Chem. Pharm. Bull. 54(11) 1592—1594 (2006)

west of China, Nepal and the northeast of India. In Tibet it is popularly known and used in traditional medicine for the treatment of liver diseases, cholic diseases, and dyspepsia. Previously a large amount of lignans have been reported from Herpetospermum caudigerum. In the previous investigation, a ethanol extract of the seeds of Herpetospermum caudigerum showed positive activity in the inhibit hepatitis b virus test. Further biological screening of the ethanol extract and ethyl acetate soluble fraction revealed significant inhibitory activity against hepatitis b virus. This prompted us to carry out bioassay-guided isolation studies on the ethyl acetate soluble fraction of this plant. In this paper, we report the isolation and structure elucidation of a new compound 3-benzofuranmethanol-2,3-dihydro-2-(4-hydroxy3-methoxyphenyl)-4-methoxy-6-[tetrahydro-2-(3-hydroxy-4methoxyphenyl)-3-methanol]-2-furanmethyl (1), and three known compounds (2—4). The compounds 1 and 2 showed promising inhibitory activity against hepatitis b virus. The ethyl acetate fraction of the ethanol extract of the seed of Herpetospermum caudigerum was subjected to column chromatography over silica gel with different mobile phases. Compounds 1—4 were finally obtained and their structures were elucidated by UV, IR, mass and NMR spectroscopy. The known compounds 2, 3, 4 were determined to be 2-hydroxymethyl-1-(3-methoyl-phenol)-3-(3,4-dimethoylbenzyl)-tetrahydrofuran (2), 2,3-dihydroxymethyl-1,4-(3,4dimethoyl-benzol)-tetrahydrofuran (3) and herpetfluorenone (4) by comparison of physical data and NMR spectral data with those previously reported. Compound 1 was obtained as a white amorphous solid. The high resolution and fast atomic bombardment mass spectrometry (HR-FAB-MS) established the molecular formula to be C30H34O9, showing a [M 1] peak at m/z 539.1332 (Calcd for C30H35O9, 539.1337) having fourteen degree of unsaturation. The infrared (IR) spectrum of 1 showed the absorption band due to hydroxyl groups (3418 cm ) and aromatic groups (1605, 1517 cm ). The ultraviolet (UV) spectrum of 1 showed a conjugated carbonyl absorption band at lmax 230 nm. The Hand C-NMR spectra of 1 exhibited signals characteristic of a benzofuran-type lignan (Table 1). The H-NMR spectrum showed the presence of four hydroxy groups and three methoxyl groups. The signals for aliphatic methylene protons appeared at d 2.58 (1H, m), 2.79 (1H, m), two aliphatic methine groups at d 2.80 (1H, m, H-8 ), 2.42 (1H, m, H-8 ), three oxygenated methylene groups at d 3.80 (1H, dd, H-9), 3.67 (1H, dd, H9 ), 3.84 (2H, dd, H-9, H-9 ), 3.79(1H, dd, H-9 ), 4.03 (1H, dd, H-9 ), two oxygenated methine groups at d 5.52 (1H, d, H-7), 4.78 (1H, d, H-7 ). The downfield region of the spectrum showed the presence of phenyl groups. The broad-band and distortionless enhancement by polarization transfer (DEPT) C-NMR spectra of 1 (Table 1) disclosed 30 carbon singles for three methyl, four methylene, thirteen methane 1592 Vol. 54, No. 11 Chem. Pharm. Bull. 54(11) 1592—1594 (2006)