Application in situ of biodegradable films produced with starch, citric pectin and functionalized with feijoa (Acca sellowiana (Berg) Burret) extracts: An effective proposal for food conservation

In this study, biodegradable films produced with starch, citric pectin, and functionalized with antioxidant compounds from feijoa (Acca sellowiana (Berg) Burret) were in situ applied for the conservation of ground beef, bread, and grapes. The results demonstrated that the films produced were an excellent source of stable antioxidant compounds, with antimicrobial activity against Escherichia coli, Salmonella, and Shigella. The bioactive films based on biological macromolecules positively stabilized the polyunsaturated fatty acids and deterioration reactions in ground beef. The release of bioactive compounds from the films was responsible for inhibiting molds and yeasts in bread, increasing their shelf life for 30 days of storage. The application of film coating and packaging in grapes increased postharvest conservation and maintained steady physicochemical characteristics. Therefore, the innovative films produced can release bioactive compounds with antioxidant and antimicrobial activity, and consequently, can be proposed as an effective material for food conservation, increasing the shelf life of perishable food products.

Physicochemical properties and biological activities of bracatinga honeydew honey from different geographical locations

Bracatinga (Mimosa scabrella Bentham) honeydew honey is a Brazilian dark honey in increasing international appreciation. In this sense, the knowledge of its composition and potential biological properties becomes indispensable. In the present study, the physicochemical characteristics, including mineral and phenolic composition, and the scavenging, reducing, and antimicrobial proprieties of bracatinga honeydew honey (bhh) from five different geographical locations, were investigated. Bhh proved to be a potential functional food due to its high content of minerals (up to 6395 mg kg^-1) and phenolic compounds (up to 2393 µg 100 g^-1) and high scavenging and reducing activities. High antimicrobial activity against four bacterial strains, with minimum inhibitory concentration values ranging from 10 to 60%, were also found. Additionally, through principal component analysis, partial discrimination of bhh was observed according to the geographical location, which favored the separation of samples from Lages, and mainly due to the presence of nectar in this honey, which was proposed for the samples from Bom Retiro.

SUPPLEMENTARY INFORMATION

The online version of this article (10.1007/s13197-020-04937-x) contains supplementary material, which is available to authorized users.

Feijoa [Acca sellowiana (Berg) Burret] accessions characterization and discrimination by chemometrics

BACKGROUND

Feijoa [Acca sellowiana (Berg) Burret] is a Brazilian native fruit with few commercial-level plantations and high agroindustrial potential. A genotype evaluation experiment was conducted from 1996 onward, aiming to obtain fruits based on the agronomical parameters; however, the selection based on chemical composition had not been evaluated with respect to developing a new cultivar. Accordingly, the present study aimed to discriminate seven accessions of feijoa in terms of nutritional composition, phenolic compounds and antioxidant activity using multivariate analysis (principal component analysis and multivariate contrast), targeting the potential production of a new cultivar with better nutritional value and high antioxidant capacity.

RESULTS

Feijoa husk presented high content of ashes, lipids, proteins, carbohydrates, phenolic compounds and antioxidant activity compared to feijoa pulp. However, only feijoa pulp was selected to multivariate analysis because it is the fruit edible part. Data variability was explained in 78% and the feijoa pulp accessions were discriminated into four groups related to their characteristics. The accession 5 discrimination can be explained by the high content of ashes, carbohydrates, soluble solids, phenolic compounds and antioxidant activity. Accession 6 was also discriminated by the high content of total acidity, pH and proteins, as well as a low content of soluble solids.

CONCLUSION

Feijoa accessions may be indicated for increasing plant selection via hybridization with the other accessions, aiming to produce new cultivars with better nutritional composition and antioxidant capacity. For example, accession 5 is the most suited fruit for human consumption and is a potential plant with respect to becoming a new cultivar. © 2020 Society of Chemical Industry.

