Laura de Andrade Moura

Anticoagulation and antiplatelet effects of a dolastane diterpene isolated from the marine brown alga Canistrocarpus cervicornis

Marine brown algae of the family Dictyotaceae are rich sources of monocyclic, bicyclic, and tricyclic diterpenes. These molecules are responsible for a wide range of pharmacological and ecological functions, as antitumor and antiviral. Here, we analyzed the effect of the dolastane diterpene (4R, 9S, 14S)-4α-Acetoxy-9β,14α-dihydroxydolast-1(15),7-diene, isolated from the marine brown alga, Canistrocarpus cervicornis on blood clotting and platelet aggregation. The dolastane diterpene was able to inhibit either plasma or fibrinogen coagulation induced by thrombin as well as delayed coagulation in the recalcification test. The dolastane diterpene impaired, in a concentration-dependent manner platelet aggregation induced by collagen or adenosine diphosphate with no lysis on such cells. Thus, the dolastane diterpene maybe a promising source of natural inhibitors for hemostatic disturbs (clotting and platelet aggregation) leading to the discovery of drugs of potential use as antithrombotic and antiplatelet. In addition, the dolastane diterpene may be used as a molecular model for development of new antithrombotic agents giving new approaches to the management to the treatment of thrombotic disturbs.

Antiplatelet and Anticoagulant Effects of Diterpenes Isolated from the Marine Alga, Dictyota menstrualis

Cardiovascular diseases represent a major cause of disability and death worldwide. Therapeutics are available, but they often have unsatisfactory results and may produce side effects. Alternative treatments based on the use of natural products have been extensively investigated, because of their low toxicity and side effects. Marine organisms are prime candidates for such products, as they are sources of numerous and complex substances with ecological and pharmacological effects. In this work, we investigated, through in vitro experiments, the effects of three diterpenes (pachydictyol A, isopachydictyol A and dichotomanol) from the Brazilian marine alga, Dictyota menstrualis, on platelet aggregation and plasma coagulation. Results showed that dichotomanol inhibited ADP- or collagen-induced aggregation of platelet-rich plasma (PRP), but failed to inhibit washed platelets (WP). In contrast, pachydictyol A and isopachydictyol A failed to inhibit the aggregation of PRP, but inhibited WP aggregation induced by collagen or thrombin. These diterpenes also inhibited coagulation analyzed by the prothrombin time and activated partial thromboplastin time and on commercial fibrinogen. Moreover, diterpenes inhibited the catalytic activity of thrombin. Theoretical studies using the Osiris Property Explorer software showed that diterpenes have low theoretical toxicity profiles and a drug-score similar to commercial anticoagulant drugs. In conclusion, these diterpenes are promising candidates for use in anticoagulant therapy, and this study also highlights the biotechnological potential of oceans and the importance of bioprospecting to develop medicines.

Purification and biochemical characterization of three myotoxins from Bothrops mattogrossensis snake venom with toxicity against Leishmania and tumor cells.

Bothrops mattogrossensis snake is widely distributed throughout eastern South America and is responsible for snakebites in this region. This paper reports the purification and biochemical characterization of three new phospholipases A2 (PLA2s), one of which is presumably an enzymatically active Asp49 and two are very likely enzymatically inactive Lys49 PLA2 homologues. The purification was obtained after two chromatographic steps on ion exchange and reverse phase column. The 2D SDS-PAGE analysis revealed that the proteins have pI values around 10, are each made of a single chain, and have molecular masses near 13 kDa, which was confirmed by MALDI-TOF mass spectrometry. The N-terminal similarity analysis of the sequences showed that the proteins are highly homologous with other Lys49 and Asp49 PLA2s from Bothrops species. The PLA2s isolated were named BmatTX-I (Lys49 PLA2-like), BmatTX-II (Lys49 PLA2-like), and BmatTX-III (Asp49 PLA2). The PLA2s induced cytokine release from mouse neutrophils and showed cytotoxicity towards JURKAT (leukemia T) and SK-BR-3 (breast adenocarcinoma) cell lines and promastigote forms of Leishmania amazonensis. The structural and functional elucidation of snake venoms components may contribute to a better understanding of the mechanism of action of these proteins during envenomation and their potential pharmacological and therapeutic applications.

