Antimicrobial activity of some important Adiantum species used traditionally in indigenous systems of medicine.

Adiantum Linn. of Adiantaceae family is one of the most common and widely distributed species. Ethnomedicinally, the genus is important and popularly known as "Hansraj" in Ayurvedic System of Medicine. It has been used in cold, tumors of spleen, liver and other viscera, skin diseases, bronchitis and inflammatory diseases. It is also considered as tonic and diuretic. In the present study its four important species, i.e. Adiantum capillus-veneris, Adiantum peruvianum, Adiantum venustum and Adiantum caudatum were collected and extracted with methanol. These extracts were tested for their antimicrobial agents against five gram positive, six gram negative (including multiresistant bacteria Staphylococcus aureus) and eight fungal strains using standard microdilution assay. The maximum activity was exhibited by the methanolic extract of Adiantum venustum followed by Adiantum capillus-veneris, Adiantum peruvianum and Adiantum caudatum. The methanolic extract of Adiantum capillus-veneris had very low MIC value (0.48 microg/ml) against Escherichia coli whereas, Adiantum venustum extract against Aspergillus terreus with MIC of 0.97 microg/ml. Total phenolic constituents of Adiantum species viz. Adiantum venustum, Adiantum capillus-veneris, Adiantum peruvianum and Adiantum caudatum were 0.81% (w/w), 0.83% (w/w), 0.71% (w/w) and 0.52% (w/w), respectively (as gallic acid equivalent); implying that the observed activity could be related to the amount of phenolics.