Staplabin, a novel fungal triprenyl phenol which stimulates the binding of plasminogen to fibrin and U937 cells

A Novel Marine Pyran-Isoindolone Compound Enhances Fibrin Lysis Mediated by Single-Chain Urokinase-Type Plasminogen Activator

Fungi fibrinolytic compound 1 (FGFC1) is a rare pyran-isoindolone derivative with fibrinolytic activity. The aim of this study was to further determine the effect of FGFC1 on fibrin clots lysis in vitro. We constructed a fibrinolytic system containing single-chain urokinase-type plasminogen activator (scu-PA) and plasminogen to measure the fibrinolytic activity of FGFC1 using the chromogenic substrate method. After FITC-fibrin was incubated with increasing concentrations of FGFC1, the changes in the fluorescence intensity and D-dimer in the lysate were measured using a fluorescence microplate reader. The fibrin clot structure induced by FGFC1 was observed and analyzed using a scanning electron microscope and laser confocal microscope. We found that the chromogenic reaction rate of the mixture system increased from (15.9 ± 1.51) × 10−3 min−1 in the control group to (29.7 ± 1.25) × 10−3 min−1 for 12.8 μM FGFC1(p < 0.01). FGFC1 also significantly increased the fluorescence intensity and d-dimer concentration in FITC fibrin lysate. Image analysis showed that FGFC1 significantly reduced the fiber density and increased the fiber diameter and the distance between protofibrils. These results show that FGFC1 can effectively promote fibrin lysis in vitro and may represent a novel candidate agent for thrombolytic therapy.

Progress in Isoindolone Alkaloid Derivatives from Marine Microorganism: Pharmacology, Preparation, and Mechanism

Compound 1 (SMTP-7, also FGFC1), an isoindolone alkaloid from marine fungi Starchbotrys longispora FG216 and fungi Stachybotrys microspora IFO 30018, possessed diverse bioactivities such as thrombolysis, anti-inflammatory and anti-oxidative properties, and so on. It may be widely used for the treatment of various diseases, including cerebral infarction, stroke, ischemia/reperfusion damage, acute kidney injury, etc. Especially in cerebral infarction, compound 1 could reduce hemorrhagic transformation along with thrombolytic therapy, as the traditional therapies are accompanied with bleeding risks. In the latest studies, compound 1 selectively inhibited the growth of NSCLC cells with EGFR mutation, thus demonstrating its excellent anti-cancer activity. Herein, we summarized pharmacological activities, preparation of staplabin congeners—especially compound 1—and the mechanism of compound 1, with potential therapeutic applications.

Impact of SMTP Targeting Plasminogen and Soluble Epoxide Hydrolase on Thrombolysis, Inflammation, and Ischemic Stroke

Stachybotrys microspora triprenyl phenol (SMTP) is a large family of small molecules derived from the fungus S. microspora. SMTP acts as a zymogen modulator (specifically, plasminogen modulator) that alters plasminogen conformation to enhance its binding to fibrin and subsequent fibrinolysis. Certain SMTP congeners exert anti-inflammatory effects by targeting soluble epoxide hydrolase. SMTP congeners with both plasminogen modulation activity and anti-inflammatory activity ameliorate various aspects of ischemic stroke in rodents and primates. A remarkable feature of SMTP efficacy is the suppression of hemorrhagic transformation, which is exacerbated by conventional thrombolytic treatments. No drug with such properties has been developed yet, and SMTP would be the first to promote thrombolysis but suppress disease-associated bleeding. On the basis of these findings, one SMTP congener is under clinical study and development. This review summarizes the discovery, mechanism of action, pharmacological activities, and development of SMTP.

1-Isoindolinone scaffold-based natural products with a promising diverse bioactivity

Isoindolin-1-one or 1-isoindolinone framework is referred to phthalimidines or benzo fused γ-lactams of the corresponding γ-amino carboxylic acids and has been of prime interest for scientists for last several decades. 1-Isoindolinone framework is found in a wide range of naturally occurring compounds with diverse biological activities and therapeutic potential for various chronic diseases. Recent developments in synthetic methods for their procurement have opened a new era of 1-isoindolinone chemistry. This review aims to provide an alphabetical quick reference guide to only 1-isoindolinone based natural products and its variable fused, oxidized and reduced state skeleton with information for advanced chemotaxonomic analyses, cellular targets/pathways and diverse biological activities and future use for medicinal chemistry.

