Synthesis, stability, biochemical and pharmacokinetic properties of a new potent and selective 4-oxo-β-lactam inhibitor of human leukocyte elastase

Figures & data

Figure 1.  Structures of elastase inhibitors 1-4.

Scheme 1.  Synthesis of 4-oxo-β-lactam 5.

Figure 2.  Progress curves for the slow-binding inhibition of HLE by 4-oxo-β-lactam 3. Reaction conditions: [HLE] = 20 nM, [MeOSuc-Ala-Ala-Pro-Val-p-NA] = 1 mM, 0.1 M HEPES buffer, pH 7.2, 25 °C. [3]: (a) 0; (b) 6.25; (c) 12.5; (d) 25; (e) 50; (f) 100 nM.

Scheme 2.  Kinetic model for acyl-enzyme inhibition of HLE by 4-oxo-β-lactam 3 in the presence of substrate.

Table 1.  Summary of enzyme inhibition at 25°C and stability kinetic data at 37°C, for 4-oxo-β-lactam 3.

HLE			Proteinase 3	Cathepsin G	PBS pH 7.4	Human plasma
Ki/nM	koff/s^−1	kon/M^−1s^−1	kon/M^−1s^−1	kon/M^−1s^−1	t1/2/h	t1/2/h
0.63 ± 0.09	9.22 × 10^−4	1.46 × 10^6	4.99 × 10^3	41.4	1.04 ± 0.25	0.11 ± 0.03

Figure 3.  A) Effect of inhibitor concentration on the onset of inhibition of HLE by 4-oxo-β-lactam 3. The values of k_obs were obtained as an average of at least duplicate assays from fits to Equation 1 of the data shown in Figure 2; B) Plot of the steady-state rates, v_s, versus [3] for the inhibition of HLE. The data were obtained from fits of the curves shown in Figure 2. The solid line was drawn using the best-fit parameters from a fit according to Equation 5.

Scheme 3.  Hydrolysis of 4-oxo-β-lactam 3 in pH 7.4 buffer and 80% human plasma.

Figure 4.  Mean ± sd pharmacokinetic profile in A) total mice blood, B) mice spleen and C) mice lung, after administration of a ip 30 mg/kg dosage of 4-oxo-β-lactam 3.

Chua F, Laurent GJ. Neutrophil elastase: mediator of extracellular matrix destruction and accumulation. Proc Am Thorac Soc 2006;3:424–427.

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