TUMOR IMAGING WITH [111niIn]MONO-DTPA-ETHYLENEGLYCOL-Ga-DEUTEROPORPHYRIN

Abstract Mono-DPTA-ethyleneglycol-Ga-deuteroporphyrin (MDEGD) was synthesized, by coordinating non-radioactive Ga in the porphyrin ring and connecting DTPA (diethylene-triamine-N,N,N,N,N,-pentaacetic acid) to its side chain. By labeling with 111_In, chemicals for scintigraphy were developed. They were applied to Syrian golden hamsters with implanted pancreatic gland cancers and C57-black mice with Lewis lung cancer to enable tumor imaging and biodistribution examination. A comparative study was also conducted with [⁶⁷Ga]citrate. In the resultant data, [¹¹¹In]MDEGD showed larger tumor/lung, tumor/kidney and tumor/blood ratio with [⁶⁷Ga]citrate. The affinity of [ⁿIn]MDEGD in inflammatory tissue was much lower than that of ⁶⁷Ga citrate. [¹¹¹In]MDEGD lost its photosensitivity.     

Geochemical record of U and Th isotopes in bottom sediments of Lake Kawaguchi at the foot of Mt. Fuji, Central Japan

Sediment cores from Lake Kawaguchi at the foot of Mt. Fuji in Japan were analyzed for U and Th isotopes (²³⁸U, ²³⁴U, ²³²Th, ²³⁰Th and ²²⁸Th) in the light of the linkage to paleoenvironmental changes. These isotopic concentrations and their ratios varied widely with depth of sediment core. A marked disequilibrium (1.1–1.5) higher than the value of 1.0 was observed for ²³⁴U/²³⁸U activity ratios, indicating that U from lake water with high ²³⁴U/²³⁸U ratio (ca. 1.6) was transferred to the bottom sediment by adsorption and/or adhesion onto the settling particles. By using model equations, the U found in the sediment core was separated into lithogenous and autogenous U fractions. These depth profiles were compared with parameters such as organic matter and biogenic-SiO₂ contents and amount of rainfall. Some variations of selected parameters with depth coincided with those of lithogenous or autogenous U. The results obtained suggest that variation in the lithogenous and/or autogenous U in the sediment with depth might be helpful in tracing the geochemical behavior of U and the past environmental changes in the area surrounding Lake Kawaguchi.The authors would like to express their gratitude to Dr. Y. Ohtsuka of Department of Radioecology, Institute for Environmental Sciences and Dr. K. Sasaki of Department of Cultural Properties and Heritage, Kanazawa Gakuin University for sampling of water and rock samples at Lake Kawaguchi.     

Synthesis of ZrO<Subscript>2</Subscript> nanoparticles for liquid scintillators used in the detection of neutrinoless double beta decay

We synthesized liquid scintillators incorporating ZrO₂ nanoparticles for application in neutrinoless double beta decay experiments. ZrO₂ nanoparticles of less than 10 nm in size were synthesized with sub- and supercritical hydrothermal methods. The Zr concentrations in the liquid scintillators were determined to be up to 1.4 wt% with inductively coupled plasma analysis, and the liquid scintillators were transparent to scintillation. These results indicate that these methods are applicable for the preparation of liquid scintillators for neutrinoless double beta decay experiments.     

X-ray-induced persistent photoconductivity in La0.9A0.1MnO3 (A=Sr, Ca)

We observed persistent photoconductivity (PPC) in La-based perovskite manganese oxides, La_0.9Sr_0.1MnO₃ (LSMO) and La_0.9Ca_0.1MnO₃ (LCMO), under X-ray irradiation. The PPC in LSMO was attributed to the collapse of the charge- and orbital-ordered (CO and OO, respectively) states, similar to that reported in previous papers. This PPC effect was different from that observed in a similar compound with a slightly different composition. This difference was explained in terms of doped carriers. This observation of PPC in LCMO is the first result of the PPC in a compound in which the ground state is not the CO phase; it was attributed to the collapse of the OO ground state. We proposed that OO ground state is a prerequisite for the occurrence of PPC in these compounds.     

Asymmetric Total Synthesis of (+)‐Ryanodol and (+)‐Ryanodine

(+)‐Ryanodine ( 1 ) is the ester derivative of 1H‐pyrrole‐2‐carboxylic acid and the complex terpenoid (+)‐ryanodol ( 2 ), which possesses eleven contiguous stereogenic centers on the ABCDE‐ring system. Compound 1 is known to be a potent modulator of intracellular calcium release channels, whereas the activity of 2 is significantly weaker. To chemically construct 1 , the multiple oxygen functional groups must be installed on the fused pentacycle in stereoselective fashions and the extremely hindered C3‐hydroxy group must be acylated in a site‐selective manner. First, the total synthesis of 2 was accomplished by introducing the five stereocenters from the previously prepared enantiopure ABDE‐ring 7 . Stereoselective construction of the C3‐secondary, C2‐ and C6‐tertiary alcohols was achieved by three nucleophilic reactions. The C9‐ and C10‐trisubstituted carbon centers were regio‐ and stereoselectively introduced by hydroboration/oxidation of the six‐membered C‐ring, which was formed by the ring‐closing metathesis reaction. Direct esterification of the C3‐alcohol with pyrrole‐2‐carboxylic acid proved unsuccessful; therefore, we developed a new, two‐step protocol for attachment of the pyrrole moiety. The C3‐hydroxy group was first converted into the less sterically cumbersome glycine ester, which was then transformed into the pyrrole ring through condensation with 1,3‐bis(dimethylamino)allylium tetrafluoroborate. This procedure resulted in the first total synthesis of 1 .     

