Evaluation of Xanthine Oxidase Inhibitory and Antioxidant Activities of Three Organs of Idat (Cratoxylum glaucum Korth.) and Correlation with Phytochemical Content

Abstract

Introduction: Idat (Cratoxylum glaucum Korth.), belonging to the genus Cratoxylum, is known to contain xanthone, quinone, flavonoids, and other phenolic compounds. Objectives: to analyze total phenolic, flavonoid, antioxidant activity, and inhibitory xanthine oxidase activities of leaves, stem, and cortex of idat. Methods: Extraction of leaves, stem, and cortex of idat was carried out by reflux using n-hexane, ethyl acetate, and ethanol as a solvent. Antioxidant activity was tested by the DPPH method and calculated to get the antioxidant activity index (AAI). Determination of total phenolic and flavonoid levels by ultraviolet-visible spectrophotometry. Results: Spectrophotometers measured the inhibitory activity on xanthine oxidase in 96-well plates with allopurinol as standard. Total phenolic and flavonoid content from C. glaucum extracts varied from 6.62 to 48.77 g GAE/g extract and 1.54 - 25.96 g QE/100 g extract, respectively. The ethanol extracts of leaves, stem, and cortex were very strong antioxidant activity with Antioxidant Activity Index (AAI) values 3.89; 4.55; 10.50, meanwhile AAI of ascorbic acid and quercetin 9.46 and 14.81 respectively. The n-hexane of stem extract had a strong xanthine oxidase inhibitory activity with the IC50 was 36.64 μg/ml, while allopurinol was 5.02 μg/ml. Conclusions: Total phenolic content contributed to antioxidant activity. Phenolic compounds in leaves extracts led to the xanthine oxidase inhibitory and antioxidant activities. The extract of C. glaucum was active as an antioxidant and potentially an inhibitor of xanthine oxidase agents. Key words: Antioxidant, Cratoxylum glaucum, Xanthine oxidase inhibitory.