Functionally substituted 2-aminothiazoles as antimicrobial agents: in vitro and in silico evaluation

Nine new functionally substituted derivatives of 2-aminothiazole were evaluated for antimicrobial activity using microdilution method against the panel of eight bacterial and eight fungal strains. Evaluation of antibacterial activity revealed that compounds are potent antibacterial agents, more active than ampicillin and streptomycin except of some compounds against B. cereus and En. cloacae. The best compound appeared to be compound 8. The most sensitive bacteria appeared to be En. cloacae, while L. monocytogenes was the most resistant. Compounds also exhibited good antifungal activity much better than two reference drugs, ketoconazole and bifonazole. Compound 1 exhibited the best antifungal activity. The most sensitive fungus was T. viride, while A. fumigatus was the most resistant. Bacteria as well as fungi in general showed different sensitivity towards compounds tested. Molecular docking studies revealed that MurB inhibition is probably involved in the mechanism of antibacterial activity, while CYP51 of C. albicans is responsible for the mechanism of antifungal activity. Finally, it should be mentioned that all compounds displayed very good druglikeness scores.

Appendix A. dithioloquinolinethiones as new potential multitargeted antibacterial and antifungal agents: Synthesis, biological evaluation and molecular docking studies

Herein we report the design, synthesis, molecular docking study and evaluation of antimicrobial activity of ten new dithioloquinolinethiones. The structures of compounds were confirmed by ¹H NMR, ¹³C NMR and HPLC-HRMS. Before evaluation of their possible antimicrobial activity prediction of toxicity was performed. All compounds showed antibacterial activity against eight Gram positive and Gram negative bacterial species. All compounds appeared to be more active than ampicillin and almost all than streptomycin. The best antibacterial activity was observed for compound 8c 4,4,8-trimethyl-5-{[(4-phenyl-5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-yl)thio]acetyl}-4,5-dihydro-1H-[1,2]dithiolo[3,4c]quino lone-1-thione). The most sensitive bacterium En.cloacae followed by S. aureus, while L.monocytogenes was the most resistant. All compounds were tested for antifungal activity also against eight fungal species. The best activity was expressed by compound 8d (5-[(4,5-Dihydro-1,3-thiazol-2-ylthio)acetyl]-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinoline-1-thione). The most sensitive fungal was T. viride, while P. verrucosum var. cyclopium was the most resistant one. All compounds were more potent as antifungal agent than reference compound bifonazole and ketoconazole. The docking studies indicated a probable involvement of E. coli DNA GyrB inhibition in the anti-bacterial mechanism, while CYP51ca inhibition is probably responsible for antifungal activity of tested compounds. It is interesting to mention that docking results coincides with experimental.

Chemical analysis and antifungal activity ofThymus striatus

The essential oil composition from Thymus striatus collected from Mountain Orjen (Montenegro) has been investigated by gas chromatography-mass spectrometry. Thymol, gamma-terpinene and p-cymene were found to be the major components. Furthermore, the oil and its major component, thymol, were analysed for potential antifungal activity against plant, animal and human pathogenic fungi from different genera by a macrodilution test. The oil exhibited a strong inhibitory effect against all fungi investigated.

Sesquiterpene lactones from Centaurea thessala and Centaurea attica. Antifungal activity

The aerial parts of Centaurea thessala ssp. drakiensis and C. attica ssp. attica afforded, in addition to several known sesquiterpene lactones, two new eudesmanolides, 4-epi-sonchucarpolide and its 8-(3-hydroxy-4-acetoxy-2-methylene-butanoyloxy) derivative and one new eudesmane derivative, named atticin. The in vitro antifungal activity of most compounds was tested against nine fungal species, using the micro-dilution method. All the compounds tested showed great antifungal activity.