Solid‐Phase Synthesis of a Combinatorial Methylated (±)‐Epigallocatechin Gallate Library and the Growth‐Inhibitory Effects of these Compounds on Melanoma B16 Cells

We report on the solid‐phase synthesis of a combinatorial methylated (±)‐epigallocatechin gallate (EGCG) library and its biological evaluation. Epigallocatechin gallate (EGCG) and its methylated derivatives, which are members of the catechin family, exhibit various anti‐cancer effects. The solid‐phase synthesis of methylated EGCG involves the preparation of the α‐acyloxyketone by the coupling of a solid‐supported aldehyde with a ketone and an acid. The subsequent release and reductive etherification reaction of the solid‐supported α‐acyloxyketone provide the protected EGCG in good total yields. Sixty‐four methylated EGCGs were successfully prepared. The growth‐inhibitory effects of the methylated EGCG library were also examined. Although methylation of EGCG generally causes reduced growth inhibition, the growth‐inhibitory effect of 7‐OMe EGCGs was comparable to that of EGCG. The 7‐OMe EGCGs are attractive drug candidates because of their enhanced bioavailability.     

Concerted and sequential Coulomb explosion processes of N2O in intense laser fields by coincidence momentum imaging

The Coulomb explosion dynamics of N2O in intense laser fields (800 nm, 60 fs, approximately 0.16 PWcm2) is studied by the coincidence momentum imaging method. From the momentum correlation maps obtained for the three-body fragmentation pathway, N2O3+-->N++N++O+, the ultrafast structural deformation dynamics of N2O prior to the Coulomb explosion is extracted. It is revealed that the internuclear N-N and N-O distances stretch simultaneously as the bond angle less than approximately N-N-O decreases. In addition, two curved thin distributions are identified in the momentum correlation maps, and are interpreted well as those originating from the sequential dissociation pathway, N2O3+-->N++NO2+-->N++N++O+.     

Line parameters of the oxygen A band and calculation of the atmospheric transmission functions for the A, B, and γ bands

Self- and nitrogen-broadened absorptions of the oxygen A band have been measured using a long pathlength, multiple-traversal absorption cell. Comparison of measured band absorptions with values calculated from the line parameters determined by several investigators under high resolution shows that the line intensities and half-widths reported by Miller, Giver, and Boese provide the best agreement with our data. Atmospheric transmissions for the oxygen A, B, and γ bands have been evaluated by line-by-line integration for these line parameters.     

Absorption properties of the near infrared CO2 bands

The equivalent widths of the near i.r. CO₂ bands at 1.4, 1.6, 2.0, 2.7, 4.8 and 5.2 μm have been measured for various sample parameters. By comparing the data obtained for pure CO₂ samples with theoretical values resulting from line0by-line calculations, band intensities have been determined for these six bands. The data obtained for the mixtures of CO₂ with N₂ have been used to check the validity of the band intensities thus determined. These data have also been used to check the applicability of the empirical formulae proposed by Howard, Burch and Williams.     

Absorption properties of the near-infrared water vapor bands

Spectral absorptances and equivalent widths of the near-infrared water vapor bands at 0.7, 0.8, 0.9, 1.1, 1.4 and 1.9 μm were measured for several sample parameters. Band strengths were determined for these six bands by comparing the measured equivalent widths with theoretical values obtained from line-by-line calculations. Absorptions estimated from empirical equations of Howard, Burch and Williams agreed reasonably well with our results for the 1.4- and 1.9-μm bands, but discrepancies were found for the 0.9- and 1.1-μm bands. Absorptions of the 0.7- and 0.8-μm bands measured by Fowle agreed with our results within 10% or less. Absorption functions are given for the specified six bands.     

Ultrafast hydrogen scrambling in methylacetylene and methyl-d3-acetylene ions induced by intense laser fields

Three-body Coulomb explosion processes of triply charged positive ions of methylacetylene (CH(3)-C≡C-H) and its isotopomer, methyl-d(3)-acetylene (CD(3)-C≡C-H), induced by an ultrashort intense laser field (790 nm, ～40 fs, 5.0 × 10(13) W cm(-2)) are investigated by the coincidence momentum imaging method. Two types of three-body decomposition processes accompanying the ejection of a proton are identified for methylacetylene, and six types of three-body decomposition processes accompanying the ejection of a proton or a deuteron are identified for methyl-d(3)-acetylene. From the observed momentum vectors of all the three fragment ions for each decomposition pathway, the proton and deuteron distributions are constructed in the coordinate space, and the hydrogen migration processes are investigated. It was shown that the hydrogen migration proceeds more efficiently from the methyl group than from the methine group. In addition to the decomposition pathways accompanying the migration of one H (or D) atom, the decomposition pathways accompanying the migration of two light atoms (H/D exchange and 2D migration) are identified. Furthermore, the decomposition pathways ascribable to the migration of three light atoms (H/D exchange followed by D migration) are identified, showing the high intramolecular mobilities of H and D atoms within methylacetylene and methyl-d(3)-acetylene in an intense laser field, resulting in the H/D scrambling.