New Bisabosquals from Stachybotrys sp. PH30583 Elicited on Solid Media

Stachybotrys sp. PH30583 cultured in liquid medium only led to one structure type of novel isochroman dimers. Using the one strain-many compounds strategy, the reinvestigation of the metabolites from Stachybotrys sp. PH30583 cultured in rice solid medium led to the isolation of four triprenyl phenols, including two new bisabosquals and two known phenylspirodrimanes. Nitrobisabosquals A and B (1 and 2) are the first case of pyrrolidone-bisabosquals reported in literature. Totally different compounds were isolated using rice solid medium, compared with those isolated using liquid medium, so that rice solid medium presents a key factor in the production of triprenyl phenols. Compound 1 exhibited cytotoxicity against tumor cells, A-549, HL-60, MCF-7 SMMC-7721, and SW480, as well as weak anticoagulant activity with activated partial thromboplastin time (APTT) of 32.1 ± 0.17 s (p < 0.05 vs. Con.) at a concentration of 5 mM. Triprenyl phenol metabolites could be used as chemotaxonomic markers for Stachybotrys.

Confirmation of the absolute configuration of Stachybotrin C using single-crystal X-ray diffraction analysis of its 4-bromobenzyl ether derivative

The absolute configuration of Stachybotrin C was confirmed in this study. After synthesizing the dimethyl ethers of Stachybotrin C, the C-8 epimer was analyzed by 1D NOESY. However, the stereochemistry determination was difficult through the NOE correlations. Instead, the di(4-bromobenzyl) ether of Stachybotrin C was derived and used for X-ray diffraction analysis, because its single crystal was easier to obtain than that of the original Stachybotrin C. The stereochemistry of Stachybotrin C was determined to be (8S, 9R). This derivatization approach may also be used to prepare single crystals of the analogues.

Producing Novel Fibrinolytic Isoindolinone Derivatives in Marine Fungus Stachybotrys longispora FG216 by the Rational Supply of Amino Compounds According to Its Biosynthesis Pathway

Many fungi in the Stachybotrys genus can produce various isoindolinone derivatives. These compounds are formed by a spontaneous reaction between a phthalic aldehyde precursor and an ammonium ion or amino compounds. In this study, we suggested the isoindolinone biosynthetic gene cluster in Stachybotrys by genome mining based on three reported core genes. Remarkably, there is an additional nitrate reductase (NR) gene copy in the proposed cluster. NR is the rate-limiting enzyme of nitrate reduction. Accordingly, this cluster was speculated to play a role in the balance of ammonium ion concentration in Stachybotrys. Ammonium ions can be replaced by different amino compounds to create structural diversity in the biosynthetic process of isoindolinone. We tested a rational supply of amino compounds ((±)-3-amino-2-piperidinone, glycine, and l-threonine) in the culture of an isoindolinone high-producing marine fungus, Stachybotrys longispora FG216. As a result, we obtained four new kinds of isoindolinone derivatives (FGFC4–GFC7) by this method. Furthermore, high yields of FGFC4–FGFC7 confirmed the outstanding production capacity of FG216. Among the four new isoindolinone derivatives, FGFC6 and FGFC7 showed promising fibrinolytic activities. The knowledge of biosynthesis pathways may be an important attribute for the discovery of novel bioactive marine natural products.

Terphenyl derivatives and drimane - Phathalide/isoindolinones from Hypoxylon fendleri BCC32408

