Background: Garcinia lateriflora Blume. which belongs to the genus Garcinia has been known to contain xanthones that can inhibit the α-glucosidase and as an antioxidant in the treatment of type 2 diabetes mellitus. Objective: This study aims to isolate and identify xanthones with antioxidant and inhibition of α-glucosidase activity in vitro from the leaves extract of G. lateriflora. Materials and Methods: The leaves of G. lateriflora was extracted by maceration with n-hexane (He), ethyl acetate (EA), and methanol (Me). Isolation process of xanthone was carried out by column chromatography with silica gel 60 and sephadex LH 20 as stationary phase. Alpha glucosidase inhibitory activity was investigated spectrofotometricaly with p-nitrophenil-α-D-glucopiranosida as the substrate. DPPH radical scavenging and FRAP method was use for testing the antioxidant activity. Result: The fraction of ethyl acetate extracts gives higher activity of inhibition of α-glucosidase and antioxidant than the n-hexane and methanol extract. Further purification and isolation was carried out at Fraction EA12 and obtained compound EA12a. Structure elucidation with ¹H-NMR and LC-MS/MS obtained the possible structure of EA12a compound was 1,3,6,7-tetrahydroxyxanton. The IC₅₀ value in inhibited α-glucosidase was 3.63 μg/mL; 27.08 μg/mL for antioxidant activity by FRAP method and 21.31 μg/mL for antioxidants activity by DPPH radical scavenging assay. Conclusion: The xanthone from G. lateriflora leaves extract had good α-glucosidase inhibitory and antioxidant activity.

Key words: Garcinia lateriflora, α-glucosidase, antioxidant, xanthone