Enrichment adsorption of a labile substance to the surface of particular mineral particles in river water as investigated by SEM-EDX and dilute-acid extraction/ICP-MS.

The selective enrichment behavior of a labile substance, such as hydroxides, to the surface of particular mineral particles in river water was clarified by scanning electron microscopy/energy dispersive X-ray microanalysis (SEM-EDX). Individual particles other than diatom collected on a 0.45 microm filter from the Fuji and Sagami rivers, central Japan, were analyzed by SEM-EDX and classified into seventeen groups according to the chemical composition and shape. Phosphorus, sulfur, chlorine, manganese and copper detected in each particle collected on the 0.45 microm filter could be successfully used as effective indicators of labile substance secondarily formed and adsorbed afresh in river water, because the detection frequencies of such elements are quite low, or negligible, in fresh mineral particles derived from igneous rocks. The labile substance adsorbed on mineral particles collected on the 0.45 microm filter was also evaluated by dilute-acid leaching, followed by inductively coupled plasma mass spectrometry (ICP-MS). Almost all parts of the manganese detected in individual particles were those adsorbed afresh as hydroxides together with iron and aluminum. Also, anionic elements, such as phosphorus, sulfur and chlorine, formed complexes with the hydroxides and/or were incorporated in them. Mg and/or Ca-rich aluminosilicate groups were the most effective adsorbers of such labile species. However, Si-rich and Na-, K- and Na-Ca rich aluminosilicates did not significantly adsorb the labile substance. Consequently, the remarkable selectivity was clarified in the adsorption process of labile substance to individual mineral particles in river water.     

Construction of a pentacyclic ring system of isoryanodane diterpenoids by SmI2-mediated transannular cyclization

Isoryanodane diterpenoids possess a densely oxygenated and intricately fused pentacycle (ABCDE-ring), although its unique ring system has not yet been assembled chemically. The 6/5/7-membered BCD-rings of isoryanodanes differ from the 5/6/6-membered rings of the structurally-related ryanodanes. We previously achieved the total synthesis of ryanodine and five other ryanodane diterpenoids by employing the common ABDE-tetracyclic intermediate 1. Herein, we report a new strategy for constructing isoryanodane ABCDE-ring structure 3 from 1 via a combination of the oxy-Cope rearrangement and SmI₂-mediated transannular cyclization.     

Symmetry‐Driven Strategy for the Assembly of the Core Tetracycle of (+)‐Ryanodine: Synthetic Utility of a Cobalt‐Catalyzed Olefin Oxidation and α‐Alkoxy Bridgehead Radical Reaction

Ryanodine ( 1 ) is a potent modulator of intracellular calcium release channels, designated as ryanodine receptors. The exceptionally complex molecular architecture of 1 comprises a highly oxygenated pentacyclic system with eleven contiguous stereogenic centers, which makes it a formidable target for organic synthesis. We identified the embedded C₂‐symmetric tricyclic substructure within 1 . This specific recognition permitted us to design a concise synthetic route to enantiopure tricycle 9 by utilizing a series of pairwise functionalizations. The four tetrasubstituted carbon centers of 9 were effectively constructed by three key reactions, a dearomatizing Diels–Alder reaction, the kinetic resolution of the obtained racemic 14 through asymmetric methanolysis, and the transannular aldol reaction of the eight‐membered diketone 10 . A new combination of cobalt‐catalyzed hydroperoxidation and NfF‐promoted elimination enabled conversion of the hindered olefin of 9 into the corresponding ketone, thus realizing the desymmetrization. Finally, the tetrasubstituted carbon was stereospecifically installed by utilizing the α‐alkoxy bridgehead radical to deliver the core tetracycle 7 with the six contiguous tetrasubstituted carbon centers. Consequently, the present work not only accomplishes efficient assembly of four out of the five fused rings of 1 , but also develops two new powerful methodologies: two‐step ketone formation and bridgehead radical reaction.     

Unified Total Synthesis of 3‐epi‐Ryanodol,Cinnzeylanol, Cinncassiols A and B,and Structural Revision of Natural Ryanodol and Cinnacasol

Ryanodane diterpenoids structurally share an extremely complex fused ring system, but differ in the substitution patterns of the hydroxy groups. Since these congeners exhibit various biologically important functions, their efficient chemical constructions have been greatly anticipated. We previously accomplished the total synthesis of ryanodine ( 1 ) using pentacycle 8 as the advanced intermediate. Here, we report the unified total syntheses of four distinct diterpenoids, 3‐epi‐ryanodol ( 3 ), cinnzeylanol ( 4 ), cinncassiols B ( 5 ), and A ( 6 ), from 8 , all within 10 steps. A series of highly optimized chemo‐ and stereoselective reactions and protecting‐group manipulations enabled assembly of the densely oxygenated structures of 3 – 6 . Furthermore, the present synthetic studies established the C13S stereochemisty of 5 – 7 and revised the proposed structures of natural ryanodol ( 2 ) and cinnacasol ( 7 ) to be those of 3 and 6 , respectively.