Enantioselective total synthesis of (+)-ottelione A, (-)-ottelione B, (+)-3-epi-ottelione A and preliminary evaluation of their antitumor activity

Enantioselective total synthesis of (+)-ottelione A (1) and (-)-ottelione B (2), novel and potent antitumor agents from a freshwater plant, and (+)-3-epi-ottelione A (3), the earlier proposed stereostructure of 1, was efficiently achieved starting from the known tricyclic compound 10. The synthesis involved the following key steps: i) coupling reactions of aldehydes 8 and 9 with the aromatic portion 7 (8+7-->15 and 9+7-->27), ii) base-induced hemiacetal-opening/epimerization reactions of the cyclic hemiacetals 6 and 27 (6-->17 and 27 a-->26 a), and iii) Corey-Winter's reductive olefination of the cyclic thiocarbonates 21 and 36 (21-->22 and 36-->37). The present total synthesis fully established the absolute configuration of these natural products. The cell growth inhibition profile, COMPARE analysis, and tubulin inhibitory assay of (+)-3-epi-ottelione A (3) and its O-acetyl derivative 24 demonstrated that these unnatural substances could be prominent lead compounds for the development of anticancer agents with a novel mode of action.     

Simple full-color rewritable film with photochromic fulgide derivatives

A trial full-color rewritable film has been prepared by mixing fulgide derivatives as three primary-coloring dyes in a polymer, giving practically colorless or black form upon irradiation with white light or UV light. A good color image was obtained by a simple, one-shot irradiation with white light above the positive-color mask attached on the black film. The image could be erased and rewritten with another positive mask though degraded after many erase–write cycles.     

Poly(ADP-ribose) polymerase-1 gene in human tumor cell lines: Its expression and structural alteration

Poly(ADP-ribose) polymerase-1 (Parp-1) is involved in DNA repair and cell-death induction after DNA damage. Parp-1^−/− mice show higher susceptibility to the carcinogenic effects of nitrosamine and azoxymethane. To elucidate the role of alterations of the PARP-1 gene in human carcinogenesis, we examined the expression level of PARP-1 gene in various human tumor cell lines. The presence of gross rearrangement of PARP-1 gene in these cell lines was also examined by Southern blot hybridization analysis. The expression levels of PARP-1 gene in several cell lines, including T-cell leukemia cell lines (Molt-4 and CCRF-CEM), colon cancer cell line (WiDr), and gastric cancer cell lines (KATOIII, OKAJIMA, and MKN45) was substantially lower than in other cancer cell lines. Among the 85 analyzed cell lines, structural alteration of PARP-1 gene was detected in a gastric cancer cell line, MKN28. A low level of PARP-1 expression in human cancer could potentially influence cancer cell growth, differentiation and cancer development by affecting genomic instability, as well as the response of tumors to chemo- and radiotherapy.     

An analysis of regional ventilation in pulmonary sarcoidosis by inspired 133Xe washout test

Xenon-133 ventilation study were used to measure regional ventilation in seven patients with pulmonary sarcoidosis and in four normal subjects. For the purpose of analyzing the washout curves on the whole lungs, two ventilation indexes were calculated, which were TA/H and T1/2. TA/H is that the area under the curve divided by the difference in mean count rate during equilibrium and at 120 s after washout started. T1/2 value represents the time required to 50% of the mean count rate during equilibrium. The average time of TA/H on the whole lung was 13.5 +/- 1.1 s in normal subjects (n = 4), 13.0 +/- 4.3 s in stage I (bilateral hilar lymphadenopathy without lung involvement on chest X-ray) sarcoidosis (n = 3), 21.3 +/- 1.8 s in stages I, II (lung involvement) sarcoidosis (n = 4). The average time of T1/2 on the whole lung was 43.7 +/- 4.7 s in normal subjects, 42.3 +/- 16.0 s in stagel sarcoidosis, 72.5 +/- 28.6 s stages II, III sarcoidosis. The ventilation indexes on the regional lungs showed almost a similar tendency to that on the whole lung. The ventilation indexes in patients with stage II, III sarcoidosis were significantly longer than in normal subjects and in patients with stage I sarcoidosis. It was suggested that 133Xe washout test might detect regional ventilation abnormalities which were not recognized on chest X-ray in pulmonary sarcoidosis.     

Time-of-flight mass and photoelectron spectroscopy study of LaC n -

Mass spectra of LaC _n ^- were taken by using a laser-vaporization source (LVS) and pulsed arc cluster ion source (PACIS) applied to La-carbon composite rods (1:130 atomic ratio). The mass spectrum using the LVS with annealing procedure has shown several magic numbers for LaC _n ^- (n = 44, 50, 60, and 70), whereas only small LaC _n ^- (up to n = 14) have been observed in the mass spectrum using the PACIS. Photoelectron spectra of some of these have been measured using a magnetic-bottle type time-of-flight electron spectrometer. These results indicate the exsistence of a few conformational isomers for small La-containing carbon cluster negative ions LaC _n ^- (n = 5–8).     

Microwave spectrum and the structure of benzoyl chloride

The microwave spectrum of benzoyl chloride was observed in the frequency range 12–18.6 GHz. Rotational constants have been obtained for the ground vibrational state, the first three excited torsional states of the COCl group, and one of the out-of-plane bending states. The residual inertial defect obtained from the ground and the torsional excited states indicates that the equilibrium conformation is planar. Ab initio MO calculations (STO-3G) showed the potential energy curve as a function of the COCl torsional angle to be rather flat around zero degrees.     

Laser-induced pinpoint hydrogen evolution from benzene and water using metal free single-walled carbon nanotubes with high quantum yields

Metal-free photocatalytic hydrogen evolution occurred efficiently in benzene containing single-walled carbon nanotubes under laser irradiation at 532 nm with an extremely high turnover number of 2 000 000 and a high quantum yield of 130%. The rate of hydrogen evolution increased with increasing laser intensity to exhibit a fourth power dependence, suggesting that hydrogen was evolved via four-photon processes in which the coupling of two radical anions derived from benzene is the rate-determining step and the benzene radical anion is produced by electron transfer from benzene to the doubly excited state of single-walled carbon nanotubes, which requires two photons. Polymerisation of benzene was induced by the photogenerated C₆H₆˙^–, accompanied by hydrogen evolution, resulting in a leverage effect to increase the quantum yield of hydrogen evolution to well over the 25% expected for the four-photon process. Laser-induced hydrogen evolution also occurred in water containing single-walled carbon nanotubes. In contrast to the case of benzene, water was not oxidized but hydrogen evolution from water was accompanied by the multi-oxidation of single-walled carbon nanotubes. The yield of hydrogen based on one mole of single-walled carbon nanotubes with 1.4 nm diameter and 1–5 mm length was determined to be 2 700 000%, when oxidations of single-walled carbon nanotubes occurred to produce the polyhydroxylated product.     

Stereoselective conversion of anhydrovinblastine into vinblastine utilizing an anti-vinblastine monoclonal antibody as a chiral mould

Dimeric indole alkaloid, anhydrovinblastine, which can be obtained from catharanthine and vindoline in a high yield, was converted stereoselectively into vinblastine through alternating oxidation-reduction with oxygen and NaBH(3)CN in the presence of anti-vinblastine monoclonal antibody.