: A fluorescent substance was isolated from the cyanobacterium with a yield of 4.5 mg per 10 g of dried Spirulina (Arthrospira) platensis cells by gentle extraction and ethanol fractionation followed by column chromatography. The fluorescent substance, which has absorption maxima at 256 nm and 362 nm (pH 8.4), was identified as biopterin-alpha-glucoside by spectrophotometry and nuclear magnetic resonance spectroscopy. Biopterin-alpha-glucoside prevented decolorization of the photosynthetic pigments, chlorophyll a, phycocyanin, and carotenoids in photosynthetic vesicles of Spirulina platensis cells, by ultraviolet irradiation.

It was reported that Df-protease from house dust mite (Dermatophagoides farinae) catalyzes the activation of the kallikrein-kinin system in human plasma and is closely associated with mite-induced allergy. Therefore, to prevent the release of kinin by Df-protease, the inhibitory activity of polyphenols including catechins and flavonols was tested in vitro and in vivo. Among them, myricetin and epigallocatechin gallate (EGCg) effectively inhibited the amidase activity of Df-protease with K(i) values of 1 x 10(-)(8) and 6 x 10(-)(4) M, respectively. The kinin release in human plasma was extensively inhibited by the addition of EGCg in comparison with myricetin. Enhancement of vascular permeability in guinea pigs caused by Df-protease was markedly suppressed by EGCg.

An aminopeptidase, Jc-peptidase, was purified from Japanese cedar pollen by seven steps, including precipitation with ammonium sulfate, ion-exchange chromatography, gel filtration, hydrophobic interaction chromatography on phenyl-agarose, and high-performance liquid chromatography. Purified Jc-peptidease has a molecular weight of 42 kDa and hydrolyzes the synthetic substrates of L-phenylalanyl-4-methylcoumaryl-7-amide (Phe-MCA) with Km = 5 x 10(-5) M, Tyr-MCA with Km = 7 x 10(-4) M, Leu-MCA with Km = 1 x 10(-3) M, and Met-MCA with Km = 1 x 10(-3) M. Other MCA analogues such as Arg-MCA or Glu-MCA failed to serve as its substrates. The activity was inhibited in the presence of phebestin, [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-valyl]-L-phenylalanine, with Ki = 4.7 x 10(-5) M, or bestatin, [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine, with Ki = 1.1 x 10(-4) M. According to amino acid sequence analysis, the N-terminal amino group seems to be blocked. The physiological function of the aminopeptidase (Jc-peptidase) has not been clarified in vivo.

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A protease (Df-protease) from house dust mites (Dermatophagoidesfarinae), which is closely related to mite-induced allergic diseases, catalyzes the activation of kallikrein-kinin system in plasma (3, 6, 12). Df-protease was competitively inhibited by guanidine and amidine derivatives with low-molecular weight. The kinetic study revealed that the Ki values of 1-[p-(p-amidinophenoxycarbonyl)benzoyl]-D-proline benzyl ester acetate and N-[p-(2-methoxycarbonyl-4-amidinophenoxycarbonyl)benzoyl]-N-phenylglycine ethyl ester acetate were 5 >< 10-9 M and 6>< 10-9 M, respectively.The allergic diseases derived from house dust are induced by two types of mite, Dermatophagoides farinae (Df) and Dermatophagoides pteronyssimzs (Dp) (9, 13), in which cysteine and serine proteases are reported as allergens (2, 11). It was demonstrated that these proteases are closely associated with mite-related allergic diseases (2). Takahashi er al.(12) isolated a serine protease, Df-protease, from Df with a similar substrate specificity to that of blood coagulation factor XIIa. Df-protease catalyzed the activation of the kallikrein-kinin system. The protease gave rise to rhythmic contraction of rat uterine horns in factor XIIa-deficient human plasma (3) and enhancement of blood permeability in guinea pigs (5, 6). Df-protease liberated kinins from kininogens with low-and high-molecular weights (4) and a kinin induced allergic rhinitis, bronchial asthma and rhinovirus-caused cold (1, 10).We previously found that Df-protease is inhibited by p-amionobenzamidine (an amidine derivative) or gabexate mesylate (a guanidine derivative) (6, 12). In the present paper, we further studied the inhibitory effect of a wide range of synthetic guanidine or amidine derivatives with low molecular weights, to explore effective therapeutic agents for mite-induced allergic diseases.A synthetic substrate of blood coagulation factor XIIa, t-butyloxycarbonyl-L-glutaminylglycyl-