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Arylhydrocarbons are inducers of monooxygenase activity in epithelial cells in culture (Hela) whereas diterpene esters are not. This is one more example of a specific biochemical difference - here in gene activation - exhibited by tumor initiators and tumor promoters of the classes of compounds assayed.
Purported biogenic features of the ALH84001 Martian meteorite (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive hypothesis is offered here. The carbonate globules were deposited from hydrothermal water, without biological mediation. Thereafter, ALH84001 was affected by an impact shock event, which raised its temperature nearly instantaneously to 500-700K, and induced iron-rich carbonate in the globules to decompose to magnetite and other minerals. The rapidity of the temperature increase caused magnetite grains to nucleate in abundance; hence individual crystals were very small. Nucleation and growth of magnetite crystals were fastest along edges and faces of the precursor carbonate grains, forcing the magnetite grains to be platy or elongated, including the "truncated hexa-octahedra" shape. ALH84001 had formed at some depth within Mars where the lithostatic pressure was significantly above that of Mars' surface. Also, because the rock was at depth, the impact heat dissipated slowly. During this interval, magnetite crystals approached chemical equilibria with surrounding minerals and gas. Their composition, nearly pure Fe(3)O(4), reflects those of equilibria; elements that substitute into magnetite are either absent from iron-rich carbonate (e.g., Ti, Al, Cr), or partitioned into other minerals during magnetite formation (Mg, Mn). Many microstructural imperfections in the magnetite grains would have annealed out as the rock cooled. In this post-shock thermal regime, carbon-bearing gas from the decomposition of iron carbonates reacted with water in the rock (or from its surroundings) to produce organic matter via Fischer-Tropschlike reactions. Formation of such organic compounds like polycyclic aromatic hydrocarbons would have been catalyzed by the magnetite (formation of graphite, the thermochemically stable phase, would be kinetically hindered).
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Four diterpenes and a nor-diterpenoid, all of which possess unusual carbocyclic skeletons, were isolated from the hexane solubles of the West Indian gorgonian Pseudopterogorgia elisabethae. The structures and relative configurations of novel metabolites elisabethin D (2), elisabethin D acetate (3), 3-epi-elisabanolide (5), elisapterosin A (6), and elisapterosin B (7) were elucidated by interpretation of overall spectral data, which included 2D NMR correlation methods, IR, UV, and accurate mass measurements (HREI-MS and HRFAB-MS), chemical reactions, and X-ray diffraction analyses. The tetracyclic carbon skeleton of the elisapterosins is undescribed and constitutes a new class of C(20) rearranged diterpenes. Elisapterosin B displays strong in vitro anti-tuberculosis activity.
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Molecular mechanics simulations and ab initio calculations were performed to investigate the mechanism of PAH-soot adsorption. Partitioning of benzene, naphthalene, fluorene, phenanthrene, anthracene, pyrene, fluoranthene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[a]pyrene, and benzo[g,h,i]perylene between water and soot was modeled with classical and quantum mechanical calculations in order to determine a method for predicting log(K(d)) values. In both cases, the predicted mechanism of adsorption is interaction of the pi-electrons in the PAH and soot (i.e., pi-pi van der Waals forces). Solvation energies, the energy difference between the solute in the gas phase and in the model aqueous phase, calculated with molecular mechanics did not follow the observed solubilities of the PAHs. Molecular dynamics simulations overestimate the favorability of PAHs in the aqueous phase. Hence, the partitioning between the aqueous phase and soot does not accurately correlate with observed log(K(d)) values. Models of PAH adsorption using structures from molecular mechanics and energies from ab initio calculations do produce water-soot partitioning energies that correlate well with observed log(K(d)) values. The log(K(d)) values for benzene, anthracene, fluorene, and benzo[a]pyrene were predicted based on the correlation between calculated partitioning energies and observed log(K(d)) values. Results presented here suggest that partitioning of PAHs onto soot should depend on the size of the PAH, the planarity of PAH molecule, and the aromaticity of the compound. The methodology developed bythis research can be used to predict PAH K(d) values that have not yet been measured.
The effects of lithocholic acid on the mutagenicity of 24 aromatic amines in the Ames assay were examined. When lithocholic acid was added to the Salmonella/mammalian--microsome mutagenicity system with the use of postmitochondrial supernatant fractions from livers of male inbred SD rats pretreated with Aroclor 1254 or phenobarbital, various effects on the mutagenic responses were observed. The effects on mutagenicity varied with the substrate and the type of 9,000 X g-supernatant fraction. With preparations from phenobarbital-treated rats, lithocholic acid caused an inhibition of the mutagenic response with 16 of 24 compounds tested. The mutagenicity of three of these test compounds (2,4-diaminoanisole, 3-methoxy-4-aminoazobenzene, and 1-aminoanthracene) was unaffected by inclusion of lithocholic acid, while the lithocholic acid enhanced the mutagenicity of three others (2-aminoanthracene, 9-aminophenanthrene, and 2-acetylaminoanthracene). With 9,000 X g-supernatant fractions from Aroclor 1254-treated rats, the mutagenicity of eight test compounds was unaffected and that of 10 others was inhibited, while the mutagenicity of six others was enhanced when lithocholic acid was included in Ames assay mixtures. These results demonstrate that lithocholic acid can cause three distinct effects on the mutagenicity of these amines when included in these assays, namely, 1) no effect--no change in mutagenicity of the test compound, 2) inhibitory--levels of mutations significantly decreased or inhibited relative to those of controls, and 3) enhancement--significantly higher levels of mutations relative to those of controls. On the basis of structure alone and without detailed knowledge of the metabolism of each test compound, no conclusions or predictions could be made regarding the effects of lithocholic acid on the mutagenicity of these or any other compounds in the Ames assay.
A new pentacyclic cucurbitane glucoside, named aoibaclyin (1) and a new triterpene (2) have been isolated from the EtOH extract of the fruits of Gymnopetalum integrifolium Kurz (Cucurbitaceae), together with three known compounds, bryoamaride (3), 25-O-acetylbryoamaride (4) and beta-sitosterol 3-O-beta-D-glucopyranoside (5). The structures of these compounds were elucidated by spectroscopic analyses.
Kinetic parameters of Streptomyces olivocinereus 11-98 growth and biosynthesis of heliomycin were studied. It was shown that carbon sources such as glycerol, mannitol and ramnose were the most favourable for the antibiotic biosynthesis. These carbon sources belonged to the group of substances providing high growth rates of the culture. Ranging of the culture growth rates and antibiotic production levels revealed a set of carbon sources providing a converse relationship between the growth rate and antibiotic biosynthesis i.e. L-arabinose, potassium gluconate, raffinose and sucrose. It was suggested that these compounds were catabolic type regulators of heliomycin biosynthesis.
This paper reports the total synthesis of (+/-) schizandrin, C, namely 5,6,7,8-tetrahydro-1, 12-dimethoxy-2, 3, 10, 11-bismethylenedioxy-6, 7-cis-dimethyldibenzo (a, c) cyclooctene (12B), a new active SGPT lowering principle isolated from the Chinese medical plant Schizandra chinensis, and its 6, 7-trans-dimethyl isomer (16B). We also synthesized two more isomers, namely 5, 6, 7, 8-tetrahydro-3, 10-dimethoxy-1, 2, 11, 12-bismethylenedioxy-6, and 7-cis-(and trans-) dimethyldibenzo (a, c) cyclooctene (12A and 16A). The NMR, UV and mass spectra of these four isomers are discussed. IR (in chloroform), UV, NMR and MS of synthetic schizandrin C (12B) are identical with those of the natural compound.
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The metabolic transformation of schizandrin, isolated from the kernel of Schizandra chinensis Bill, was studied in vitro with phenobarbital-induced rat liver microsomal fractio containing the NADPH-generating system. The major metabolites were isolated by preparative HPLC and identified as 7,8-dihydroxy-schizandrin, 7,8-dihydroxy-2-demethyl schizandrin and 7,8-dihydroxy-3-demethyl schizandrin by UV, NMR, MS spectral analysis. The 7,8-dihydroxy-schizandrin was confirmed further by comparison with spectral and chromatographic behavior of the authentic compound. The metabolic biotransformation of schizandrin in vivo was also determined.
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A total of 101 carcinogens, noncarcinogens, metals, and promoters representing a wide variety of chemical classes was tested to determine whether they increased mitotic recombination in Saccharomyces cerevisiae D3. A metabolic activation system prepared from homogenates of livers from rats that had been pretreated with Aroclor 1254 (a mixture of polychlorinated biphenyls) was incorporated in the assay procedure. All of the ultimate carcinogens (20/20) and 38% of the procarcinogens (18/48) increased mitotic recombination. Of the noncarcinogens 29% (6/21) also increased mitotic recombination. A improved metabolic activation procedure appears to be required to increase the probability of detecting procarcinogens by this method. The carcinogens thioacetamide, natulan, auramine, safrole, and 1'-hydroxysafrole increased mitotic recombination in S. cerevisiae D3 (the last compound was marginally positive), but they were negative in assays with Salmonella typhyimurium.
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