Carbohydrate-Isoxazole Hybrids: Design, Synthesis, and Therapeutic Applications in Drug Discovery

Natural products have long served as a cornerstone for drug discovery due to their structural diversity and biological relevance. However, their clinical utility is often limited by poor solubility, low bioavailability, and metabolic instability. To overcome these challenges, structural modification through carbohydrate conjugation has emerged as a promising strategy to enhance physicochemical properties and pharmacological efficacy. Among these modifications, carbohydrate-isoxazole hybrids have garnered significant attention due to their broad-spectrum biological activities, including anti-tumor, anti-inflammatory, anti-fungal, anticoagulant, and anti-parasitic effects. These hybrids leverage the inherent bioactivity of the isoxazole ring—a five-membered heterocycle known for its role in drug design—while the carbohydrate moiety improves solubility and target specificity. Notable examples include compound 11, a potent factor Xa (fXa) inhibitor with a remarkable binding affinity (Ki = 60 pM), highlighting its potential as a next-generation anticoagulant. Conversely, not all modifications yield enhanced activity; for instance, galactose-conjugated mofezolac derivatives showed no improvement in COX-1 inhibition, underscoring the need for rational design in hybrid optimization. Additionally, glycosylated isoxazole derivatives have demonstrated efficacy against Mycobacterium tuberculosis (MIC = 3.125 μg/mL) and Trypanosoma cruzi, the causative agent of Chagas disease, further expanding their therapeutic scope. This review comprehensively examines the medicinal chemistry of carbohydrate-isoxazole hybrids, focusing on their synthesis, structure-activity relationships (SAR), and mechanisms of action. We also discuss key challenges in clinical translation, such as metabolic stability and selective targeting, while highlighting future directions for optimizing these hybrids as multifunctional therapeutics.