Synergistic antibiotic mixtures

Unlike the situation with ephedra, in many cases we simply have no idea what the components do. The constituents of some herbal drugs seem to work synergistically and cannot be separated without loss of activity of the preparation. Herbal preparations are most often used as crude mixtures and are not standardized or analyzed for the content of the active principlc(s). Hence, the chemistry of medicinal herbs cannot be treated in the same way as that of. say. a pure antibiotic or a calcium channel blocker. The medicinal chemistry of the actions, interactions, and side effects of herbal products is complex and difficult to assess clinically and chemically. Frequently, some of the compounds present... 

Synergistic Effects. In view of the antibiotic effect of CO, it was appropriate to investigate the effect of two compounds (G and CO) fed as a mixture. The effect could be simply additive, greater-than-additive (synergistic) or less-than-additive (antagonistic). 

When fed as a mixture, G and CO act synergistically both hormetic and antibiotic effects are intensified. 

These results indicate that host plant resistance in cotton will remain a fertile ground for future research. The association of volatile terpenes with glands, and the hormetic and antibiotic effects of one member of this group, are persuasive arguments for bioassaying other compounds. The unexpected synergistic effects observed when G and CO are fed as a mixture demand further study. Thus we intend to expand these studies to more fully define the contours of this growth-response surface, and extend this research to other terpenes. 

Individual antibiotics do not occur in the environment on their own but occur as a mixture, which introduces the possibility of synergistic or additive interactions or environmental contraindications between an environmental residue and a medicine taken by a patient for an existing condition. 

However, the mixture of the two components has an activity of 0.1 mg L" on 97 to 98% of the strains, including those strains of Staphylococcus aureus that are resistant to other commonly used antibiotics (for example erythromycin and lincomycin). The synergistic behavior between pristinamycin I and pristinamycin II not only results in increased potency and greatly improves the spectrum of activity, but in addition also renders the mixture bactericidal [8]. 

Borohydride reduction of the 37-ketone function of pristinamycin 11 has been shown [119, 124] to afford a mixture of the two possible isomeric alcohols (60) and (61), (Scheme 13), although the stereochemistry of the hydroxy function in the individual isomers was not determined. These semi-synthetic pristinamycin IIa derivatives were shown to retain substantial antibiotic activity associated with a powerful synergistic effect when associated with a pristinamycin component [22]. The reduction procedure was used for the preparation of biologically active derivatives of pristinamycin 11 labeled with in the 16-position which have been used extensively in investigations of the ribosomal binding and mechanism of action of the pristinamycins [124]. 

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