant antifungal activity against Aspergillus niger and Candida a/Means. Bioautography using Saccharomyces cerevisiae revealed one component in the ethyl acetate extract with remarkable antifungal activity. 7-hydroxysitosterol and the yet to be identified fourth isolate exhibited modest antibacterial activity against Bacillus pumilus. The present study gives scientific credence to the traditional use of Girardinia diversifolia in the treatment of bacterial and fungal infections. The antimicrobial activity seems to be concentrated in the polar fractions and these should be investigated further to isolate the bioactive components. In vivo studies should also be carried out to establish therapeutic efficacy and toxicity of the isolates.