Market-driven fortification of vitamins and minerals in packaged foods targeted at children in Brazil

This study aimed to characterise the market-driven fortification of vitamins and minerals in packaged foods targeted at children in Brazil. We analysed 535 food labels using data collected in a census-type method (n = 5620) of food labels in a Brazilian supermarket in 2013. Micronutrients declared in nutrition claims and the ingredients list (synthetic compounds) were considered to be added for commercial purposes. Analysis of the ingredients list and nutrition claims showed that market-driven fortification of vitamins and minerals was present in 27.1% of foods. The main vitamins and minerals were vitamins A, B complex, C, D, calcium, iron and zinc. The food groups 'Milk and dairy products' and 'Sugars, sugary foods and snacks' had the highest frequencies of micronutrients declared in the ingredients list. Calcium, iron, phosphorus, zinc and all vitamins, except B7, were found to be added for commercial purposes. Micronutrients were found to be commonly added to packaged foods as a marketing strategy directed at parents and their children. Future studies should assess the amount of vitamins and minerals added to packaged foods targeted at children and whether intakes of vitamins and minerals in children are potentially excessive.

University Students' Knowledge and Perceptions About Concepts, Recommendations, and Health Effects of Added Sugars

It is recommended to limit added sugars to below 10% of the daily energy intake, as excessive consumption has been associated with several chronic non-communicable diseases. This exploratory qualitative study used focus groups to investigate the knowledge and perception of Brazilian university students about added sugars concepts, consumption recommendations, and health effects. Focus groups were led by a moderator using a semi-structured discussion guide. The focus groups were recorded, transcribed verbatim, and subjected to thematic analysis. Five focus groups were conducted with a total of 32 participants (50% women, mean age 23 years). Participants could not distinguish added sugars from sugars naturally present in foods and were unaware of the health impacts associated with excessive added sugar consumption, except for the risk of diabetes. Although most participants reported limiting sugar consumption, they had no knowledge of official consumption recommendations. Given that current public policy agendas aim to reduce added sugar intake, there is a need to strengthen strategies for disseminating information on added sugar concepts, recommendations, health effects and how to identify them in the foods products.

Food additives in childhood: a review on consumption and health consequences

OBJECTIVE

To discuss the context of scientific publications on the consumption of food additives by children and the possible health consequences in this age group.

METHODS

A literature review, with a search carried out between April 2020 and April 2021 in the Web of Science, Scopus, PubMed and Google Scholar databases, as well as in websites of Brazilian and foreign official bodies. Official documents and studies published since 2000 were selected. Keywords related to food additives, children, food consumption, and health were used for the search.

RESULTS

Food additives are substances intentionally added to foods for technological purposes. Processed foods are the main sources of additives in food and their consumption occurs since childhood. It is observed, however, that there are limitations inherent to the scientific method regarding the analysis of consumption and toxicity of food additives in humans, causing scarcity of data in the scientific literature. Additionally, existing data suggest that the additives have a higher toxic potential in children, considering that the body weight in this age group is lower than in adults. This context emphasizes the need to observe the precautionary principle, according to which risks of harm must be prevented.

CONCLUSIONS

This is a scenario in which the literature points to a risk to people's health and, in particular, to children, about whom the duty of protection must be even greater, with absolute priority. Thus, the relevance of an expanded technical-scientific debate regarding the establishment of specific and stricter parameters for children is considered, regarding the consumption and toxicity of additives, as well as the different sources of exposure to these substances.

Association of personal characteristics and cooking skills with vegetable consumption frequency among university students

Most university students are transitioning to adulthood, and tend to adopt unhealthy eating habits characterised by a low intake of fruits and vegetables. Few studies have specifically addressed the consumption of vegetables, which have a high content of minerals, fibre, and active compounds. The aim of this investigation was to assess vegetable consumption frequency among university students in a Brazilian capital and examine associations with individual characteristics and cooking skills. This crosssectional study used a online questionnaire to collect data. Cooking skills were evaluated in eight dimensions. Vegetable consumption was recorded in five frequency groups and then categorised into daily and non-daily consumption. Data were subjected to Pearson's chi-squared or analysis of variance followed by Bonferroni post hoc test. Associations between cooking skill dimensions and daily vegetable consumption were identified by crude and adjusted logistic regression analyses.Adjustment was performed for sex, age, paternal education, and overweight/obesity.Results are expressed as odds ratios (p < 0.05). Less than half of the respondents (N = 237; 45%) reported consuming vegetables daily. Higher level of paternal education, not being overweight or obese, and higher scores on seven cooking skill dimensions were positively associated with daily vegetable consumption. Given the scarcity of research on the topic, the findings of this study make a significant contribution to knowledge and may support public health strategies for promoting vegetable consumption among university students.

