5 , 9 , 11-Trihydroxy-2 , 2-dimethyl-3-( 2-methylbut-3-en-2-yl ) pyrano [ 2 , 3-a ] xanthen-12 ( 2 H )-one from the Stem Bark of Calophyllum tetrapterum Miq

A new pyranoxanthone namely 5,9,11-trihydroxy-2,2-dimethyl-3-(2-methylbut-3-en-2-yl) pyrano[2,3-a]xanthen-12(2H)-one (1) was isolated from the stem bark of Calophyllum tetrapterum Miq. The structure of compound 1 was determined by means of spectroscopic methods including UV, IR, HRESIMS, 1D and 2D NMR.


General
Melting points were obtained on a Thermo Scientific Fisher-Johns Melting Point Apparatus 220 VAC (Waltham, MA, USA).NMR spectra were recorded on a JEOL 400 ECA spectrophotometer (Tokyo, Japan) in acetone-d6 at 400 ( 1 H), 100 ( 13 C) MHz using APT experiment with TMS as the internal standard.The UV spectra was measured with Shimadzu series 1800 spectrophotometer (Kyoto, Japan).The IR spectra was recorded with Perkin-Elmer spectrum-100 FT-IR (Waltham, MA, USA).The mass spectra was recorded using a Waters LCT Premier XE (Santa Clara, CA, USA).Coloumn chromatography and radial chromatography were carried out using silica gel 60 G Cat. No. 1.07734.1000and Si gel 60 PF254 Cat.No. 1.07749.1000(Merck, Darmstadt, Germany).

Plant Material
The stem bark of C. tetrapterum Miq. was collected in October 2015 from Lungkut Layang Village, District Kapuas, West Kalimantan, Indonesia.The sample was identified by Mr. Ismail Rachman, Herbarium Bogoriense, Center of Biological Research and Development, National Institute of Science, Bogor, Indonesia.

Extraction and Isolation
The dried stem bark of C. tetrapterum Miq.(2.0 kg) were macerated in 10 L methanol twice for 2 days each.After evaporating of the solvent in a rotary evaporator, it was obtained 260 g of pale brown semi-solid.Further, the methanol extract were partitioned first with n-hexane (1:1 v/v).The methanol extract was added with water (10% v/v) to increase the polarity and then partitioned with ethyl acetate (1:1 v/v).The ethyl acetate extract (35 g) was subjected to coloumn chromatography over silica gel and eluted with n-hexane-ethyl acetate (from 9:1 to 1:1) to give fractions A-C.Fraction B was then subjected further to coloumn chromatography and eluted with n-hexane-ethyl acetate On inhibition of human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT) against human lymphocytes in vitro, compound 1 exhibited IC 50 values of 84.60 µg/mL.Those anti-HIV-1 RT data suggested that compound 1 has weak activity.

General
Melting points were obtained on a Thermo Scientific Fisher-Johns Melting Point Apparatus 220 VAC (Waltham, MA, USA).NMR spectra were recorded on a JEOL 400 ECA spectrophotometer (Tokyo, Japan) in acetone-d 6 at 400 ( 1 H), 100 ( 13 C) MHz using APT experiment with TMS as the internal standard.The UV spectra was measured with Shimadzu series 1800 spectrophotometer (Kyoto, Japan).The IR spectra was recorded with Perkin-Elmer spectrum-100 FT-IR (Waltham, MA, USA).The mass spectra was recorded using a Waters LCT Premier XE (Santa Clara, CA, USA).Coloumn chromatography and radial chromatography were carried out using silica gel 60 G Cat. No. 1.07734.1000and Si gel 60 PF 254 Cat.No. 1.07749.1000(Merck, Darmstadt, Germany).

Plant Material
The stem bark of C. tetrapterum Miq. was collected in October 2015 from Lungkut Layang Village, District Kapuas, West Kalimantan, Indonesia.The sample was identified by Mr. Ismail Rachman, Herbarium Bogoriense, Center of Biological Research and Development, National Institute of Science, Bogor, Indonesia.

Extraction and Isolation
The dried stem bark of C. tetrapterum Miq.(2.0 kg) were macerated in 10 L methanol twice for 2 days each.After evaporating of the solvent in a rotary evaporator, it was obtained 260 g of pale brown semi-solid.Further, the methanol extract were partitioned first with n-hexane (1:1 v/v).The methanol extract was added with water (10% v/v) to increase the polarity and then partitioned with ethyl acetate (1:1 v/v).The ethyl acetate extract (35 g) was subjected to coloumn chromatography over silica gel and eluted with n-hexane-ethyl acetate (from 9:1 to 1:1) to give fractions A-C.Fraction B was then subjected further to coloumn chromatography and eluted with n-hexane-ethyl acetate (from 9:1 to 1:1) to produce subfractions B 1 -B 3 .Subfraction B 3 was purified by planar radial chromatography using n-hexane-chloroform (from 3:7 to 7:3), chloroform and chloroform-ethyl acetate 9:1 to yielded compound 1 (10 mg).