Trapping of 1,8-biradical intermediates by molecular oxygen in photocycloaddition of naphthyl-N-(naphthylcarbonyl)carboxamides; formation of novel 1,8-epidioxides and evidence of stepwise aromatic cycloaddition.

The photocycloaddition reaction of naphthyl-N-(naphthylcarbonyl)carboxamides (1) was examined under argon and oxygen atmospheres. In addition to the [2 + 2] and [4 + 4] cycloadducts, 3 and 4, respectively, novel 1,8-epidioxides (5) were formed under oxygen atmosphere. The transient absorption at lambda max of 360 nm with the lifetime of 360 ns was observed by laser flash photolysis of 1c and was interpreted as the absorption of biradical intermediate 2. On the basis of the anti stereochemistry of 5, which was different from that of the major [4 + 4] cycloadducts, syn-4, it was deduced that equilibrium between biradical intermediates syn-2 and anti-2 would exist. Retro [2 + 2] cycloaddition of 3 was responsible for the efficient trapping of the biradical intermediate with molecular oxygen. The photocycloaddition of the anthryl derivatives, 9-anthryl-N-(methylethyl)-N-(naphthylcarbonyl)carboxamides (7), afforded the [4 + 4] cycloadducts (8) exclusively in a quantitative yield even under oxygen atmosphere. The absence of trapping with molecular oxygen was interpreted to be due to the lack of retro [4 + 4] cycloaddition of 8.

Enantioselective intramolecular aromatic [4 + 4] photocycloaddition in crystalline state: parameters for reactivity.

Photoreactivity of seven 9-anthryl-N-(naphthylcarbonyl)carboxamide derivatives, 1a-g, in their intramolecular [4 + 4] photocycloadditions in solid state is discussed on the basis of their single-crystal X-ray analyses. The distances (d(1) and d(2)) between the two carbon atoms to be reacted, the angles (theta(1) and theta(2)), and the torsion angle (theta(3)) between the anthracene and naphthalene rings were chosen as structural parameters for reactivity. For 1a and 1e, the first example of absolute asymmetric synthesis in [4 + 4] photocycloaddition was attained. [reaction: see text]

Triggering of the vascular permeability reaction by activation of the Hageman factor-prekallikrein system by house dust mite proteinase.

A 30-kilodalton (kDa) proteinase from the house dust mite Dermatophagoides farinae (Df-proteinase) was recently purified (Takahashi et al. (1990) Int. Arch. Allergy Appl. Immunol. 91, 80-85). In this paper we detailed the biological activities of the Df-proteinase. The activation of the kinin cascade by Df-proteinase was examined in vitro by using purified guinea pig Hageman factor (HF), prekallikrein (PK) and high-molecular-weight kininogen (HMWK) and the effect of this proteinase on endogenous human plasma proteinase inhibitors (serpins) and alpha 2-macroglobulin was tested. In addition, enhancement of the vascular permeability reaction in guinea pig skin by Df-proteinase was examined in vivo. These experiments showed that Df-proteinase could activate all the steps of the kinin-generating cascade, i.e., HF, PK and HMWK, and that Df-proteinase retained proteolytic activity even in the presence of an excess amount of endogenous proteinase inhibitors in plasma. We also found that the marked enhancement of the vascular permeability reaction was induced by Df-proteinase via the activation of the kinin-generating cascade without the release of histamine. From these results, we conclude that the proteinase of the house dust mite, Df-proteinase, has the potential to generate bradykinin and that the presence of this proteinase in biological systems would exacerbate inflammatory reactions in some pathological conditions.

Activation of kallikrein-kinin system in human plasma with purified serine protease from Dermatophagoides farinae.

An aqueous extract from a mite culture, of Dermatophagoides farinae, activated prekallikrein to kallikrein in normal plasma. Crude protein preparation, obtained by ammonium sulfate precipitation (95% saturation) from the extract, exhibited high activity (0.81 units/mg protein) towards a synthetic substrate of coagulation factor XIIa, Boc-Gln-Gly-Arg-MCA, and had also activity to form kallikrein in human plasma deficient in coagulation factor XII. Treatment of the protein preparation with phenylmethylsulfonyl fluoride (PMSF), an inhibitor of serine enzyme, gave rise to inactivation of both activities. Thus, the serine protease specific for Boc-Gln-Gly-Arg-MCA in mite cultures of D. farinae was purified by ammonium sulfate precipitation and chromatographies on p-aminobenzamidine-sepharose CL-4B, DEAE-Toyopearl 650M, Sephadex G-75 superfine and Sephacryl S-200. The purified protease was homogeneous electrophoretically, and its molecular weight was estimated to be 30,000. The optimum pH and temperature were around 7.5 and 50 degrees C, respectively. The specific activity was 36 units/mg protein at pH 7.4 and 37 degrees C. The activity was completely inhibited by PMSF. The serine protease had the activity to activate the kallikrein-kinin system in normal human plasma.