The genus Hypoxylon, a member of the family Xylariaceae, has been known to produce significant secondary metabolites in terms of chemical diversity. Moreover, the compounds isolated can also be used as chemotaxonomic characters for differentiation among the two sections, which are sect. Annulata and sect. Hypoxylon. In our continuing chemical screening programme for novel compounds, the crude extracts of H. fendleri BCC32408 gave significant chemical profiles in HPLC analyses. Thus, the chemical investigation of these crude extracts was then carried out. The investigation led to the isolation of ten previously undescribed compounds including three terphenylquinones (fendleryls A - C), one terphenyl (fendleryl D), and six novel drimane - phthalide-type lactone/isoindolinones derivatives (fendlerinines A - F) along with seven known compounds (2-O-methylatromentin, rickenyl E, atromentin, rickenyls C - D, (+)-ramulosin, and O-hydroxyphenyl acetic acid). The chemical structures were determined on the basis of spectroscopic analyses, including 1D, 2D NMR and high-resolution mass spectrometry, as well as chemical transformations. In addition, these isolated compounds were assessed for antimicrobial activity including antimalarial (against Plasmodium falciparum, K-1 strain), antifungal (against Candida albicans), antibacterial (against Bacillus cereus) activities. Cytotoxicity against both cancerous (KB, MCF-7, NCI-H187) and non-cancerous (Vero) cells of these compounds were also evaluated.

Isoindolone-Containing Meroperpenoids from the Endophytic Fungus Emericella nidulans HDN12-249

Six isoindolone containing meroterpenoids, emericellolides A-C (1-3) and emeriphenolicins E-G (4-6), were isolated from a plant endophytic fungus Emericella nidulans HDN12-249. Emericellolides A-C (1-3) feature the unprecedented macrolide skeleton composed of an unusual l-glutamate fragment, an isoindolone unit, and a sesquiterpene moiety, while structures of emeriphenolicins E-G (4-6) with two farnesyl groups attached to one isoindolone unit are rare in isoindolone-derived meroterpenoids. These structures including the absolute configurations were established on the basis of MS, NMR, Mo2(AcO)4-induced ECD, Marfey's method, and chemical conversion. Compound 4 exhibited cytotoxicity against HeLa cells with IC50 value of 4.77 μM.

Structure-activity relationships of the plasminogen modulator SMTP with respect to the inhibition of soluble epoxide hydrolase

A family of fungal metabolites, SMTP, is a small-molecule plasminogen modulator that enhances plasminogen activation, leading to thrombolysis. We recently demonstrated that SMTP-7 effectively treats ischemic stroke due to its thrombolytic activity as well as anti-inflammatory action, which is attributable to soluble epoxide hydrolase (sEH) inhibition. In this paper, we studied detailed structure-activity relationships of plasminogen modulation and sEH inhibition using 25 SMTP congeners including six newly synthesized ones. The results clearly demonstrate that the structure of the N-linked side chain of SMTP congeners markedly affect their activities toward plasminogen modulation and inhibitions of the two activities of sEH (C-terminal epoxide hydrolase and N-terminal phosphatase). A slight change in the N-linked side chain results in affording selectivity of SMTP congeners. Many congeners, which lacked plasminogen modulation activity, differently inhibited the two sEH activities depending on the structures of the N-linked side chain. Some congeners were active in plasminogen modulation and inhibition of both activities of sEH. These results help comprehensive understanding of ideal design of a drug useful for ischemic diseases that are associated with inflammation, such as stroke.

Effects of a novel marine natural product: pyrano indolone alkaloid fibrinolytic compound on thrombolysis and hemorrhagic activities in vitro and in vivo

Fungi fibrinolytic compound 1 (FGFC1) is a novel marine natural product as a low-weight fibrinolytic pyranoindole molecule, whose thrombolytic effects were evaluated on FITC-fibrin (Fluorescein isothiocyanate, FITC) degradation methods in vitro and on acute pulmonary thromboembolism animal model in vivo. We determined the FGFC1 induced thrombolysis that stems from its fibrin(ogen)olytic activities as measured by fibrin(ogen) degradation products (FDPs) experiment, acute pulmonary thromboembolism animal model experiment, and euglobulin lysis assay. In vitro, measurement of FITC-fibrin degradation revealed that fibrin hydrolysis occurred in a concentration-dependent manner of FGFC1 from 5 to 25 μ mol/L. In vivo test of a classical acute pulmonary thromboembolism model in rat showed that when the injected dose was 5 mg/kg or above, FGFC1 was effective in dissolution of extrinsic FITC-fibrin induced blood clots. Euglobulin lysis time (ELT) in FGFC1-treated rats was shortened 30 s compared with rats in the positive control group, which were injected with clopidogrel sulfate and single-chain urokinase-type plasminogen activator. As compared to the control, FGFC1 (5-25 mg/kg) did not significantly alter the formation of fibrinogen and FDPs in vivo. Our research indicates that FGFC1 presents pharmacodynamic action in both the thrombolysis and the hemolytic procedure, which can be characterized by fibrinogenolysis in blood and FDPs in plasma. In vivo, increasing fibrinolytic doses of FGFC1 from 5 to 25 mg/kg did not induce fibrinogenolysis when compared with control group, this result corresponds to that FGFC1 did not induce the increasing of FDPs (compared with the saline-treated control). It indicates that the FGFC1 may act as a novel thrombolytic agent and represent an effective approach to the treatment of thrombus without significant risk of hemorrhagic activity.

