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The 80% aqueous acetone extract and the ethyl acetate-soluble portion from the dried fruit of Alpinia oxyphylla MIQUEL were found to show inhibitory effects on nitric oxide production in lipopolysaccharide-activated macrophages and antigen-induced degranulation in RBL-2H3 cells. A new eudesmane-type sesquiterpene, oxyphyllol A, and two eremophilane-type sesquiterpenes, oxyphyllols B and C, were isolated from the ethyl acetate-soluble portion, together with 16 known constituents. The absolute stereostructures of oxyphyllols A, B, and C were determined on the basis of chemical and physicochemical evidence. The effects of isolated components on nitric oxide production were examined, and nine constituents including oxyphyllol A and nootkatone were found to show inhibitory activity. On the other hand, five constituents inhibited the release of beta-hexosaminidase from RBL-2H3 cells.

The Myricaceae plant Myrica rubra SIEB. et ZUCC. is widely distributed in China, Taiwan, Japan and Korea. The bark of M. rubra (Myricae cortex) has been used locally as an astringent, antidote, and antidiarrheic in Japanese folk medicine, and has also been used externally for burns and skin diseases in Chinese traditional medicine. Previously, several flavonoids, 2) tannins, 2) triterpenes, 3) and diarylheptanoids [4][5][6][7][8] were isolated from the bark of M. rubra. Pharmacological studies of this natural medicine have reported that its methanolic extract showed protective effects on CCl 4Ϫ and a-naphthylisothiocyanate-induced liver injury, 9) whereas the 50% aqueous ethanolic extract and some constituents inhibited melanin biosynthesis 10) and showed anti-androgenic activity. 11)In the course of characterization studies on the bioactive constituents of Chinese natural medicines, 1,12) we have iso-

The Aceraceae plant Acer nikoense MAXIM is indigenous to Japan (Japanese name, megusurinoki) and its stem bark has been used as a folk medicine for the treatment of hepatic disorders and eye disease. Recently, the stem bark of this plant has been consumed as a health food in Japan. Among the chemical constituents of this folk medicine, diarylheptanoids and three phenolic compounds were characterized. [2][3][4][5] In addition, the methanolic extract was reported to have hepatoprotective effects and (ϩ)-rhododendrol (15) was isolated as the active principle. 2,6) During the course of our studies on bioactive constituents of natural medicines [7][8][9][10][11][12][13] and medicinal foodstuffs, [14][15][16][17][18][19] we have reported three new cyclic diarylheptanoids called acerosides B 1 (5) and B 2 (6) and aceroketoside (7) from the stem bark of A. nikoense as well as the inhibitory effects of the principal diarylheptanoids on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophages. 1)As a continuation of the characterization studies on bioactive constituents of the stem bark of A. nikoense, we have isolated four new aromatic compounds called rhododendroketoside (1), (Ϫ)-sakuraresinoside (2), acernikol (3), and nikoenoside (4) together with six known compounds (9, 14, 17, 27-29). In this paper, we describe the isolation and structure elucidation of new aromatic constituents (1-4) and the inhibitory effects of the principal constituents (8, 10-13, 15, 20-25, 31) on the release of b-hexosaminidase in RBL-2H3 cells.The methanolic extract from the stem bark of A. nikoense collected in Miyagi prefecture, Japan, was partitioned into an ethyl acetate (EtOAc)-water mixture to furnish the EtOAcsoluble portion and aqueous phase. The aqueous phase was extracted with n-butanol (n-BuOH) to give the n-BuOH-soluble and H 2 O-soluble potions as previously described.1) The nBuOH-soluble portion was subjected to normal-phase silica gel column chromatography to provide six fractions. Previously, three then new cyclic diarylheptanoids (5-7) and 20 known compounds (8, 10-13, 15, 16, 18-26, 30-33) were isolated from the EtOAc-soluble portion and fractions 2 and 3 of the n-BuOH-soluble portion.1) In the present experiments, the fractions of the n-BuOH-soluble portion were further separated by normal-phase and reverse-phase silica gel column chromatography and repeated HPLC to give rhododendroketoside (1, 0.0009%), (Ϫ)-sakuraresinoside (2, Four new aromatic constituents, rhododendroketoside, (؊)-sakuraresinoside, acernikol, and nikoenoside, were isolated from a Japanese folk medicine, the stem bark of Acer nikoense MAXIM. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. The principle cyclic diarylheptanoids were found to show inhibitory effects on the release of b b-hexosaminidase in RBL-2H3 cells.

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