Purification and characterization of fibrinolytic protease from Streptomyces parvulus by polyethylene glycol-phosphate aqueous two-phase system.

Fibrinolytic proteases are a promising alternative in the pharmaceutical industry, they are used in the treatment of cardiovascular diseases, especially thrombosis. Microorganisms are the most interesting source of fibrinolytic proteases. The aim of this study was the production of fibrinolytic protease from Streptomyces parvulus DPUA 1573, the recovery of the protease by aqueous two-phase system and partial biochemical characterization of the enzyme. The aqueous two-phase system was performed according to a 24-full factorial design using polyethylene glycol molar mass, polyethylene glycol concentration, citrate concentration and pH as independent variables. It was analyzed the effect of different ions, surfactants, inhibitors, pH and temperature on enzyme activity. The best conditions for purifying the enzyme were 17.5% polyethylene glycol 8,000, 15% Phosphate and pH 8.0, it was obtained a partition coefficient of 7.33, a yield of 57.49% and a purification factor of 2.10-fold. There was an increase in enzyme activity in the presence of Fe2+ and a decrease in the presence of $\beta$-Mercaptoethanol, phenylmethylsulfonyl fluoride and Iodoacetic acid. The optimum pH was 7.0 and the optimum temperature was 40 ºC. The purified protease exhibited a molecular mass of 41 kDa. The fibrinolytic protease from Streptomyces parvulus proved to be a viable option for the development of a possible drug with fibrinolytic action.

Antimicrobial properties of heterocyclic compounds against clinical mastitis isolates

ABSTRACT: Mastitis causes significant economic losses to the dairy cattle industry. The present study aimed to evaluate the antibacterial properties of 39 heterocyclic derivatives (1,3-thiazoles and 4-thiazolidinones) against clinical mastitis isolates from dairy cows. Milk samples were collected from cows with clinical mastitis and the bacterial species were identified by PCR. Antibacterial activity was assessed using the broth microdilution method. First, 39 heterocyclic compounds were tested against four bacterial isolates (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis and Escherichia coli) randomly chosen from those recovered from the milk samples (Study 1). Subsequently, the compounds with the strongest antibacterial activity were tested against all the bacterial isolates recovered from the milk samples (Study 2). 1,3-thiazoles showed the strongest antibacterial activity, specially compounds 30 and 38, which also showed bactericidal properties according to their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values. Corynebacterium spp. and Enterobacteriaceae isolates were the most susceptible to compounds 30 and 38. Compounds 30 and 38 are promising targets for new antimicrobial agents.

RESUMO: A mastite causa significativas perdas econômicas à indústria leiteira bovina. O presente estudo teve como objetivo avaliar as propriedades antibacterianas de 39 derivados heterocíclicos (1,3-tiazóis e 4-tiazolidinonas) contra isolados clínicos de mastite em vacas leiteiras. Amostras de leite foram coletadas de vacas com mastite clínica e as espécies bacterianas isoladas foram identificadas por PCR. A atividade antibacteriana foi avaliada pelo método de microdiluição em caldo. Primeiramente, os 39 compostos heterocíclicos foram testados contra quatro isolados bacterianos (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis e Escherichia coli) escolhidos aleatoriamente dentre os recuperados das amostras de leite (Estudo 1). Posteriormente, compostos com atividade antibacteriana mais forte foram testados contra todos os isolados bacterianos recuperados das amostras de leite (Estudo 2). Os compostos 1,3-tiazóis apresentaram a maior atividade antibacteriana, principalmente os compostos 30 e 38, que também apresentaram propriedades bactericidas de acordo com seus valores de concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM). Os isolados Corynebacterium spp. e Enterobacteriaceae foram os mais suscetíveis aos compostos 30 e 38. Os compostos 30 e 38 mostraram-se promissores como novos agentes antimicrobianos.

