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

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.     

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.     

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.     

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.     

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.     

Photo-oxidation of histidine as a probe for aminoterminal conformational changes during fibrinogen-fibrin conversion

Fibrinogen is known to become unclottable when irradiated with light in the presence of methylene blue, the loss of clottability being due to photo-oxidation of the histidine at position 16 of the B<beta> chain. In the present investigation it could be demonstrated that not only this histidine but also the one at position 24 of the A<alpha> chain was modified and that the rates of modification could be modulated by fibrinopeptide release, polymerization inhibition and denaturation. Accordingly, the histidine modifications can be used as probes for surface accessibility of and conformational differences among the various forms of the protein. Both histidines are shielded by the fibrin polymer structure. Fibrinopeptide A release alone leads to maximal protection of the one in the A<alpha> chain, but only partial protection of the one in the B<beta> chain. Subsequent fibrinopeptide B release leads to maximal protection of the one in the B<beta> chain. The differential effects indicate that two conformational changes have occurred. Polymerization inhibition reverses the protective effect. Denaturation leads to maximal and equal modification in all samples as a consequence of the loss of native conformation. Received 8 October 1996; accepted 15 October 1996     

2-amino-1,4-naphthoquinone-N4,2-naphtylimine. A photo-oxidation product of 2-aminonaphthalene

Zusammenfassung Es wurde gezeigt, dass das Chinonimin 2-Amino-1,4-naphtochinon-N⁴-2-naphtylamin die Farbe von gealtertem Ö1 in der 2-Aminonaphtalinlösung verursacht. Diese farbige Verbindung entsteht durch die Photooxydation des Amins und scheint eine wichtige Rolle für die erhöhte krebserzeugende Wirksamkeit des alten Öls zu spielen.     

Structure specificity of some immunoadjuvant synthetic glycopeptides.

The immunoadjuvant activity of muramyl dipeptide seems to be critically dependent on the type of substitution of the gamma-carboxyl group of the D-isoglutamine residue. Moreover the nonapeptide L-Ala-D-isoGlu-L-lys-D-Ala-(Gly)5-OME also shows a definite effect.     

Structure and stereochemistry of brianolide,a new antiinflammatory diterpenoid from the Okinawan gorgonianBriareum sp.

Summary Brianolide (1), a new antiinflammatory diterpenoid of the briarein class, possessing a substituent at C-12 (R), has been isolated from the Okinawan gorgonianBriareum sp. Its structure has been established from spectral data in conjunction with a single crystal X-ray analysis.     

Structure and stereochemistry of attenuol,a new lignan fromKnema attenuata (Wall.) Warb.

Summary A new lignan attenuol has been isolated from the bark ofKnema attenuata (Wall.) Warb. Its structure (I) is deduced on the basis of analytical and spectral data. The compound has been assigned the absolute configuration as 2S,3R-dimethyl-1S-(p-hydroxyphenyl)-6,7-methylenedioxytetralin (III).Contribution No. 487 from the Ciba-Geigy Research Centre.Acknowledgments. We thank Dr H. Fuhrer and Dr P. Moser of Ciba-Geigy Ltd. Basle for the NMR spectral data and ORD determinations and Dr S. Selvavinayakam and his colleagues for the analytical results.