Brominated plastoquinone analogs: Synthesis, structural characterization, and biological evaluation

• Published in: Journal of molecular structure 2020-11, Vol.1219, p.128560, Article 128560
• Main Authors: Bayrak, Nilüfer, Yıldız, Mahmut, Yıldırım, Hatice, Mataracı Kara, Emel, Ozbek Celik, Berna, Tuyun, Amaç Fatih
• Format: Article
• Language: English
• Subjects: Aminobenzoquinone; Antibacterial activity; Antifungal activity; Aromatic amines; Bromine; Plastoquinones
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2020.128560

A series of brominated PQ analogs (BrPQ1-13) was synthesized by employing two different routes: 1) dibromination followed by oxidation and amination of dimethyl hydroquinone, respectively, 2) oxidation of dimethyl hydroquinone followed by amination and bromination, respectively. In addition to the single-crystal X-ray structural characterization of two analogs (BrPQ2 and BrPQ3), the structures of all analogs were determined based on spectral (FTIR, 1H NMR, 13C NMR, and HRMS) data. We evaluated the analogs for in vitro antibacterial and antifungal activity against ATCC® strains (panel of seven bacterial strains with three Gram-positive and four Gram-negative bacteria and three fungi) using the broth microdilution method. The structure–activity relationship of brominated PQ analogs indicated that the electron-withdrawing group (EWG) on the phenyl ring (-CF3, trifluoromethyl group) has a positive effect on antibacterial activity. These in vitro data show that brominated analogs, especially for BrPQ1, BrPQ2, and BrPQ3, have the potential to be developed as new antibacterial agents against S. aureus and/or S. epidermidis with low MIC values. [Display omitted] •Brominated PQ analogs were designed and synthesized.•Brominated PQ analogs were spectroscopically described.•The structures of BrPQ2 and BrPQ3 were confirmed by X-ray crystallography.•All analogs were evaluated for their antimicrobial activity.