A series of 3-descladinosyl-2,3-anhydro-6-O-methylerythromycin A 11, 12-carbamate analogues have been synthesized and evaluated for antibacterial activity. These compounds were found to be potent antibacterial agents against Gram-positive organisms in vitro, many having MIC values below 1 microg/mL for the macrolide-susceptible Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae, as well as improved activity compared to erythromycin A against the inducibly MLS (macrolide, lincosamide, and streptogramin B)-resistant organisms. Structure-activity studies revealed that arylalkyl carbamates with two and four carbon atoms between the aromatic moiety and carbamate nitrogen have the best in vitro activity. All of the C-10 epi analogues evaluated were found to have substantially less activity than the corresponding natural C-10 isomer. Several analogues demonstrated moderate antibacterial activity against the constitutively resistant S.aureus A-5278, S. pneumoniae5979, and S.pyogenes 930. However, despite potent in vitro activity, these analogues showed only moderate in vivo activity in mouse protection studies.

Animals↗

PubMed1998

HIV.

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Journal Article↗

PubMed1994

3-(2-(3-Pyridinyl)thiazolidin-4-oyl)indoles, a novel series of platelet activating factor antagonists.

(2RS,4R)-3-(2-(3-Pyridinyl)thiazolidin-4-oyl)indoles represent a new class of potent, orally active antagonists of platelet activating factor (PAF). The compounds were prepared by acylation of the magnesium or zinc salts of substituted indoles with (2RS,4R)-2-(3-pyridinyl)-3-(tert-butoxycarbonyl)thiazolidin-4-oyl chloride. The 3-acylindole moiety functions as a hydrolytically stabilized and conformationally restricted anilide replacement, which imparts a considerable boost in potency to the series. Structure-activity relationships observed for substitution on the indole ring system are discussed. Members of the series compare favorably with other reported PAF antagonists.

Administration, Oral↗

PubMed1993

Potent in vitro and in vivo inhibitors of platelet aggregation based upon the Arg-Gly-Asp-Phe sequence of fibrinogen. A proposal on the nature of the binding interaction between the Arg-guanidine of RGDX mimetics and the platelet GP IIb-IIIa receptor.

Peptide mimetics of the RGDF sequence in which Arg-Gly has been replaced with 5-(4-amidinophenyl)pentanoyl mimetic has led to a 1000-fold increase in inhibitory potency over the natural RGDF ligand. The guanidine residue of the arginine may be involved in a reinforced ionic interaction with a carboxylate of the receptor which could explain the dramatic increase in potency upon replacement with benzamidine. This hypothesis is supported by the observation of low inhibitory potency of the corresponding benzylamine (18) and no activity with the corresponding imidazoline derivative (19); plus, ab initio calculations on the respective complexes suggest that the benzamidine-carboxylate is more favorable than the guanidine-carboxylate interaction. The ED50 for the inhibition of ex vivo collagen induced platelet aggregation in the dog for SC-52012 (1) was 0.32 microgram/kg/min by iv infusion with a pharmacodynamic half-life for recovery of approximately 40 min.

Amino Acid Sequence↗