Kadsura coccinea (LEM.) A. C. SMITH is widely distributed throughout southwestern of China. Plant extracts have been used in Chinese folk medicine for treatment of cancer and dermatosis and as an anodyne to relieve aches in China.
2)Previous investigations of K. coccinea have yielded some lignans and triterpenoids. [3][4][5][6][7][8][9][10][11][12] However, little work on the isolation and characterization of anti-inflammatory constituents from this plant has been made. As a part of our continuing phytochemical investigation of anti-allergic agents from natural sources, 1) the chemical composition of the rhizoma of K. coccinea has been examined.The roots of K. coccinea were extracted with 80% acetone. The extract was then partitioned with hexane, chloroform, ethyl acetate, n-butanol and water, successively. The chloroform fractions showed strong NO production inhibitory activity. Further bioassay-directed fractionation of this fraction led to the isolation of two new dibenzocyclooctadiene lignans, kadsuralignan A (1), kadsuralignan B (2), and one new arylnaphthalene lignan kadsuralignan C (3), with three known dibenzocyclooctadiene lignans gomisin R (4), schizanrin F (5), and schizanrin H (6).To our knowledge, it's the first report about arylnaphthalene lignan was isolated from K. coccinea.Here, we describe the isolation, structure elucidation and biological evaluation of these compounds.The configuration of biphenyl groups in all isolated dibenzocyclooctadiene lignans was determined basing on their characteristic circular dichroism (CD) spectra. The CD spectra of 1, 2, 4-6 showed a positive Cotton effect around 215-225 nm and a negative Cotton effect around 230-255 nm, suggesting that these dibenzocyclooctadiene lignans possessed an S-biphenyl configuration as gomisin B.
13,14)Kadsuralignan A (1) was obtained as colorless needles and assigned to possess a molecular formula of C 22 H 26 O 7 by high resolution electron impact ionization MS (HR-EI-MS) ([M] ϩ , m/z 402.1679) with ten unsaturation. The UV spectrum of 1 possessed characteristic UV spectrum (l max 220, 255, 289sh nm) of dibenzocyclooctadiene lignans.15) It possessed a biphenyl moiety due to two aromatic protons at d 6.67 and 6.34 (each 1H, s, H-4 and H-11) and twelve carbon atoms at d 150. 6, 138.3, 148.5, 113.5, 133.7 and 121.1 (C-1, 2, 3, 4, 5, 16, respectively); d 138.2, 102.5, 148.7, 135.7, 141.1, 119.2 (C-10, 11, 12, 13, 14, 15, respectively). Moreover, one methylenedioxy moiety at d 5.97 (2H, s, CH 2 -19) and three methoxyl groups at d 3.63, 3.79 and 3.95 (each 3H, s) occurred, and predictably located them at the biphenyl rings. In the cyclooctadiene ring, two secondary methyl groups at d 0.93 (3H, d, Jϭ7.5 Hz) and 1.16 (3H, d, Jϭ6.9 Hz) were assigned to CH 3 -17 and CH 3 -18, respectively. Moreover, the signal of oxygenated methine at d 83.9, 4.61 (1H, d, Jϭ11.7 Hz, C-9 and H-9).The detailed analysis of 1 using 1 H-1 H COSY and HMQC disclosed partial structure unit with correlated protons: CH 2 -CH(CH 3 )-CH(CH 3 )-CH(OH), this unit should...