Geographical discrimination of uvaia (Eugenia pyriformis Cambess) by principal component analysis

BACKGROUND

The international marketing of native Brazilian fruits may benefit from research into discrimination between plants with particular properties. Plants with certain characteristics have strong potential for use in agroindustry and for the development of new processed products. In the current study, 12 uvaia plants (Eugenia pyriformis Cambess), native to Brazil, were geographically discriminated by chemometric methods, using nutritional composition, physicochemical characterization, bioactive compounds, and antioxidant capacity data.

RESULTS

Uvaia fruits presented good nutritional value, with a high moisture and carbohydrate content. All fruits presented a pH value lower than 4, being classified as highly acidic, and the total soluble solids (°Brix) ranged between 2.90 and 9.80. Some plants had a higher vitamin C content, and all the plants had a high bioactive compound content (phenolic and flavonoids) and antioxidant capacity in 1,1-difenil-2-picrilhidrazil (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays. Hydroethanolic solution was the best extraction solvent tested when compared with water and ethanol. Using principal component analysis, it was possible to discriminate among the plants in five different groups; however, just one group was responsible for higher antioxidant compound content.

CONCLUSION

In this work, 12 native uvaia plants were discriminated by their geographical origin using a chemometric approach. Genetic improvement based on natural selection could be accomplished with some of the plants to improve the quality of uvaia pulp and to develop new cultivars. © 2019 Society of Chemical Industry.

Evaluation of oral sugar test response for detection of equine metabolic syndrome in obese Crioulo horses

Owing to the high prevalence of obesity in Crioulo horses, information allowing early diagnosis of equine metabolic syndrome (EMS) and prevention of the associated laminitis is of great value. The aim of this study was to evaluate the occurrence of EMS and the response to an oral sugar test (OST) in obese Crioulo horses. Twenty-two Crioulo horses were allocated into 3 groups according to their body condition score (BCS out of 9) and presence or absence of laminitis as follows: CON (6/22), BCS < 7; OB (8/22), BCS ≥ 7; and LAM (8/22), BCS ≥7 with clinical and/or radiographic signs of laminitis. A complete clinical history was obtained, followed by a physical examination, morphometric measurements, radiographic evaluation of front feet, and ultrasonography measurements of subcutaneous body fat. For the OST, animals were fasted overnight, and blood samples were collected for glucose and insulin concentration before and after sugar administration. Morphometric and metabolic differences (P < 0.05) were observed between CON animals and obese ones, with horses from the LAM group presenting the highest morphometric measurements and insulin plasma concentrations. A delayed peak glucose response for OST was observed in the majority of obese animals, indicating that sampling between 60 and 90 min after sugar administration without glycemic curve follow-up, as previously used for hyperinsulinism detection, can be inadequate. The observed delay in the return to glucose baseline levels, combined with high insulin levels, supports the diagnosis of insulin dysregulation. These results indicate that there are clear obesity-related differences in the glucose and insulin responses of Crioulo horses to an OST.

Proteome comparison for discrimination between honeydew and floral honeys from botanical species Mimosa scabrella Bentham by principal component analysis

BACKGROUND

Due to the increasing valuation and appreciation of honeydew honey in many European countries and also to existing contamination among different types of honeys, authentication is an important aspect of quality control with regard to guaranteeing the origin in terms of source (honeydew or floral) and needs to be determined. Furthermore, proteins are minor components of the honey, despite the importance of their physiological effects, and can differ according to the source of the honey. In this context, the aims of this study were to carry out protein extraction from honeydew and floral honeys and to discriminate these honeys from the same botanical species, Mimosa scabrella Bentham, through proteome comparison using two-dimensional gel electrophoresis and principal component analysis.

RESULTS

The results showed that the proteome profile and principal component analysis can be a useful tool for discrimination between these types of honey using matched proteins (45 matched spots). Also, the proteome profile showed 160 protein spots in honeydew honey and 84 spots in the floral honey.

CONCLUSION

The protein profile can be a differential characteristic of this type of honey, in view of the importance of proteins as bioactive compounds in honey. © 2017 Society of Chemical Industry.

Effect of in vitro gastrointestinal digestion on the bioaccessibility of phenolic compounds, minerals, and antioxidant capacity of Mimosa scabrella Bentham honeydew honeys

Honey is a product traditionally consumed due to its possible health benefits promoted by natural antioxidants. However, few studies have evaluated the effect of in vitro gastrointestinal digestion on these compounds in honeys. To improve the knowledge of this subject, the present study aimed to investigate the influence of simulated digestion on the stability of antioxidant capacity (FRAP, DPPH, and Folin-Ciocalteu assays), phenolic compounds (LC-ESI-MS/MS), and minerals (CE-DAD) in Mimosa scabrella Bentham honeydew honeys. The results show that the digestive system, mainly after duodenal digestion, significantly decreased the antioxidant capacity assessed by FRAP (410.3±18.3 to 564.7±8.4μmolFe⁺²100g^-1), DPPH (30.1±0.8 to 33.9±1.4mgAAE100g^-1), and Folin-Ciocalteu assays (58.3±2.6 to 142.0±1.6mgGAE100g^-1) of this honey. However, phenolic compounds and minerals showed high stability and in some cases, significantly increased after the simulated digestion, presenting a bioaccessible fraction that ranged from 78.2±6.4 to 174.38±6.82% and 94.0±4.3 to 220.5±3.4%, respectively. Therefore, these honey constituents may be considered highly bioaccessible and potentially bioavailable. Additionally, the correlation between the investigated parameters suggests that other honey constituents could also possibly affect antioxidant capacity of this honey. In conclusion, the bracatinga (Mimosa scabrella Benth.) honeydew honey can be highlighted as an important natural source of bioaccessible polyphenols, besides presenting highly bioaccessible minerals in its composition, maintaining a satisfactory antioxidant capacity.

Maternal attitudes towards tooth decay in children aged 12-18 months in Pelotas, Brazil

AIM

This was to assess mothers' attitudes towards dental caries in children aged 12-18 months.

METHODS

This study targeted mothers of children aged 12-18 months. Data about demographic and socioeconomic status were collected by interviews with each mother. In addition, the mother was asked about her attitudes regarding caries in her child's primary teeth. A dental examination of each child was also conducted. Chi-square, bivariate, and multiple logistic regression analyses were performed.

RESULTS

A total of 262 mother-child pairs were included, and 18.7 % of the children had dental caries. If a child presented with dental caries in their primary teeth, 93.5 % of the mothers reported that they would take the child to a dentist. Mothers who had only one child and those who had children with dental caries were more likely to report that they did not expect primary dental caries treatment by the dentist.

CONCLUSION

Most mothers reported that they would take their children to a dentist when they presented with dental caries. Despite this positive result, educational measures should continue to be emphasised, especially among mothers of children at a higher risk of caries and among first-time mothers.

Correlation between the cariogenic response in biofilms generated from saliva of mother/child pairs

This study aimed to correlate the cariogenic responsiveness of biofilms generated from the saliva of mothers and children. The mother-child pairs were classified according to the children's caries levels: caries-free, early childhood caries (ECC) or severe ECC. Microcosm biofilms were grown on enamel discs for 10 days. Factors under evaluation were caries experience levels, inoculum source (mothers and children) and growth conditions including cariogenic challenge (growth medium provided with and without sucrose) and no cariogenic challenge (growth medium sucrose-free). Statistical analysis was performed with ANOVA and Tukey's test, and the Spearman correlation test. Regular sucrose exposure resulted in a higher surface hardness change (%SHC). The correlation between biofilms formed from saliva of mother-child pairs was significant regarding pH, total aciduric microorganisms and lactobacilli counts under cariogenic challenge. Biofilm growth originating from mother-child pairs under regular sucrose exposure promoted the same cariogenic response independently of caries experience and the microbiological profile of the donors.

