Inhibition Of Plasmin Activity Research Articles

Exploration of Novel Plasmin Inhibitor from β-Lactoglobulin for Enhancing the Storage Stability of UHT Milk.

Plasmin-induced protein hydrolysis significantly compromises the stability of ultrahigh-temperature (UHT) milk. β-Lactoglobulin (β-Lg) was observed to inhibit plasmin activity, suggesting that there were active sites as plasmin inhibitors in β-Lg. Herein, plasmin inhibitory peptides were explored from β-Lg using experimental and computational techniques. The results revealed that increased denaturation of β-Lg enhanced its affinity for plasmin, leading to a stronger inhibition of plasmin activity. Molecular dynamics simulations indicated that electrostatic and van der Waals forces were the primary binding forces in the β-Lg/plasmin complex. Denatured β-Lg increased hydrogen bonding and reduced the binding energy with plasmin. The sites of plasmin bound to β-Lg were His624, Asp667, and Ser762. Four plasmin inhibitory peptides, QTMKGLDI, EKTKIPAV, TDYKKYLL, and CLVRTPEV, were identified from β-Lg based on binding sites. These peptides effectively inhibited plasmin activity and enhanced the UHT milk stability. This study provided new insights into the development of novel plasmin inhibitors to improve the stability of UHT milk.

Study of vascular sclerosing agent based on the dual mechanism of vascular endothelial cell damage-plasmin system inhibition

Venous malformations are a vascular disorder. Currently, the use of chemical sclerosing agents is a common clinical approach for the treatment of venous malformations. However, the effectiveness of existing sclerosing agents is unsatisfactory and often accompanied by severe side effects. In this study, we have developed a novel cationic surfactant-based sclerosing agent (POL-TA) by conjugating the plasmin inhibitor tranexamic acid (TA) with a nonionic surfactant polidocanol (POL) through an ester bond. POL-TA induces endothelial cell damage, triggering the coagulation cascade and thrombus formation. Moreover, it releases TA in vivo, which inhibits plasmin activity and the activation of matrix metalloproteinase (MMPs), thereby stabilizing the fibrin network of the thrombus and promoting vascular fibrosis. We have established a cell model using venous malformation endothelial cells and assessed the cellular damage and underlying mechanisms of POL-TA. The inhibitory effects of POL-TA on the plasmin-MMPs system were evaluated using MMP-9 activity assay kit. Additionally, the mice tail vein model was employed to investigate the vascular sclerosing effects and mechanisms of POL-TA.

Phytochemical investigation of aerial parts of Woodsia ilvensis and its plasmin-inhibitory activity in vitro

The fern plant Woodsia ilvensis (L.) R. Br. belongs to the Woodsiaceae family and its leaves are used to treat diarrhea, soft-tissue injuries, and external injuries. Investigations of the compounds obtained from the plasmin-inhibitory-active extracts of W. ilvensis led to the isolation of two undescribed maleimide N-glycosides, an undescribed stilbenoid glycoside, and five undescribed acetylated flavonol bisdesmosides, together with 19 known compounds. The chemical structures of the isolated compounds were determined using spectroscopy. The absolute configurations of the sugar moieties were determined via HPLC after acid hydrolysis. Among the isolated compounds, some flavonoids and stilbenoid glycosides exhibited plasmin-inhibitory activity.

Tissue factor pathway inhibitor 2: Current understanding, challenges, and future perspectives.

