Climate-Driven Modulation of Plant Secondary Metabolites: Implications for Medicinal Quality, Standardization, and Therapeutic Efficacy

Secondary metabolites are key biochemical compounds regulating plant defense mechanisms, ecological interactions, and environmental adaptation processes. Terpenoids, phenolics, alkaloids, and polyketides play roles in plant–microbe and plant–herbivore interactions while serving as sources of pharmacologically important compounds. Climate change, including increased temperature, altered precipitation, elevated CO₂, and UV-B radiation, affects plant metabolite biosynthesis. This review aims to examine the effects of climate change on secondary metabolism. Studies published between 2015 and 2025 were retrieved from PubMed, Web of Science, and Scopus databases. Results show that elevated CO₂ increases phenolics and flavonoids, while heat and drought stress enhance terpenoid and alkaloid biosynthesis via ROS-mediated signaling and transcription factors including MYB, bHLH, WRKY, and NAC families. UV-B radiation also increases flavonoid accumulation. In conclusion, climate change significantly affects plant secondary metabolite biosynthesis.