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Megastigmane glycosides are now an expanding class of compounds and their relatively wide distribution in plant kingdom has been reported. In a previous work, 1) a megastigmane was isolated as a non-glycosidic form from Euscaphis japonica and its absolute configuration was determined by the modified Mosher's method. Leaves of Turpinia ternate collected in Okinawa also afforded one megastigmane (1) and seven megastigmane glycosides (2-8). The structure of the megastigmane (1) was elucidated to be the same as that of that isolated from E. japonica, including absolute configurations. Compounds 2 and 3 were found to be known compounds, corchoionoside C 2) and icariside B 4 , 3) respectively. The structures of the remaining megastigmane glucosides were elucidated by NMR spectroscopic analyses and the absolute configurations of turpinionosides A-E (4-8) were elucidated in this work by the modified Mosher's method. Results and DiscussionMegastigamane (1) and megastigamane glucosides (2-8) were isolated from the n-BuOH-soluble fraction of a MeOH extract of leaves of Turpinia ternata by means of a combination of several kinds of chromatographic methods, and details being given in the experimental section. The structures of other known compounds (2, 3) were identified by comparison of spectroscopic data with those reported.Compound 1, C 13 H 24 O 4 , was isolated as a syrup and its planar structure was elucidated to be the same as that of the megastigamane isolated from a related plant, Euscaphis japonica.1) On comparison of the optical rotation values of 1 from both sources, the absolute configurations were presumed to be the same. This was confirmed by that compound 1 from the title plant was also determined with the modified Mosher's method 4) to have the 3S, 5R, 6R and 9S configurations (Fig. 1).Turpenionoside A (4), [a] D 22 Ϫ38.4°, was isolated as an amorphous powder and its elemental composition was determined to be C 19 H 34 O 8 by negative-ion high-resolution (HR) FAB-MS. The IR spectrum of 4 showed a strong absorption band at 3401 cm Ϫ1 suggestive of a glycosidic structure. The 1 H-and 13 C-NMR spectra of 4 showed signals attributable to a b-glucopyranosyl unit, and two tertiary methyls at a geminal position, two secondary methyls, two methylenes, one methine without and two methines with hydroxyl groups, one disubstituted trans double bond, and two quarternary carbon atoms with and without a hydroxyl group, respectively. These functionalities were the same as those of megastigmane glucoside, dendranthemoside A (9) ([a] D 22 Ϫ44.2°), isolated from Dendranthema shiwogiku, 5) and the NMR spectroscopic data of 4 and 9 were essentially indistinguishable from each other. The absolute structure for 9 has been determined by Xcrystallographic analysis of its pentaacetate to have the 3S, 5R, 6S and 9R configurations.6) Since most glucose in Nature is of the D-series, the b-D-glucosylation-induced shift-trend in the 13 C-NMR spectroscopy was applied for the elucidation of absolute configuration. 7) On b-D-glucosylation o...

Litter decomposition, governing nutrient and C cycling, is strongly influenced by the chemical litter quality. In order to determine the interspecific variation in leaf decomposition rates and to understand the chemical basis for such variation, decomposition dynamics of seven common canopy species was investigated over 2 year using the litterbag technique in a subtropical evergreen broad-leaved forest on Okinawa Island, Japan. The species studied are representatives of the vegetation in the study area and differed significantly in their chemical litter quality. Dry mass loss at the end of study varied in the order: Distylium racemosum < Quercus miyagii < Rapanea neriifolia < Symplocos confusa < Castanopsis sieboldii < Schima wallichii < Daphniphyllum glaucescens. All species showed a pattern characterized by a rapid initial decomposition followed by lower rates except for D. glaucescens which decomposition rate appeared to be rather constant. In the late phase, decomposition rates were correlated positively to initial N and ash contents and negatively to lignin content, lignin:N, C:N, and C:P ratios. The effects of N and lignin content or lignin:N ratio were stronger than other quality parameters. There was a wide range in patterns of N and P concentrations, from a net accumulation to a rapid loss in decomposition. The correlation between N and P release suggests that N and P dynamics may have influenced each other during litter decomposition. Analysis of initial quality for species showed that the C:P ratios were extremely high (range 1639-3811) but the N:P ratios were from 28 to 56, indicating a likely P-limitation for this forest. Our results suggest that P is an important control of litter decomposition and N and P dynamics.

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More than 10 species belonging to the Myrsinaceae are distributed in temperate and subtropical areas of Japan. 1) Plants in this family are generally used as anthelmintics, 2) and in China Ardisia japonica is used as an antitussive, expectorant, antidote and diuretic.3) Myrsine seguinii (syn. Rapanea neriifolia) is known to contain rapanone, which is isolated from stem bark, and also used as an anthelmintic for cattle. Antiviral activity has been found in crude extracts of M. australis and M. salicina growing in New Zealand. 4)From the leaves of M. seguinii, collected in Okinawa, flavonol glycosides, lignan sulfate and arbutin derivatives have been isolated. 5) Although quantitative analysis was not performed, the content of arbutin, which is currently used in cosmetics as an antioxidant, seemed to be fairly high. 5c)On further extensive phytochemical investigation, several megastigmane glycoside derivatives, which comprise a currently expanding family, were isolated. This paper deals with their structural elucidation. Results and DiscussionA n-BuOH-soluble fraction obtained by solvent partitioning of a MeOH extract of the leaves of Myrsine seguinii was separated by column chromatography on a highly porous synthetic resin , and normal and reversed-phase silica gels, and by liquid-liquid partition chromatography to afford compounds 1-8 in the yields shown in the experimental section.Compound Eight megastigmane glycosides were isolated from the leaves of Myrsine seguinii collected in Okinawa. Three of them were found to be known compounds, i.e., ampelopsisionoside, alangionoside J, and linarionoside A. The structures of the new megastigmane glycosides were elucidated from the spectroscopic data and their absolute stereochemistries were determined in detail using a modified Mosher's method.