Tissue factor pathway inhibitor 2 (TFPI2) is a structural homolog of tissue factor pathway inhibitor 1 (TFPI1). Since TFPI2 is a placenta-derived protein, dynamic changes in TFPI2 levels may be related to pregnancy-related diseases. Furthermore, TFPI2 has been reported to be a novel serum biomarker for detecting ovarian cancer, especially clear cell carcinoma (CCC). This review aims to summarize the current knowledge on the biological function of TFPI2, highlight the major challenges that remain to be addressed, and discuss future research directions. Papers published up to March 31, 2023 in the PubMed and Google Scholar databases were included in this review. We also provide novel complementary information to what is known about the action of TFPI2. Since TFPI2 concentrations in the blood of pregnant women, preeclampsia patients, and cancer patients vary greatly, its pathophysiological functions have attracted attention. Downregulation of TFPI2, a tumor-suppressor gene, by hypermethylation may contribute to the progression of several cancers. On the other hand, TFPI2 overexpressed in CCC is a risk factor for the development of thrombosis, possibly through inhibition of plasmin activity. However, agreement on the biological function of TFPI2 is still lacking and there are many scientific questions to be addressed. In particular, the lack of international standardization for the quantification of TFPI2 concentrations makes it difficult for researchers and clinicians to evaluate, pool, and compare data from different studies across countries. This review summarizes current understandings and challenges in TFPI2 research and discusses future perspectives.

Aprotinin – Conjugated biocompatible porous nanocomposite for dentine remineralization and biofilm degradation

A nanocomposite (141 nm and +12.46 mV surface charge at pH 2.4) that could provide a single treatment for S. mutans-associated dental carries has been developed. The composite had six components, viz., aprotinin (Apr) that enzymatically inhibits plasmin activity of the bacterium, chitosan (Chi) that inhibits bacterial cell adhesion and biofilm formation, calcium phosphate (CaP) for remineralization of dentine, dexamethasone (DEX) for odontoblast differentiation, collagen (Cen) for crosslinking, and chlorogenic acid (CGA) for bacterial cell death. The structure of nanocomposite (HR SEM) consisted of interconnected pores and was amorphous post incorporation of chitosan. A sustained release of calcium and phosphate ions, lasting from 1 to 20 days at pH 4, an appropriate pH to combat demineralization, was observed, which is essential for remineralization. A 68.79% biofilm degradation was observed after 24 h of treatment, indicating good inhibition of the bacteria. While S. mutans grew well on denture resin specimen, the adhesion was reduced when the specimen was treated with the nanocomposite, indicating deterrence to biofilm formation. 5 Day hemolysis assay revealed red blood cell compatibility of up to 100 μg/25 μL, indicating that the nanocomposite was compatible with RBC. Against L132 cells, cytotoxicity was not observed up to 40 μg/mL for 72 h, a clear indication of non-cytotoxic character of the nanocomposite. CaP(NP)@Chi@CGA@DEX@Cen@Apr nanocomposite thus helps remineralization at cariogenic pH and biofilm degradation of S. mutans.

Plasminogen and plasmin can bind to human T cells and generate truncated CCL21 that increases dendritic cell chemotactic responses

Plasmin is a broad-spectrum protease and therefore needs to be tightly regulated. Active plasmin is formed from plasminogen, which is found in high concentrations in the blood and is converted by the plasminogen activators. In the circulation, high levels of α2-antiplasmin rapidly and efficiently inhibit plasmin activity. Certain myeloid immune cells have been shown to bind plasmin and plasminogen on their cell surface via proteins that bind to the plasmin(ogen) kringle domains. Our earlier work showed that T cells can activate plasmin but that they do not themselves express plasminogen. Here, we demonstrate that T cells express several known plasminogen receptors and that they bind plasminogen on their cell surface. We show T cell–bound plasminogen was converted to plasmin by plasminogen activators upon T cell activation. To examine functional consequences of plasmin generation by activated T cells, we investigated its effect on the chemokine, C-C motif chemokine ligand 21 (CCL21). Video microscopy and Western blotting confirmed that plasmin bound by human T cells cleaves CCL21 and increases the chemotactic response of monocyte-derived dendritic cells toward higher CCL21 concentrations along the concentration gradient by increasing their directional migration and track straightness. These results demonstrate how migrating T cells and potentially other activated immune cells may co-opt a powerful proteolytic system from the plasma toward immune processes in the peripheral tissues, where α2-antiplasmin is more likely to be absent. We propose that plasminogen bound to migrating immune cells may strongly modulate chemokine responses in peripheral tissues.

