ABSTRACT
A series of N (alpha)-acyl (alkyl)- and N (alpha)-alkoxycarbonyl-derivatives of L- and D-ornithine were prepared, characterized, and analyzed for their potency toward the bacterial enzyme N (alpha)-acetyl-L-ornithine deacetylase (ArgE). ArgE catalyzes the conversion of N (alpha)-acetyl-L-ornithine to L-ornithine in the fifth step of the biosynthetic pathway for arginine, a necessary step for bacterial growth. Most of the compounds tested provided IC(50) values in the muM range toward ArgE, indicating that they are moderately strong inhibitors. N (alpha)-chloroacetyl-L-ornithine (1g) was the best inhibitor tested toward ArgE providing an IC(50) value of 85 microM while N (alpha)-trifluoroacetyl-L-ornithine (1f), N (alpha)-ethoxycarbonyl-L-ornithine (2b), and N (alpha)-acetyl-D-ornithine (1a) weakly inhibited ArgE activity providing IC(50) values between 200 and 410 microM. Weak inhibitory potency toward Bacillus subtilis-168 for N (alpha)-acetyl-D-ornithine (1a) and N (alpha)-fluoro- (1f), N (alpha)-chloro- (1g), N (alpha)-dichloro- (1h), and N (alpha)-trichloroacetyl-ornithine (1i) was also observed. These data correlate well with the IC(50) values determined for ArgE, suggesting that these compounds might be capable of getting across the cell membrane and that ArgE is likely the bacterial enzymatic target.
Subject(s)
Amidohydrolases/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/chemical synthesis , Escherichia coli Proteins/antagonists & inhibitors , Ornithine/analogs & derivatives , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Bacillus subtilis/drug effects , Chromatography, High Pressure Liquid , Drug Design , Enzyme Inhibitors/pharmacology , Kinetics , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Molecular Structure , Molecular Weight , Ornithine/chemical synthesis , Ornithine/chemistry , Ornithine/pharmacology , Phosgene/analogs & derivatives , Phosgene/chemistry , Polystyrenes/chemistry , Spectrometry, Mass, Electrospray IonizationABSTRACT
Theophylline and enprofylline have been demonstrated to reduce mast cell-mediator release, inhibit polymorphonuclear leukocyte activation, and have been reported to reduce the late bronchial response to antigen. The effects of theophylline and enprofylline on the late cutaneous response (LCR) to compound 48/80 and antigen were studied in 29 patients enrolled in a placebo-controlled, double-blind study of the effect of the xanthines in mild asthma. Skin testing to a common environment allergen and compound 48/80 was performed during a baseline period and in the second phase of the study after stable drug levels were achieved, at least 6 weeks later. During baseline, the mean immediate wheal diameter (IWD) with antigen was 15.7 mm +/- 0.5, resulting in 27/29 LCRs with a mean wheal diameter of 37.1 mm +/- 5.2. The mean IWD with compound 48/80 was 16.1 mm +/- 0.7, resulting in 26/29 LCRs with a mean wheal diameter of 19.6 mm +/- 2.8. Repeat skin testing during treatment revealed no statistically significant changes in the LCR elicited by antigen or 48/80 in any of the treatment groups. There was little correlation between the size of the immediate wheal produced by antigen or 48/80 and the resulting size of the late response (r = 0.174 to 0.519). However, for the same IWD, the resulting late response was smaller with 48/80 than with antigen (p = 0.003). We conclude that (1) theophylline and enprofylline have no effect on the LCR to 48/80 and antigen and (2) for equivalent immediate wheal sizes, the resulting late response is smaller with 48/80 than with antigen.
