Aglycones aromatic

In all the crystal structures of anthracycline-DNA complexes, the drug molecule is intercalated at the CpG steps. A common feature of the more simple anthracycline antibiotics such as daunomycin and adriamycin is the aglycone aromatic system. 

Vancomycin, ristocetin A and teicoplanin are produced as fermentation products of Streptomyces orientalis, Nocardia lurida and Actinoplanes teichomyceticus, respectively. All three of these related compounds consist of an aglycone basket made up of fused macrocyclic rings and pendant carbohydrate moieties (Fig. 2-1). The macrocycles contain both ether and peptide linkages. The aglycones of vancomycin and teicoplanin contain two chloro-substituted aromatic rings, while the analogous portion of ristocetin A contains no chloro substituents. 

Several elegant syntheses of anthra-cyclinone aglycons are based on the ability to intercept the intermediate radical cation (76) formed from the oxidation of aromatic ethers (75) and (79) in situ with alkanols [9, 44, 45]. Inter- and intramolecular capture can occur. As illustrated in Scheme 19, the methodology leads to the facile construction of substituted quinone mono- and bisketals. 

Elisabethol (13) [4] shows the same stereochemistry as the pseudopterosin aglycone 10. Elisabatins A-C (14,15,16) [ 14] have the same amphilectane skeleton found in the aglycone portion of the pseudopterosins. The elisabatins are unique among the amphilectane-type diterpenoids because they possess an unusually high unsaturation number that leads to extended aromatic conjugation. 

Thio-p-D-xylopyranosides that contain aromatic aglycons, such as Beciparcil (246, Fig. 24), and related analogues have potent antithrombotic activity in... 

The application of standardized UV (or UV-Vis) spectroscopy has for years been used in analyses of flavonoids. These polyphenolic compounds reveal two characteristic UV absorption bands with maxima in the 240 to 285 and 300 to 550 nm range. The various flavonoid classes can be recognized by their UV spectra, and UV-spectral characteristics of individual flavonoids including the effects of the number of aglycone hydroxyl groups, glycosidic substitution pattern, and nature of aromatic acyl groups have been reviewed in several excellent books. ... 

The UV-Vis spectral data on anthocyanins (typically measured in methanol containing O.OP/o HCl) give important information about the nature of the aglycone and aromatic acyl... 

The method was used for oxidation of an unsaturated nitrile (1) to an aromatic acyloin (2) in a projected synthesis of a model for olivin (4), an aglycone of olivomycin antibiotics.2... 

Figure F1.1.2 Structural and spectral characteristics of the major naturally occurring aglycons. The chemical structure indicates the two aromatic rings (A, B) as well as the R1 and R2 substitution sites.

Figure F1.4.2 The aromatic region of the 1-D 1H NMR of cyanidin gives rise to a characteristic splitting pattern (upper spectrum). The lower spectrum shows the aromatic region of the 1-D 13C compensated attached proton test (CAPT) NMR spectrum of cyanidin. This spectrum contains all the fifteen 13C resonances of the aglycone in addition to solvent signals (labeled S) and the anomeric sugar proton labeled 1". In this spectrum, the 13C nuclei which have a proton attached are represented with resonances pointing downwards, while the quaternary 13C nuclei are pointing upwards. The 1H NMR experiment was obtained within 25 sec, while the CAPT experiment was obtained within 1 hr 46 min.

Most phenolic glycosides are water soluble, but the corresponding aglycones are usually less so. Phenolic substances are aromatic and therefore show intense absorption in the UV region of the spectrum (2). Most of the benzoic acid derivatives displayed their maxima at 246-262 nm, with a shoulder at 290 - 315 nm, except gallic and syringic acid, which have absorption maxima at 271 and 275 nm, respectively (4). The cinnamic acids absorb in two regions in the ultraviolet, one... 

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