Screening bioactive compounds from Danggui-shaoyao-san for treating sodium retention in nephrotic syndrome using bio-affinity ultrafiltration

Ethnopharmacological relevanceDanggui-shaoyao-san (DSS), a representative formula of Traditional Chinese Medicine (TCM) for promoting blood circulation and diuresis (Huo-Xue-Li-Shui) therapy, has been used to clinically nephrotic syndrome (NS) and relieve nephrotic edema. Aim of the studyTo explore the effects and mechanisms of DSS in improving sodium retention and to identify the bioactive compounds from DSS. Materials and methodsDSS prescriptions were disassembled into Yangxue-Huoxue (YXHX) and Jianpi-Lishui (JPLS). A nephrotic rat model was induced with puromycin aminonucleoside (PAN), and the effects on urinary sodium excretion, urinary plasmin(gen) content, and plasmin activity of DSS, YXHX, and JPLS extracts were assessed. The inhibitory effects on urokinase-type plasminogen activator (uPA) and plasmin activity of extracts were evaluated in vitro. Bio-affinity ultrafiltration and high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (BAU-UPLC-Q/TOF-MS) were used to rapidly screen and qualitatively analyze the uPA/plasmin affinity compounds from DSS extract. Additionally, uPA/plasmin inhibition assays and molecular docking were used to verify the activity and affinity mechanisms of the potential bioactive compounds. ResultsIn vivo, DSS, YXHX, and JPLS prevented sodium retention in nephrotic rats. DSS and YXHX treatment decreased urinary plasmin activity but did not alter urinary plasmin(ogen) concentration, and their extracts showed strong uPA and plasmin inhibitory activity in vitro. These results suggested that uPA and plasmin are direct targets of DSS and YXHX in intervening NS sodium retention. Using BAU-UPLC-Q/TOF-MS, gallic acids, methyl gallate, albiflorin, and 1,2,3,4,6-O-pentagalloylglucose (PGG) were screened as uPA or plasmin affinity compounds. Among them, PGG was found to be a uPA and plasmin dual inhibitor, with an IC50 of 6.861 μM against uPA and an IC50 of 149.0 μM against plasmin. The molecular docking results of PGG with uPA and plasmin were consistent with the verification results. ConclusionIntervening in sodium retention by inhibiting uPA-mediated plasmin generation and plasmin activity in the kidneys could be possible mechanisms for DSS, as indicated by the results in PAN-induced nephrotic rats. We conclude that PGG is a potential bioactive compound responsible for the effect of DSS on natriuresis.

New and Off-Label Uses of Tranexamic Acid.

New and Off-Label Uses of Tranexamic Acid.

Inhibition of early plasmin activation following thermal injury attenuates systemic inflammatory markers and inflammation within injured muscle

