Abstract
Costus speciosus has long been used as a herbal medicine in different countries. Globally, there are two familiar and common species of costus, Indian costus and Sea-Qust. In the present study, we evaluated the antifungal abilities of Dimethylsufoxide (DMSO) extract and antibacterial capabilities of DMSO and methanolic extracts of Indian costus rhizome. Three fungal species were tested using different concentrations of DMSO extracts, namely, Retroconis fusiformis, Pythium ultimum, and Fusarium oxysporum. We found that 40 mg/ml of Indian costus extract prevented the growth of the tested fungi; by contrast, Sea-Qust extracts had no effect on fungi at the tested concentrations. The DMSO extracts in the range of 10-40 mg/ml showed higher activity, as measuring of the diameter of the inhibition zone, than methanolic extracts and prevented the growth of the gram-positive bacteria Bacillus sp. and Staphylococcus aureus and the gram-negative bacteria Escherichia coli and Aeromonas hydrophila. We also evaluated the genotoxicity of DMSO extracts to bacterial genomes using repetitive element PCR analysis (Rep-PCR). Rep-PCR identified polymorphic bands in E. coli treated with rhizome extracts that were absent in untreated bacteria. Our findings indicate that Indian costus is a potential source of antifungal, antimicrobial and mutagenic agents.