Insights into the antiviral activity of phospholipases A2 (PLA2s) from snake venoms

Viruses are associated with several human diseases that infect a large number of individuals, hence directly affecting global health and economy. Owing to the lack of efficient vaccines, antiviral therapy and emerging resistance strains, many viruses are considered as a potential threat to public health. Therefore, researches have been developed to identify new drug candidates for future treatments. Among them, antiviral research based on natural molecules is a promising approach. Phospholipases A₂ (PLA₂s) isolated from snake venom have shown significant antiviral activity against some viruses such as Dengue virus, Human Immunodeficiency virus, Hepatitis C virus and Yellow fever virus, and have emerged as an attractive alternative strategy for the development of novel antiviral therapy. Thus, this review provides an overview of remarkable findings involving PLA₂s from snake venom that possess antiviral activity, and discusses the mechanisms of action mediated by PLA₂s against different stages of virus replication cycle. Additionally, molecular docking simulations were performed by interacting between phospholipids from Dengue virus envelope and PLA₂s from Bothrops asper snake venom. Studies on snake venom PLA₂s highlight the potential use of these proteins for the development of broad-spectrum antiviral drugs.

Nutritional Composition of Brazilian Food Products Marketed to Children

Most food industry marketing in products targeted at children is found in packages of foods containing either excessive fat, sugar, or salt. This study audited all 5620 packaged foods available in a store of a large Brazilian supermarket chain and retrieved information from the nutrition facts tables on package labels. Products were photographed for further visual analysis to determine the presence of marketing strategies directed at children. Comparison of nutrient content per 100 g between children's and non-children's food products employed the Student t-test or the Mann-Whitney U-test (p-value < 0.05), due to the non-normal distribution of the nutritional composition data as verified through the Shapiro-Wilk test. Brazilian children's food products from groups 4, 5, and 7 presented higher carbohydrate content than similar non-children's products, while children's food products from groups 1 and 7 presented lower fiber content. Results indicate that regulation on food labeling needs revising as it has not been effective in stopping the marketing of energy-dense nutrient-poor foods towards children.

Nutritional quality of packaged foods targeted at children in Brazil: which ones should be eligible to bear nutrient claims?

OBJECTIVES

This study aimed to assess the nutritional quality of food products marketed at children, with and without nutrient claims, using two different approaches.

METHODS

Analyses were performed based on a data set with food composition and labelling data from every packaged food marketed at children sold in a major Brazilian supermarket (n=535). Foods were classified as 'healthier' and 'less healthy' according to the UK/Ofcom nutrient profile model and to the NOVA classification based on the level of food processing. Pearson's χ² test was used to compare proportions between models. Agreement was assessed using Cohen's κ-statistic (P<0.05).

RESULTS

The NOVA model was stricter than the UK/Ofcom model, classifying more products as 'less healthy' (91.4%) compared with the nutrient profile-based model (75.0%; P<0.001). Agreement between models was 79.4% (k=0.30), because 72.9% (n=390) of products were categorised as 'less healthy' by both models, and 6.5% (n=35) as 'healthier'. Half of the food products marketed at children from the database (270; 50.5%) bore nutrient claims. From these products with nutrient claims, 95.9% (92.8-98.0) were classified as 'less healthy' by the NOVA model, whereas this percentage was 74.1% (68.4-79.2) according to the UK/Ofcom model (P<0.05).

CONCLUSIONS

The high number of foods with low nutritional quality being marketed at children via product packaging and nutrient claims should be of concern to policy makers wanting to improve children's diets and to tackle childhood obesity. The implementation of nutritional quality criteria to ensure that foods targeted at children should be eligible to bear nutrient claims on their labels could avoid a situation where claims mask the overall nutritional status of a food.

Perceptions of university students regarding calories, food healthiness, and the importance of calorie information in menu labelling

This study investigated Brazilian university students' perceptions of the concept of calories, how it relates to food healthiness, and the role of calorie information on menus in influencing food choices in different restaurant settings. Focus groups were conducted with 21 undergraduate students from various universities. Transcriptions were analysed for qualitative content, by coding and grouping words and phrases into similar themes. Two categories were obtained: Calorie concept and connection to healthiness; and Calorie information and food choices in restaurants. Calories were understood as energy units, and their excessive intake was associated with weight gain or fat gain. However, food healthiness was not associated to calorie content, but rather to food composition as a whole. Calorie information on restaurant menus was not considered enough to influence food choices, with preferences, dietary restrictions, food composition, and even restaurant type mentioned as equally or more important. Only a few participants mentioned using calorie information on menus to control food intake or body weight. Students' discussions were suggestive of an understanding of healthy eating as a more complex issue than calorie-counting. Discussions also suggested the need for more nutrition information, besides calorie content, to influence food choices in restaurants.

