Investigations on antimicrobial activity of cobaltabisdicarbollides

Metallacarboranes have been identified as promising pharmacophores and building blocks in drug designed as well as inhibitors of HIV. The aim of this study was to evaluate the putative antimicrobial properties in vitro of cobaltabisdicarbollide [3,3′-Co(1,2-C2B9H11)2]−, H[1], and its derivatives [3,3′-Co(8-R(CH2CH2O)2-1,2-C2B9H10)(1′,2′-C2B9H11)]− (R = −OOCCH3 (Na[3]); –OCH3 (Na[6]); –OCH2CH3 (Na[7])). Pure cultures of 16 pathogenic bacterial strains (isolated from animals and humans as well as control strains) and 3 strains of Candida spp. were applied in antimicrobial studies that were performed by the agar-diffusion method of Bauer–Kirby and the method of minimum inhibitory concentrations. The obtained results revealed that among the compounds examined Na[7] and Na[4] exhibited the highest antimicrobial activity that was equal or even higher than those of the commercially available broad-spectrum antibiotic thiamphenicol. The cobaltabisdicarbollide H[1] was shown to express comparatively lower antibacterial and antifungal properties as compared to its derivatives. From a practical point of view it is important to emphasize that the meticillin-resistant strain of Staphylococcus aureus (TSA MRSA), the poliresistant strains of Pseudomonas aeruginosa, as well as of Candida spp., are sensitive to the compounds Na[7] and Na[4].