Development of a fast and selective separation method to determine histamine in tuna fish samples using capillary zone electrophoresis

This paper reports on the development of a fast and selective separation method by capillary zone electrophoresis (CZE) for the determination of histamine in tuna fish samples. The background electrolyte was composed of 60 mmol L(-1) hydroxyisobutyric acid and 10 mmol L(-1) sodium hydroxide at pH 3.3. The internal standard used was imidazole. Separations were performed in a fused uncoated silica capillary (32 cm total length, 8.5 cm effective length and 50 μm internal diameter) with direct UV detection at 210 nm. The samples and standards were injected hydrodynamically (50 mbar, 3s) from the outlet capillary end (nearest to the detector) and the electrophoretic system was operated under normal polarity and constant voltage conditions of 30 kV (positive polarity on the injection side). The migration time of histamine in the proposed method was only 0.34 min. The method was then validated and different tuna fish samples were analyzed. Good linearity (R(2)>0.999), a limit of detection 0.14 mg L(-1), intra-day precision better than 3.5% (peak area of sample), and recovery in the range of 94-108% were obtained. The results of the histamine concentration determined in the samples by the CZE method were compared with the LC-MS/MS method.

An in vitro biofilm model for enamel demineralization and antimicrobial dose-response studies

Microcosm biofilms formed in microplates have demonstrated complex community dynamics similar to natural dental biofilm. No simplified microcosm models to evaluate enamel demineralization and dose-response effect to anticariogenic therapies have yet been established, thus this study was designed to develop a pre-clinical model fulfilling this purpose. Experiments were carried out to establish the time of biofilm formation and the sucrose concentration and exposure regimen. Biofilms were initiated from saliva and grown for up to 10 days on bovine enamel discs in 24-well plates, with a saliva analogue medium. Data were collected as pH readings and the percentage enamel surface hardness change. A dose-response evaluation was performed with chlorhexidine, which significantly affected the pH and mineral loss. Overall, the established model parameters, 5 days of biofilm growth with intermittent 1% sucrose exposure of 6 h per day, was suitable as a pre-clinical model for enamel demineralization and dose-response studies.

Viremia and nasal and rectal shedding of rotavirus in gnotobiotic pigs inoculated with Wa human rotavirus

Respiratory symptoms with rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (Zheng et al., 1991, J. Med. Virol. 34:29-37). To investigate if attenuated and virulent human rotavirus (HRV) strains cause upper respiratory tract infections or viremia in gnotobiotic pigs, we inoculated them with attenuated or virulent HRV intranasally, intravenously, or orally or via feeding tube (gavage) and assayed virus shedding. After oral or intranasal inoculation with attenuated HRV, the pigs remained asymptomatic, but 79 to 95% shed virus nasally and 5 to 17% shed virus rectally. After inoculation by gavage, no pigs shed virus nasally or rectally, but all pigs seroconverted with antibodies to HRV. No viremia was detected through postinoculation day 10. Controls inoculated intranasally with nonreplicating rotavirus-like particles or mock inoculated did not shed virus. In contrast, 100% of pigs inoculated with virulent HRV (oral, intranasal, or gavage) developed diarrhea, shed virus nasally and rectally, and had viremia. The infectivity of sera from the viremic virulent HRV-inoculated pigs was confirmed by inoculating gnotobiotic pigs orally with pooled HRV-positive serum. Serum-inoculated pigs developed diarrhea and fecal and nasal virus shedding and seroconverted with serum and intestinal HRV antibodies. Pigs inoculated intravenously with serum or intestinal contents from the viremic virulent HRV-inoculated pigs developed diarrhea, virus shedding, and viremia, similar to the orally inoculated pigs. This study provides new evidence that virulent HRV causes transient viremia and upper respiratory tract infection in addition to gastrointestinal infection in gnotobiotic pigs, confirming previous reports of rotavirus antigenemia (Blutt et al., Lancet 362:1445-1449, 2003). Our data also suggest that intestinal infection might be initiated from the basolateral side of the epithelial cells via viremia. Additionally, virus shedding patterns indicate a different pathogenesis for attenuated versus virulent HRV.

