Free radical scavenging, antibacterial potentials and spectroscopic characterizations of benzoyl thiourea derivatives and their metal complexes

Abstract

In this work, two series of benzoyl thiourea derivatives (TH01-TH05), (TH06-TH10) and their metal complexes were successfully synthesized in good yields (up to 90%) using efficient two-pot synthesis by reacting isothiocyanate with amines and amino acids. The FTIR, 1HNMR, 13CNMR and MALDI-TOF-MS were used for structural elucidation. The FTIR spectra of first series (TH01-TH05) displayed broad absorption band of -OH group at 3600-2800 cm−1 while for 2nd series (TH06-TH10) the absence of OH confirmed the synthesis. The 1HNMR spectra confirmed the synthesis of 1st series have shown singlet peak at 10 to 11.480 ppm for OH proton and two singlets for NH protons at 11.105 ppm and 10.790 ppm respectively. The 13CNMR confirmed synthesis of 1st series by appearance of peaks at 181.328 ppm for (C=S), 170.308 ppm and 168.680 ppm for two (C=O) and aromatic carbons at 133.56-128.954 ppm. The MALDI-TOF-MS results showed presence of molecular ion peaks at appropriate positions. Antimicrobial activity results showed that TH-01, TH-08 and TH-09 have promising antibacterial potential against K. pneumoniae (12 mm) and P. aeruginosa (16 mm and 14 mm) respectively. The DPPH radical scavenging activity of Co-TH05 showed more potential with IC50 value 11.4±0.2 µg/mL than standard ascorbic acid (IC50 10.8±0.5 µg/mL). Results confirmed that the synthesized thiourea derivatives can be efficiently used as radical scavenger and antimicrobial agents.