5 , 9 , 11-Trihydroxy-2 , 2-dimethyl-10-( 3 ′-methyl-2 ′-butenyl )-3-( 2 ′′-methyl-3 ′′-butenyl ) pyrano [ 2 , 3-a ] xanthen-12 ( 2 H )-one from the Stem Bark of Calophyllum pseudomole

5,9,11-Trihydroxy-2,2-dimethyl-10-(3′-methyl-2′-butenyl)-3-(2”-methyl-3”-butenyl)pyrano[2,3-a]xanthen-12(2H)-one (1) was isolated from the stem bark of Calophyllum pseudomole. The structure of 1 was established by spectroscopic analysis which included UV, IR, HRESIMS and NMR experiments.

On antioxidant evaluation against DPPH radical scavenging, compound 1 exhibited IC 50 values 76 µg/mL more active than apigenin as control positive (IC 50 130 µg/mL).Those antioxidant data suggested that compound 1 has high activity.

General
The UV spectrum was measured with Shimadzu series 1800 spectrophotometer (Kyoto, Japan).The IR spectrum was recorded with Perkin-Elmer spectrum-100 FT-IR (Waltham, MA, USA).NMR spectra were recorded on a JEOL 400 ECA spectrophotometer (Tokyo, Japan) in acetone-d6 at 400 ( 1 H) and 100 ( 13 C) MHz using TMS as the internal standard.The mass spectra were recorded using a Waters LCT Premier XE (Santa Clara, CA, USA).Column chromatography and radial chromatography were carried out using silica gel 60 and silica gel 60 PF254 (Merck, Darmstadt,

General
The UV spectrum was measured with Shimadzu series 1800 spectrophotometer (Kyoto, Japan).The IR spectrum was recorded with Perkin-Elmer spectrum-100 FT-IR (Waltham, MA, USA).NMR spectra were recorded on a JEOL 400 ECA spectrophotometer (Tokyo, Japan) in acetone-d 6 at 400 ( 1 H) and 100 ( 13 C) MHz using TMS as the internal standard.The mass spectra were recorded using a Waters LCT Premier XE (Santa Clara, CA, USA).Column chromatography and radial chromatography were carried out using silica gel 60 and silica gel 60 PF 254 (Merck, Darmstadt, Germany).

Plant Material
The stem bark of C. pseudomole was collected in Sungai Mendawak, anak Sungai Kapuas, District Kubu Raya, Kalimantan, Indonesia on April 2015.The sample was identified and deposited in the Herbarium Bogoriense, Center of Biological Research and Development, National Institute of Science, Bogor, Indonesia.

Extraction and Isolation
The dried stem bark of C. pseudomole (3.0 kg) was macerated in methanol twice for 4 days, and then evaporated under reduced pressure to give a dark brown residue (120 g).Further, the methanol extract was partitioned first with n-hexane.The methanol extract was mixed with water (10% v/v) to increase the polarity and then partitioned with ethyl acetate.The ethyl acetate extract (24 g) was subjected to column chromatography over silica gel and eluted with n-hexane-ethyl acetate (from 9:1 to 3:7) to give fractions A-D.Fraction B showed the most potent antioxidant activity.Fraction B was then subjected to column chromatography and eluted with n-hexane-ethyl acetate (from 9:1 to 7:3) to produce subfractions B 1 -B 3 .Subfraction B2 was purified by planar radial chromatography using n-hexane-acetone (from 9:2 to 4:1) to yield compound 1 (16 mg).

DPPH Radical Scavenging
The antioxidant assay of compound 1 against DPPH (2,2-diphenyl-1-picrihidrazil) radical was measured by UV spectrometer at λ 517 nm as described previously [12][13][14].The inhibition percentage (%) of radical scavenging activity was calculated using the following equation: where A o is the absorbance of the control reaction (containing all reagents except the active compound), and A s is the absorbance of the active compound.
) was isolated as a yellow solid, m.p. 160-162 • C. The molecular formula of compound is C 28 H 30 O 6 , whereas that of the deprotonated molecule [M − H] − is C 28 H 29 O 6 at m/z 461.1971 (calcd.461.1964) by the HRESIMS.The UV spectrum exhibited four absorption bands characteristic of a xanthone chromophore at λ maks 247, 264, 322 and 396 nm