Introduction Burn injuries drive systemic inflammation, increasing the risk of organ dysfunction, and impeding the repair of injured tissues. Traumatic injuries provoke excess activation of plasmin, the protease responsible for degrading fibrin clots, causing bleeding complications. Although burn injuries rarely carry bleeding risks, excess plasmin activity can drive inflammatory signaling and vascular permeability, suggesting plasmin contributes to burn-induced inflammation. Therefore, we hypothesized that excess plasmin activation provoked by burn injury exacerbates inflammation at the site of tissue injury and systemically. Methods A validated, murine burn model in combination with muscle injury was employed to assess the study hypothesis. Sham animals received only calf muscle injuries. Mice expressing an NF-κB-inducible luciferase reporter were used to quantify inflammatory signaling by bioluminescence in tissues. To inhibit plasmin activity, mice received plasminogen antisense oligonucleotide (Plg ASO, IONIS Pharmaceuticals) before injury, or antifibrinolytic drug tranexamic acid (TXA) administered for 12 hours post-burn. Controls received control (Ctl) ASO or saline. Plasmin activation was measured by circulating complexes of plasmin and its inhibitor α2-antiplasmin (PAP). Inflammation was measured serially by plasma interleukin-6 (IL-6), neutrophil to lymphocyte ratio (NLR), and NF-κB activity in the injured muscle. Results Burn injury resulted in a 3-5 fold increase in plasmin activity measured by PAP(P<0.05) compared with sham animals and provoked a significant increase in plasma IL-6(P<0.005) and NLR(P<0.05) within 6-12 hours post-injury, at levels consistent with transient systemic inflammation. In mice without burns, muscle injury alone provoked NF-κB activity from 1-3 days post-injury with resolution by 5 days. With the addition of the burn injury, NF-κB activity within the injured calf muscle was significantly elevated between 1-3 days post-injury (P<0.01) and prolonged in the injured muscle (Figure 1). When plasmin was reduced with Plg ASO and TXA treatments, plasma IL-6 and NLR levels were reduced within 24 hours post-burn (P<0.05), and NF-κB activity within muscle was significantly reduced between 1-3 days post-burn (P<0.05)(Figure 1). Conclusion Burns provoke systemic and augment local inflammation in a muscle injury remote to the burn site. Inhibition of early plasmin activation after burn reduces systemic inflammatory markers and local inflammation within injured tissues. Significance Burn injuries incite significant global inflammation, increasing the risk of life-threatening complications, and chronic comorbidities. Because plasma drives inflammation after acute injury, it may be a therapeutic target to reduce tissue inflammation. However, plasmin is essential for fibrinolysis and tissue repair, and the beneficial effects of inhibiting plasmin following burn are likely time-dependent.

Binding characteristics of polyphenols as milk plasmin inhibitors.

The potential use of polyphenols to improve the functional characteristics of dairy products has gained much attention. However, the effects of the polyphenols on naturally occurring enzymes in milk have not been studied extensively. Excess plasmin activity in dairy products might result in several quality defects. The objective of this study was to assess the ability of polyphenols to inhibit plasmin in milk using a molecular and kinetic approach. Epicatechin gallate (ECG), epigallocatechin gallate (EGCG), quercetin (QUER), and myricetin (MYR) caused a significant decrease in plasmin activity by 60, 86, 65, and 90%, respectively. The inhibition rates were alleviated in the presence of milk proteins. EGCG, QUER, and MYR, exhibited noncompetitive inhibition against plasmin, whereas ECG caused a mixed-type inhibition. A decrease in the random structure of plasmin upon the complex formation with ECG, EGCG, QUER, and MYR was found. The other phenolics that were evaluated did not cause any significant changes in plasmin conformation. The observed inhibitory phenolic-plasmin interactions were dominated by H-bonds and electrostatic attractions. Green tea extract (GTE) rich in catechins also inhibited plasmin activity in the milk. Significant changes in the secondary structure of plasmin upon binding of ECG, EGCG, QUER, and MYR led to diminished plasmin activity both in the absence and presence of milk proteins. These flavonoids with promising plasmin inhibitory potential could be used in new dairy formulations leading to controlled undesired consequences of plasmin activity. © 2019 Society of Chemical Industry.

Glaucoma is associated with plasmin proteolytic activation mediated through oxidative inactivation of neuroserpin

Neuroserpin is a serine protease inhibitor that regulates the activity of plasmin and its activators in the neuronal tissues. This study provides novel evidence of regulatory effect of the neuroserpin on plasmin proteolytic activity in the retina in glaucoma. Human retinal and vitreous tissues from control and glaucoma subjects as well as retinas from experimental glaucoma rats were analysed to establish changes in plasmin and neuroserpin activity. Neuroserpin undergoes oxidative inactivation in glaucoma which leads to augmentation of plasmin activity. Neuroserpin contains several methionine residues in addition to a conserved reactive site methionine and our study revealed enhanced oxidation of Met residues in the serpin under glaucoma conditions. Met oxidation was associated with loss of neuroserpin inhibitory activity and similar findings were observed in the retinas of superoxide dismutase (SOD) mutant mice that have increased oxidative stress. Treatment of purified neuroserpin with H2O2 further established that Met oxidation inversely correlated with its plasmin inhibitory activity. Dysregulation of the plasmin proteolytic system associated with increased degradation of the extracellular matrix (ECM) proteins in the retina. Collectively, these findings delineate a novel molecular basis of plasmin activation in glaucoma and potentially for other neuronal disorders with implications in disease associated ECM remodelling.

