Palladium complexes of bidentate pyridine N‐heterocyclic carbenes: Optical resolution, antimicrobial and cytotoxicity studies

• Published in: Applied organometallic chemistry Vol. 32; no. 8
• Main Authors: Choo, Kar Bee, Mah, Wee Li, Lee, Sui Mae, Lee, Wai Leng, Cheow, Yuen Lin
• Format: Journal Article
• Language: English
• Published: Chichester Wiley Subscription Services, Inc 01.08.2018
• Subjects: Antiinfectives and antibacterials; antimicrobial activity; Biocompatibility; Biomedical materials; Cancer; Carbenes; Chemistry; Chirality; Colon; Cytotoxicity; Microorganisms; N‐heterocyclic carbene; Palladium; palladium NHC complexes; Toxicity
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.4377

A series of bidentate pyridine‐functionalized palladium N‐heterocyclic carbene (Pd NHC) complexes with various wingtip substituents (R = methyl, phenyl and tert‐butyl) have been synthesized and evaluated for their potential biomedical applications as antimicrobials and antiproliferative drug candidates. The obtained Pd NHC complexes were applied in a standard broth microdilution assay for determination of their antimicrobial activities against thirteen strains of pathogenic microorganisms. In addition to that, cytotoxic activities of the Pd NHC complexes were also evaluated against three human cancer cell lines, namely breast (MCF‐7), colon (HCT116) and oral (H103) cancer cells, using a standard MTT assay. Upon coordination to palladium, the Pd NHC complexes show significant antimicrobial activities with minimum inhibitory concentrations in the micromolar range, and they are cytotoxic to the tested carcinomas with IC50 ranging from 13 to 38 μM. Evidences for influence of both wingtip substituents and optical isomerism on the biological activities of the complexes have been found. Bidentate palladium complexes bearing N‐heterocyclic carbene and pyridine ligands were optically resolved. Biomedical application studies revealed that they exhibited substantial cytotoxicity against tested human carcinoma cell lines and demonstrated antimicrobial activities.