Coral health rapid assessment in marginal reef sites

Abstract The Brazilian reef fauna shows high levels of endemism, with both the continental coast and oceanic islands considered as unique biogeographic provinces divided in tropical coral reefs (northern and northeast) and subtropical rocky reefs (southern). While assessments and descriptions for the tropical reefs have reported different levels of impact in different regions, the southern ones have not yet been considered. In addition to a baseline assessment of benthic cnidarian cover, we evaluated the condition of the massive coral colonies of Arraial do Cabo, southeastern Brazil. Results indicated Palythoa caribaeorum as the most abundant cnidarian in all sites followed by Millepora alcicornis, octocorals and scleractinian corals. Most Siderastrea stellata colonies assessed had filamentous algae covering a major area of their tissues and roughly one-third of Mussismilia hispida colonies were also covered by algae. Bleaching was detected in less than 5% of colonies of these species. Coral deterioration in the region is historical and includes unreported diseases and bleaching with subsequent algal settlement and succession over colonies. The lack of previous monitoring programmes on benthic organisms makes the discernment of natural and anthropogenic impacts a difficult task. The scenario described here for native corals in Arraial do Cabo requires urgent action with further experimental work on factors that contribute to the demise of the corals.

Evaluation of marine brown algae and sponges from Brazil as anticoagulant and antiplatelet products.

The ischemic disorders, in which platelet aggregation and blood coagulation are involved, represent a major cause of disability and death worldwide. The antithrombotic therapy has unsatisfactory performance and may produce side effects. So, there is a need to seek molecules with antithrombotic properties. Marine organisms produce substances with different well defined ecological functions. Moreover, some of these molecules also exhibit pharmacological properties such as antiviral, anticancer, antiophidic and anticoagulant properties. The aim of this study was to evaluate, through in vitro tests, the effect of two extracts of brown algae and ten marine sponges from Brazil on platelet aggregation and blood coagulation. Our results revealed that most of the extracts were capable of inhibiting platelet aggregation and clotting measured by plasma recalcification tests, prothrombin time, activated partial thromboplastin time, and fibrinogenolytic activity. On the other hand, five of ten species of sponges induced platelet aggregation. Thus, the marine organisms studied here may have molecules with antithrombotic properties, presenting biotechnological potential to antithrombotic therapy. Further chemical investigation should be conducted on the active species to discover useful molecules for the development of new drugs to treat clotting disorders.The ischemic disorders, in which platelet aggregation and blood coagulation are involved, represent a major cause of disability and death worldwide. The antithrombotic therapy has unsatisfactory performance and may produce side effects. So, there is a need to seek molecules with antithrombotic properties. Marine organisms produce substances with different well defined ecological functions. Moreover, some of these molecules also exhibit pharmacological properties such as antiviral, anticancer, antiophidic and anticoagulant properties. The aim of this study was to evaluate, through in vitro tests, the effect of two extracts of brown algae and ten marine sponges from Brazil on platelet aggregation and blood coagulation. Our results revealed that most of the extracts were capable of inhibiting platelet aggregation and clotting measured by plasma recalcification tests, prothrombin time, activated partial thromboplastin time, and fibrinogenolytic activity. On the other hand, five of ten species of sponges induced platelet aggregation. Thus, the marine organisms studied here may have molecules with antithrombotic properties, presenting biotechnological potential to antithrombotic therapy. Further chemical investigation should be conducted on the active species to discover useful molecules for the development of new drugs to treat clotting disorders.

BbrzSP-32, the first serine protease isolated from Bothrops brazili venom: Purification and characterization.

