By A. Douglas Kinghorn, Heinz Falk, Junichi Kobayashi, Herbert Budzikiewicz, Rogelio Pereda-Miranda, Daniel Rosas-Ramírez, Jhon Castañeda-Gómez
Resin glycosides are a part of a really vast family members of secondary metabolites often called glycolipids or lipo-oligosaccharides and are elements of complicated resins (glycoresins) (1) targeted to the morning glory relations, Convolvulaceae (2). those energetic ideas are answerable for the drastic purgative motion of all of the very important Convolvulaceous species utilized in conventional medication in the course of the global seeing that precedent days. numerous advertisement purgative crude medicinal drugs should be ready from the roots of other species of Mexican morning glories. Their incorporation as healing brokers in Europe is a phenomenal instance of the assimilation of botanical medicinal drugs from the Americas as substitutes for standard outdated international treatments (3). even supposing phytochemical investigations at the parts of those medicines have been initiated in the course of the moment 1/2 the 19th century, the constitution in their energetic parts nonetheless continues to be poorly recognized for a few examples of those purgative roots. over the past twenty years, the better solution c- talents of contemporary analytical isolation suggestions utilized in conjunction with pow- ful spectroscopic equipment have facilitated the elucidation of the energetic rules of those suitable natural items. This bankruptcy describes the ethnobotanical info linked to the p- gative morning glory species and the way conventional usages have been instrumental in plant choice for chemical experiences. the benefits and boundaries of obtainable analy- cal suggestions for the isolation, puri?cation, and constitution characterization of the person parts of those advanced glycoconjugates also are mentioned.
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Additional info for Progress in the Chemistry of Organic Natural Products, Volume 92
Sample text
For steric considerations only cis-(SR0 ) or cis-(RS0 ) arrangements can be considered. Uptake experiments with 55Fe showed that it is a true siderophore (193). 5. Legiobactin Legionella pneumophila produces a siderophore named legiobactin, which shows no catecholate or hydroxamate reactions (206). Enzymatic studies suggest a citrate structure in agreement with the data obtained by mass spectrometry (molecular mass ca. 350 Da) and NMR (three carbonyl and ten aliphatic C atoms). It is not clear yet as to whether legiobactin is essential for the iron acquisition in the aqueous habitat of the bacterium or during lung infection (2, 65).
In an acidic milieu equimolar concentrations form [FeCit]-, at about pH 4 polymerization starts resulting at pH 8–9 in an insoluble complex with an iron hydroxide core and citrate ions bound to the surface. With a citrate excess species like [FeCit2]5- are discussed. It should be mentioned that the central carbon atom of citric acid becomes chiral when the two peripheral carboxy groups are substituted differently (examples will be found below). For enzyme reactions it is a prochirality center. This has been shown for vibrioferrin (58) and staphyloferrin B (59).
Some structurally related compounds will also be mentioned here. Salicylic acid isolated from Burkholderia (Pseudomonas) cepacia was named azurochelin (333). g. for Pseudomonas fluorescens (230) and P. syringae (178); see also Mycobacterium smegmatis (Sect. 8). For details on the siderophore activity of salicylic acid, see (359). The structure of pyochelin (for a detailed bibliography, see (37)), a secondary siderophore of Pseudomonas aeruginosa and of Burkholderia cepacia was established (73) as 2-(2-o-hydroxyphenyl-2-thiazolin-4-yl)-3-methylthiazolidine-4carboxylic acid.