STRUCTURE-ACTIVITY RELATIONSHIPS OF BIOACTIVE COMPOUNDS FROM SRI LANKAN PLANTS: A REVIEW

Sri Lanka, with its remarkable biodiversity and long history of traditional medicine, harbors a wealth of plant-derived chemical diversity. Numerous endemic species have yielded secondary metabolites spanning alkaloids, flavonoids, terpenoids, phenolic acids, coumarins, and other structural classes. Many of these compounds exhibit valuable pharmacological properties, including antioxidants, antimicrobial, antidiabetic, anti-inflammatory, and anticancer activities. However, only a limited number of studies have systematically probed the relationship between the chemical structure of these natural products and their biological activity, known as the structure-activity relationship (SAR). This review systematically examines available data on bioactive compounds isolated from Sri Lankan plants. It identifies tentative SAR trends: functional groups, ring systems, degree of conjugation, and lipophilicity recur as key determinants of activity. Additionally, significant research gaps are highlighted, along with strategic directions, including bioassay-guided fractionation, computational modeling, and semi-synthetic derivatization, that could transform primarily descriptive phytochemical literature into a resource for rational drug discovery.