Snake venom toxins are related not only in detention, death and the promotion of initial digestion of prey but also due to their different biochemical, structural and pharmacological effects they can result in new drugs. Among these toxins snake venom serine proteases (SVSPs) should be highlighted because they are responsible for inducing changes in physiological functions such as blood coagulation, fibrinolysis, and platelet aggregation. This article presents the first serine protease (SP) isolated from Bothrops brazili: BbrzSP-32. The new SP showed 36 kDa of relative molecular mass and its absolute mass was confirmed by mass spectrometry as 32,520 Da. It presents 79.48% identity when compared to other SVSPs and was able to degrade the α-chain of fibrinogen, in in vitro models, because of this it is considered a SVTLE-A. It showed dose-dependent activity in the process of degradation of fibrin networks demonstrating greater specificity for this activity when compared to its thrombolytic action. BbrzSP-32 demonstrated proteolytic activity on gelatin and chromogenic substrates for serine proteases and thrombin-like enzymes (S-2288 and S-2238 respectively), besides having coagulant activity on human plasma. After pre-incubation with PMSF and benzamidine the coagulant and proteolytic activities on the S-2288 and S-2238 substrates were reduced. BbrzSP-32 shows stability against pH and temperature variations, demonstrating optimum activity between 30 and 40 °C and in the pH range 7.5 to 8.5. A new SP with potential biotechnological application was isolated.

Antivenom effects of 1,2,3-triazoles against Bothrops jararaca and Lachesis muta snakes.

Snake venoms are complex mixtures of proteins of both enzymes and nonenzymes, which are responsible for producing several biological effects. Human envenomation by snake bites particularly those of the viperid family induces a complex pathophysiological picture characterized by spectacular changes in hemostasis and frequently hemorrhage is also seen. The present work reports the ability of six of a series of 1,2,3-triazole derivatives to inhibit some pharmacological effects caused by the venoms of Bothrops jararaca and Lachesis muta. In vitro assays showed that these compounds were impaired in a concentration-dependent manner, the fibrinogen or plasma clotting, hemolysis, and proteolysis produced by both venoms. Moreover, these compounds inhibited biological effects in vivo as well. Mice treated with these compounds were fully protected from hemorrhagic lesions caused by such venoms. But, only the B. jararaca edema-inducing activity was neutralized by the triazoles. So the inhibitory effect of triazoles derivatives against some in vitro and in vivo biological assays of snake venoms points to promising aspects that may indicate them as molecular models to improve the production of effective antivenom or to complement antivenom neutralization, especially the local pathological effects, which are partially neutralized by antivenoms.

Anti-platelet aggregation activity of two novel acidic Asp49-phospholipases A2 from Bothrops brazili snake venom

Phospholipases A2 (PLA2s) are important enzymes present in snake venoms and are related to a wide spectrum of pharmacological effects, however the toxic potential and therapeutic effects of acidic isoforms have not been fully explored and understood. Due to this, the present study describes the isolation and biochemical characterization of two new acidic Asp49-PLA2s from Bothrops brazili snake venom, named Braziliase-I and Braziliase-II. The venom was fractionated in three chromatographic steps: ion exchange, hydrophobic interaction and reversed phase. The isoelectric point (pI) of the isolated PLA2s was determined by two-dimensional electrophoresis, and 5.2 and 5.3 pIs for Braziliase-I and II were observed, respectively. The molecular mass was determined with values ​​of 13,894 and 13,869Da for Braziliase-I and II, respectively. Amino acid sequence by Edman degradation and mass spectrometry completed 87% and 74% of the sequences, respectively for Braziliase-I and II. Molecular modeling of isolated PLA2s using acid PLA2BthA-I-PLA2 from B. jararacussu template showed high quality. Both acidic PLA2s showed no significant myotoxic activity, however they induced significant oedematogenic activity. Braziliase-I and II (100μg/mL) showed 31.5% and 33.2% of cytotoxicity on Trypanosoma cruzi and 26.2% and 19.2% on Leishmania infantum, respectively. Braziliase-I and II (10μg) inhibited 96.98% and 87.98% of platelet aggregation induced by ADP and 66.94% and 49% induced by collagen, respectively. The acidic PLA2s biochemical and structural characterization can lead to a better understanding of its pharmacological effects and functional roles in snakebites pathophysiology, as well as its possible biotechnological applications as research probes and drug leads.