Protective immunity and antibody-secreting cell responses elicited by combined oral attenuated Wa human rotavirus and intranasal Wa 2/6-VLPs with mutant Escherichia coli heat-labile toxin in gnotobiotic pigs

Two combined rotavirus vaccination regimens were evaluated in a gnotobiotic pig model of rotavirus infection and disease and were compared to previously tested rotavirus vaccination regimens. The first (AttHRV/VLP2x) involved oral inoculation with one dose of attenuated (Att) Wa human rotavirus (HRV), followed by two intranasal (i.n.) doses of a rotavirus-like particle (2/6-VLPs) vaccine derived from Wa (VP6) and bovine RF (VP2) rotavirus strains. The 2/6-VLPs were coadministered with a mutant Escherichia coli heat-labile toxin, LT-R192G (mLT) adjuvant. For the second regimen (VLP2x/AttHRV), two i.n. doses of 2/6-VLPs+mLT were given, followed by one oral dose of attenuated Wa HRV. To compare the protective efficacy and immune responses induced by the combined vaccine regimens with individual rotavirus vaccine regimens, we included in the experiments the following vaccine groups: one oral dose of attenuated Wa HRV (AttHRV1x and Mock2x/AttHRV, respectively), three oral doses of attenuated Wa HRV (AttHRV3x), three i.n. doses of 2/6-VLPs plus mLT (VLP3x), three i.n. doses of purified double-layered inactivated Wa HRV plus mLT (InactHRV3x), mLT alone, and mock-inoculated pigs. The isotype, magnitude, and tissue distribution of antibody-secreting cells (ASCs) in the intestinal and systemic lymphoid tissues were evaluated using an enzyme-linked immunospot assay. The AttHRV/VLP2x regimen stimulated the highest mean numbers of intestinal immunoglobulin A (IgA) ASCs prechallenge among all vaccine groups. This regimen induced partial protection against virus shedding (58%) and diarrhea (44%) upon challenge of pigs with virulent Wa HRV. The reverse VLP2x/AttHRV regimen was less efficacious than the AttHRV/VLP2x regimen in inducing IgA ASC responses and protection against diarrhea (25% protection rate) but was more efficacious than VLP3x or InactHRV3x (no protection). In conclusion, the AttHRV/VLP2x vaccination regimen stimulated the strongest B-cell responses in the intestinal mucosal immune system at challenge and conferred a moderately high protection rate against rotavirus disease, indicating that priming of the mucosal inductive site at the portal of natural infection with a replicating vaccine, followed by boosting with a nonreplicating vaccine at a second mucosal inductive site, may be a highly effective approach to stimulate the mucosal immune system and induce protective immunity against various mucosal pathogens.

Genotyping of group A rotavirus samples from Brazilian children by probe hybridization

The G genotyping of 74 group A rotavirus samples was done by RNA-DNA hybridization (dot-blot) using oligonucleotide probes for the VP7 gene region of the human rotavirus serotypes/genotypes 1, 2, 3 and 4. Thirty-one samples could be genotyped by dot-blot showing the following results: G1 = 16, G4 = 6, G3 = 5, and G2 = 4. The data show circulation of genotypes G1-G4 and the predominance of G1. The knowledge of genotypes provides important information concerning rotavirus circulation in Central Brazil.

