摘要:

Five dihydro-β-agarofuran [5,11-epoxy-5β,10α-eudesm-4(14)-ene] sesquiterpenes, three of which have a novel substitution pattern were isolated fromMaytenus magellanicaand their structures were elucidated by means of1H and13C NMR spectroscopic studies, including1H-13C heteronuclear correlation (HETCOR), long range correlation spectra with inversal detection (HMBC) and NOE experiments. Their absolute configurations were determined by application of the CD exciton chirality method while hydrolysis and preparation of derivatives provides additional information. Two of the sesquiterpenes exhibited significant antifeedant activity againstSpodoptera littoralis.

ISSN:1057-5634    

DOI:10.1080/10575639308043803

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Evolution of secondary metabolites in angiosperms is postulated to imply superposition of 1. stepwise abandonment of the intermediates of the shikimate pathway and their replacement by the intermediates of the acetate routes as biosynthetic precursors, and 2. gradual replacement of polyphenols by intermediate metabolites within binary antioxidant systems for the regulation of the oxidation level.

ISSN:1057-5634    

DOI:10.1080/10575639308043804

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The phycocolloids ofC. jubataharvested in Cap Lévy (Normandy, France) are a mixture of iota-carrageenan type, with its precursor nu-carrageenan. Throughout the yearC. jubataproduces only an iota-carrageenan, with seasonal fluctuation in physicochemical properties.

ISSN:1057-5634    

DOI:10.1080/10575639308043805

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

1,2-Polyol synthesis based on the iterative and diastereofacially selective carbonyl addition of 2-lithio-1,3-dithiane to chiral α-alkoxy aldehydes by starting from 1,2-O-cyclohexylidene-D-glyceraldehyde was studied in synthesizing aldose derivatives.

ISSN:1057-5634    

DOI:10.1080/10575639308043806

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

NMR spectral data and single crystal X-ray diffraction analysis on a new neoflavonoid, isolated from the heartwood ofCalophyllum inophylloide, have established its structure as (+)-(2R,3S,16S)-2,3-dimethyl-5-hydroxy-6-(3-methyl-but-2-enyl)-7-methoxy-8-(2-carboxyl-1-phenylethyl)-2,3-dihydrobenzopyran.

ISSN:1057-5634    

DOI:10.1080/10575639308043807

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The poppy alkaloid, nudaurine, was shown by X-ray crystallography to have an (S)-configuration at C-7 opposite to the configuration previously assigned by oxidative degradation.

ISSN:1057-5634    

DOI:10.1080/10575639308043808

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

One novel saponin, mabioside B (1), containing asecoring D dammarane triterpenoid aglycone has been isolated from the bark ofColubrina elliptica. The structure was established by spectroscopic methods.

ISSN:1057-5634    

DOI:10.1080/10575639308043809

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The polysaccharide extracted fromSchizymenia dubyiwas studied with several methodes; multiple analysis demonstrate that the carrageenan is similar to lambda type.

ISSN:1057-5634    

DOI:10.1080/10575639308043810

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The syntheses of the 4α,4β,8β,10β-tetramethyl perhydrophenanthrene3and the 13α-ethyl (4) and 14β-ethyl (5) derivatives are described. GC-MS analyses demonstrated identity between the first two synthetic tricyclanes and the novel C18and C20terpanes found in Chinese oils.

ISSN:1057-5634    

DOI:10.1080/10575639308043811

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The structures of the metabolites ofCeratocystis piceaewere revealed to be (3R,5R)-(+)-3-hydroxytetradecan-5-olide (1), (5R)-(-)-2-tetradecen-5-olide (2), (3R,5R,12R)-(+)-3,12-dihydroxytetradecan-5-olide (3), and (3R,5R,11R)-(+)-3,11-dihydroxytetradecan-5-olide (4). The absolute configurations of novel compounds (1), (3), and (4) were determined via chemical correlation and spectral data. (1) inhibited the growth of red pine seedlings at 10 ppm.

ISSN:1057-5634    

DOI:10.1080/10575639308043812

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor