Synthetic Naphthoquinone Inhibits Herpes Simplex Virus Type-1 Replication Targeting Na+, K+ ATPase.

Since 1970 acyclovir (ACV) has been the reference drug in treating herpes simplex virus (HSV) infections. However, resistant herpes simplex virus type 1 (HSV-1) strains have emerged, narrowing the treatment efficacy. The antiviral activity of classical Na+, K+ ATPase enzyme (NKA) inhibitors linked the viral replication to the NKA's activity. Herein, we evaluated the anti-HSV-1 activity of synthetic naphthoquinones, correlating their antiviral activity with NKA inhibition. We tested seven synthetic naphthoquinones initially at 50 µM on HSV-1-infected African green monkey kidney cells (VERO cells). Only one compound, 2-hydroxy-3-(2-thienyl)-1,4-naphthoquinone (AN-06), exhibited higher antiviral activity with a low cytotoxicity. AN-06 reduced the viral titer of 9 (log10) to 1.32 (log10) and decreased the steps of attachment and penetration. The addition of AN-06 up to 20 h postinfection (hpi) interfered with the viral cycle. The viral infection alone increases NKA activity 3 h postinfection (hpi), scaling up to 6 hpi. The addition of AN-06 in a culture infected with HSV-1 decreased NKA activity, suggesting that its antiviral action is linked to NKA inhibition. Also, docking results showed that this compound binds at the same site of NKA in which adenosine triphosphate (ATP) binds. AN-06 exhibited promising pharmacokinetic and toxicology properties. Thus, we postulate that AN-06 may be a good candidate for antiviral compounds with a mechanism of action targeting NKA activity.

Spider's Silk as a Potential Source of Antibiotics: An Integrative Review.

Spiders produce webs, which are still a largely unexplored source of antibacterial compounds, although the reports of its application in the medical field. Therefore, this study aims to present an integrative review of the antibacterial activity of spider webs. The research was conducted using Google Scholar, Scielo, Web of Science, PubMed, ScienceDirect, Medline EBSCO, LILACS, and Embase. The inclusion criteria were original articles written in English that studied the antibiotic properties of the web or isolated compounds tested. The studies were compared according to the spider species studied, the type of web, treatment of the sample, type of antimicrobial test, and the results obtained. Nine hundred and seventy-three publications were found, and after applying the inclusion and exclusion criteria, sixteen articles were selected. Bacterial inhibition was found in seven studies against various species of bacteria such as Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella Typhi, Bacillus megaterium, Listeria monocytogenes, Acinetobacter baumannii, Streptococcus pneumoniae, Pasteurella multocida, and Bacillus subtilis. Additionally, there was no apparent relationship between the proximity of the spider species evaluated in the studies and the presence or absence of activity. Methodological problems detected may affected the reproducibility and reliability of the results in some studies, such as the lack of description of the web or microorganism strain, as well as the absence of adequate controls and treatments to sterilize the sample. Spider webs can be a valuable source of antibiotics; however, more studies are needed to confirm the real activity of the web or components involved.

N, N'-disubstituted Ureas as Novel Antiplatelet Agents: Synthesis, Pharmacological Evaluation and In Silico Studies.

INTRODUCTION: Thrombotic disorders are among the leading causes of morbidity and mortality worldwide. Drugs used in the prevention and treatment of atherothrombosis have pharmacokinetic limitations and adverse effects such as hemorrhagic conditions, highlighting the importance of developing more effective antiplatelet agents. ethod: In this work, we synthesized N,N'-disubstituted ureas 3a-3j and evaluated their antiplatelet profiles through in vitro, ex vivo, and in silico studies. The synthesized derivatives exhibited a selective inhibitory profile against platelet aggregation induced by arachidonic acid (AA) in vitro, without significantly affecting other aspects of primary hemostasis and blood coagulation. The compounds that showed inhibition greater than 85% were submitted to the analysis of their potency by calculating the concentration required to inhibit 50% of platelet aggregation induced by AA (IC50). Urea derivative 3a was the most potent with IC50 of 1.45 µM. Interestingly, this derivative inhibited more than 90% of platelet aggregation induced by AA ex vivo, with a similar effect to acetylsalicylic acid. In the hemolysis assay, most of the urea derivatives presented values below 10% suggesting good hemocompatibility. Additionally, the compounds tested at 100 µM also showed no cytotoxic effects in HepG2 and Vero cells. RESULT: The in silico results suggested that compound 3a may bind to the key residue of COX-1 similar to AA and known COX-1 inhibitors, and the results are also in agreement with our SAR, which suggests that the inhibition of this enzyme is the most likely mechanism of antiplatelet activity. CONCLUSION: Therefore, these results demonstrated that N,N'-disubstituted ureas are promising candidates for the development of novel antiplatelet agents.

Antiviral evaluation of 1,4-disubstituted-1,2,3-triazole derivatives against Chikungunya virus.

Aim: This work aimed to investigate the antiviral activity of two 1,4-disubstituted-1,2,3-triazole derivatives (1 and 2) against Chikungunya virus (CHIKV) replication. Materials & methods: Cytotoxicity was analyzed using colorimetric assays and the antiviral potential was evaluated using plaque assays and computational tools. Results: Compound 2 showed antiviral activity against CHIKV 181-25 in BHK-21 and Vero cells. Also, this compound presented a higher activity against CHIKV BRA/RJ/18 in Vero cells, like compound 1. Compound 2 exhibited virucidal activity and inhibited virus entry while compound 1 inhibited virus release. Molecular docking suggested that these derivatives inhibit nsP1 protein while compound 1 may also target capsid protein. Conclusion: Both compounds exhibit promising antiviral activity against CHIKV by blocking different steps of virus replication.

Anticancer Activity and Molecular Targets of Piper cernuum Substances in Oral Squamous Cell Carcinoma Models.

Oral squamous cell carcinoma (OSCC) is a worldwide public health problem, with high morbidity and mortality rates. The development of new drugs to treat OSCC is paramount. Piper plant species have shown many biological activities. In the present study, we show that dichloromethane partition of Piper cernuum (PCLd) is nontoxic in chronic treatment in mice, reduces the amount of atypia in tongues of chemically induced OSCC, and significantly increases animal survival. To identify the main active compounds, chromatographic purification of PCLd was performed, where fractions 09.07 and 14.05 were the most active and selective. These fractions promoted cell death by apoptosis characterized by phosphatidyl serine exposition, DNA fragmentation, and activation of effector caspase-3/7 and were nonhemolytic. LC-DAD-MS/MS analysis did not propose matching spectra for the 09.07 fraction, suggesting compounds not yet known. However, aporphine alkaloids were annotated in fraction 14.05, which are being described for the first time in P. cernuum and corroborate the observed cytotoxic activity. Putative molecular targets were determined for these alkaloids, in silico, where the androgen receptor (AR), CHK1, CK2, DYRK1A, EHMT2, LXRß, and VEGFR2 were the most relevant. The results obtained from P. cernuum fractions point to promising compounds as new preclinical anticancer candidates.

Chloroquinolone Carboxamide Derivatives as New Anti-HSV-1 Promising Drugs.

BACKGROUND: Since the emergence of HSV resistant strains, new antiviral agents have emerged and still are urgently needed, especially those with alternative targets. OBJECTIVE: In this work, we evaluated new quinolone derivatives as anti-HSV. METHODS: For this study, cells were infected and treated with different components to evaluate the profile of HSV replication in vitro. In addition, studies were performed to determine the pharmacokinetic toxicity and profile of the compound. RESULTS: Indeed the EC50 values of these promising molecules ranged between 8 µM and 32 µM. We have also showed that all compounds inhibited the expression of ICP27 viral proteins, which gives new insights in the search for new target for antiherpetic therapy. Chlorine in positions C6 and phosphonate in position C1 have shown to be important for viral inhibition. The chloroquinolone carboxamide derivatives fulfilled "Lipinsky Rule of Five" for good oral bioavailability and showed higher intestinal absorption and blood brain barrier penetration, as well as lower toxicity profile. CONCLUSION: Although the inhibition activities of chloroquinolone carboxamide derivatives were lower than acyclovir, they showed different modes of action in comparison to the drugs currently available. These findings encourage us to continue pre-clinical studies for the development of new anti-HSV-1 agents.

Structural insights into the inhibition of the nsP2 protease from Chikungunya virus by molecular modeling approaches.

Chikungunya virus (CHIKV) is the etiological agent of the Chikungunya fever which has spread worldwide. Clinically, this disease may lead to prolonged incapacitating joint pain that can compromise remarkably the patients' quality of life. However, there are no licensed vaccines or specific drugs to fight this infection yet, making the search for novel therapies an imperative need. In this scenario, the CHIKV nsP2 protease emerged as an attractive therapeutic target once this protein plays a pivotal role in viral replication and pathogenesis. Hence, we investigated the structural basis for the inhibition of this enzyme by using molecular docking and dynamics simulations. Compounds with inhibitory activities against CHIKV nsP2 protease determined experimentally were selected from the literature. Docking studies with a set of stereoisomers showed that trans isomers, but not cis ones, bound close to the catalytic dyad which may explain isomerism requirements to the enzyme's inhibition. Further, binding mode analyses of other known inhibitors revealed highly conserved contacts between inhibitors and enzyme residues like N1011, C1013, A1046, Y1079, N1082, W1084, L1205, and M1242. Molecular dynamics simulations reinforced the importance of some of these interactions and pointed to nonpolar interactions as the main forces for inhibitors' binding. Finally, we observed that true inhibitors exhibited lower structural fluctuation, higher ligand efficiency and did not induce significant changes in protein correlated motions. Collectively, our findings might allow discerning true inhibitors from false ones and can guide drug development efforts targeting the nsP2 protease to fight CHIKV infections in the future.

Pro-Apoptotic Antitumoral Effect of Novel Acridine-Core Naphthoquinone Compounds against Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is a global public health problem with high incidence and mortality. The chemotherapeutic agents used in the clinic, alone or in combination, usually lead to important side effects. Thus, the discovery and development of new antineoplastic drugs are essential to improve disease prognosis and reduce toxicity. In the present study, acridine-core naphthoquinone compounds were synthesized and evaluated for their antitumor activity in OSCC cells. The mechanism of action, pharmacokinetics, and toxicity parameters of the most promising compound was further analyzed using in silico, in vitro, and in vivo methods. Among the derivatives, compound 4e was highly cytotoxic (29.99 µM) and selective (SI 2.9) at levels comparable and generally superior to chemotherapeutic controls. Besides, compound 4e proved to be non-hemolytic, stable, and well tolerated in animals at all doses tested. Mechanistically, compound 4e promoted cell death by apoptosis in the OSCC cell, and molecular docking studies suggested this compound possibly targets enzymes important for tumor progression, such as RSK2, PKM2, and topoisomerase IIα. Importantly, compound 4e presented a pharmacological profile within desirable parameters for drug development, showing promise for future preclinical trials.

Targeting Chikungunya virus by computational approaches: from viral biology to the development of therapeutic strategies.

Introduction: Chikungunya virus (CHIKV) is the causative agent of Chikungunya fever, a reemerging infectious disease. This disease can cause severe manifestations that persist for months or years after acute infection and alas, there are no antiviral drugs or vaccines available. Hence, the development of new therapeutic approaches is necessary.Areas covered: We review how computational tools have provided insights on CHIKV proteins and examine the advances in the development of potential and novel antiviral drugs. A literature search was performed using PubMed and ScienceDirect databases up to April 2019.Expert opinion: Computational approaches are valuable for gaining insights into CHIKV proteins and for the design of new anti-CHIKV agents. The collaboration between computational and experimental researchers should be strengthened so that new agents can be developed in a more rational manner. Computer-aided tools could assist in the discovery and development of safer and more efficacious novel antiviral agents from unexplored chemical spaces. Technological advances dictate that this is likely to emerge soon, thus boosting interest and research on CHIKV biology and drug, vaccine and diagnostics development.