TSG-6- a double-edged sword for osteoarthritis

TSG-6- a double-edged sword for osteoarthritis

Novel Plasminogen Activator Inhibitor-1 Inhibitors Prevent Diabetic Kidney Injury in a Mouse Model

Diabetic nephropathy is the leading cause of end-stage renal disease worldwide, but no effective therapeutic strategy is available. Because plasminogen activator inhibitor-1 (PAI-1) is increasingly recognized as a key factor in extracellular matrix (ECM) accumulation in diabetic nephropathy, this study examined the renoprotective effects of TM5275 and TM5441, two novel orally active PAI-1 inhibitors that do not trigger bleeding episodes, in streptozotocin (STZ)-induced diabetic mice. TM5275 (50 mg/kg) and TM5441 (10 mg/kg) were administered orally for 16 weeks to STZ-induced diabetic and age-matched control mice. Relative to the control mice, the diabetic mice showed significantly increased (p < 0.05) plasma glucose and creatinine levels, urinary albumin excretion, kidney-to-bodyweight ratios, glomerular volume, and fractional mesangial area. Markers of fibrosis and inflammation along with PAI-1 were also upregulated in the kidney of diabetic mice, and treatment with TM5275 and TM5441 effectively inhibited albuminuria, mesangial expansion, ECM accumulation, and macrophage infiltration in diabetic kidneys. Furthermore, in mouse proximal tubular epithelial (mProx24) cells, both TM5275 and TM5441 effectively inhibited PAI-1-induced mRNA expression of fibrosis and inflammation markers and also reversed PAI-1-induced inhibition of plasmin activity, which confirmed the efficacy of the TM compounds as PAI-1 inhibitors. These data suggest that TM compounds could be used to prevent diabetic kidney injury.

ChemInform Abstract: Natural and Engineered Plasmin Inhibitors: Applications and Design Strategies

AbstractReview: 246 refs.

Thrombomodulin enhances the antifibrinolytic and antileukemic effects of all–trans retinoic acid in acute promyelocytic leukemia cells

This study found that levels of thrombomodulin (TM) were downregulated in freshly isolated leukemia cells from patients with acute promyelocytic leukemia (APL, n = 7) and acute myelogenous leukemia (n = 14), as compared with CD34(+)/CD38(-) hematopoietic stem/progenitor cells and CD34(-)/CD33(+)/CD11b(-) promyelocytes isolated from healthy volunteers (n = 3). Exposure of APL NB4 cells to recombinant human soluble TM (rTM, 1500 ng/mL) inhibited clonogenic growth of these cells by approximately 30%, and induced expression of CD11b, a marker of myeloid differentiation, on their surfaces, in association with upregulation of nuclear levels of myeloid-specific transcription factor CCAAT/enhancer binding protein ε. These antileukemic effects of rTM were mediated by thrombin/activated protein C-dependent mechanisms, as hirudin, an inhibitor of thrombin and a blocking antibody against endothelial receptor for protein C to which activated protein C binds, hampered the ability of rTM to induce expression of CD11b in NB4 cells. This study also found that rTM downregulated expression of Annexin II, a receptor for both plasminogen and tissue plasminogen activator, and inhibited plasmin activity in APL cells. Interestingly, rTM significantly enhanced the ability of all-trans retinoic acid to induce growth arrest, differentiation and apoptosis, and inhibited plasmin activity in APL cells. Taken together, these results suggest that administration of rTM should be considered for treatment of individuals with disseminated intravascular coagulation associated with APL.

Natural and Engineered Plasmin Inhibitors: Applications and Design Strategies

The serine protease plasmin is ubiquitously expressed throughout the human body in the form of the zymogen plasminogen. Conversion to active plasmin occurs through enzymatic cleavage by plasminogen activators. The plasminogen activator/plasmin system has a well-established function in the removal of intravascular fibrin deposition through fibrinolysis and the inhibition of plasmin activity; this has found widespread clinical use in reducing perioperative bleeding. Increasing evidence also suggests diverse, although currently less defined, roles for plasmin in a number of physiological and pathological processes relating to extracellular matrix degradation, cell migration and tissue remodelling. In particular, dysregulation of plasmin has been linked to cancer invasion/metastasis and various chronic inflammatory conditions; this has prompted efforts to develop inhibitors of this protease. Although a number of plasmin inhibitors exist, they commonly suffer from poor potency and/or specificity of inhibition that either results in reduced efficacy or prevents clinical use. Consequently, there is a need for further development of high-affinity plasmin inhibitors that maintain selectivity over other serine proteases. This review summarises clearly defined and potential applications for plasmin inhibition. The properties of naturally occurring and engineered plasmin inhibitors are discussed in the context of current knowledge regarding plasmin structure, specificity and function. This includes design strategies to obtain the potency and specificity of inhibition in addition to controlled temporal and spatial distribution tailored for the intended use.

Paracrine SLPI secretion upregulates MMP-9 transcription and secretion in ovarian cancer cells

Objectives Secretory leukocyte protease inhibitor (SLPI) is amplified in serous ovarian cancer. We have dissected its function, showing it is a survival factor for ovarian cancer and promotes tumorigenesis and paclitaxel-resistance. We hypothesized that the protease inhibitory function was responsible for modulating SLPI's invasive capacity. Methods Stable HEYA8 ovarian cancer transfectants expressing vector, wild type SLPI, and protease inhibitor null (F-)SLPI were examined in vitro and in xenografts. Invasion, enzyme activity, and MMP production and function assays were applied. SLPI and MMP immunoexpression was graded on tissue microarray and clinical samples. Statistical comparisons used unpaired t test and ANOVA, where appropriate. Results SLPI and F-SLPI cells caused greater parenchymal and peritoneal dissemination over control cells in xenografts and invasion assays (p < 0.001). MMP-9 protease activity was increased in SLPI and F-SLPI cells over control. SLPI, but not F-SLPI, inhibited plasmin activity, necessary for MMP-9 activation and release, and inhibited activation of MMP-9. However, paradoxically, both induced quantitative MMP-9 transcription (p < 0.05) and protein (p < 0.008), yielding an increased net MMP-9 activity in the face of plasmin inhibition. SLPI and MMP-9 expression were strongly correlated in serous ovarian cancers (r 2 = 0.986) and a set of ovarian cancers (p < 0.02). SLPI expression was greater in serous than endometrioid ovarian cancers (p = 0.04). Conclusions SLPI stimulates ovarian cancer invasion, modulated in part by its serine protease inhibitory activity attenuating MMP-9 release. However, SLPI induction of MMP-9, independent of protease inhibition activity, is greater yielding a net pro-invasive behavior. These findings further support SLPI as a molecular target for ovarian cancer.

Continuous Localized Monitoring of Plasmin Activity Identifies Differential and Regional Effects of the Serine Protease Inhibitor Aprotinin: Relevance to Antifibrinolytic Therapy

Antifibrinolytic therapy, such as the use of the serine protease inhibitor aprotinin, was a mainstay for hemostasis after cardiac surgery. However, aprotinin was empirically dosed, and although the pharmacological target was the inhibition of plasmin activity (PLact), this was never monitored, off-target effects occurred, and led to withdrawn from clinical use. The present study developed a validated fluorogenic microdialysis method to continuously measure PLact and tested the hypothesis that standardized clinical empirical aprotinin dosing would impart differential and regional effects on PLact. Pigs (30 kg) were instrumented with microdialysis probes to continuously measure PLact in myocardial, kidney, and skeletal muscle compartments (deltoid) and then randomized to high-dose aprotinin administration (2 mKIU load/0.5 mKIU/hr infusion; n = 7), low-dose aprotinin administration (1 mKIU load/0.250 mKIU/hr infusion; n = 6). PLact was compared with time-matched vehicle (n = 4), and PLact was also measured in plasma by an in vitro fluorogenic method. Aprotinin suppressed PLact in the myocardium and kidney at both high and low doses, indicative that both doses exceeded a minimal concentration necessary for PLact inhibition. However, differential effects of aprotinin on PLact were observed in the skeletal muscle, indicative of different compartmentalization of aprotinin. Using a large animal model and a continuous method to monitor regional PLact, these unique results demonstrated that an empirical aprotinin dosing protocol causes maximal and rapid suppression in the myocardium and kidney and in turn would likely increase the probability of off-target effects and adverse events. Furthermore, this proof of principle study demonstrated that continuous monitoring of determinants of fibrinolysis might provide a novel approach for managing fibrinolytic therapy.

ChemInform Abstract: Aeruginosins, Protease Inhibitors from the Cyanobacterium Microcystis aeruginosa.

Abstract Five new protease inhibitors, related to aeruginosins 298-A (5), 98-A (1) and 98-B (2), were isolated from the cyanobacterium Microcystis aeruginosa. Aeruginosins 98-C (3) and 101 (4) differed from 1 in the Hpla unit. Aeruginosin 298-B (6) lacked the argininol unit in 5. Aeruginosins 89-A (7) and 89-B (8) were observed as the tautomers in HPLC because of the presence of the argininal units. Structures 3, 4 and 6–8 were determined on the basis of spectral data and chromatographic analyses of degradation products. The absolute stereochemistry of 1–8 was deduced by a combination of spectral and chemical studies. Aeruginosins 98-A to 98-C, 101, 298-A, 298-B, 89-A and 89-B were isolated from the cyanobacterium Microcystis aeruginosa. These compounds except aeruginosin 298-B had trypsin, plasmin and thrombin inhibitory activities. Their structures were determined on the basis of spectral data and amino acid analysis. Their absolute stereochemistries were deduced by a combination of spectral and chemical studies.

Temporally and Regionally Disparate Differences in Plasmin Activity by Tranexamic Acid

A major complication associated with cardiac surgery is excessive and prolonged bleeding in the perioperative period. Improving coagulation by inhibiting fibrinolysis, primarily through inhibition of plasmin activity (PLact) with antifibrinolytics such as tranexamic acid (TXA), has been a pharmacological mainstay in cardiac surgical patients. Despite its almost ubiquitous use, the temporal and regional modulation of PLact profiles by TXA remains unexplored. Accordingly, we developed a fluorogenic-microdialysis system to measure in vivo dynamic changes in PLact after TXA administration in a large animal model. Pigs (25-35 kg) were randomly assigned to receive TXA (30 mg/kg, diluted into 50 mL normal saline; n = 9) or vehicle (50 mL normal saline; n = 7). Microdialysis probes were placed in the liver, myocardium, kidney, and quadriceps muscle compartments. The microdialysate infusion contained a validated plasmin-specific fluorogenic peptide. The fluorescence emission (standard fluorogenic units [SFU]) of the interstitial fluid collected from the microdialysis probes, which directly reflects PLact, was determined at steady-state baseline and 30, 60, 90, and 120 min after TXA/vehicle infusion. Plasma PLact was determined at the same time points using the same fluorogenic substrate approach. TXA reduced plasma PLact at 30 min after infusion by >110 SFU compared with vehicle values (P < 0.05). Specifically, there was a decrease in liver PLact at 90 and 120 min after TXA infusion of >150 SFU (P < 0.05) and 175 SFU (P < 0.05), respectively. The decrease in liver PLact occurred 60 min after the maximal decrease in plasma PLact. In contrast, kidney, heart, and quadriceps PLact transiently increased followed by an overall decrease at 120 min. Using a large animal model and in vivo microdialysis measurements of PLact, the unique findings from this study were 2-fold. First, TXA induced temporally distinct PLact profiles within the plasma and selected interstitial compartments. Second, TXA caused region-specific changes in PLact profiles. These temporal and regional differences in the effects of TXA may have important therapeutic considerations when managing fibrinolysis in the perioperative period.