Serotypes and subgroups of rotavirus isolated from children in central Brazil

Group A rotavirus, obtained from children of Goiânia, Brazil, during 1987-1994, were analyzed for subgroup and G serotype by enzyme-linked immunosorbent assay with monoclonal antibodies. The index of serotyping obtained was 61.4% with the following proportions: G1--19.7%, G2--28.0%, G3--9.8%, G4--1.5%, and G5--2.3%. It was observed that G1 occurred from 1987 to 1989 and from 1993 to 1994, and G2 from 1990 to 1993. About 94% of the samples (85/90) could be subgrouped with the following results: 55.5% for SG II, 7.8% SG I, and 31.1% for SG non-I-non-II. Unusual relationship patterns were also detected among serotypes, subgroups, and profiles of electropherotypes in 57.0% of the samples: 20 of them were G2/SG II/"long" profile. The results suggest that variation in temporal and regional characteristics should be considered in the development of rotavirus vaccine.

Superoxide anion radical generation during the oxidation of various amines by diamine oxidase

Diamine oxidase (DAO) or histaminase is an enzyme which deaminates histamine and several aliphatic amines to their corresponding aldehydes. Hydrogen peroxide and ammonia are side products of this reaction. The purpose of the present work was to evaluate if determination of produced hydrogen peroxide reflects DAO activity or if intermediate formation of the superoxide radical could be a reason for lack of correspondence between oxygen uptake and hydrogen peroxide production at different pH. Superoxide radical formation was determined by cytochrome c reduction in the presence and absence of superoxide dismutase (SOD). Oxygen uptake was measured with an oxygen electrode and hydrogen peroxide production by a spectrophotometric method. At pH 6.6 there was no superoxide production, but at pH 7.4 there was some, and it increased markedly at pH 9.5. Oxygen uptake also increased with increasing pH, especially with histamine as substrate. These results lead us to suggest that the mechanism of action of DAO involves the intermediate generation of superoxide radicals.

Risk factors and prevalence of antibodies against hepatitis A virus (HAV) in children from day-care centers, in Goiania, Brazil

A seroepidemiologic survey about hepatitis A virus (HAV) infection was carried out in a group comprising 310 children, ranging in age from 3 months to 9 years, from day-care centers, in Goiania, a middle sized city in the central region of Brazil. The biomarkers employed in the investigation of previous infection include total IgG and IgM anti-HAV antibodies, and for the detection of more recent infection, IgM anti-HAV antibodies were analyzed. The study was performed in 1991 and 1992. According to the results, 69.7% of the children presented total IgG/IgM anti-HAV antibodies, with 60% of the group in the age range of 1 to 3 years. Among 10 day-care centers analyzed, the prevalence of the biomarker IgM anti-HAV was 3.2%, with an uniform distribution of the cases in the group of children ranging in age from 1 to 4 years. Multivariate analysis was performed to investigate the sociodemographic factors that could influence the results. It was verified that the risk for the infection increased with the length of the attendance in the day-care centers, i.e., the risk for children with attendance of one year or more was 4.7 times higher, when compared with children with one month attendance (CI 95% 2.3-9.9). According to the results, hepatitis A is an endemic infection in day-care centers in the study area. The length of attendance in the day-care settings was demonstrated to be a risk factor for the HAV infection. Such findings suggest that if hepatitis A vaccination becomes available as a routine policy in our region, the target group should be children under one year. Moreover, those children should receive the vaccine before they start to attend the day-care centers.

[Seroepidemiology of hepatitis A virus infection in street children of Goiânia-Goiás]

A cross-sectional study was performed to determine the age-prevalence of hepatitis A virus (HAV) among street youth from Goiania city--Central Brazil, and to determine if any risk factors could be identified. The surveys were conducted between 1991/1992. The street youth were 397 individuals aged 7 to 21 years old living in institutions and teenagers working at streets. Then, 313 adolescents working at streets and with family links, and 84 institutionalized ones without family were screened for antibodies against HAV. Prevalences ranged from 80.0% to 92.2% to total anti-HAV and there was not a statistically significant trend of positivity with age in this group. Univariate analysis for risk factors associated with HAV infection was performed with no statistically significant difference for adolescents working at streets and living with parents, and street youth with family links. Economic variables were not statistically associated with seropositivity, probable due to homogeneous characteristics of the group. This study disclosed that street youth have a high rate of HAV infection. These findings do not suggest differences between subgroups of populations in acquiring immunity to HVA. The public health implication and the need of screening other subgroups of population of the same city were suggested in order to discuss vaccine strategy in underdeveloped countries.