Fungal natural products in research and development

To date approximately 100 000 fungal species are known although far more than one million are expected. The variety of species and the diversity of their habitats, some of them less exploited, allow the conclusion that fungi continue to be a rich source of new metabolites. Besides the conventional fungal isolates, an increasing interest in endophytic and in marine-derived fungi has been noticed. In addition new screening strategies based on innovative chemical, biological, and genetic approaches have led to novel fungal metabolites in recent years. The present review focuses on new fungal natural products published from 2009 to 2013 highlighting the originality of the structures and their biological potential. Furthermore synthetic products based on fungal metabolites as well as new developments in the uses or the biological activity of known compounds or new derivatives are discussed.

The chemistry of isoindole natural products

This review highlights the chemical and biological aspects of natural products containing an oxidized or reduced isoindole skeleton. This motif is found in its intact or modified form in indolocarbazoles, macrocyclic polyketides (cytochalasan alkaloids), the aporhoeadane alkaloids, meroterpenoids from Stachybotrys species and anthraquinone-type alkaloids. Concerning their biological activity, molecular structure and synthesis, we have limited this review to the most inspiring examples. Within different congeners, we have selected a few members and discussed the synthetic routes in more detail. The putative biosynthetic pathways of the presented isoindole alkaloids are described as well.

A new series of the SMTP plasminogen modulators with a phenylamine-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.

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

Background

Stachybotrys 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.

Results

To 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.

Conclusions

Our 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.

Stachybotrys microspora triprenyl phenol-7, a novel fibrinolytic agent, suppresses superoxide production, matrix metalloproteinase-9 expression, and thereby attenuates ischemia/reperfusion injury in rat brain

Stachybotrys microspora triprenyl phenol-7 (SMTP-7) is a novel fibrinolytic agent with anti-inflammatory effect. Previous study demonstrated that SMTP-7 further ameliorated infarction volume in a mouse embolic stroke model compared with tissue type plasminogen activator (tPA), but the reason SMTP-7 has more beneficial effect than tPA has not yet been determined. In the present study, we investigated whether SMTP-7 has an intrinsic neuroprotective effect against transient focal cerebral ischemia (tFCI). Sprague-Dawley rats were subjected to tFCI by intraluminal middle cerebral artery occlusion for 2h. Following induction of tFCI, rats were randomized into two groups based on the agent administered: SMTP-7 group and vehicle group. We examined cerebral infarction volume 24h after reperfusion, and evaluated superoxide production, the expressions of nitrotyrosine and matrix metalloproteinase-9 (MMP-9), which play major roles in secondary brain injury and hemorrhagic transformation. The findings showed that SMTP-7 significantly suppressed superoxide production, the expression of nitrotyrosine and MMP-9 after tFCI, and consequently attenuated ischemic neuronal damage. These results suggest that SMTP-7 has an intrinsic neuroprotective effect on ischemia/reperfusion injury through the suppression of oxidative stress and MMP-9 activation.

Antiviral isoindolone derivatives from an endophytic fungus Emericella sp. associated with Aegiceras corniculatum

Chemical investigation of the endophytic fungus Emericella sp. (HK-ZJ) isolated from the mangrove plant Aegiceras corniculatum led to isolation of six isoindolones derivatives termed as emerimidine A and B and emeriphenolicins A and D, and six previously reported compounds named aspernidine A and B, austin, austinol, dehydroaustin, and acetoxydehydroaustin, respectively. Their structures were elucidated on the basis of NMR spectroscopic evidence while the anti-influenza A viral (H₁N₁) activities of eight compounds were also evaluated using the cytopathic effect (CPE) inhibition assay.