Mechanism of resistance to acyclovir in thymidine kinase mutants from Herpes simplex virus type 1: a computational approach.

Herpes simplex virus type 1 (HSV-1) infections affect about two-thirds of the world population, and the standard treatment consists of acyclovir (ACV) and its analogs, which interact with thymidine kinase (TK) blocking viral replication. Lately, the emergence of ACV-resistant strains has been reported, especially associated with TK mutations. In this context, ACV therapy fails against isolates encoding Y172C and Y53H/R163H TK mutants, but the molecular mechanism of drug resistance remains unclear. Thus, we examined the effects of these mutations on ACV and the cofactor ATP binding through molecular modeling approaches. We showed that Y172C prevents the anchoring of the aromatic ring of ACV through π-π stacking interactions, leading to an inversed binding mode and different interactions. On the other hand, Y53H/R163H remarkably affected the cofactor binding mode which shifted away from its binding site and also influenced the interaction network of ACV. This is likely due to the loss of polar interactions with R163 residue. Unlike what was observed in the wild-type complex, both drug and cofactor binding poses were not well positioned to allow the phosphorylation reaction which explains the resistance observed. Moreover, energy analysis corroborated the experimental data and showed lower theoretical affinity of ACV with mutant enzymes resulted from energetic loss in polar solvation in Y172C and electrostatic terms in Y53H/R163H mutant enzyme. Therefore, our study shed light on the resistance mechanism toward ACV of two mutant TKs identified in clinical HSV-1 strains and may further support the development of new anti-herpetic drugs to treat resistant infections. [Formula: see text] Communicated by Ramaswamy H. Sarma.

Etiologia e epidemiologia da tinea capitis: relato de série de casos e revisão da literatura / Etiology and epidemiology of tinea capitis: case-serie report and literature review

Dermatofitose é uma micose superficial, causada por fungos filamentosos denominados dermatófitos, que são capazes de degradar estruturas queratinizadas. Os agentes dessas infecções em humanos pertencem a três gêneros: Microsporum, Trichophyton e Epidermophyton. O objetivo deste trabalho é revisar os estudos epidemiológicos e relatos de casos de tinea capitis, a partir de artigos publicados entre 2000 e 2018. Com base nos dados analisados, o gênero masculino foi o mais afetado pela tinea capitis e a faixa etária mais relatada foi a de indivíduos menores de 10 anos. As principais espécies isoladas foram: T. tonsurans e M. canis, sendo o primeiro mais encontrado nas regiões norte, nordeste e centro-oeste, e o segundo, nas regiões sudeste e sul do Brasil. Nos relatos de casos foram reportadas lesões com diferentes características, sendo algumas mais inflamatórias, eritematosas, com pústulas, placas de alopécia ou descamativas do que outras. Dor e prurido foram sintomas observados em alguns casos. A griseofulvina e os derivados azólicos foram os principais fármacos empregados na terapia, ainda que em associação em alguns casos. As avaliações dos tratamentos empregados nos casos de tinea capitis devem ser minuciosamente realizadas, visto que há relatos de casos em que a reposta terapêutica não é eficiente, agravando as lesões e prolongando o tempo de tratamento.

Dermatophytosis is a superficial mycosis, caused by filamentous fungi called dermatophytes, which are capable of degrading keratinized structures. The agents of these infections in humans belong to three genera: Microsporum, Trichophyton and Epidermophyton. The objective of this study is to review the epidemiological studies and reports of tinea capitis cases in Brazil, based on articles published between 2000 and 2018. Based on the data analyzed, the male gender was the most affected by Tinea capitis and the most reported age group was of individuals with less than 10 years. The main species isolated from the samples were: T. tonsurans and M. canis, being the first one most found in the north, northeast and center-west regions and the second one found in the southeastern and southern regions of Brazil. In the case reports, lesions with different characteristics were reported, being some more inflammatory, erythematous, with pustules, others with plaques of alopecia or desquamative than others. Pain and itching were symptoms observed in some cases. Griseofulvin and azole derivatives were the main drugs used in therapy, although in association in some cases. The evaluations of the treatment employed in the cases of Tinea capitis should be thoroughly done since there are reports of cases in which the therapeutic response is not efficient, aggravating the lesions and prolonging the treatment time

Computational strategy for visualizing structures and teaching biochemistry.