Synthesis, Anticlotting and Antiplatelet Effects of 1,2,3-Triazoles Derivatives

Cardiovascular diseases, such as thrombosis and stroke, represent the major cause of disability and death worldwide; and dysfunctions in platelet aggregation and blood coagulation processes are involved. The regular antithrombotic drugs have unsatisfactory results and may produce side effects. Therefore, alternative therapies have been extensively investigated. OBJECTIVE The anticoagulant and antiplatelet aggregation potential of a series of six synthetic 1,2,3-triazole derivatives were investigated through in vitro models. METHODS Coagulation tests included the prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) assays, and were performed on a multichannel coagulometer, using human plasma. The platelet aggregation assays were carried out using human platelet-rich-plasma (PRP). Aggregation was initiated by adding ADP or collagen and monitored turbidimetrically on a Whole Blood Aggregometer. Toxicity of derivatives was evaluated on platelets and red blood cells, by measuring the release of lactate dehydrogenase and hemoglobin, respectively. Moreover, theoretical toxicity of derivatives was calculated using the software Osiris® Property Explorer. RESULTS All the six derivatives tested inhibited, but with different potencies, the plasma coagulation assessed by the PT and TT assays, and also inhibited platelet aggregation of PRP induced by collagen or ADP. The derivatives did not interfere in the aPTT assay and did not affect the viability of platelets or red blood cells. Theoretical studies also revealed that all derivatives will likely to have low toxicity, great pharmacological and oral bioavailability profiles, and a Druglikeness and Drug score similar to some commercial anticoagulant and antiplatelet drugs. CONCLUSION 1,2,3-triazoles are potential candidates for molecular modeling of new antithrombotic drugs.

Pharmacological characterization of cnidarian extracts from the Caribbean Sea: evaluation of anti-snake venom and antitumor properties

BackgroundCnidarians produce toxins, which are composed of different polypeptides that induce pharmacological effects of biotechnological interest, such as antitumor, antiophidic and anti-clotting activities. This study aimed to evaluate toxicological activities and potential as antitumor and antiophidic agents contained in total extracts from five cnidarians: Millepora alcicornis, Stichodactyla helianthus, Plexaura homomalla, Bartholomea annulata and Condylactis gigantea (total and body wall).MethodsThe cnidarian extracts were evaluated by electrophoresis and for their phospholipase, proteolytic, hemorrhagic, coagulant, fibrinogenolytic, neuromuscular blocking, muscle-damaging, edema-inducing and cytotoxic activities.ResultsAll cnidarian extracts showed indirect hemolytic activity, but only S. helianthus induced direct hemolysis and neurotoxic effect. However, the hydrolysis of NBD-PC, a PLA2 substrate, was presented only by the C. gigantea (body wall) and S. helianthus. The extracts from P. homomalla and S. helianthus induced edema, while only C. gigantea and S. helianthus showed intensified myotoxic activity. The proteolytic activity upon casein and fibrinogen was presented mainly by B. annulata extract and all were unable to induce hemorrhage or fibrinogen coagulation. Cnidarian extracts were able to neutralize clotting induced by Bothrops jararacussu snake venom, except M. alcicornis. All cnidarian extracts were able to inhibit hemorrhagic activity induced by Bothrops moojeni venom. Only the C. gigantea (body wall) inhibited thrombin-induced coagulation. All cnidarian extracts showed antitumor effect against Jurkat cells, of which C. gigantea (body wall) and S. helianthus were the most active; however, only C. gigantea (body wall) and M. alcicornis were active against B16F10 cells.ConclusionThe cnidarian extracts analyzed showed relevant in vitro inhibitory potential over the activities induced by Bothrops venoms; these results may contribute to elucidate the possible mechanisms of interaction between cnidarian extracts and snake venoms.