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Journal of Chemistry, Vol. 45 (6), P. 749 - 750, 2007 Contribution to the Study on Polar Constituents from the Buds of Rhodomyrtus tomentosa (Ait.) Hassk. (Myrtaceae) Received 28 August 2006 Phan Minh Giang, Tran Thi Ha, Nguyen Thi Hong Anh, Phan Tong Son Laboratory of Chemistry of Natural Products, Faculty of Chemistry, College of Natural Science, Vietnam National University, Hanoi, Vietnam Summary A flavonol glycoside, kaempferol 3-O- -sambubioside (1) was isolated in a study on the polar constituents of the buds of Rhodomyrtus tomentosa Ait. Hassk. (Myrtaceae). Its structure was determined by spectroscopic methods. Keywords: Rhodomyrtus tomentosa; Myrtaceae; flavonol glycoside. Rhodomyrtus tomentosa Ait. Hassk. (Myrtaceae) [1] (Vietnamese name: Sim) is a small shrub, 1-2 m high. The plant occurs rather widely in Asian tropical and subtropical regions. In Vietnam, R. tomentosa is extensively found in all the midland and low mountainous regions, sometimes in higher mountains. Recently, it has been grown in medicinal plant gardens at hospitals and village health-care stations for convenience of use. The young buds and leaves are collected in spring, they are then sun-dried. The buds and young leaves of R. tomentosa are effective for treatment of abdominal pain, diarrhoea, and dysentery. They are used in the form of oral decoction. In external use, the decoction of the leaves is used for lavage of wound [1]. Triterpenoids, steroids [2, 3], malvidin-3-glucoside [4], tannins [5, 6], and flavone glycosides [7] were isolated from the leaves, stems, and flowers of R. tomentosa. Our study is the first report dealing with the buds of the plant. We investigated the n-BuOH-soluble fraction of the MeOH extract from the buds of R. tomentosa [8] and isolated a flavonol glycoside [9]. The 1H- and 13C-NMR spectra [10] showed the presence of a kaempferol glycoside [11]. The glycoside moiety was determined to be 3-O- -D-xylopyranosyl-(1 2)-O- -D-glucopyr anoside (sambubioside) on the basis of 13 comparison of the1Hand C-NMR spectroscopic data of 1 with those reported in the literature [12]. The downfield 13C shift at C-2 and upfield 13C shift at C-3 when compared with those of kaempferol were reliable for the placement of the sambubioside moiety at C-3. Therefore the structure of 1 was determined to be kaempferol 3-O- -D-xylopyranosyl-(1 2) (kaempferol -O- -D-glucopyranoside 3-O- -sambubioside), which was isolated from Aesculus hippocastanum L. (Hippocastanaceae) [13] and Astragalus camplanatus R. BR. (Leguminosae) [14]. It is worthwhile to mention the complexity in the isolation of the other polar minor constituents in the n-BuOH-soluble fraction. The analysis of the fractions obtained after column separation by TLC and HPLC showed the isolation and purification of the others remain an arduous task with the conditions used in this study. 749 3' 8 HO 7 9 2 6 10 3 4 5 OH 2. 1' O OH 4' 2' 5' 6' O Glc 3. 2 Xyl O 4. 1 Kaempferol 3-O- -sambubioside (1): Yellow amorphous powder. [ ]25D -69.5 (c = 3.36, MeOH). 5. 6. 