Computational techniques have great potential to improve the teaching-learning. In this work, we used a computational strategy to visualize three-dimensional (3D) structures of proteins and DNA and help the student to comprehend biochemistry concepts such as protein structure and function, substrate, and inhibitors as well as DNA structural features. The practical classes included tutorials to be done in the computer using structures from Protein Data Bank and a free 3D structure visualization software, Swiss PDB Viewer. The activity was done with 76 students from biology and pharmacy undergraduate courses. Questionnaires were administered to evaluate the knowledge regarding specific biochemistry contents before and after the activity and the opinion of the students. An overall increased percentage of correct answers post-classes (75.91%) were observed in comparison to pre-classes (35.53%). All the students indicated that it could contribute to the learning of DNA and protein structure contents; approximately 90% stated that it enables structures visualization or makes the learning and understanding easier. Therefore, the strategy has shown to be effective, allowing the contextualization of biochemistry themes and may complement theoretical classes. © 2018 International Union of Biochemistry and Molecular Biology, 47(1):76-84, 2018.

Virtual screening and drug repositioning as strategies for the discovery of new antifungal inhibitors of oxidosqualene cyclase.

Candidiasis is the most common fungal infection in immunocompromised patients, and Candida albicans is the fourth leading agent of nosocomial infections. Mortality from this infection is significant; however, the therapeutic treatment is limited, which demands the search for new drugs and new targets. In this context, oxidosqualene cyclase (OSC) catalyzes the cyclization of the 2,3-oxidosqualene to form lanosterol, an intermediate of ergosterol biosynthesis. Therefore, this enzyme constitutes an attractive therapeutic target. Thus, the aim of this study is to identify potential inhibitors of C. albicans OSC (CaOSC) from a marketed drugs database in order to discover new antifungal agents. The CaOSC 3D model was constructed using the Swiss-Model server and important features for CaOSC inhibition were identified by molecular docking of known inhibitors using Autodock Vina 1.1.2. Subsequently, virtual screening helped to identify calcitriol, the active form of vitamin D, and other four drugs, as potential inhibitors of CaOSC. The selected drugs presented an interesting pattern of interactions with this enzyme, including hydrogen bond with Asp450, a key residue in the active site. Thus, the antifungal activity of calcitriol was evaluated in vitro against Candida spp strains. Calcitriol showed antifungal activity against C. albicans and C. tropicalis, which reinforces the potential of this compound as candidate of CaOSC inhibitor. In short, the present study provides important insights for the development of new oxidosqualene cyclase inhibitors as antifungals.

A divulgação de vídeos de anatomia do sistema nervoso central no Youtube / Dissemination of videos on the anatomy of the central nervous system by Youtube

O estudo visa avaliar os métodos de exposição de conteúdos de neuroanatomia utilizados nos vídeos compartilhados no YouTube, o impacto destes vídeos e a aceitação dos usuários. Trata-se de uma pesquisa quantitativa, com abordagem descritiva e analítica observacional, envolvendo a análise de vídeos de neuroanatomia divulgados em português no site do YouTube. A pesquisa foi realizada no Youtube utilizando as palavras-chave "telencéfalo", "diencéfalo" e "tronco encefálico". Os vídeos foram categorizados de acordo com o método de exposição do conteúdo de neuroanatomia como equipamentos multimídia (EM), peças plásticas (PPT), peças plastinadas (PPN), e peças cadavéricas formolizadas (PCF) para avaliação do número de visualizações e aceitação dos usuários (número de likes e dislikes). Foi observado que as PPT foram mais utilizadas nos vídeos de neuroanatomia. Porém, os vídeos que utilizaram EM tiveram mais visualizações diárias e maior aceitação pelos usuários do Youtube. Os resultados do presente estudo sugerem que os vídeos de neuroanatomia utilizando EM podem contribuir de forma complementar para o ensino-aprendizado destes conteúdos.