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.

Small-molecule modulators of zymogen activation in the fibrinolytic and coagulation systems

The coagulation and fibrinolytic systems are central to the hemostatic mechanism, which works promptly on vascular injury and tissue damage. The rapid response is generated by specific molecular interactions between components in these systems. Thus, the regulation mechanism of the systems is programmed in each component, as exemplified by the elegant processes in zymogen activation. This review describes recently identified small molecules that modulate the activation of zymogens in the fibrinolytic and coagulation systems.

A novel embolic model of cerebral infarction and evaluation of Stachybotrys microspora triprenyl phenol-7 (SMTP-7), a novel fungal triprenyl phenol metabolite

The aim of the present study was to establish a novel embolic model of cerebral infarction and to evaluate the effect of Stachybotrys microspora triprenyl phenol-7 (SMTP-7), a novel fungal triprenyl phenol metabolite. Thrombotic occlusion was induced by transfer of acetic acid-induced embolus into the brain. The regional cerebral blood flow was measured by a laser Doppler flowmeter to check the ischemic condition. Infarction area was assessed by 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining. Neurological scores were determined by a modified version of the method described by Longa et al. Emboli were accumulated at the temporal or parietal region of the middle cerebral artery. Additionally, we found that this model showed decreased cerebral blood flow and increased infarction area and neurological scores. Treatment with tissue plasminogen activator (t-PA) reduced infarction area and the neurological scores in a dose-dependent manner; moreover, the decreased cerebral blood flow recovered. SMTP-7 also reduced these values. The therapeutic time window of SMTP-7 was longer than that of t-PA. These results indicate that this model may be useful for understanding the pathophysiological mechanisms of cerebral infarction and evaluating the effects of therapeutic agents. Additionally, SMTP-7 is a promising approach to extend the therapeutic time window. Therefore, this novel compound may represent a novel approach for the treatment of cerebral infarction.

A novel finding of a low-molecular-weight compound, SMTP-7, having thrombolytic and anti-inflammatory effects in cerebral infarction of mice

Tissue plasminogen activator (t-PA) has a short therapeutic time window for administration (3 h) and carries a risk of promoting intracerebral hemorrhage. The aim of the present study was to investigate a therapeutic time window and frequency of hemorrhagic region by treatment with Stachybotrys microspora triprenyl phenol-7 (SMTP-7). Thrombotic occlusion was induced by transfer of acetic acid-induced thrombus at the right common carotid artery into the brain of mice. Infarction area, neurological score, edema percentage, and regional cerebral blood flow (CBF) were determined as the index of the efficacy of SMTP-7. In order to evaluate the mechanism of SMTP-7, plasmin activities and the expressions of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-6 mRNA were examined. SMTP-7 (0.1, 1, 10 mg/kg) dose dependently reduced infarction area, neurological score, and edema percentage. Additionally, its therapeutic time window was longer than that of t-PA, a high-molecular-weight compound. In addition, little hemorrhagic region was induced by treatment with SMTP-7. SMTP-7 showed plasmin activity in vivo and caused a decreased CBF to recover. Furthermore, the expressions of inflammatory cytokine mRNA (IL-1β, TNF-α, IL-6) were increased by t-PA treatment 3 h after ischemia but were not induced by SMTP-7 treatment. These results indicate that SMTP-7 shows potential thrombolytic and anti-inflammatory effects as well as a wide therapeutic time window and little hemorrhagic region compared with that of t-PA. Therefore, this novel low-molecular-weight compound may represent a novel approach for the treatment of cerebral infarction.

Stachybotrydial selectively enhances fibrin binding and activation of Glu-plasminogen

Stachybotrydial, a triprenyl phenol metabolite from a fungus, has a plasminogen modulator activity selective to Glu-plasminogen. Stachybotrydial enhanced fibrin binding and activation of Glu-plasminogen (2- to 4-fold enhancement at 60-120 microM) but not of Lys-plasminogen. Approximately 1.2-1.6 moles of [3H]stachybotrydial bound to Glu-plasminogen to exert such effects. The selective modulation of the Glu-plasminogen function by stachybotrydial may be related to alteration of its conformational status.

