Multicomponent Synthesis of 2,4,5-Trisubstituted Thiazoles Using a Sustainable Carbonaceous Catalyst and Assessment of Its Herbicidal and Antibacterial Potential

Herein, a novel, biocatalyzed, and on-water microwave-assisted multicomponent methodology have been developed for the synthesis of trisubstituted thiazoles (4a-4v). The reaction was catalyzed using a sulfonated peanut shell residue-derived carbonaceous catalyst (SPWB). The developed catalyst was characterized using Fourier transform infrared (FTIR), a Brunauer-Emmett-Teller (BET) surface area analyzer, a field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray (EDX), and a particle size analyzer (PSA). The acidic sites have been established using acid-base back-titration methods. The molecular structures of all the synthesized compounds were validated using FT-IR, ¹H NMR, ¹³C NMR, elemental, and HRMS analyses. Herbicidal potential was evaluated by using Raphanus sativus L. as a model. Furthermore, the Antibacterial potential of thiazoles was evaluated against Staphylococcus aureus, Bacillus subtilis, Xanthomonas campestris, Escherichia coli, Micrococcus luteus, and Pseudomonas aeruginosa Bacterial strains. The compound 4r displayed improved seed growth inhibition in Raphanus sativus L. versus a commercially available herbicide, i.e., pendimethalin. The Antibacterial activity was promising against Bacterial strains (MIC: 4-64 μg/mL). The compound 4r was the most potent against P. aeruginosa and S. aureus (MIC: 0.0076 μM) versus standard drug streptomycin (MIC: 0.0138 μM). Moreover, in silico studies performed with the most effective compound 4r against P. aeruginosa revealed its potential binding mode within the protein binding pocket. The biological data revealed compound 4r as a potential candidate for the development of potent herbicidal and Antibacterial agents. In a nutshell, this study offers peanut shell biowaste to be a sustainable biomass for heterogeneous acid catalyst preparation and its application in the multicomponent synthesis of bioactive thiazoles, accommodating the concept of sustainable development goals and circular bioeconomy.

Multicomponent synthesis; antibacterial; biochar; herbicidal activity; in silico study; microwave; on-water; peanut waste; sustainable catalyst; thiazoles.