Triacontyl p-coumarate: an inhibitor of snake venom metalloproteinases

Snake venom metalloproteinases (SVMPs) participate in a number of important biological, physiological and pathophysiological processes and are primarily responsible for the local tissue damage characteristic of viperid snake envenomations. The use of medicinal plant extracts as antidotes against animal venoms is an old practice, especially against snake envenomations. Such plants are sources of many pharmacologically active compounds and have been shown to antagonize the effects of some venoms and toxins. The present study explores the activity of triacontyl p-coumarate (PCT), an active compound isolated from root bark of Bombacopsis glabra vegetal extract (Bg), against harmful effects of Bothropoides pauloensis snake venom and isolated toxins (SVMPs or phospholipase A(2)). Before inhibition assays, Bg or PCT was incubated with venom or toxins at ratios of 1:1 and 1:5 (w/w; venom or isolated toxins/PCT) for 30 min at 37°C. Treatment conditions were also assayed to simulate snakebite with PCT inoculated at either the same venom or toxin site. PCT neutralized fibrinogenolytic activity and plasmatic fibrinogen depletion induced by B. pauloensis venom or isolated toxin. PCT also efficiently inhibited the hemorrhagic (3MDH - minimum hemorrhagic dose injected i.d into mice) and myotoxic activities induced by Jararhagin, a metalloproteinase from B. jararaca at 1:5 ratio (toxin: inhibitor, w/w) when it was previously incubated with PCT and injected into mice or when PCT was administered after toxin injection. Docking simulations using data on a metalloproteinase (Neuwiedase) structure suggest that the binding between the protein and the inhibitor occurs mainly in the active site region causing blockade of the enzymatic reaction by displacement of catalytic water. Steric hindrance may also play a role in the mechanism since the PCT hydrophobic tail was found to interact with the loop associated with substrate anchorage. Thus, PCT may provide a alternative to complement ophidian envenomation treatments.

Hábitos alimentares e comportamento de consumo infantil: influência da renda familiar e do hábito de assistir à televisão

OBJETIVO: Comparar hábitos alimentares e comportamento de consumo de crianças de diferentes níveis de renda familiar de Florianópolis (SC), Brasil, relacionando-os com o hábito de assistir à televisão. MÉTODOS: Estudo qualitativo com análise de conteúdo de manuscritos originados de 23 grupos focais, realizados em uma escola pública e uma escola particular de Florianópolis (SC), compostos por 111 estudantes de 7 a 10 anos. Para verificar a renda familiar dos estudantes, dados sobre a ocupação dos pais foram classificados pela Classificação Brasileira de Ocupações. Os estudantes da escola particular pertenciam a famílias de maior renda em relação aos da escola pública. RESULTADOS: Nas duas escolas, a maioria das crianças entrevistadas referiu assistir à televisão sempre que possível, sem sentir controle dos pais sobre esse hábito. Além disso, afirmaram ter dinheiro para gastos independentes e vontade de comprar os produtos anunciados nas propagandas de televisão. Estudantes da escola pública relataram ingerir e adquirir guloseimas mais frequentemente e ter maior liberdade para fazer compras do que os estudantes da escola particular, que revelaram sentir-se controlados pelos pais em relação aos seus hábitos alimentares e compras realizadas. CONCLUSÃO: O fato de os estudantes da escola particular sentirem-se mais controlados por seus pais pode ter reduzido uma provável influência da televisão sobre seus hábitos alimentares e de compras. Evidencia-se a importância da formulação de estratégias para auxiliar os pais a reduzirem os efeitos da televisão sobre os hábitos de seus filhos e de políticas públicas que incentivem o consumo saudável, além da regulamentação do marketing de alimentos pouco nutritivos para o público infantil.

BnP1, a novel P-I metalloproteinase from Bothrops neuwiedi venom: biological effects benchmarking relatively to jararhagin, a P-III SVMP

Snake venom metalloproteinases (SVMPs) have been extensively studied and their effects associated with the local bleeding observed in human accidents by viper snakes. Representatives of P-I and P-III classes of SVMPs similarly hydrolyze extracellular matrix proteins or coagulation factors while only P-III SVMPs induce significant hemorrhage in experimental models. In this work, the effects of P-I and P-III SVMPs on plasma proteins and cultures of muscle and endothelial cells were compared in order to enlighten the mechanisms involved in venom-induced hemorrhage. To reach this comparison, BnP1 was isolated from B. neuwiedi venom and used as a weakly hemorrhagic P-I SVMPs and jararhagin was used as a model of potently hemorrhagic P-III SVMP. BnP1 was isolated by size exclusion and anion-exchange chromatographies, showing apparent molecular mass of approximately 24kDa and sequence similarity with other members of SVMPs, which allowed its classification as a group P-I SVMP. The comparison of local effects induced by SVMPs showed that BnP1 was devoid of significant myotoxic and hemorrhagic activities and jararhagin presented only hemorrhagic activity. BnP1 and jararhagin were able to hydrolyze fibrinogen and fibrin, although the latter displayed higher activity in both systems. Using HUVEC primary cultures, we observed that BnP1 induced cell detachment and a decrease in the number of viable endothelial cells in levels comparable to those observed by treatment with jararhagin. Moreover, both BnP1 and jararhagin induced apoptosis in HUVECs while only a small increase in LDH supernatant levels was observed after treatment with jararhagin, suggesting that the major mechanism involved in endothelial cell death is apoptosis. Jararhagin and BnP1 induced little effects on C2C12 muscle cell cultures, characterized by a partial detachment 24h after treatment and a mild necrotic effect as evidenced by a small increase in the supernatants LDH levels. Taken together, our data show that P-I and P-III SVMPs presented comparable effects except for the hemorrhagic activity, suggesting that hydrolysis of coagulation factors or damage to endothelial cells are not sufficient for induction of local bleeding.

