Variations of Mitragynine Content in Kratom Leaves From Southeast Asia: An Updated Review

Kratom (Mitragyna speciosa Korth.), a tropical psychoactive plant native to Southeast Asia has garnered significant attention for its unique phytochemical profile and notable effects, particularly for its analgesic properties. Traditionally, its leaves have been consumed by labourers in Thailand, Malaysia, and Indonesia to mitigate pain and boost energy. This review examines the botany and chemistry of kratom, with a particular focus on the mitragynine (MG) content in leaf extracts, which accounts for the majority of its observed pharmacological effects. The structure-activity relationship (SAR) of MG is explored in detail to understand its role in mediating these effects. Additionally, spectroscopic methods for MG characterization, as well as techniques for its quantification, are discussed. Factors influencing MG content, including geographical distribution, and environmental conditions are critically reviewed. This review aims to provide a comprehensive understanding of kratom's botanical and chemical properties in relation to the variations in MG content.