Carbohydrate-molybdate complexes

The present volume reflects these developments, and there is a growing emphasis on bioactive natural products. Articles in this volume include those on structure-activity relationships of highly sweet natural products, chemical constituents of cchinodenns, diterpenoids from Rabdosia and Eremophila sp., structural studies on saponins, marine sesquiterpene quinoncs and antimicrobial activity of amphibian venoms. The reviews on bioactive metabolites of Phomopsis, cardenolide detection by ELISA, xenocoumacins and bioactive dihydroisocoumarins, CD studies of carbohydrate-molybdate complexes, oncogene function inhibitors from microbial secondary metabolites and Gelsemium and Lupin alkaloids present frontier developments in several areas of natural product chemistry. It is hoped that the present volume, which contains articles by eminent authorities in each field, will be received with the same enthusiasm as the previous volumes of this series. 

Another type of carbohydrate complex is the cyclic ester formed between a glycitol and a polyanion such as borate or molybdate (4). The possible species present at equilibrium have not previously been evaluated by iteration. The system mannitol-borate has been so analyzed, and it was possible to use the same approach as that for the metal chelates. 

The derivatization of aldehydes in reducing carbohydrates can also be performed by a condensation reaction between the active hydrogens of l-phenyl-3-methyl-5-pyrazolone (PMP) and the aldehyde functionality under slightly basic condition. The formed bis-PMP derivatives can be separated by CZE and detected by UV absorbance. Oligosaccharides can also be separated as complexes with a variety of compounds, including acetate, molybdate, germanate, stannate, arsenite, wolfra-mate, vanadate, and tellurate of various alkali and alkaline... 

Earlier structural studies of carbohydrates by CD involved introduction of suitable chromophores into the sugar molecule thereby affording derivatives which exibit Cotton effects. These include, among others, xanthates (4-8) or azides (9). Later it was found that some metal ions (10), i.e. copper (11,13), vanadate (14), chromium (15), molybdate (16-22), nickel (23) or cobalt (24,25) ions form complexes with carbohydrates, which show appreciable Cotton effects. 

A review has appeared on the synthetic, analytical, and biological uses of borate complexes of carbohydrates. The interaction of molybdate and tungstate with mannitol and glucitol have been further studied in dilute solution by potentiometric methods. ... 

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