Streptomyces ravidus S50905was found to produce a new antibiotic, deacetylravidomycin TV-oxide, together with ravidomycin and deacetylravidomycin in a culture mediumcontaining sodiumanthraquinone-/3-sulfonate. The structure of this newcompound was determined from NMRand mass spectrometric data, and further confirmed by chemical synthesis from deacetylravidomycin. Deacetylravidomycin iV-oxide was antitumor active against P388 leukemia and Meth A fibrosarcoma in a wide range of doses, and considerably less toxic than deacetylravidomycin. Its antibacterial activity was less potent than deacetylravidomycin. Ravidomycin JV-oxide was also synthesized from ravidomycin and its biological properties were tested.In the course of our screening program for new antibiotics, a streptomycete, strain S50905, designated as Streptomyces ravidus S50905 was found to produce a new antibiotic, deacetylravidomycin iV-oxide (1), along with ravidomycin (4)x~4) and deacetylravidomycin (2)4). The present paper describes the taxonomy and fermentation of the producing strain and the isolation, physico-chemical properties, structure assignment and biological properties of deacetylravidomycin iV-oxide.Taxonomy
Radiation-induced reactions of cinnamic acid derivatives have been examined and compared with photoreactions in the crystalline state; all the reaction products were exactly the same as those of the photoreactions, indicating that the reactions proceed only via the lowest excited state to give [2 + 2] cycloadducts, E/Z isomerization products, or starting molecules.
Interfacial reactions in Al-alloy/Ti/borophosphosilicate glass (BPSG)/Si-substrate structures have been investigated up to the annealing temperature of 550° C. The interfacial reaction changes according to the annealing temperature. Below 500° C, a reaction between Al alloy and Ti occurs, and the main reaction product is Al3Ti. The underlying BPSG film remains almost inert. At 550° C, the substrate BPSG film is no longer inert and a reaction between Al alloy, Ti and underlying BPSG film takes place. The reaction never occurs without the Ti layer. Reactions in the Al-Ti-Si-O four-component system must be considered in this temperature range. The main reaction product is Ti7Al5Si12. After the Ti layer is consumed for Al3Ti formation, Al3Ti and BPSG react to form Ti7Al5Si12, and a lot of Al moves into BPSG film through the Ti7Al5Si12. Reaction retardation by alloying Al with Si also occurs in this temperature range.
Articles you may be interested inOptimization of postgrowth electron-beam curing for focused electron-beam-induced Pt deposits Electron-beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in situ electron-beam-induced desorption Comparative study of thermally cured and electron-beam-exposed hydrogen silsesquioxane resistsThe electron-beam ͑EB͒-induced reaction of triphenylsulfonium methanesulfonate ͑1-Ms͒ in the solid state afforded the benzene-substituted product, biphenyldiphenylsulfonium methanesulfonate ͑2-Ms͒, which has not been observed by either photolysis or EB-induced reaction in a solution. Biphenyl salt 2-Ms was accumulated as an intermediate product at an early stage and consequently decomposed to diphenylsulfide ͑3͒ and three regioisomers of phenylthiobiphenyls ͑4͒. The kinetic data of both formation and consumption of 2-Ms revealed that the biphenyl salt 2-Ms exhibited 3.7 times greater kinetic constants for consumption than that of 1-Ms. The EB-induced reaction of benzene-substituted triphenylsulfonium salts, p-biphenyldiphenylsulfonium methanesulfonate ͑2p-Ms͒ and ͑4-phenylthiophenyl͒diphenylsulfonium methanesulfonate ͑7͒, showed the consumption rates of 3.8 and 5.7 times greater than that of 1-Ms. The sulfonium salts with aromatic counteranions showed somewhat higher reactivity than those with aliphatic counteranions. Accordingly, it is concluded that the triphenylsulfonium salts having aryl groups, which exhibit lower ionization potential, in both cation and anion moieties should exhibit greater decomposition rates. Detailed kinetic analysis of 1-Ms revealed that the EB-induced reaction of 1-Ms comprises two disparate pathways, one pathway is a unimolecular rearrangement via the lowest excited state leading to only orthoisomer of 4 and the other is a bimolecular displacement of phenyl radical via the upper excited state leading to 2-Ms and 3.
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