Competition, estimated, and test maximum heart rate

AIM

The aim of the present study was to compare the highest heart rate (HR) of soccer players recorded during competition matches with the maximum HR (HR(max)) estimated from age and the highest HR recorded in effort tests within a single category (intracategory) and between categories (intercategories).

METHODS

The sample was made up of 19 under-17 athletes, 12 under-20 athletes and 14 professional athletes of a Brazilian first division soccer team. Players' HR was monitored during official competition matches and maximum effort test with a set of HR monitors. The highest HR recorded during competitive matches (MHR1) was considered as the highest HR value attained by each player during matches. HR(max) estimated from age (MHR2) was estimated by using the equation HR(max)= (220-age). The highest HR recorded in effort tests (MHR3) was determined as being the highest HR value recorded during a maximum effort test (1 000-m run). The Wilcoxon test was used in intracategory statistical analysis. The Kruskal Wallis test was used in intercategory statistical analysis. The significance level adopted was P<0.05.

RESULTS

In all categories, MHR3 was lower than MHR1. Concerning intercategory analysis, the three categories did not exhibit a difference in MHR1

RESULTS

Relative to MHR3, the under-17 and under-20 categories were not different from each other. These two categories exhibited larger MHR3 values than the professional one did.

CONCLUSION

HR(max) measured during field tests can be underestimated in relation to that measured during competition activities, maybe because the tests represent an artificial situation for athletes, who do not feel as motivated as during competitions.

Neutralizing properties of Musa paradisiaca L. (Musaceae) juice on phospholipase A2, myotoxic, hemorrhagic and lethal activities of crotalidae venoms

The use of plants as medicine has been referred to since ancient peoples, perhaps as early as Neanderthal man. Plants are a source of many biologically active products and nowadays they are of great interest to the pharmaceutical industry. The study of how people of different culture use plants in particular ways has led to the discovery of important new medicines. In this work, we verify the possible activity of Musa paradisiaca L. (Musaceae) against the toxicity of snake venoms. Musa paradisiaca, an important source of food in the world, has also been reported to be popularly used as an anti-venom. Interaction of Musa paradisiaca extract (MsE) with snake venom proteins has been examined in this study. Phospholipase A2 (PLA2), myotoxic and hemorrhagic activities, including lethality in mice, induced by crotalidae venoms were significantly inhibited when different amounts of MsE were mixed with these venoms before assays. On the other hand, mice that received MsE and venoms without previous mixture or by separated routes were not protected against venom toxicity. Partial chemical characterization of MsE showed the presence of polyphenols and tannins and they are known to non-specifically inactivate proteins. We suggest that these compounds can be responsible for the in vitro inhibition of the toxic effects of snake venoms. In conclusion, according to our results, using mice as experimental model, MsE does not show protection against the toxic effects of snake venoms in vivo, but if was very effective when the experiments were done in vitro.

Neutralization of some hematological and hemostatic alterations induced by neuwiedase, a metalloproteinase isolated from Bothrops neuwiedi pauloensis snake venom, by the aqueous extract from Casearia mariquitensis (Flacourtiaceae)

The aqueous extract from the leaves of Casearia mariquitensis (C. m.), a plant found in Brazilian open pastures, was assayed for its ability to inhibit some hematological and hemostatic effects induced by neuwiedase, a 22 kDa class P-I metalloproteinase from the venom of the South American pit viper Bothrops neuwiedi pauloensis. The aqueous extract from C. m. was able to neutralize the hematological alterations induced by the crude venom (C.V.) upon erythrocytes when the venom was incubated at a ratio of 1:10 (w/w, venom/extract), but it did not neutralize the platelet decreasing ability of C.V. The plasma fibrinogen concentration decreased approximately 36% and 83% when 0.6 LD(50) of the C.V. or neuwiedase, respectively, were injected by i.p. route in mice, and the aqueous extract from C. m. was able to inhibit this effect. The Bbeta fibrinogen chain was protected against degradation caused by crude venom and neuwiedase when the venom or toxin were incubated with C. m. extract. We also observed that this extract exerted a very slight effect on the clotting time, prolonging it only to a little extent. The pulmonary hemorrhage induced by neuwiedase when injected intravenously with 0.6 LD(50) was completely inhibited when this toxin was incubated with the extract at a ratio of 1:10 (w/w, toxin/extract). It is concluded that C. m. displays components able to inhibit some hematological and systemic alterations induced by C.V.

