Antioxidant Activity and Isolation of Xanthine Oxidase Inhibitor from Ruellia tuberosa L. Leaves

Introduction: The leaves of Ruellia tuberosa L. have been known to demonstrate strong antioxidant and xanthine oxidase (XOD) inhibitory activities. The aim of this study was to isolate antioxidant and XOD inhibitor from the leaves of the plants. Methods: Isolation of antioxidant and XOD inhibitor were conducted using chromatography techniques. The structure of the isolated compound was elucidated by spectroscopic methods. Results: In this study, a flavonoid was isolated and characterized as methoxylated flavonoid based on the spectral data including UV, IR, GC-MS, and NMR. The compound demonstrated DPPH free radical scavenging activity with IC₅₀ of 28.79 μg/ml, and XOD inhibitory with IC₅₀ of 0.67 μg/mL. Conclusion: The isolated compound was determined as 5-hydroxy-3,7-dimethoxy-2-(4-((3S,4S,5S,6R)-4,5, 6-trihydroxy-2(hydroxymethoxy)-tetrahydro-2H-pyrane-3-iloxy) phenyl)-4H-chromen-4-on or camarosids. The isolated compound demonstrated strong DPPH free radical scavenging and XOD inhibitory activity.