The aim of this work is to access the exposure methods of neuroanatomy used in YouTube-shared videos, their impact and acceptance by users, by a quantitative, descriptive and analytic research. Research was undertaken in YouTube with keywords "telencephalon", "diencephalon" and "brainstem". Videos were categorized according to the exposure method of the neuroanatomic contents, such as multimedia equipments (ME), plastic parts (PPT), plastinated parts (PPN), and cadaver pieces in formaldehyde (PCF), to evaluate the number of visualizations and acceptance by the users (number of likes and dislikes). The exposure method based on PPT was the most used one in neuroanatomy videos. However, ME videos had more daily visualizations and greater acceptance by the Youtube users. Results suggest that neuroanatomy videos with ME may contribute in a complementary manner towards the teaching-learning of these contents.

Class A ß-lactamases and inhibitors: In silico analysis of the binding mode and the relationship with resistance.

ß-lactams are one of the most common antimicrobials used to treat bacterial infections. However, bacterial resistance has compromised their efficacy, mainly due to the ß-lactamase enzyme production. To overcome this resistance, ß-lactamase inhibitors can be used in association with these antimicrobials. Herein, we analyzed the structural characteristics of ß-lactamases and their interactions with classical inhibitors, such as clavulanic acid (CA), sulbactam (SB) and tazobactam (TZ) to gain insights into resistance. The homology models of five class A ß-lactamases, namely CARB-3, IMI-1, SFO-1, SHV-5 and TEM-10, were constructed and validated and revealed an overall 3D structural conservation, but with significant differences in the electrostatic potential maps, especially at important regions in the catalytic site. Molecular dockings of CA, SB and TZ with these enzymes revealed a covalent bond with the S70 in all complexes, except Carb-3 which is in agreement with experimental data reported so far. This is likely related to the less voluminous active site of Carb-3 model. Although few specific contacts were observed in the ß-lactamase-inhibitor complexes, all compounds interacted with the residues in positions 73, 130, 132, 236 and 237. Therefore, this study provides new perspectives for the design of innovative compounds with broad-spectrum inhibitory profiles against ß-lactamases.

Antileishmanial Thioureas: Synthesis, Biological Activity and in Silico Evaluations of New Promising Derivatives.

Leishmaniasis is a neglected tropical disease caused by protozoan parasites belonging to the genus Leishmania. Currently, the drugs available for treatment of this disease present high toxicity, along with development of parasite resistance. In order to overcome these problems, efforts have been made to search for new and more effective leishmanicidal drugs. The aim of this study was to synthesize and investigate the leishmanicidal effect of N,N'-disubstituted thioureas against Leishmania amazonensis, with evaluation of their in silico pharmacokinetics and toxicity profiles. Our results showed that different thioureas could be obtained in high to moderate yields using simple reaction conditions. Nine thiourea derivatives (3e, 3i, 3k, 3l, 3p, 3q, 3v, 3x and 3z) were active against parasite promastigotes (IC50 21.48-189.10 µM), with low cytotoxicity on mice peritoneal macrophages (CC50>200 µM), except for thiourea 3e (CC50=49.22 µM). After that, the most promising thioureas (3k, 3l, 3p, 3q and 3v) showed IC50 ranging from 70 to 150 µM against L. amazonensis amastigotes in infected macrophages. Except for thiourea 3p, the leishmanicidal activity of the derivatives were independent of nitric oxide (NO) production. Thioureas 3q and 3v affected promastigotes cell cycle without disturbing the mitochondrial membrane potential. Furthermore, our derivatives showed satisfactory theoretical absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. These data indicate that thiourea derivatives are good candidates as leading compounds for the development of new leishmanicidal drugs.

Design strategies of oxidosqualene cyclase inhibitors: Targeting the sterol biosynthetic pathway.

