Investigation of an In Vitro Antimicrobial Activity of Angiopteris evecta (Forst.) Hoffm

摘要

The number of multi drug resistant starins and strains with reduced suceptibility to antibiotics are continuoesly increased. Hence searching for noval antibiotics from medicinal plants are vital. An ethno medicinal survey conducted in two different districts in Sri Lanka, especially with tribal community showed the heavy used of Angiopteris evecta (Forst.) Hoffm to cure various types of diseases. The present study was carried out to examine the in vitro antimicrobial activity of A. evecta, a pteridophyte, against the bacterial strains of Escherichia coli (ATCC 35218), Staphylococcus aureus (ATCC 25928), Klebsiella pneumonia (ATCC 13883) and Streptococcus faecalis (ATCC 9790) by agar disc diffusion assay and the fungal stains of Aspegillus niger, Fusaium oxisforum and Curvularia sp by food poison technique. The crude extracts of A. evecta were prepared in dichloromethane, acetone, methanol, chloroform and ethanol from fronds, roots and rhizomes to select the best solvent to be used in the assay. Among all the extracts tested, acetone crude extract prepared from fronds, rhizomes and roots showed the highest activity against E. coli (ATCC 35218) and S. aureus (ATCC 25928). Compared to them, K. pneumonia (ATCC 13883) and S. faecalis (ATCC 9790) showed very low level of activity. Hence, the acetone extract was used to determine the minimum inhibitory concentration (MIC) of S. aureus (ATCC 25928) and E. coli (ATCC 35218) and the MIC values were determined as 290 μg/disc and 195 μg/disc respectively. The assessment of fungal toxicity was carried in terms of percentage of mycelial growth inhibition in five different concentrations (500, 400, 300, 200, and 100 μg/ml) of ethanol, methanol, dichloromethane, and acetone, for leaves, rhizomes and roots. The ethanol and methanol extracts of leaves, roots and rhizomes showed the highest activity against the all fungal strains tested. However, A. niger showed the highest activity showing 100% inhibition of the growth at 300 μg/ml of ethanol and methanol extracts. Taking together, our results showed A. evecta is a potential source to isolate novel antimicrobial compounds.