No abstract

Recently, an esthetic tooth coating material has been developed. The material consisted of a primer solution, a base coat, and a top coat. The purpose of this study, therefore, was to evaluate the color change of this tooth coating material and two resin composites after immersion in food-simulating, staining solutions. To this end, the newly developed coating material with and without its top coat, a flowable resin composite, and a hybrid resin composite were employed for the evaluation.The specimens were subjected to an experimental 24-hour staining cycle: 7-hour immersion in coffee, green tea or red wine, then 17-hour immersion in artificial saliva solution containing 0.3％ mucin. After 24 hours, 3 days, 1, 2, and 4 weeks of immersion, the color changes of all specimen surfaces were measured.Compared with the other materials, the ΔE ＊ value of coating material without its top coat tended to increase as the immersion period increased until 4 weeks. On the other hand, the ΔE ＊ value of coating material with its top coat measured the lowest among the materials tested. Based on the results obtained, it was concluded that when using this recently developed tooth coating material in dental clinics, its top coat should be properly applied.

The purpose of this study was to evaluate the bleaching effect of sodium percarbonate on artificially stained pulpless teeth. Twenty extracted human mandibular premolars were stained by immersing them in human blood mixed with iron sulfide, and divided into three test groups and one control group. The following bleaching agents were used: sodium perborate mixed with 30% hydrogen peroxide (WB), sodium percarbonate mixed with distilled water (PW) or 30% hydrogen peroxide (PH). On days 5, 10, and 15, each pulp chamber was refilled with fresh bleaching paste. The L* (average lightness) of the midbuccal area of specimens was measured before and after staining, and on days 5, 10, 15, and 20 by colorimeter. The bleaching effect was evaluated by the lightness recovery rate (LRR) calculated from L*. WB showed the highest LRR among all groups, and PW and PH showed significantly higher LRR when compared with the control group. PW and PH were not significantly different. Results showed that sodium percarbonate had an obvious bleaching effect without hydrogen peroxide and indicated that it could be a safe intracoronal bleaching agent.

Eight alkylated benzoquinone derivatives, named ardisiaquinones A-H, were isolated together with four known compounds from the leaves of Ardisia quinquegona using a combination of different chromatography techniques. Their structures were elucidated by spectroscopy and by the preparation of methyl ethers. Anti-Leishmania activity and cytotoxicity of the isolated compounds were assayed. Some compounds showed moderate anti-Leishmania activity, however, always associated with cytotoxicity.

No abstract

From the stems of Croton cascarilloides, further crotofolane-type diterpenoids, named crotocascarins L-Q (1-6), and a rearranged one (7), named neocrotocascarin were isolated. Their structures were elucidated from spectroscopic evidence. Also, the structures of crotocascarin O (4) and neocrotocascarin (7) were determined by X-ray crystallographic analyses. As a result, neocrotocascarin (7) was found to possess a new carbon framework. A plausible mechanism for the formation of neocrotocascarin (7) is also discussed.

From the 1-BuOH-soluble fraction of a methanol (MeOH) extract of the leaves of Croton cascarilloides, crotofolanes: crotocascarins I-K, nor-crotofolane: crotocascarin γ, isocrotofolane glucoside and phenolic glycoside were isolated by a combination of various separation techniques. Their structures were elucidated mainly from the NMR spectroscopic evidence. The structure of crotocascarin K was first elucidated by spectroscopic analysis and then was confirmed by X-ray crystallographic analysis. Its absolute structure was finally determined by the modified Mosher's method. Isocrotofolane glucoside was found to possess a new skeleton, however, its absolute structure remains to be determined.Key words Croton cascarilloides; Euphorbiaceae; crotocascarin; crotofolane; nor-crotofolane; isocrotofolane A diterpenoid, phorbol 12-myristate 13-acetate, isolated from Croton oil is known to have a potent tumor-promoting effect 1,2) and is often employed in biomedical research to activate protein kinase C.3) Thus, Croton species plants attracted our attention. C. cascarilloides RÄUSCHEL is an evergreen shrubby tree that grows on elevated coral reefs of the Okinawa Islands, Taiwan, southern China, the Malay Peninsula and Malaysia. The leaves are oblong-lanceolate to oblong-oval, and their undersurface is covered by shiny white ramenta.4) In a previous study, 5) investigation of the constituents of the stems of Croton cascarilloides provided eight rare crotofolane-type and two rearranged crotofolane-type diterpenoids. In this study, from the 1-BuOH-soluble fraction of a MeOH extract of the leaves of C. cascarilloides, three crotofolane-type diterpenoids, named crotocascarins I-K (1-3), a nor-diterpenoid, crotocascarin γ (4), a diterpenoid glucoside with a new skeleton, which was named isocrotofolane glucoside (5), and one phenolic glycoside (6) along with two known compounds (7, 8) were isolated. The structures of the new compounds isolated were elucidated from spectroscopic evidence and that of crotocascarin K (3) was determined by X-ray crystallographic analysis, followed by application of the modified Mosher's method to clarify its absolute structure. The known compounds were identified as angelicoidenol 2-O-β-D-glucopyranoside (7) 6) and senecrassidiol (8) 7) by comparison of the physico-chemical data with those reported in the literature. Results and DiscussionFrom the 1-(butanol) BuOH-soluble fraction of a MeOH extract of the leaves of C. cascarilloides, three crotofolane-type diterpenoids, named crotocascarins I-K (1-3), a nor-diterpenoid, crotocascarin γ (4), a diterpenoid glucoside with a new skeleton, which was named isocrotofolane glucoside (5), and a phenolic glycoside (6) H-NMR spectrum, signals for one singlet methyl at δ H 1.05, two doublet methyls at δ H 1.02 (J=7.2 Hz) and 1.91 (J=1.2 Hz), and two olefinic protons at δ H 5.06 (1H, s) and 5.07 (1H, s) were observed. The 13 C-NMR spectrum together with distortionless enhancement polarization transfer (DEPT) results revealed a total of 20 resonances, which compris...

No abstract