[Rotavirus and adenovirus in 0- to 5-year-old children hospitalized with or without gastroenteritis in Goiâna, GO, Brazil]

In order to detect rotavirus and adenovirus 557 feces samples from hospitalized children (0-5 years of age) were analysed from June 1987 to July 1990 in Goiânia city. Two hundred and ninety one samples were from children with diarrhoea and 266 were from children without diarrhoea. Amongst this later group, 64 samples were from children from the nursery. Two hundred and sixty one out of 557 samples were analysed by immunoelectron microscopy (IEM), polyacrylamide gel electrophoresis (SDS-PAGE) and enzymatic immunoassay for rotavirus and adenovirus (EIARA) whereas the rest (296 samples) were analysed by SDS-PAGE and EIARA. Positivity of rotavirus and adenovirus was 17.2% and 2.1% respectively. Concerning rotavirus and adenovirus there was 29.2% and 2.4% positivity within the group with diarrhoea and 4.1% and 1.5% positivity amongst children without diarrhoea (p < 0.05). Rotavirus were more prevalent amongst children which age ranged from 1 to 11 months of age. No newborn child from the nursery was positive for rotavirus. Adenovirus were detected amongst children from 1 to 3 years of age. Rotavirus circulation peak occurred between May and August (p < 0.05) and no positive case was detected from December to February. Two hundred out of 291 diarrheic samples were also studied concerning bacteria and pathogenic parasites and equal percentages (17.0%) were found for both rotavirus and pathogenic bacteria. Eighty nine samples of rotavirus were detected by SDS-PAGE and 86 of these (96.6%) belonged to the subgroup II with 13 different electrophoretic patterns. Predominance of a given electrophoretic profile was observed in each year of the study.

Oxidative inhibition of red blood cell ATPases by glyceraldehyde

Glyceraldehyde and other simple monosaccharides autoxidize under physiological conditions, forming dicarbonyl compounds and hydrogen peroxide via intermediate free radicals. These products may have deleterious effects on cell components. In this paper we study the effect of glyceraldehyde autoxidation on red-cell ATPase activities. The autoxidation of glyceraldehyde in imidazole-glycylglycine buffer, measured by oxygen consumption, depends on the buffer concentration and decreases in the presence of superoxide dismutase and catalase. The addition of DETAPAC inhibits the autoxidation almost completely. When human red-blood-cell membranes are incubated with glyceraldehyde, the red-blood-cell ATPase activities decrease significantly. The addition of DETAPAC, GSH and DTE (dithioerythritol) protects the enzyme from inactivation, but superoxide dismutase and catalase have no effect. Methylglyoxal (a dicarbonyl which is analogous to hydroxypyruvaldehyde derived from glyceraldehyde autoxidation) proved to have a powerful inhibitory action on ATPase activities. The addition of DTE completely protects the enzyme from inactivation, suggesting that the sulphydryl groups of the active site of the enzyme are the critical targets for dicarbonyl compounds.

Decrease in blood histamine in drug-treated parkinsonian patients

Blood histamine and serum histaminase activity were determined in a group of patients with Parkinson disease (PD) and in a group of healthy controls. Untreated PD patients present significantly higher blood histamine than normal controls. Therapy with L-dopa + cardidopa results in a significant decrease in blood histamine. This decrease becomes more accentuated when anticholinergics are added to this therapy. No significant changes were detected in plasma histaminase. The authors suggest, as a hypothesis, that the CNS contributes to blood histamine concentration and that its rise is the result of increased neuronal destruction.

