J a u m l of Medicinal Chemistry 0 Copyright 1987 by the American Chemical Society
April 1987
Volume 30, Number 4
Communications to the Editor Design of Alternate Substrate Inhibitors of Serine Proteases. Synergistic Use of Alkyl Substitution To Impede Enzyme-Catalyzed Deac ylation’
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There is considerable interest in the design of stable small molecule inhibitors of serine proteases and in devising tactics to enhance the specificity and potency of such reagents. A particular challenge is to design specific inhibitors of high potency without resorting to peptide functionality as a means of delivering covalent labels to the target enzyme active site.2 4H-3,1-Benzoxazin-4-one (1) represents an attractive lead structure for accomplishing this taskM provided that electron-donating groups are present at Czto counter the lability of the oxazinone ring to nu~leophiles.~
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Recently, 2-aminobenzoxazinone 2 (R = H, R5 = H) has been reported to be rapidly isomerized to the 2,4(lH,3H)-quinazolinedione4 by ~hymotrypsin.~ Apparently, deacylation to regenerate free enzyme with concomitant formation of 4 occurs via cyclization of the acyl enzyme 3 and is considerably faster than the “normal” enzyme-catalyzed hydrolysis observed for 2-oxa and 2carba benzoxa~inones.~ We have observed similar results with 2 (R = H, R5 = H) and human leukocyte elastase (HLE),an enzyme of potential clinical interest?^^ We now Contribution No. 253 from the Institute of Bioorganic Chemistry. Ringrose, P. S. Biochem. SOC.Trans. 1983,11, 804-808. Alazard, R.; BBchet, J.-J.; Dupaix, A.; Yon, J. Biochim. Biop h p . Acta 1973,309, 379-396. Teshima, T.; Griffin, J. C.; Powers, J. C. J. Biol. Chem. 1982, 257,5085-5091. Hedstrom, L.; Moorman, A. R.; Dobbs, J.; Abeles, R. H. Biochemistry 1984, 23, 1753-1759. Spencer, R. W.; Copp, L. J.; Bonaventura, B.; Tam,T. F.; Liak, T. J.; Billedeau, R.; Krantz, A. Biochem. Biophys. Res. Commun. 1986, 140, 928-933. Alkaline hydrolysis serves as a measure of lability. For example, a potent 2-carba benzoxazinone (1, R = C3F,) has kOH-= 1900 M-’ 8’ (25 “C, aqueous)! A 2-(alkylamino)benzoxazinone with comparable Ki (2-n-butylamino) has kOH-= 12 M-’ s-’. Schnebli, H. P. In Handbook of Inflammation; Bonta, I. L.; Bray, M. A.; Parnham, M. J., Eds.; Elsevier: New York, 1985; Vol. 5, pp 321-333. 0022-2623/87/1830-0589$01.50/0
report that the lifetime of acyl elastases derived from benzoxazinones can be enormously increased by using tactics that are intended to obstruct deacylation pathways.
Experimental Section 2-(Alkylamino)-4H-3,l-benzoxazin-4-ones were prepared by HL elastase was obtained from human leukocyte^^^^^-^^ and assayed by the progress curve m e t h ~ d ~ * ~ ~ J ’ as follows. HL elastase (20 pL of 0.3 gM) and a fluorogenic substrate (5 p L of 1 mM 7-(methoxysuccinylalanylalanylprolylvalinamido)-4-(trifluoromethyl)coumarin(Enzyme Systems published
Powers, J. C.; Harper, J. W.; Hemmi, K.; Yasutake, A.; Hori, H. 3rd SCZ-RSC Med. Chem. Symp., 1985 1986, 241-256. Papodopoulos, E. P.; Torres, C. D. J.Heterocycl. Chem. 1982, 19, 269-272. Papodopoulos, E. P.; Petridou-Fischer, J. J. Heterocycl. Chem. 1982,19,123-126. Papodopoulos, E. P. J. Heterocycl. Chem. 1980, 17, 1553; 1981, 18, 515-518. Butula, I.; Vela, V.; Zorc, B. Croatia Chemica Acta 1981, 54, 105-108. Lempert, K.; Doleschall, G. Tetrahedron Lett. 1963, 781-784; 1963, 1195-1199. Sayigh, A. A. R.; Haven, N.; Ulrich, H. US. Patent 3450700, Upjohn Co. Karl, D. H.; Wolfgang, G. German Patent 2315303; Chem. Abstr. 1975, 82, 16851g. Hamprecht, G.; Weierzer, B. German Patent 2 914 915. Copp, L. J.; Krantz, A.; Spencer, R. W. Biochemistry 1987,26, 169-178. Englebrecht, S.; Pieper, E.; Macartney, H. W.; Rautenberg, W.; Wenzel, H. R.; Tschesche, H. 2. Phys. Chem. 1982, 363, 305-315. Barrett, A. J. Methods Enzymol. 1981, SOC, 581-588. Daniels, S. B.; Cooney, E.; Sofia, M. J.; Chakravarty, P. K.; Katzenellenbogen, J. A. J. Biol. Chem. 1983, 258, 1504615053. 0 1987 American Chemical Society
590 Journal of Medicinal Chemistry, 1987, Vol. 30, No.4 Table I. HL Elastase Inhibition by Benzoxazinones 2 R Rs K ; , UM k , , M-' 8-l k , , " 8-l % 4b H H 63 81OC 0.051' 91 f 1 Me =0.47 2100d Et 5.1
