Carbohydrate-containing Antibiotics

The following six groups encompass about fifty individual antibiotic substances. 

Group 1 includes those antibiotics which are entirely carbohydrate in nature, for example, streptomycin, neomycin, kanamycin, and paromomycin. 

Group 2 consists of some related compounds possessing unusual amino acids, in addition to the carbohydrate moiety, for example, streptothricin and streptolin. 

Group 3 is the large family of macrolide antibiotics which includes erythromycin, carbomycin, and methjnnycin. 

Group 4 is a small group of pigmented substances including rhodomycin and cinerubin. 

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Oligosaccharides also occur widely as components (via glycosidic bonds) of antibiotics derived from various sources. Figure 7.20 shows the structures of a few representative carbohydrate-containing antibiotics. Some of these antibiotics also show antitumor activity. One of the most important of this type is bleomycin A2, which is used clinically against certain tumors. 

The anomeric effect is of prime consideration in synthetic carbohydrate chemistry in fact, some of the most important problems in this area, for example, the synthesis of oligosaccharides and carbohydrate-containing antibiotics, involve an understanding of the reactivity and properties of the anomeric center. In a detailed article concerned with the influence of reactant structure and solvent on glycoside synthesis, Schuerch explores how the anomeric effect of a number of reactants influences the course of kinetically controlled glycosidations. 

A review on some recent trends in the chemistry of carbohydrate-containing antibiotics has been published (in Russian). ... 

A review on field-desorption mass spectrometry has referred to studies on oligosaccharides, carbohydrate-containing antibiotics, plant glycosides, steroidal... 

Active immobilized forms of antibiotics have been prepared by treating the amino-groups of carbohydrate-containing antibiotics with cellulose trans-2,3-carbonate, and by chelation to transition-metal hydroxides and transition-metal derivatives of cellulose. ... 

Pulse amperometric detection (PAD) has been used for the detection on a PDMS chip. This method is useful for analysis of underivatized compounds, such as carbohydrates, amino acids, and sulfur-containing antibiotics, which easily caused electrode fouling. In PAD, a high positive potential (1.4-1.8 V) is first applied in order to clean the electrode (e.g., Au) surface. This is followed by a negative potential step (-0.5 V) to reactivate the electrode surface. A third moderate potential (+0.5 to +0.7 V) is applied for detection of the target analyte [752]. 

Work in our laboratories has demonstrated that free-radicals can be harnessed to provide beneficial products and chemical technologies. This paper highlights some of our recent quests for the Holy Grail of free-radical chemistry and includes the preparation of selenium-containing antibiotics, carbohydrates, antioxidants and anti-inflammatory agents and the development of reagents for use in enantioselective synthesis. 

If a carbohydrate already contains a nitro group, the nitro-bearing carbon atom can become the nucleophilic center for the coupling of two monosaccharide units (see Section 3.2.2). Suami and coworkers have used this method for the synthesis of antibiotics bearing sugars.102 Atypical example is presented in Eq. 3.63.102b... 

The number of naturally occurring, organic fluorine compounds is very small indeed. Compound 1 is1 a nucleoside antibiotic that contains fluorine attached to the carbohydrate ring, replacing H-4 in the D-ribosyl moiety. The presence of fluorine was shown by -n.m.r.-, 19F-n.m.r.-, and mass-spectral data, and the structure of this compound has been confirmed by independent synthesis.9,10... 

With respect to five-membered lactones fused to hexopyranose units, some approaches have been reported so far and the exploitation of their synthetic potential has led to the access of new carbohydrate derivatives. Bicyclic derivatives of this type are key intermediates in the synthesis of the epimer at C-3 of the sugar moiety contained in miharamycins [212, 213]. The latter are antibiotics known to inhibit strongly Pyricularia oryzae, which produces the rice blast disease. These compounds are also considered to be a potential bioterrorism agent (Scheme 42). Hence, the 3,3-spiroepoxide 176 was converted into the 3-C-cyanomethyl derivative 177, the hydrolysis of which led to spontaneous cyclization in the presence of... 

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