Zn(II) and Cd(II) thiosemicarbazones for stimulation/inhibition of kojic acid biosynthesis from Aspergillus flavus and the fungal defense behavior against the metal complexes' excesses.

Ghada Abd-Elmonsef Mahmoud, Ahmed B M Ibrahim, Peter Mayer

Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry 2020 Aug

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The complexes {[ZnL1Cl] C1, [ZnL2Cl].0.5H2O C2, [CdL1Cl] C3, and [CdL2Cl] C4} were prepared from tridentate thiosemicarbazones {HL1 = 4-(3-nitrophenyl)-1-((pyridin-2-yl)methylene) thiosemicarbazide and HL2 = 4-(2,4-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} and identified by elemental CHNS, spectroscopic {IR and UV-Vis.}, thermal and DMF solution electrical conductivity data. On another hand, kojic acid (KA) which represents important secondary metabolite with numerous hot spot applications was successfully biosynthesized from Aspergillus flavus and structurally analyzed by single crystal analysis. The Zn(II) complexes C1&C2 (0.3 mM) enhanced the KA biosynthesis by 70.87% and 42.26%, while 76.09% of C1 and 72.78% of C2 were absorbed by the fungal cells. The Cd(II) complexes C3&C4 at 0.3 mM inhibited KA production by 87.95% and 97.03% with Cd(II) consumption reaching to 40.09% & 37.3%, while 0.4 mM of C3&C4 resulted in 100% inhibition of kojic acid biosynthesis. Light microscopic analysis showed the fungal structural abnormalities and the cell antioxidant behavior was detected. These complexes could be highly applicable as new stimulators and inhibitors of kojic acid production.

Citation

Ghada Abd-Elmonsef Mahmoud, Ahmed B M Ibrahim, Peter Mayer. Zn(II) and Cd(II) thiosemicarbazones for stimulation/inhibition of kojic acid biosynthesis from Aspergillus flavus and the fungal defense behavior against the metal complexes' excesses. Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry. 2020 Aug;25(5):797-809