Medicinal Foodstuffs. XXXI. Structures of New Aromatic Constituents and Inhibitors of Degranulation in RBL-2H3 Cells from a Japanese Folk Medicine, the Stem Bark of Acer nikoense.

Abstract

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.

Medicinal Flowers. XXXI. Acylated Oleanane-Type Triterpene Saponins, Sasanquasaponins I-V, with Antiallergic Activity from the Flower Buds of Camellia sasanqua

“…In the course of our studies on antiallergic constituents from natural medicines, [21][22][23][24][25][26][27][28][29][30][31][32] we previously reported that some triterpenes and oleanane-type triterpene oligoglycosides showed inhibitory effects on histamine release from rat exudate cells induced by an antigen-antibody reaction 33,34) and on b-hexosaminidase release induced by dinitrophenylated bovine serum albumin (DNP-BSA) from RBL-2H3 cells sensitized with anti-DNP immunoglobulin E (IgE). 8,14) As a continuation of this study, we examined the effects of acylated oleanane-type triterpene saponins, sasanquasaponins, on the release of b-hexosaminidase from RBL-2H3 cells.…”

Medicinal Flowers. XIV.1) New Acylated Oleanane-Type Triterpene Oligoglycosides with Antiallergic Activity from Flower Buds of Chinese Tea Plant (Camellia sinensis)

“…As a part of our characterization studies on the bioactive components of natural medicines, we previously reported several inhibitors of the release of b-hexosaminidase such as flavonoids, 33) diarylheptanoids, [34][35][36] sesquiterpenes, 37) diterpenes, 38) anthraquinones, 39) stilbenes, 40) phenanthrenes, 40) phenylpropanoids, 41) and alkaloids. 42,43) On the other hand, dammarane-type triterpene glycoside, ginsenoside Rh2, was reported to exhibit inhibitory activity on b-hexosaminidase release from RBL-2H3 cells and this activity was suggested to originate from cell membrane stabilizing action.…”

Natural compounds, fraxin and chemicals structurally related to fraxin protect cells from oxidative stress

“…glabbra leaves (Caprifoliaceae), purified and characteri-zed as described (Morikawa et al, 2002). The methanolic extract was suspended with water and then partitioned with ether.…”