Pb (II) and Hg (II) thiosemicarbazones for inhibiting the broad‐spectrum pathogen Cladosporium sphaerospermum ASU18 (MK387875) and altering its antioxidant system

Abstract

Pb (II) and Hg (II) ions were reacted in aqueous solution with two tridentate thiosemicarbazones, resulting in four complexes {[Pb(L1)2] 1, [Pb(L2)2] 2, [Hg(L1)2] 3, and [Hg(L2)2] 4; HL1 = 4‐(4‐nitrophenyl)‐1‐[(pyridin‐2‐yl)methylene]thiosemicarbazide and HL2 = 4‐(2‐chlorophenyl)‐1‐[(pyridin‐2‐yl)methylene]thiosemicarbazide}. The solid‐state structures of complexes 2 and 3 were determined by X‐ray crystallography, which also confirmed the monobasic tridentate NNS nature of the ligands, and the octahedral coordination geometry around the metal centers. Complexes 1–4 exhibited high antifungal activity against the pathogen Cladosporium sphaerospermum; all four complexes give rise to a reduction in the fungal dry mass and sugar consumption. Complexes 2 and 4 that inhibited C. sphaerospermum growth at the concentration of 1.8 mM are more efficient inhibitors than the free ligand and metal ions. Further, the complexes gave varied values of the fungal total antioxidants (TA), superoxide dismutase (SOD), and catalase (CAT) activities dependent on their concentrations.

Trivalent Cobalt Complexes with NNS Tridentate Thiosemicarbazones: Preparation, Structural Study and Investigation of Antibacterial Activity and Cytotoxicity against Human Breast Cancer Cells

“…However, HL 2 and C2 gave moderate antibacterial activities slightly higher for the complex against the two bacterial strains, but the activities are still less when compared with the standard. The inactivity of HL 1 and its complex, compared with the activities of HL 2 and C2, is probably due to their higher nitrogen content, as nitrogen is a vital element required for the growth of the microorganisms [42]. Indeed, metal complexes have been reported in several papers as long-acting drugs with slow releases in the cells, and the higher activities given by complexes relative to those of their ligands have been documented in several papers that concluded that upon coordination, the ligands bio-active or -inactive improved their antimicrobial activities or attained some pharmacological action [43,44].…”