Glycosides from the Bark of Adina polycephala Yanling Zhang, Maoluo Gan, Sheng Lin, Mingtao Liu, Weixia Song, Jiachen Zi, Sujuan Wang, Shuai Li, Yongchun Yang, and Jiangong Shi* Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College (Key Laboratory of BioactiVe Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education), Beijing 100050, People’s Republic of China ReceiVed December 31, 2007 Four new dimeric phenolic glycosides (1-4), a new iridoid diglycoside (5), and 15 known glycosides have been isolated from an ethanolic extract of the bark of Adina polycephala. Their structures were determined by spectroscopic and chemical methods. Compounds 1, 3, and 5 showed in Vitro inhibitory activity against the release of -glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor. Adina polycephala Benth (Rubiaceae) is distributed widely in southern China. 1,2 Different parts of this plant are used in Chinese traditional medicine for treatment of inflammatory diseases and cattle anthrax. 1,3 Alkaloids, iridoid glycosides, coumarins, fla- vonoids, triterpenoids, and chromones 4–7 have been reported from several species of the genus Adina. However, no investigations of the chemical constituents of A. polycephala have been reported. As part of a program to access chemical and biological diversities of several Chinese traditional medicines, we carried out an investigation of A. polycephala. In this paper we describe the isolation and structural characterization of four new dimeric phenolic glycosides (1-4) and a new iridoid diglycoside (5) from an ethanolic extract of the bark of A. polycephala. Some in Vitro bioassay results are also included. Compound 1 was obtained as a white, amorphous solid, and the IR spectrum indicated the presence of OH (3294 cm -1 ), conjugated carbonyl (1692 and 1650 cm -1 ), and aromatic (1620, 1547, and 1516 cm -1 ) functional groups. Positive and negative ESIMS of 1 gave quasi-molecular ion peaks at m/z 833 [M + K] + and 817 [M + Na] + , and m/z 793 [M - H] - . The molecular formula C 36 H 42 O 20 was indicated by HRESIMS (m/z 817.2190 [M + Na] + ). The 1 H NMR spectrum of 1 in DMSO-d 6 showed two sets of ABX couplings attributed to two 1,3,4-trisubstituted aromatic rings at δ 6.33 (1H, d, J ) 2.0 Hz), 6.06 (1H, dd, J ) 8.5 and 2.0 Hz), and 6.82 (1H, d, J ) 8.5 Hz) and at δ 7.42 (1H, brs), 7.30 (1H, brd, J ) 8.5 Hz), and 7.16 (1H, d, J ) 8.5 Hz), respectively. It also showed a singlet assignable to a symmetrical 1,3,4,5-tetrasubstituted aromatic ring at δ 7.13 (2H, s) and four aromatic methoxy singlets at δ 3.77, 3.69, 3.69, and 3.63. Two doublets due to anomeric protons at δ 5.15 (1H, d, J ) 7.0 Hz, H-1′′′) and 4.74 (1H, d, J ) 7.5 Hz, H-1′), together with partially overlapped signals attributable to oxymethylenes and oxymethines between δ 3.20 and 4.60, as well as signals of exchangeable OH protons between δ 5.10 and 5.45, indicated that there were two -glycosyl groups in 1. Acid hydrolysis of 1 produced a glucose that gave a positive optical rotation [R] 20 D +35.9 indicating that it was D-glucose. 8 The 13 C NMR spectrum of 1 showed carbon signals corresponding to the above structural units (Table 1) and two conjugated ester carbonyls at δ 165.1 and 165.5. 1D TOCOSY and 2D NMR experiments were carried out to determine the connectivity of the three aromatic and two glucose moieties in 1. Analyses of the 1D TOCOSY and gHSQC spectra of 1 led to unambiguous assignment of proton and corresponding carbon signals in the NMR spectra (Table 1). HMBC correlations of C-1 with H-3, H-5, H-6, and the anomeric proton (H-1′), of C-2 with H-3, H-6, and the methoxy protons at δ 3.63, and of C-4 with H-3, H-5, and H-6, in combination with chemical shifts and coupling patterns of these protons and carbons, provided evidence for the 2-methoxy-p-hydroxyquinone 1-O--D-glucopyranoside moiety in 1. HMBC correlations of the carbonyl carbon (C-7′′) with H-2′′ and H-6′′, C-3′′ with H-2′′, H-5′′, and the methoxy protons at δ 3.77, and C-4′′ with H-2′′, H-5′′, H-6′′, and the remaining anomeric proton (H-1′′′), in combination with the chemical shifts and coupling patterns, demonstrated that there was a 4--D- glucopyranosyloxy-3-methoxybenzoyl moiety in 1. Meanwhile, HMBC correlations from H-2′′′′ and/or H-6′′′′ (overlapped) to C-1′′′′, C-3′′′′ and/or C-5′′′′ (overlapped), and C-4′′′′ and from the overlapped methoxy protons at δ 3.69 (6H) to C-3′′′′ and C-5′′′′ demonstrated that there was a syringyloyl in 1. Basic hydrolysis of 1 with 0.5 N NaOH yielded isotachioside, 9 vanillic acid 4-O- -D-glucopyranoside, 10 and syringic acid. 11 In addition, HMBC correlations of C-7′′ with H-6′a and H-6′b and of C-7′′′′ with H-6′′′a and H-6′′′b, in combination with chemical shifts of these protons and carbons, indicated ester linkages between C-6′ and C-7′′ and between C-6′′′ and C-7′′′′. Therefore, the structure of 1 was determined as 1-O- {6-O-[4-O-(6-O-syringyloyl--D-glucopyranosyl)vanilloyl]--D-glu- copyranosyl}-2-methoxy-p-hydroxyquinone. Compound 2 exhibited ESIMS, IR, and NMR spectroscopic data similar to those of 1. However, comparison of the NMR data between 1 and 2 indicated that H-3 and H-5 of 2 were deshielded 0.20 and 0.34 ppm from those of 1, respectively, and H-6 was shielded 0.33 ppm. Meanwhile, C-1, C-3, and C-5 of 2 were * To whom correspondence should be addressed. Tel: 86-10-83154789. Fax: 86-10-63017757. E-mail: shijg@imm.ac.cn. J. Nat. Prod. 2008, 71, 905–909 905 10.1021/np700758q CCC: $40.75  2008 American Chemical Society and American Society of Pharmacognosy Published on Web 02/28/2008