Antimicrobial Activity of the Leaves of Endemic Stachys pseudopinardii in Turkey

Purpose: The ethanol extract of the leaves of Stachys pseudopinardii R. Bhattacharjee and Hub.–Mor. (Lamiaceae) were investigated for their antimicrobial activities. Methods: The antimicrobial activity of the leaf extract of the plant was tested against Bacillus subtilis ATCC 6633, Bacillus cereus ATCC 7064, Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 10538, Proteus vulgaris ATCC 6899, Salmonella typhimurium CCM 5445 and Pseudomonas aeruginosa ATCC 27853, as well as Candida albicans ATCC 10239, Debaryomyces hansenii DSM 70238, Kluyveromyces fragilis ATCC 8608 and Rhodotorula rubra DSM 70403, by disc diffusion and microdilution methods. Selected antibacterial agents (penicillin, tobramycin and ampicillin) and antifungal agents (nystatin, clotrimazole and ketoconazole) antibiotics were used as positive reference standards in the tests. Results: The extracts showed strong antibacterial activity against Bacillus cereus ATCC 7064, with an inhibition zone of 25.0 mm, and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 16 and 32 μg/mL, respectively. Debaryomyces hansenii DSM 70238 was among the most susceptible of the yeast cultures, with an inhibition zone of 17.0 mm and MIC and minimum fungicidal concentration (MFC) of 32 and 32 μg/mL, respectively. The extract exhibited moderate activity against the other test microorganisms. Conclusion: The results demonstrate that the ethanol extract of the leaves of Stachys pseudopinardii has significant antimicrobial activity and suggest that it may be useful in the treatment of infections.