Syntheses and biological applications of thiourea derivatives: developments and challenges

Thiourea SC(NH2)2 (1), sulfur analog of urea (2), possesses unique hydrogen-bonding ability, mesomeric effects, and tautomeric versatility, making it a valuable scaffold in pharmaceuticals, agrochemicals, and materials science. Thiourea derivatives have diverse physical, chemical and biological properties. This review consolidates recent advances (2015–2025) in the synthesis of thiourea derivatives, emphasizing green methodologies: ultrasound-assisted, photochemical, solvent-free, and on-water reactions. Biological activities, i.e. antibacterial, antifungal, antiparasitic, antioxidant, antidiabetic, anti-inflammatory, antiviral, enzyme inhibitory and herbicidal are critically analyzed with a focus on structure–activity relationships (SAR), substituent effects, and chirality. Notable progress includes derivatives that are effective against drug-resistant pathogens and synergistic antifungal mixtures. By identifying research gaps (toxicity, selectivity, scalability) and advocating for sustainable synthesis, this review positions thiourea derivatives as versatile leads for next-generation therapeutic and agricultural solutions.