[Possibilities and limits of epidemiologic surveillance at the local level towards health surveillance]

The aim of this study is to describe and analyze Epidemiological Surveillance activities (ES) developed in a Health Care Unit and to identify their adherence to recommended Health Surveillance (HS) strategies. A checklist with the activities recommended by the Ministry of Health was used to conduct interviews with health professionals involved in ES activities. The data obtained from these interviews showed that Epidemiological Surveillance activities are limited to the notification and control of infectious diseases, and the nurses' labor is characterized by bureaucratic tasks. This shows that further discussion about Health Surveillance strategies is necessary to find ways to better implement them in health services.

Neutralization of proteases from Bothrops snake venoms by the aqueous extract from Casearia sylvestris (Flacourtiaceae)

Aqueous extract from Casearia sylvestris leaves, a typical plant from Brazilian open pastures, was able to neutralize the hemorrhagic activity caused by Bothrops asper, Bothrops jararacussu, Bothrops moojeni, Bothrops neuwiedi and Bothrops pirajai venoms. It also neutralized two hemorrhagic metalloproteinases from Bothrops asper venom. Proteolytic activity on casein induced by bothropic venoms and by isolated proteases, including Bn2 metalloproteinase from B. neuwiedi venom, was also inhibited by the C. sylvestris extract in different levels. The alpha-fibrinogen chain was partially protected against degradation caused by B. jararacussu venom, when this venom was incubated with C. sylvestris extract. We also observed that this extract partially increased the time of plasma coagulation caused by B. jararacussu, B. moojeni and B. neuwiedi venoms. C. sylvestris extract did not induce proteolysis in any substrate assayed.

Pathological alterations induced by neuwiedase, a metalloproteinase isolated from Bothrops neuwiedi snake venom

The pathological alterations induced by neuwiedase, a 22 kDa class P-I metalloproteinase from the venom of the South American pit viper Bothrops neuwiedi, were studied in mice. Neuwiedase was devoid of hemorrhagic activity when tested in the skin up to a dose of 200 microgram, and also after intramuscular injection in the gastrocnemius. However, it induced bleeding when applied onto the mouse cremaster muscle in intravital microscopy experiments, and caused pulmonary hemorrhage when injected intravenously at doses higher than 5 microgram/g. Median lethal dose (LD(50)) by the intravenous route was 5 microgram/g, whereas LD(50) of crude venom was 0.47 microgram/g. After intramuscular injection, neuwiedase induced a mild myotoxic effect, evidenced histologically and by the increment in plasma creatine kinase activity, but it was devoid of hemorrhagic and thrombotic effects. In contrast, crude B. neuwiedi venom induced prominent hemorrhage and myonecrosis in gastrocnemius muscle. Both venom and neuwiedase induced an inflammatory reaction in muscle tissue characterized by abundant polymorphonuclear leukocytes. Moreover, a conspicuous edema developed in the foot pad after subcutaneous injection of neuwiedase. Anti-neuwiedase antibodies produced in rabbits were effective in the neutralization of hemorrhagic activity of crude venom, evidencing immunological cross-reactivity between neuwiedase and other hemorrhagic metalloproteinases present in the venom, and suggesting that metalloproteinases devoid of, or having low, hemorrhagic activity could be good immunogens to generate antibodies effective against high molecular mass metalloproteinasas having potent hemorrhagic activity. It is concluded that neuwiedase, despite its lack of hemorrhagic effect when injected in the gastrocnemius muscle, contributes to local tissue damage by inducing edema, inflammatory infiltrate and mild myotoxicity, and by degrading extracellular matrix components. In addition, large doses of neuwiedase may contribute to pulmonary bleeding

Structural and functional characterization of neuwiedase, a nonhemorrhagic fibrin(ogen)olytic metalloprotease from Bothrops neuwiedi snake venom

