TITLE:
In Vitro Antischistosomal Potentials of 1-(quinolin-2-yl)-N-(quinolin-8-yl)methanimine, 2-((quinolin-8-ylimino)methyl)quinolin-8-ol and N-(pyridin-2-ylmethyl)-1-(quinolin-2-yl)methanimine] Heteroaryl Schiff Bases and Their Zn(II) Complexes: Synthesis, Characterisation, Density Functional Theory Studies, Molecular Docking and in Silico Pharmacokinetics Properties
AUTHORS:
Celine Kekwi Ngwang, Mireille Sylviane Dongmo Nguepi, Jean Hubert Nono, Marius Belmondo Tincho, Mirabel Akongwi, Domiriane Ornela Madjougne Foudjo, Darline Dize, Diana Sandra Wendji Monkam, David Woutouoba Ntieche, Alvine Kengne, Felicite Majoumo-Mbe
KEYWORDS:
Zn(II) Complexes, Heteroaryl Schiff Bases, DFT Studies, In Vitro and in Silico Cercaricidal Potential, Pharmacokinetics Prediction
JOURNAL NAME:
Open Journal of Inorganic Chemistry,
Vol.16 No.2,
April
14,
2026
ABSTRACT: Zn(II) complexes of three heteroaryl Schiff bases L1, HL2 and L3 of general formula [ZnL1Cl2]∙2H2O (1), [ZnL2Cl]∙H2O (2), [ZnL3Cl2]∙H2O (3) [L1 = 1-(quinolin-2-yl)-N-(quinolin-8-yl)methanimine, HL2 = 2-((quinolin-8-ylimino)methyl)quinolin-8-ol, L3 = N-(pyridin-2-ylmethyl)-1-(quinolin-2-yl)methanimine] have been synthesised. Based on spectroscopic analyses, five-coordinate geometries were proposed where L1 and L3 coordinated through the azomethine N and the two quinolines N as neutral NNN-donor modes, while HL2 coordinated through the azomethine N, the two quinolines N and the O atom of the OH group as deprotonated with NNNO-donor mode. DFT calculations were used to investigate the electronic properties of the ligands and complexes, and their optimised structures were generated. Complexation and the presence of the OH group enhanced the activity against cercariae of Schistosoma mansoni while L1 with fused benzene backbone and its complex were inactive compared to L3 with CH2 backbone from 2-picolylamine derivative. Molecular docking studies revealed that the active compounds displayed higher binding affinity to the active sites of SmCE2a, SER, SmTGR, and SmPNP, with binding energies ranging from −6.1 to −10.1 kcal/mol, indicating that the ligands (HL2), L3 and complex (2) can be potential inhibitors of the four main target proteins of S. mansoni. In silico pharmacokinetics properties of HL2, L3 and Zn(II) complex (2) agree with the four drug likeness rules (Lipinski, Ghose, Veber, and Egan rules) and these derivatives can be considered as potential lead candidates for an antischistosomal therapeutic development. Furthermore, the active ligands and complex showed a good bioavailability score of 0.55.