Inhibition of serine proteases by benzoxazinones: effects of electron withdrawal and 5-substitution

13C nuclear magnetic resonance and reactivity of 4H-3,1-benzoxazin-4-ones

“…There are no significant correlations between these pKi and the 13c chemical shifts in multiple regression, though limited data sets show a clear correspondence between C4 electrophilicity and pKi (1,4). Clearly other factors in enzyme acylation and deacylation, such as specific steric or hydrophobic interactions and hydrogen bonding that are not reflected in 13C spectra, mask any simple correlations with chemical shift.…”

“…Heteronuclear shift correlation spectra were obtained using the pulse sequence: delay+n/2(lH)+ t l / 2 + n ( 1 3~) + t 1 / 2 + A I + n / 2 ( ' H ) , n/2(I3C) + A2 + acquisition Compounds 1-4 and 8-21 have been previously reported (4,12), as have compounds 7 and 23' (13,14). Compounds 5, 6, and 22 were prepared by Marshall's procedure (13 Alkaline hydrolysis rate constants were measured at 25°C by the disappearance of the long wavelength uv chromophore (A,,,,, typically 300-345 nm) (4)(5)(6). Human leukocyte elastase (HLE) was obtained and its inhibition assayed as previously described (4)(5)(6).…”

“…Compounds 5, 6, and 22 were prepared by Marshall's procedure (13 Alkaline hydrolysis rate constants were measured at 25°C by the disappearance of the long wavelength uv chromophore (A,,,,, typically 300-345 nm) (4)(5)(6). Human leukocyte elastase (HLE) was obtained and its inhibition assayed as previously described (4)(5)(6).…”

“…4H-3,l-Benzoxazin-4-ones are potent inhibitors of serine proteases (1)(2)(3)(4)(5)(6) with clinical potential in a number of degradative diseases (7). It is well established that benzoxazinones inhibit by acting as alternate substrates, acylating the target protease via attack of serine 195 at C4, and then slowly deacylating (2-6) (Scheme I).…”

Direct thrombin inhibitors – a survey of recent developments

“…However, inhibitor 37 exibited significantly diminished cardiovascular side effects and had an improved profile with respect to therapeutic index [172]. The inhibitory activity of 2-substituted benzoxazinones toward serine proteases has been known for more than two decades [174][175][176], and structural information on inhibitor-protease complexes is available [177]. Recently, two papers described the thrombin inhibitory activity of a new synthetic benzoxazinone-derivative, HPW-RX2 38 [178,179].…”