Naoko Nishimura

Polyamine-promoted autoactivation of plasma hyaluronan-binding protein

See also Kanse SM, Etscheid M. Factor VII activating protease (FSAP): caught in the cross‐fire between polycations and polyanions. This issue, pp 556–8.

SMTP-7, a novel small-molecule thrombolytic for ischemic stroke: a study in rodents and primates

SMTP-7 (Stachybotrys microspora triprenyl phenol-7), a small molecule that promotes plasminogen activation through the modulation of plasminogen conformation, has excellent therapeutic activity against cerebral infarction in several rodent models. Detailed evaluations of SMTP-7 in a primate stroke model are needed for effective, safe drug development. Here we evaluated SMTP-7 in a monkey photochemical-induced thrombotic middle cerebral artery (MCA) occlusion model (n=6), in which MCA occlusion was followed by recanalization/reocclusion. SMTP-7 (10 mg/kg, intravenous infusion) significantly increased the postinfusion MCA recanalization rate (32.5-fold, P=0.043) and ameliorated the post-24-h neurologic deficit (by 29%, P=0.02), cerebral infarct (by 46%, P=0.033), and cerebral hemorrhage (by 51%, P=0.013) compared with the vehicle control animals. In normal monkeys, SMTP-7 did not affect general physiologic or hemostatic variables, including coagulation and platelet parameters. Investigations in rodent models of transient and permanent focal cerebral ischemia, as well as arterial thrombosis and bleeding tests, suggest a role for SMTP-7s regulated profibrinolytic action and neuroprotective properties in the monkey MCA occlusion model. In conclusion, SMTP-7 is effective in treating thrombotic stroke in monkeys. SMTP-7 is thus a promising candidate for the development of alternative therapy for ischemic stroke.

SMTP (Stachybotrys microspora triprenyl phenol) enhances clot clearance in a pulmonary embolism model in rats

BackgroundStachybotrys microspora triprenyl phenols (SMTPs) are a novel family of small molecules that enhance both activation and fibrin-binding of plasminogen. While their effects on fibrinolysis have been characterized in vitro, little is known about their activity in vivo with respect to plasminogen activation and blood clot clearance.ResultsTo select a potent SMTP congener for the evaluation of its action in vitro and in vivo, we tested several SMTP congeners with distinct structural properties for their effects on plasminogen activation. As a result, SMTP-7 (orniplabin) was found to have distinguished activity. Several lines of biochemical evidence supported the idea that SMTP-7 acted as a plasminogen modulator. SMTP-7 elevated plasma level of plasmin-α2-antiplasmin complex, an index of plasmin formation in vivo, 1.5-fold in mice after the intravenous injections at doses of 5 and 10 mg kg-1. In a rat pulmonary embolism model, SMTP-7 (5 mg kg-1) enhanced the rate of clot clearance ~3-fold in the absence of exogenous plasminogen activator. Clot clearance was enhanced further by 5 mg kg-1 of SMTP-7 in combination with single-chain urokinase-type plasminogen activator.ConclusionsOur results show that SMTP-7 is a superior plasminogen modulator among the SMTP family compounds and suggest that the agent enhances plasmin generation in vivo, leading to clearance of thrombi in a model of pulmonary embolism.

A new series of the SMTP plasminogen modulator with a phenylglycine-based side chain

SMTPs are a family of small-molecule plasminogen modulators that enhance plasminogen activation. SMTP-7, one of the most potent congeners, is effective in treating thrombotic cerebral infarction. The SMTP molecule consists of a tricyclic γ-lactam moiety, a geranylmethyl group, and an N-linked side chain. The presence of both an aromatic group and a negatively ionizable group in the N-linked side chain is crucial for activity. Investigations of the congeners with a phenylglycine-based side chain suggest that a phenolic hydroxy group affects potency. In this study, we isolate and characterize a series of novel SMTP congeners with a phenylamine-based N-linked side chain. Of the 11 congeners isolated, SMTP-19 (with a 4-phenylcarboxylic acid moiety), SMTP-22 (with a 3-hydroxyphenyl-4-carboxylic acid moiety) and SMTP-25 (with a 2-hydroxyphenyl-3-carboxylic acid moiety) are as potent as SMTP-7 in plasminogen-modulating activity. Their isomers with a carboxylic acid group and/or a phenolic hydroxy group at different positions have <40% of the activity of these congeners. Both SMTP-22 and SMTP-25 have >1.7 times more oxygen radical absorbance capacity as compared with SMTP-7.

Structure-activity relationships of 11 new congeners of the SMTP plasminogen modulator

The fungal metabolite Stachybotrys microspora triprenyl phenols (SMTPs) are small-molecule plasminogen modulators that enhance plasminogen activation. The SMTP molecule consists of a tricyclic γ-lactam moiety, an isoprene side-chain and an N-linked side-chain. Previous investigations have demonstrated that the N-linked side-chain is crucial for its activity. In this study, we have isolated 11 new SMTP congeners with a variety of N-linked side-chain structures, to investigate structure–activity relationships. Active compounds included congeners with a carboxyl or a sulfonic acid group in the N-linked side-chain, whereas not all the congeners with a carboxyl group were active. Of these congeners, that with methionine or tyrosine as the N-linked side-chain moiety was more active than that with an aliphatic amino acid. Congeners without ionizable group in the N-linked side-chain were essentially inactive.

Pre-SMTP, a key precursor for the biosynthesis of the SMTP plasminogen modulators

SMTPs are triprenyl phenol metabolites obtained from the fungus Stachybotrys microspora.1 SMTP enhances the activation of plasminogen by modulating its conformation.1–4 SMTP-7, one of the most potent congeners, is effective in enhancing blood clot clearance and treating thrombotic stroke.4–8 The SMTP molecule consists of a tricyclic g-lactam moiety, a geranylmethyl group and an N-linked side chain. Our previous studies identified 30 SMTP congeners, which differ in the N-linked side chain.9–16 Plasminogen modulator activities of the congeners differ depending on the N-linked side-chain structure.15,16 These congeners can be produced by a precursor amine-fed culture.17 In this method, some metabolites existing in the culture are consumed following the amine feeding, with a concomitant formation of an SMTP congener, which has the fed amine as the N-linked side chain. Thus, the presence of a key precursor for the biosynthesis of SMTPs is suggested. In this study, we isolated a compound, designated pre-SMTP (1), which directly affords SMTP congeners by reacting nonenzymatically with amines. In the precursor amine-fed culture, S. microspora is grown in medium containing limited amounts of amine compounds before amine feeding. During this ‘‘starvation phase’’, significant amounts of possible precursors are accumulated. We purified two of the candidates, compounds 1 and 2 (Figure 1a), by solvent extraction

Inhibition of Plasma Hyaluronan-Binding Protein Autoactivation by Laccaic Acid

Plasma hyaluronan-binding protein (PHBP) is a serine protease implicated in proteolysis under inflammatory conditions. We identified laccaic acid, a widely used food coloring from scale insects, as a potent inhibitor of the protease in terms of both autoactivation of the PHBP proenzyme (IC50 = 0.35–0.55 μg/ml) and the catalytic activity of the active enzyme (IC50 = 1.1 μg/ml).