Isolation and absolute configuration of SMTP-0, a simplest congener of the SMTP family nonlysine-analog plasminogen modulators

SMTP-0, a new simple congener of the SMTP nonlysine-analog plasminogen modulators, was isolated from a culture of Stachybotrys microspora. Based on the physico-chemical data, SMTP-0 was shown to be an enantiomer of the antimicrobial compound stachybotrin B. The absolute configuration of SMTP-0 was determined by the modified Mosher method. The stereochemistry was further confirmed using an epimer of SMTP-0. Unlike most SMTPs with an amino acid side chain linked to the nitrogen atom of the lactam moiety, SMTP-0, which lacks the N-linked side chain, showed no plasminogen modulator activity.

Ligneous conjunctivitis: biochemical evidence for hypofibrinolysis

Ligneous conjunctivitis (LC) is a rare disease of unknown etiology characterized by the growth of "woody" plaques on ocular and extraocular mucosa. These lesions are comprised of fibrin and both direct and indirect evidence implicates hypofibrinolysis as the primary defect in LC. To further elucidate the pathophysiology of LC we investigated the biochemical aspects of ligneous lesions with respect to the fibrinolytic system. Ligneous lesions were obtained from the right eye of a 15 year-old female patient with longstanding LC since age 2.5 year. Ligneous conjunctivitis in this patient has exhibited a chronic recurrent coarse and has involved multiple muscosal sites. Samples analyzed included an abundant mucoid thread from the conjunctival fornix and the ligneous plaque attached to the inferior tarsus. Samples were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to characterize protein profiles and by a variety of zymographic methods to visualize fibrinolytic enzymes. We found that mucoid and ligneous samples were distinct entities. Specifically, ligneous samples contained polypeptides with electrophoretic profiles characteristic of intact fibrin, and were replete in fibrin-bound tissue plasminogen activator (t-PA). Despite the presence of ample t-PA, ligneous samples were essentially devoid of fibrinolytic activity. In contrast, neither proteins nor t-PA could be detected in mucoid samples when fractionated by 7.5-15% SDS-PAGE or analyzed by fibrin zymography, respectively. Despite the absence of t-PA, mucoid samples were replete in fibrinolytic activity. This activity was plasminogen independent, heterogenous and inhibited by PMSF. Degradation profiles suggested that this activity represented in part alpha-chymotrypsin, consistent with this patient's treatment regime, as well as plasmin, elastase and an unidentified neutrophil-derived activity. Interestingly, ligneous samples contained both latent and activated forms of matrix metalloproteinase-9 (MMP-9), whereas mucoid samples contained predominantly activated forms of MMP-9. LC is characterized by defective fibrinolysis, despite the presence of ample t-PA and intact fibrin, and by an abundant mucoid thread which binds both endogenous and exogenous enzymes including serine protease(s) and collagenase(s). The implications of these results with respect to a role for exuberant mucus production or abnormal mucins in the development of a relative mucosal-site specific plasmin(ogen) deficiency is discussed.

Enhancement of fibrin binding and activation of plasminogen by staplabin through induction of a conformational change in plasminogen

Staplabin (0.3-0.6 mM), a fungal triprenyl phenol, enhanced 3-fold the plasminogen activator-catalyzed activation of Glu-plasminogen and Lys-plasminogen as well as their binding to fibrin. Staplabin was not stimulatory to the amidolytic activity of plasmin and plasminogen activators. Even in the presence of epsilon-aminocaproic acid (EACA) and fibrinogen fragments, allosteric effectors for Glu-plasminogen, staplabin increased the activation of both forms of plasminogen. In size-exclusion chromatography of Glu-plasminogen and Lys-plasminogen, the molecular elution time, which varies as the conformation of a protein changes, was shortened by staplabin. These results suggest that staplabin causes plasminogens to be more susceptible to activation and fibrin binding by inducing a conformational change that is, at least in part, different from that induced by EACA and fibrinogen fragments.