SECONDARY METABOLITES FROM MEDICINAL PLANTS THRIVING IN EXTREME ENVIRONMENTS

Plants inhabiting extreme environments—including arid deserts, hypersaline coastal areas, high-altitude mountains, and high-UV radiation zones—produce unique secondary metabolites that enable their survival under severe stress conditions. These extremophilic medicinal plants represent an underexplored resource for drug discovery, offering novel chemical architectures and potent bioactivities. This review comprehensively examines the secondary metabolites of medicinal plants thriving in extreme environments, focusing on their chemical diversity, ecological roles, and pharmacological potential. Halophytes and xerophytes have been recognized for their nutritional and medicinal values owing to their comparatively higher productions of secondary metabolites, primarily phenolics and flavonoids. Plants thriving in high-altitude regions synthesize secondary metabolites like flavonoids and phenolic compounds in bulk quantities, which act to form a robust antioxidant defence against oxidative stress, including UV radiation and temperature fluctuations. We evaluate the unique adaptation strategies that drive the production of specialized metabolites, including osmotic regulators, UV protectants, and stress-responsive antioxidants. The review synthesizes evidence from plants across diverse extreme habitats, including halophytes (salt-tolerant plants), xerophytes (drought-tolerant plants), and psychrophytes (cold-tolerant plants). Structural features, biosynthetic pathways, and pharmacological activities—including antioxidant, antimicrobial, anticancer, and anti-inflammatory properties—are critically assessed. This review identifies significant opportunities for drug discovery from extremophilic plants and highlights research gaps requiring future investigation.