A fibrino(geno)lytic nonhemorrhagic metalloprotease (neuwiedase) was purified from Bothrops neuwiedi snake venom by a single chromatographic step procedure on a CM-Sepharose column. Neuwiedase represented 4.5% (w/w) of the crude desiccated venom, with an approximate Mr of 20,000 and pI 5.9. As regards the amino acid composition, neuwiedase showed similarities with other metalloproteases, with high proportions of Asx, Glx, Leu, and Ser. Atomic absorption spectroscopy showed that one mole of Zn2+ and one mole of Ca2+ were present per mole of protein. The cDNA encoding neuwiedase was isolated by RT-PCR from venom gland RNA, using oligonucleotides based on the partially determined amino-acid sequences of this metalloprotease. The full sequence contained approximately 594 bp, which codified the 198 amino acid residues with an estimated molecular weight of 22,375. Comparison of the nucleotide and amino acid sequences of neuwiedase with those of other snake venom metalloproteases showed a high level of sequential similarity. Neuwiedase has two highly conserved characteristics sequences H142E143XXH146XXG149XXH152 and C164I165M166. The three-dimensional structure of neuwiedase was modeled based on the crystal structure of Crotalus adamanteus Adamalysin II. This model revealed that the zinc binding site region showed a high structural similarity with other metalloproteases. The proteolyitc specificity, using the Bbeta-chain of oxidized insulin as substrate, was shown to be directed to the Ala14-Leu15 and Tyr16-Leu17 peptide bonds which were preferentially hydrolyzed. Neuwiedase is a Aalpha,Bbeta fibrinogenase. Its activity upon the Aalpha chain of fibrinogen was detected within 15 min of incubation. The optimal temperature and pH for the degradation of both Aalpha and Bbeta chains were 37 degrees C and 7.4-8.0, respectively. This activity was inhibited by EDTA and 1,10-phenantroline. Neuwiedase also showed proteolytic activity upon fibrin and some components of the extracellular matrix. However, it did not show TAME esterase activity and was not able to inhibit platelet aggregation.

Effects of aqueous extract of Casearia sylvestris (Flacourtiaceae) on actions of snake and bee venoms and on activity of phospholipases A2

The crude aqueous extract from the leaves of Casearia sylvestris, a plant found in Brazilian open pastures, was assayed for its ability to inhibit phospholipase A2 (PLA2) activity and some biological activities of bee and several snake venoms, and of a number of isolated PLA2s. The extract induced partial inhibition of the PLA2 activity of venoms containing class I, II and III PLA2s. When tested against the purified toxins, it showed the highest efficacy against class II PLA2s from viperid venoms, being relatively ineffective against the class I PLA2 pseudexin. In addition, C. sylvestris extract significantly inhibited the myotoxic activity of four Bothrops crude venoms and nine purified myotoxic PLA2s, including Lys-49 and Asp-49 variants. The extract was able to inhibit the anticoagulant activity of several isolated PLA2s, with the exception of pseudexin. Moreover, it partially reduced the edema-inducing activity of B. moojeni and B. jararacussu venoms, as well as of myotoxins MjTX-II and BthTX-I. The extract also prolonged the survival time of mice injected with lethal doses of several snake venoms and neutralized the lethal effect induced by several purified PLA2 myotoxins. It is concluded that C. sylvestris constitutes a rich source of PLA2 inhibitors.

Myotoxic phospholipases A(2) in bothrops snake venoms: effect of chemical modifications on the enzymatic and pharmacological properties of bothropstoxins from Bothrops jararacussu

Venoms from eight Bothrops spp. were fractionated by ion-exchange chromatography on CM-Sepharose at pH 8.0 for the purification of myotoxins. Chromatographic profiles showed differences regarding myotoxic components among these venoms. B. alternatus, B. atrox and B. jararaca venoms did not show the major basic myotoxic fractions identified in the other venoms. Polyacrylamide gel electrophoresis for basic proteins also showed distinct patterns for these toxins. In vivo, all the isolated myotoxins induced release of creatine kinase due to necrosis of muscle fibers, accompanied by polymorphonuclear cell infiltration, and edema in the mouse paw. In addition, the toxins showed cytotoxic and liposome-disrupting activities in vitro. B. jararacussu bothropstoxins-I (BthTX-I) and II (BthTX-II) were submitted to chemical modifications of: His, by 4-bromophenacyl bromide (BPB) or photooxidation by Rose Bengal (RB); Tyr, by 2-nitrobenzenesulphonyl fluoride (NBSF); and Trp, by o-nitrophenylsulphenyl chloride (NPSC). The myotoxic and cytotoxic activities of BthTX-I, a Lys49 PLA(2) homologue, after modification by BPB, RB, NBSF and NPSC, were reduced to 50%, 20%, 75%, 65% and 13%, 0.5%, 76%, 58%, respectively. However, the edema-inducing and liposome-disrupting activities were not significantly reduced by the above modifications. BPB-treated BthTX-II, an Asp49 PLA(2) homologue, lost most of its catalytic, indirect hemolytic, anticoagulant, myotoxic and cytotoxic activities. The edema-inducing and liposome-disrupting activities were reduced to 50% and 80%, respectively. Lethality caused by BthTX-I and -II was strongly reduced after treatment with BPB or RB, but only partially with NBSF or NPSC. BthTX-I and -II, both native or modified, migrated similarly in a charge-shift electrophoresis. Antibodies raised against BthTX-I or -II, B. asper Basp-II and the C-terminal 115-129 peptide from Basp-II did not show significant differences in their cross-reactivity with the modified toxins, except with RB photooxidized toxins.