Targeting the sterol biosynthesis pathway has been explored for the development of new bioactive compounds. Among the enzymes of this pathway, oxidosqualene cyclase (OSC) which catalyzes lanosterol cyclization from 2,3-oxidosqualene has emerged as an attractive target. In this work, we reviewed the most promising OSC inhibitors from different organisms and their potential for the development of new antiparasitic, antifungal, hypocholesterolemic and anticancer drugs. Different strategies have been adopted for the discovery of new OSC inhibitors, such as structural modifications of the natural substrate or the reaction intermediates, the use of the enzyme's structural information to discover compounds with novel chemotypes, modifications of known inhibitors and the use of molecular modeling techniques such as docking and virtual screening to search for new inhibitors. This review brings new perspectives on structural insights of OSC from different organisms and reveals the broad structural diversity of OSC inhibitors which may help evidence lead compounds for further investigations with various therapeutic applications.

Marine Diterpenes: Molecular Modeling of Thrombin Inhibitors with Potential Biotechnological Application as an Antithrombotic.

Thrombosis related diseases are among the main causes of death and incapacity in the world. Despite the existence of antithrombotic agents available for therapy, they still present adverse effects like hemorrhagic risks which justify the search for new options. Recently, pachydictyol A, isopachydictyol A, and dichotomanol, three diterpenes isolated from Brazilian marine brown alga Dictyota menstrualis were identified as potent antithrombotic molecules through inhibition of thrombin, a key enzyme of coagulation cascade and a platelet agonist. Due to the biotechnological potential of these marine metabolites, in this work we evaluated their binding mode to thrombin in silico and identified structural features related to the activity in order to characterize their molecular mechanism. According to our theoretical studies including structure-activity relationship and molecular docking analysis, the highest dipole moment, polar surface area, and lowest electronic density of dichotomanol are probably involved in its higher inhibition percentage towards thrombin catalytic activity compared to pachydictyol A and isopachydictyol A. Interestingly, the molecular docking studies also revealed a good shape complementarity of pachydictyol A and isopachydictyol A and interactions with important residues and regions (e.g., H57, S195, W215, G216, and loop-60), which probably justify their thrombin inhibitor effects demonstrated in vitro. Finally, this study explored the structural features and binding mode of these three diterpenes in thrombin which reinforced their potential to be further explored and may help in the design of new antithrombotic agents.

In silico structural characteristics and α-amylase inhibitory properties of Ric c 1 and Ric c 3, allergenic 2S albumins from Ricinus communis seeds.

The major Ricinus communis allergens are the 2S albumins, Ric c 1 and Ric c 3. These proteins contain a trypsin/α-amylase inhibitor family domain, suggesting that they have a role in insect resistance. In this study, we verified that Ric c 1 and Ric c 3 inhibited the α-amylase activity of Callosobruchus maculatus, Zabrotes subfasciatus, and Tenebrio molitor (TMA) larvae as well as mammalian α-amylase. The toxicity of 2S albumin was determined through its incorporation in C. maculatus larvae as part of an artificial diet. Bioassays revealed that 2S albumin reduced larval growth by 20%. We also analyzed the tridimensional structures of Ric c 1 and Ric c 3 by (a) constructing a comparative model of Ric c 1 based on Ric c 3 NMR structure and (b) constructing the theoretical structure of the Ric c 1-TMA and Ric c 3-TMA complexes. Our biological and theoretical results revealed that Ric c 1 and Ric c 3 are a new class of α-amylase inhibitors. They could potentially be used to help design inhibitors that would be useful in diverse fields, ranging from diabetes treatment to crop protection.

Identification and characterization of a new member of snake venom thrombin inhibitors from Bothrops insularis using a proteomic approach.

Snake venom C-type lectin-like proteins (CLPs) are ubiquitously found in Viperidae snake venoms and differ from the C-type lectins as they display different biological activities but no carbohydrate-binding activity. Previous analysis of the transcriptome obtained from the Bothrops insularis venom gland showed the presence of two clusters homologous to bothrojaracin (BJC) chains alpha and beta. In an effort to identify a new BJC-like molecule, we used an approach associated with proteomic technologies to identify the presence of the expressed protein and then to purify and characterize a new thrombin inhibitor from B. insularis venom. We also constructed homology models of this protein and BJC, which were compared with other C-type lectin-like family members and revealed several conserved features of this intriguing snake venom toxin family.