Early increase in histamine concentration in the islets of Langerhans isolated from rats made diabetic with streptozotocin

Sprague-Dawley rats were separated in 4 groups. G1 received streptozotocin (ST). G2 received nicotinamide (NC) followed by ST. G3 was a NC control and G4 was a citrate control. The rats were sacrificed after 28 h and the islets isolated. Histamine and histaminase were determined. In the islets there was an increase in histamine content in G1 and a smaller increase in G2. The first two groups differ significantly and also in relation to the control groups. A decrease in islet histaminase does not seem responsible for the increased histamine, since group 2 (NC + ST) which had no diabetes, had a lower activity than group 1 (ST). It is suggested that histamine liberation by ST may be related to the diabetogenic effect of this drug.

[Maillard compounds as a cause of aging]

Several theories have been presented to explain the mechanism of aging. Among those theories, two are supported by strong reasons: the generation of oxygen radicals and nonenzymatic glycosylation of proteins. Oxygen and glucose are essential for the central nervous system (and practically for all tissues) and at the same time they are the main cause of aging. Through our demonstration that Maillard compounds generate oxygen free radicals, both theories may be united in one.

Oxygen radical generation by Maillard compounds

Amino sugars such as galactosamine are hepatotoxic. It has been verified that toxic hepatitis induced by galactosamine is similar to that of CCl4 poisoning, and that both were inhibited by O2* scavengers. Fructosamine results from the union of glucose with the epsilon-amine of lysine. A test for fructosamine quantification is based on nitroblue tetrazolium (NBT) reduction, in which O2- is involved, the reduction being inhibited in the presence of superoxide dismutase (SOD). Given these facts, we attempted to elucidate if galactosamine and glucosamine reduce NBT and if that reduction is inhibited by SOD. This was confirmed. Subsequently, we incubated aminoacids (glycine, lysine, alanine) with glucose and galactose for 7 days and studied the action of the incubation products on NBT, using amino acids and sugars as controls. We found that NBT reduction increases proportionally to the length of incubation time of glucose/galactose with lysine, but not with other amino acids. Reduction of NBT by the Amadori compounds formed is inhibited by SOD. We suggest that oxygen radical generation by Amadori compounds must be taken into consideration as one cause of damage in diabetes of long duration.

Mechanisms of hemolysis induced by copper

An excess of copper is the cause of hemolysis in a number of clinical conditions. Incubation of human erythrocyte (RBC) suspensions with copper (II) causes the formation of methemoglobin, lipid peroxidation and hemolysis. A new variant of the thiobarbituric acid (TBA) method, which minimizes the formation of interfering chromophores, was used to detect lipid peroxidation. Lipid peroxidation precedes hemolysis and the antioxidant vitamins C and E, which inhibit lipid peroxidation, also inhibit hemolysis. Consequently lipid peroxidation appears to be the cause of RBC destruction. Lipid peroxidation arises mostly from the oxidation of oxyhemoglobin by copper as it is inhibited in RBCs with carbon monoxyhemoglobin or methemoglobin. A direct interaction of copper with the red cell membrane seems to play only a minor role. Copper effects depend on the presence of free SH groups. Lipid peroxidation is probably initiated by activated forms of oxygen as it is increased by an inhibitor of catalase and reduced by hydroxyl radical scavengers. With higher copper concentrations hemolysis is greater: its mechanism appears different as lipid peroxidation is smaller but hemoglobin alterations, namely precipitation, are more pronounced.

The neutralization of hydroxyl radical by silibin, sorbinil and bendazac

The compounds silibin, sorbinil and bendazac act as hydroxyl radical scavengers, when the hydroxyl radical is generated by the Fenton reaction. Hydroxyl was detected by the degradation of deoxyribose. The Authors discuss the possibility that the scavenger activities of those compounds may explain, at least in part, their therapeutic activity.