Structural and functional characterization of BnSP-7, a Lys49 myotoxic phospholipase A(2) homologue from Bothrops neuwiedi pauloensis venom

BnSP-7, a Lys49 myotoxic phospholipase A(2) homologue from Bothrops neuwiedi pauloensis venom, was structurally and functionally characterized. Several biological activities were assayed and compared with those of the chemically modified toxin involving specific amino acid residues. The cDNA produced from the total RNA by RT-PCR contained approximately 400 bp which codified its 121 amino acid residues with a calculated pI and molecular weight of 8.9 and 13,727, respectively. Its amino acid sequence showed strong similarities with several Lys49 phospholipase A(2) homologues from other Bothrops sp. venoms. By affinity chromatography and gel diffusion, it was demonstrated that heparin formed a complex with BnSP-7, held at least in part by electrostatic interactions. BnSP-7 displayed bactericidal activity and promoted the blockage of the neuromuscular contraction of the chick biventer cervicis muscle. In addition to its in vivo myotoxic and edema-inducing activity, it disrupted artificial membranes. Both BnSP-7 and the crude venom released creatine kinase from the mouse gastrocnemius muscle and induced the development of a dose-dependent edema. His, Tyr, and Lys residues of the toxin were chemically modified by 4-bromophenacyl bromide (BPB), 2-nitrobenzenesulfonyl fluoride (NBSF), and acetic anhydride (AA), respectively. Cleavage of its N-terminal octapeptide was achieved with cyanogen bromide (CNBr). The bactericidal action of BnSP-7 on Escherichia coli was almost completely abolished by acetylation or cleavage of the N-terminal octapeptide. The neuromuscular effect induced by BnSP-7 was completely inhibited by heparin, BPB, acetylation, and CNBr treatment. The creatine kinase releasing and edema-inducing effects were partially inhibited by heparin or modification by BPB and almost completely abolished by acetylation or cleavage of the N-terminal octapeptide. The rupture of liposomes by BnSP-7 and crude venom was dose and temperature dependent. Incubation of BnSP-7 with EDTA did not change this effect, suggesting a Ca(2+)-independent membrane lytic activity. BnSP-7 cross-reacted with antibodies raised against B. moojeni (MjTX-II), B. jararacussu (BthTX-I), and B. asper (Basp-II) myotoxins as well as against the C-terminal peptide (residues 115-129) from Basp-II.

Crystallization and preliminary X-ray diffraction analysis of a myotoxic phospholipase A(2) homologue from Bothrops neuwiedi pauloensis venom

Crystals of a myotoxic phospholipase A(2) from Bothrops neuwiedi pauloensis have been obtained. They diffracted at 2.5 A resolution using a synchrotron radiation source and belong to space group P3(1)21. Preliminary analysis shows that there are two molecules in the asymmetric unit.

Purification and partial characterization of a new proteolytic enzyme from the venom of Bothrops moojeni (CAISSACA)

A basic serine protease which is active on casein and fibrinogen was purified from Bothrops moojeni venom using a single step chromatography on a CM-Sepharose fast flow column. The enzyme, MOO3, was not hemorrhagic and presented only a trace of blood-clotting activity. Synthetic chromogenic substrates (azoacasein and azoalbumin) where not hydrolyzed by MOO3. Using polyacrylamide gel electrophoresis at pH 4.3, MOO3 showed as a single protein band. Using sodium dodecyl sulfate-polyacrylamide electrophoresis, MOO3 behaved as a single-chain protein with an approximate mol. weight of 27,000, both in the presence and absence of beta-mercaptoethanol. Its pI was 7.8 by electrofocusing. The enzyme did not contain neutral carbohydrates and its N-terminal amino acid was alanine. The amino acid composition showed 249 residues/mole, a high content of hydrophilic amino acids and 14 half-cystine residues, which should account for 7 disulfide bonds. The protease cleaved the A-alpha chain faster than the B-beta of bovine fibrinogen and showed no effect on the delta-chain. Specific esterolytic activity of MOO3 on alpha-N-tosyl-l-arginine methyl ester was 29.64 mumol min-1 x mg-1. MOO3 represented 1.42% (w/w) of the initial desiccated venom. Its proteolytic activity was inhibited by beta-mercaptoethanol, leupeptin, phenylmethylsulphonyl fluoride and ethylenediamine tetraacetate.

Isolation and characterization of an arginine ester hydrolase from Bothrops jararacussu venom which induces contractions of the isolated rat uterus

The isolation and partial characterization of a serine protease with arginine ester hydrolase activity from Bothrops jararacussu snake venom are described. The purification procedure consisted of a gel filtration of the crude venom on Sephadex G-75 followed by an ion-exchange chromatography of the active fraction on DEAE-cellulose and a rechromatography on Bio-Rex 70 resin. The esterase fraction (DI-III), M(r) = 25,000 by SDS-PAGE, showed proteolytic activity on fibrinogen and casein. After 2 hr incubation, the A alpha and B beta chains of fibrinogen were intensely hydrolysed, while the gamma chain kept apparently intact, even after 20 hr of incubation. In spite of that, DI-III did not clot fibrinogen. DI-III induced edema in the rat paw. Although unable to release bradykinin, it induced contractions of the isolated rat uterus. DI-III did not catalyse the hydrolysis of bradykinin. Its arginine ester hydrolase activity was completely inhibited by diisopropyl fluorophosphate after 1 hr incubation, but not by phenylmethylsulfonyl fluoride under the same conditions.

