Proton-pumping-ATPase-targeted antifungal activity of cinnamaldehyde based sulfonyl tetrazoles.

Azoles are generally fungistatic, and resistance to fluconazole is emerging in several fungal pathogens. We designed a series of cinnamaldehyde based sulfonyl tetrazole derivatives. To further explore the antifungal activity, in vitro studies were conducted against 60 clinical isolates and 6 standard laboratory strains of Candida. The rapid irreversible action of these compounds on fungal cells suggested a membrane-located target for their action. Results obtained indicate plasma membrane H(+)-ATPase as site of action of the synthesized compounds. Inhibition of H(+)-ATPase leads to intracellular acidification and cell death. Presence of chloro and nitro groups on the sulfonyl pendant has been demonstrated to be a key structural element of antifungal potency. SEM micrographs of treated Candida cells showed severe cell breakage and alterations in morphology.

Anticandidal activity of cinnamaldehyde, its ligand and Ni(II) complex: effect of increase in ring and side chain.

To increase efficacy of cinnamaldehyde as an antimycotic agent, N, N'- Bis (trans-cinnamadehyde) ethylenediimine [C(20)H(20)N(2)] and Ni(II) complex of the type [Ni(C(40)H(40)N(4))Cl(2)] have been synthesized. The ligand [P] and Ni(II) complex have been characterized on the basis of elemental analysis, FTIR, ESI- MS, IR, (1)H NMR, UV-Vis spectroscopic techniques, conductivity and magnetic measurements. MIC of cinnamaldehyde against clinical isolate of Candida albicans and Candida tropicalis was 400 microg/ml and 500 microg/ml, respectively. Synthesized ligand has markedly reduced MIC; 200 microg/ml and 300 microg/ml whereas Ni(II) complex of ligand displayed MIC of 90 microg/ml and 120 microg/ml. Growth and sensitivity of the organisms were effected by ligand & complex at significantly reduced concentration. Plasma membrane ATPase activity and ergosterol content have been investigated as site of action. Result obtained indicates ergosterol biosynthesis pathway as site of action of cinnamaldehyde, synthesized ligand and its Ni(II) complex.