Juvenile hormone catabolism inManduca sexta: Homologue selectivity of catabolism and identification of a diol-phosphate conjugate as a major end product

We studied time-dependent metabolism of (10R)-[³H] juvenile hormone (JH) III and (10R, 11S)-[³H]JH I injected intoManduca sexta larvae; the hormones are metabolized to polar metabolites, expecially the JH acid-diol, and an unknown. Products were analyzed using a reversed-phase liquid chromatography assay. (10R)-JH III is metabolized much more rapidly than (10R, 11S)-[³H]JH I, whether injected seperately or as a mixture of hormones. The unknown metabolites of JH I and JH III were identified as phosphate conjugates of JH I and JH III diol by tandem mass spectral analysis of isolated samples. The phosphate conjugate of JH I diol is the principle end product of JH I metabolism.     

Structure of victorin C,the major host-selective toxin fromCochliobolus victoriae

Summary The predominant host-selective toxin fromCochliobolus victoriae, victorin C, is a peptide with an apparent mol. wt of 796, representing a cyclic array of the subunits1–6. The structure of the toxin has now been established as in16 through analysis of the degradation products generated by enzymic and non-enzymic partial hydrolysis. The presence of a hydrated aldehydo group requires for victorin C the composition C₃₁H₄₅O₁₃N₆Cl₃ with an amended mol. wt of 814, for which independent experimental support has been secured.     

Oxygenation of a dipyrromethene model for bilirubin: formation of a singlet oxygen-like product.

An oxodipyrromethene model compound for bilirubin is found to undergo oxidation to a blue tetrapyrrole and a water-propentdyopent on a silica gel thin layer chromatography plate. The reaction involves ground state oxygen and requires silica gel, although the propentdyopent is an expected product from reaction with singlet oxygen.     

Confirmation of the structure of nisin and its major degradation product by FAB-MS and FAB-MS/MS

FAB-MS has been applied to the analysis of a nisin complex and FAB-MS and FAB-MS/MS data from the major component used to provide confirmation of the amino sequence and positions of the sulphur-bridged rings in these highly modified peptides.     

Confirmation of the structure of nisin and its major degradation product by FAB-MS and FAB-MS/MS

Summary FAB-MS has been applied to the analysis of a nisin complex and FAB-MS and FAB-MS/MS data from the major component used to provide confirmation of the amino sequence and positions of the sulphur-bridged rings in these highly modified peptides.     

Identification of a major cytokinin in coconut milk

A major cytokinin found in coconut milk was isolted by using the tobacco callus growth-promoting assay as a guide during purification. The structure of the factor was determined to be 14-O-{3-O-[-d-galactopyranosyl-(12)--d--galactopyranosyl-(13)--L-arabinofuranosyl]-4-O-(-L-arabinofuranosyl)--d-galactopyranosyl}-trans-zeatin riboside [G₃A₂-ZR] by various NMR techniques, including heteronuclear multiple bond connectivity by 2D multiple quantum NMR (HMBC), as well as mass spectroscopy and sugar analysis. The optimum concentration of G₃A₂-ZR for cytokinin activity in the tobacco callus assay was estimated to be 5×10^–6 M, so that G₃A₂-ZR is one order of magnitude more potent than 1,3-diphenylurea and one order less potent than zeatin riboside. At least 20% of the cytokinin activity of coconut milk could be attributed to G₃A₂-ZR.     

Characterization of victorin C,the major host-selective toxin fromCochliobolus victoriae: Structure of degradation products

Summary Several host-selective toxins have been isolated in pure form culture filtrates ofCochliobolus victoriae. Acid hydrolysis of the major toxin, victorin C (apparent mol.wt 796), produced five fragments to which structures1–5 have been assigned. Spectroscopic techniques revealed that the toxin contains an additional subunit corresponding to6; thus all the components of victroin C are accounted for.     

Anticonvulsant activity of farnesylacetone epoxide--a novel marine natural product.

A marine natural product, farnesylacetone epoxide, which is chemically related to juvenile hormone, has anticonvulsant properties at nonsedative doses in mice.     

Biogenesis of rifamycins. The conversion of rifamycin B into rifamycin Y

Riassunto È stata studiata la biogenesi della rifamicina Y, prodotta accanto alla rifamicina B da culture diS. mediterranei. I dati riportati dimostrano che la rifamicina Y deriva dalla rifamicina Be che la sua produzione dipende dalla concentrazione di fosfati nel terreno di cultura.

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Presented in part at the Vth International Congress of Chemotherapy, Wien, 26 June 1967.     

Constituents of labiatae XIX. Structure of galdosol,a new diterpene fromSalvia canariensis L.

Résumé Le nouveau diterpène galdosol (I) a été isolé de laSalvia canariensis L. et sa structure déterminée comme 7-oxo-11, 12-dihydroxy-8, 11, 13-abiétatrién-20, 6-olide.     

Oxygenation of a dipyrromethene model for bilirubin: Formation of a singlet oxygen-like product

Summary An oxodipyrromethene model compound for bilirubin is found to undergo oxidation to a blue tetrapyrrole and a water-propentdyopent on a silica gel thin layer chromatography plate. The reaction involves ground state oxygen and requires silica gel, although the propentdyopent is an expected product from reaction with singlet oxygen.The authors wish to thank the National Science Foundation for generous support of this work. We also thank Mr.Richard Gillespie and Ms.Elizabeth Irwin for running the high resolution mass spectra.     

DNA,a controlling factor in the conversion of plasminogen to plasmin

Résumé Les résultats de ces études démontrent la formation de «complexes» entre l'acide désoxyribonucléique et la plasminogène. L'acide désoxyribonucléique inhibe l'action catalytique de la plasminogène humaine sur la plasmine.     

Anticonvulsant activity of farnesylacetone epoxide—a novel marine natural product

Summary A marine natural product, farnesylacetone epoxide, which is chemically related to juvenile hormone, has anticonvulsant properties at nonsedative doses in mice.     

Structure of nepseudin. Synthesis of dehydronepseudin

Zusammenfassung Die Konstitution (I) für Nepseudin wird durch die Syntheses des Dehydronepseudins (II), das aus 6-Oxy-2, 3-dihydrobenzo[b]furan und 2,3,4-Trimethoxyphenylessigsäurenitril in drei Reaktionsstufen erhalten wird, aufgeklärt.