Antimicrobial properties of heterocyclic compounds against clinical mastitis isolates / Propriedades antimicrobianas de compostos heterocíclicos contra isolados de mastite clínica

Mastitis causes significant economic losses to the dairy cattle industry. The present study aimed to evaluate the antibacterial properties of 39 heterocyclic derivatives (1,3-thiazoles and 4-thiazolidinones) against clinical mastitis isolates from dairy cows. Milk samples were collected from cows with clinical mastitis and the bacterial species were identified by PCR. Antibacterial activity was assessed using the broth microdilution method. First, 39 heterocyclic compounds were tested against four bacterial isolates (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis and Escherichia coli) randomly chosen from those recovered from the milk samples (Study 1). Subsequently, the compounds with the strongest antibacterial activity were tested against all the bacterial isolates recovered from the milk samples (Study 2). 1,3-thiazoles showed the strongest antibacterial activity, specially compounds 30 and 38, which also showed bactericidal properties according to their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values. Corynebacterium spp. and Enterobacteriaceae isolates were the most susceptible to compounds 30 and 38. Compounds 30 and 38 are promising targets for new antimicrobial agents.(AU)

A mastite causa significativas perdas econômicas à indústria leiteira bovina. O presente estudo teve como objetivo avaliar as propriedades antibacterianas de 39 derivados heterocíclicos (1,3-tiazóis e 4-tiazolidinonas) contra isolados clínicos de mastite em vacas leiteiras. Amostras de leite foram coletadas de vacas com mastite clínica e as espécies bacterianas isoladas foram identificadas por PCR. A atividade antibacteriana foi avaliada pelo método de microdiluição em caldo. Primeiramente, os 39 compostos heterocíclicos foram testados contra quatro isolados bacterianos (Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium bovis e Escherichia coli) escolhidos aleatoriamente dentre os recuperados das amostras de leite (Estudo 1). Posteriormente, compostos com atividade antibacteriana mais forte foram testados contra todos os isolados bacterianos recuperados das amostras de leite (Estudo 2). Os compostos 1,3-tiazóis apresentaram a maior atividade antibacteriana, principalmente os compostos 30 e 38, que também apresentaram propriedades bactericidas de acordo com seus valores de concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM). Os isolados Corynebacterium spp. e Enterobacteriaceae foram os mais suscetíveis aos compostos 30 e 38. Os compostos 30 e 38 mostraram-se promissores como novos agentes antimicrobianos.(AU)

Thiosemicarbazones as Aedes aegypti larvicidal.

A set of aryl- and phenoxymethyl-(thio)semicarbazones were synthetized, characterized and biologically evaluated against the larvae of Aedes aegypti (A. aegypti), the vector responsible for diseases like Dengue and Yellow Fever. (Q)SAR studies were useful for predicting the activities of the compounds not included to create the QSAR model as well as to predict the features of a new compound with improved activity. Docking studies corroborated experimental evidence of AeSCP-2 as a potential target able to explain the larvicidal properties of its compounds. The trend observed between the in silico Docking scores and the in vitro pLC50 (equals -log LC50, at molar concentration) data indicated that the highest larvicidal compounds, or the compounds with the highest values for pLC50, are usually those with the higher docking scores (i.e., greater in silico affinity for the AeSCP-2 target). Determination of cytotoxicity for these compounds in mammal cells demonstrated that the top larvicide compounds are non-toxic.

Subversion of early innate antiviral responses during antibody-dependent enhancement of Dengue virus infection induces severe disease in immunocompetent mice.

Dengue is a mosquito-borne disease caused by one of four serotypes of Dengue virus (DENV-1-4). Epidemiologic and observational studies demonstrate that the majority of severe dengue cases, dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS), occurs predominantly in either individuals with cross-reactive immunity following a secondary heterologous infection or in infants with primary DENV infections born from dengue-immune mothers, suggesting that B-cell-mediated and antibody responses impact on disease evolution. We demonstrate here that B cells play a pivotal role in host responses against primary DENV infection in mice. After infection, µMT(-/-) mice showed increased viral loads followed by severe disease manifestation characterized by intense thrombocytopenia, hemoconcentration, cytokine production and massive liver damage that culminated in death. In addition, we show that poly and monoclonal anti-DENV-specific antibodies can sufficiently increase viral replication through a suppression of early innate antiviral responses and enhance disease manifestation, so that a mostly non-lethal illness becomes a fatal disease resembling human DHF/DSS. Finally, treatment with intravenous immunoglobulin containing anti-DENV antibodies confirmed the potential enhancing capacity of subneutralizing antibodies to mediate virus infection and replication and induce severe disease manifestation of DENV-infected mice. Thus, our results show that humoral responses unleashed during DENV infections can exert protective or pathological outcomes and provide insight into the pathogenesis of this important human pathogen.