Geographic variations in the composition of myotoxins from Bothrops neuwiedi snake venoms: biochemical characterization and biological activity

(1) Venom pools from Bothrops neuwiedi (Bn) and from two subspecies, namely Bothrops neuwiedi pauloensis (Bnp) and Bothrops neuwiedi urutu (Bnu), collected in the States of São Paulo (SP) and Minas Gerais (MG), Brazil, were electrophoretically examined. Basic toxins with different isoelectric points were identified in the venom collected in São Paulo (BnSP). These toxins were absent in the corresponding pools from Minas Gerais (BnMG, BnpMG and BnuMG). (2) BnSP, but not BnMG, BnpMG or BnuMG, showed two myotoxins (pI approximately equal to 8.6 and 8.8, respectively) which were isolated by ion-exchange chromatography on CM-Sepharose. (3) From BnMG, three myotoxic isoforms (pI approximately equal to 8.2 and M(r) = 13,600) were isolated by chromatography on CM-Sepharose followed by reversed-phase high-performance liquid chromatography. (4) The chemical and biological characterization of these toxins showed a high similarity with the Lys-49 myotoxins from other bothropic venoms. (5) Doses up to 5 LD50 (i.p.) of p-bromophenacyl bromide alkylated BnSP-7 caused a total loss of lethality in 18-22-g mice, thus indicating that the LD50 was increased by greater than 5-fold. At this dose myotoxicity was also not detectable, but the edematogenic activity on the rat paw apparently did not change.

A rapid procedure for the isolation of the Lys-49 myotoxin II from Bothrops moojeni (caissaca) venom: biochemical characterization, crystallization, myotoxic and edematogenic activity

Bothtrops moojeni snake venom was fractionated on a CM-Sepharose column which was previously equilibrated with 0.05 M ammonium bicarbonate buffer at pH 8.0 and subsequently eluted with an ammonium bicarbonate concentration gradient from 0.05 to 0.5 M at constant pH (8.0) and temperature (25 degrees C). The fraction which eluted last (M-VI) showed, after direct lyophilization, a single band by polyacrylamide gel electrophoresis (PAGE) and SDS-PAGE, indicating an approximate Mr of 14000 and 27000, in the presence and absence of dithiothreitol, respectively. Its amino acid composition revealed a high level of hydrophobic and basic amino acids as well as 14 half-cystine residues. Its isoelectric point and extinction coefficient (E(1.0 mg/ml) (1.0 cm) at 278 nm and pH 7.0) were 8.2 and 1.170, respectively. M-VI was devoid of phospholipase A2 (PLA2) activity on egg yolk, as well as of hemorrhagic, anticoagulant and coagulant activities, but could induce drastic necrosis on skeletal muscle fibres as well as rapid and transient edema on the rat paw. Its N-terminal sequence: SLFELGKMILQETGKNPAKSYGVYGCNCGVGGRGKPKDATDRCCYVHKCCYK... revealed high homology with other Lys 49 PLA2-like myotoxins from other bothropic venoms. Orthorhombic crystals of M-VI, which diffracted to a maximal resolution of 1.6 A, were obtained and indicated the presence of a dimer in the asymmetrical unit.

Inhibition of proteases, myotoxins and phospholipases A2 from Bothrops venoms by the heteromeric protein complex of Didelphis albiventris opossum serum

The antibothropic complex (ABC) from opossum (species Didelphis albiventris) serum was purified by chromatography on DEAE-Sephacel. It showed an acidic character and two polypeptide chains of ca. 45 kDa and 48 kDa, respectively. Lyophilized opossum serum or the ABC (100 micrograms), as well as ethylenediamine tetraacetate (0.25 mumoles) were able to completely neutralise the hemorrhagic effect of 50 micrograms of the desiccated venoms of Bothrops moojeni, Bothrops pirajai and Bothrops jararacussu. The myotoxic (100 micrograms venom in mice) and edematogenic (90 micrograms venom in rats) activities of Bothrops moojeni and Bothrops jararacussu venoms, as well as of the major myonecrotic protein (myotoxin-I) isolated from Bothrops moojeni venom, were also totally inhibited by the ABC (200 micrograms and 270 micrograms, respectively). The lyophilized opossum serum (30 micrograms) and the ABC (30 micrograms) reduced to 50% the phospholipase A2 activity of Bothrops moojeni venom (10 micrograms). The clotting activity of Bothrops alternatus and Bothrops moojeni (20 micrograms) on bovine plasma was also significantly inhibited by the ABC (60 micrograms).