Objective: To design and synthesize amino acetylenic and thiocarbonate of 2-mercapto-1,3-benthiazoles as potential antimicrobial agents. Methods:A new series of 2-{[4-(t-amino-1-yl) but-2-yn-1-yl] sulfanyl}-1,3-benzothiazole derivatives (AZ1-AZ6), and S-1,3-benzothiazol-2-yl-Oalkyl carbonothioate derivatives were synthesised, with the aim that the target compounds show new and potential antimicrobial activity. The elemental analysis was indicated by the EuroEA elemental analyzer, and biological characterization was via IR, 1 Results:The IR, H-NMR, [13]C-NMR, DSC were determined with the aid of Bruker FT-IR and Varian 300 MHz spectrometer using DMSO-d6 as a solvent. In vitro antimicrobial activity, evaluation was done for the synthesised compounds, by agar diffusion method and broth dilution test. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined. H-NMR, 13Conclusion: These promising results promoted our interest to investigate other structural analogues for their antimicrobial activity further.C-NMR, DSC and elemental analysis were consistent with the assigned structures. Compound of 2-{[4-(4-methylpiperazin-1-yl)but-2-yn-1-yl] sulfanyl}-1,3-benzothiazole (AZ1), 2-{[4-(2-methylpiperidin-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzothiazole (AZ2), 2-{[4-(piperidin-1-yl) but-2-yn-1-yl]sulfanyl}-1, 3-benzothiazole (AZ6), S-1,3-benzothiazol-2-yl-O-ethyl carbonothioate (AZ7), and S-1,3-benzothiazol-2-yl-O-(2-methylpropyl) carbonothioate (AZ9) showed the highest antimicrobial activity against Pseudomonas aeruginosa (P. aeruginosa), AZ-9 demonstrated the highest antifungal activity against Candida albicans (C. albicans), with MIC of 31.25 µg/ml.

A new series of 7-methoxy-2-[4-(t-amino-1-yl)oxy]-naphthalene derivatives; 7-methoxy-2-{[4-(2-methylpiperidine)but-2-yn-1-yl]oxy}-naphthalene (RZ2), 7-methoxy-2-{[4-(2,6-dimethylpiperidine)but-2-yn-1-yl]oxy}-naphthalene (RZ3), 7-methoxy-2{[4-(piperidine)but-2-yn-1-yl]oxy}-naphthalene (RZ4), 7-methoxy-2-{[4-(pyrrolidine)but-2-yn-1-yl]oxy}-naphthalene (RZ5), 7-methoxy-2-{[4-(N-methylpiperazine)but-2-yn-1-yl]oxy}-naphthalene (RZ6), 7-methoxy -2-{[4-(hexamethyleneimine)but-2-yn-1-yl]oxy}-naphthalene (RZ7) were synthesized and screened in vitro as potential antimicrobial agents. Antimicrobial activity were evaluated by measuring the minimum inhibitory and bactericidal/fungicidal concentration (MIC, MBC and MFC). RZ2, RZ5, RZ6 and RZ7 showed the highest antimicrobial activity against S. aureus with MIC value 62.5 µg/ml, compounds RZ2, RZ4, RZ5, and RZ7 have the highest antimicrobial activity against B. subtilis with MIC vale 62.5 µg/ml, RZ3, RZ6 have the same antimicrobial activity with MIC value 125µg/ml, compounds. RZ4, RZ5, RZ6 and RZ7 have the highest antimicrobial activity against E. coli with MIC value 125 µg/ml, all compounds have the same MIC value against P. aeruginosa (125 µg/ml). RZ2, RZ4, RZ5, RZ6, RZ7 showed the highest antifungal activity with MIC of 62.5 µg/ml. In conclusion, the synthesized compounds showed good antimicrobial activity and promising potency against gram positive bacteria, gram negative bacteria and fungi.

Objective: To determine the time needed for killing different types of microorganisms by a newly synthesized 2-mercapto-1,3-benzothiazole derivative in comparison to ciprofloxacin and fluconazole. Methods:The minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) for 2-{[4-(2,6-dimethylPiperidin-1-yl)but-2-yn-1-yl]Sulfanyl}-1,3-benzothiazole(AZ3) compound were determined, using the broth dilution method. The MBC and MFC dilutions were prepared. Broth cultures of Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) were incubated at 37 °C for 24 h, and Candida albicans (C. albicans) was incubated at 25 °C for 48 h. 0.1 ml of each broth culture represent 1.5 x 10 6Results: The viability of the P. aeruginosa, E. coli, S. aureus, B. subtilis and C. albicans were killed within 3.5 h, 5 h, 24 h, 3 h and 5 h respectively. The time killing curves showed that AZ3 needed longer time for killing S. aureus than the time needed to kill B. subtilis. On the other hand, AZ3 needed a shorter time to kill P. aeruginosa, than the time needed to kill E. coli. In comparison with ciprofloxacin, AZ3 needed a shorter time to kill P. aeruginosa and E. coli, and the same time to kill B. subtilis, while it needed longer time than ciprofloxacin to kill S. aureus. In comparison with fluconazole, AZ3 with lower MFC than fluconazole needed longer time to kill C. albicans. CFU/ml was challenged with 9.9 ml broth containing the MBC or MFC concentrations of the AZ3 compound. From each sample at different time intervals, 1 ml was taken and added to 9 ml of sterile distilled water, in order to neutralize the effect of AZ3. Serial dilution was done and a viable count was determined from the appropriate dilutions.Conclusion: AZ3 showed promising antimicrobial killing activities, in compared with ciprofloxacin and fluconazole, which promoted our interest to investigate the time of killing needed for other 2-mercaptobenzothiazole derivatives against different types of microorganisms.