1 H-NMR (DMSO-d6): 4.58 (1H, d, J = 7.2 Hz, Xyl-1), 5.69 (1H, d, J = 7.6 Hz, Glc-1), 6.17 (1H, d, J = 2.0 Hz, H-8), 6.41 (1H, d, J = 2.0 Hz, H-6), 6.88 (2H, d, J = 8.8 Hz, H-3 , H-5 ), 8.06 (2H, d, J = 8.8 Hz, H-2 , H-6 ). 13C-NMR (DMSO-d6): 60.5 (Glc-6), 65.7 (Xyl-5), 69.4 (Xyl-4), 69.6 (Glc-4), 73.8 (Xyl-2), 76.1 (Glc-5), 76.8 (Xyl-3), 77.5 (Glc-3), 81.7 (Glc-2), 93.5 (C-8), 97.9 (Glc-1), 98.6 (C-6), 103.9 (C-10), 104.4 (Xyl-1), 115.1 (C-3 , C-5 ), 120.9 (C-1 ), 130.8 (C-2 , C-6 ), 132.8 (C-3), 155.2 (C-9), 156.3 (C-2), 159.9 (C-4 ), 161.2 (C-5), 164.2 (C-7), 177.4 (C-4). 7. 8. 9. 1 H-NMR (CD3OD): 4.77 (1H, overlapped with HOD signal, Xyl-1), 5.47 (1H, d, J = 7.3 Hz, Glc-1), 6.19 (1H, d, J = 2.0 Hz, H-8), 6.38 (1H, d, J = 2.0 Hz, H-6), 6.89 (2H, d, J = 8.8 Hz, H-3 , H-5 ), 8.05 (2H, d, J = 8.8 Hz, H-2 , H-6 ). 13 C-NMR (CD3OD): 62.8 (Glc-6), 67.0 (Xyl-5), 71.4 (Xyl-4), 71.5 (Glc-4), 75.2 (Xyl-2), 77.4 (Glc-5), 78.5 (Xyl-3), 78.6 (Glc-3), 82.7 (Glc-2), 95.1 (C-8), 100.2 (Glc-1), 101.2 (C-6), 105.7 (C-10), 106.2 (Xyl-1), 116.6 (C-3 , C-5 ), 123.3 (C-1 ), 132.6 (C-2 , C-6 ), 135.4 (C-3), 158.8 (C-9), 158.9 (C-2), 161.8 (C-4 ), 163.5 (C-5), 166.2 (C-7), 179.9 (C-4). Acknowledgments: This work was supported by the International Foundation for Science (IFS, Stockholm, Sweden) through a Research Grant to Phan Minh Giang and the Basic Research Program in Natural Sciences of Vietnam. References and Notes 1. Selected Medicinal Plants in Vietnam, eds. Le V. T., Nguyen G. C., Vol. II, 241-243, 750 10. 11. 12. 13. 14. Science and Technology, Hanoi (1999). Hui W. H., Li M. M., Luk K., Phytochemistry, 14, 833-834 (1975). Hui W. H., Li M. M., Phytochemistry, 15, 1741-1743 (1976). Lowry J. B., Phytochemistry, 15, 513-516 (1976). Liu Y. Z., Hou A. J., Ji C. R., Wu Y. J., Chin. Chem. Lett., 8, 39-40 (1997). Liu Y. Z., Hou A. J., Ji C. R., Wu Y. J., Tianran Chanwu Yanjiu Yu Kaifa., 10, 14-19 (1998). Hou A., Wu Y., Liu Y., Zhongcaoyao, 30, 645-648 (1999). The flower buds of R. tomentosa were collected in June 2004 in province Thai Nguyen and identified by Dr Tran Ngoc Ninh, Institute of Ecology and Biological Resources, Vietnamese Academy of Science and Technology, Hanoi, Vietnam. The dried flower buds of R. tomentosa was extracted with MeOH at room temperature. The MeOH extract (100 g) was fractionated successively between H2O and n-hexane, CH2Cl2, EtOAc, and n-BuOH. The n-BuOH-soluble fraction (11.0 g) was subjected to column chromatography (CC) on Diaion to give five fractions on eluting with H2O, 20%, 40%, 60% MeOH in H2O, and MeOH. The fifth fraction was separated by silica gel CC, eluted with CHCl3-MeOH-H2O (9:1:0, 7:3:0, and 15:6:1), and preparative octadecyl silica gel HPLC (17% MeCN in H2O and 50% MeOH in H2O) to afford compound 1 (33.6 mg). 1 H-NMR (400 MHz) and 13C-NMR (100 MHz) spectra were obtained on a JEOL JNM- 400 NMR spectrometer. The Flavonoids: Advances in Research, eds. Harborne J. B., Marbry T. J., Chapman and Hall, London (1982). Webby R. F., Phytochemistry, 30, 2443-2444 (1991). Hübner G., Wray V., Nahrstedt A., Planta Med., 65, 636-642 (1999). Cui B., Nakamura M., Kinjo J., Nohara T., Chem. Pharm. Bull., 41, 178-182 (1993). 751