348 resultados para GALACTO-OLIGOSACCHARIDES
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Background: Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results: Three different chemogenomic fitness assays, haploinsufficiency (HIP), homozygous deletion (HOP), and multicopy suppression (MSP) profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms), membrane functions (e.g. signalling, transport and targeting), membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Conclusions: Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS-induced cell membrane permeability and damage. We found that the ARL1 COS-resistant over-expression strain was as sensitive to Amphotericin B, Fluconazole and Terbinafine as the wild type cells and that when COS and Fluconazole are used in combination they act in a synergistic fashion. The gene targets of COS identified in this study indicate that COS’s mechanism of action is different from other commonly studied fungicides that target membranes, suggesting that COS may be an effective fungicide for drug-resistant fungal pathogens.
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Background: Tumour metastasis remains the principal cause of treatment failure and poor prognosis in patients with cancer. Recent advances in our understanding of the biology of metastasis are providing novel potential targets for anti-cancer therapies. Aim: This paper reviews the current concepts in tumour metastasis. Methods: A review of Medline publications relating to the molecular biology and therapy of human tumour metastasis was conducted. Results and Discussion: Early metastasis models were based upon the premise of uninterrupted tumour growth, with the inevitable formation of distant metastases and eventual death of the patient. However, current research suggests that metastasis is an inefficient process governed by several rate-limiting steps, and that failure to negotiate these steps can lead to tumour dormancy. Successful metastatic tumour growth depends upon appropriate tumour-host microenvironment interactions and, ultimately, the development of vascularised metastases post-extravasation in the target organ. An understanding of the molecular mechanisms involved in this dynamic process will aid in the identification of therapeutic targets that may allow earlier diagnosis and more specific therapies for patients with metastasis.
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The phosphosulfomannan 1 (PI-88) is a mixture of highly sulfated oligosaccharides that is currently undergoing clinical evaluation in cancer patients. As well as it's anticancer properties, 1 displays a number of other interesting biological activities. A series of analogues of 1 were synthesized with a single carbon (pentasaccharide) backbone to facilitate structural characterization and interpretation of biological results. In a fashion similar to 1, all compounds were able to inhibit heparanase and to bind tightly to the proangiogenic growth factors FGF-1, FGF-2, and VEGF. The compounds also inhibited the infection of cells and cell-to-cell spread of herpes simplex virus (HSV-1). Preliminary pharmacokinetic data indicated that the compounds displayed different pharmacokinetic behavior compared with 1. Of particular note was the n-octyl derivative, which was cleared 3 times less rapidly than 1 and may provide increased systemic exposure.
Resumo:
Purpose: PI-88 is a mixture of highly sulfated oligosaccharides that inhibits heparanase, an extracellular matrix endoglycosidase, and the binding of angiogenic growth factors to heparan sulfate. This agent showed potent inhibition of placental blood vessel angiogenesis as well as growth inhibition in multiple xenograft models, thus forming the basis for this study. Experimental Design: This study evaluated the toxicity and pharmacokinetics of PI-88 (80-315 mg) when administered s.c. daily for 4 consecutive days bimonthly (part 1) or weekly (part 2). Results: Forty-two patients [median age, 53 years (range, 19-78 years); median performance status, 1] with a range of advanced solid tumors received a total of 232 courses. The maximum tolerated dose was 250 mg/d. Dose-limiting toxicity consisted of thrombocytopenia and pulmonary embolism. Other toxicity was generally mild and included prolongation of the activated partial thromboplastin time and injection site echymosis. The pharmacokinetics were linear with dose. Intrapatient variability was low and interpatient variability was moderate. Both AUC and C-max correlated with the percent increase in activated partial thromboplastin time, showing that this pharmacodynamic end point can be used as a surrogate for drug exposure, No association between PI-88 administration and vascular endothelial growth factor or basic fibroblast growth factor levels was observed. One patient with melanoma had a partial response, which was maintained for >50 months, and 9 patients had stable disease for >= 6 months. Conclusion: The recommended dose of PI-88 administered for 4 consecutive days bimonthly or weekly is 250 mg/d. PI-88 was generally well tolerated. Evidence of efficacy in melanoma supports further evaluation of PI-88 in phase II trials.
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An increase in the production of palm kernel meal (PKM) coupled with the concern for continued availability of conventional feedstuffs in some parts of the world has led to research to establish the maximum inclusion level of palm kernel meal in broiler diets. The results suggested that palm kernel meal has no anti-nutritional properties and thus its inclusion is safe up to at least 40% in the diet, provided the diet is balanced in amino acids and metabolisable energy. Although feed digestibility is decreased due to high dietary fibre when PKM is included in the diet, the feed intake is increased. This makes total digestible nutrient intake relatively high. beta-mannan is the main component of palm kernel meal non-starch polysaccharide (NSP). Both mannose and manno-oligosaccharides have been reported to act as prebiotics. The inclusion of palm kernel meal in the diet improves the immune system of birds and reduces pathogenic bacteria and increases the population of nonpathogenic bacteria in the intestine. These two benefits should be considered as strong recommendations for using palm kernel meal in broiler diets, particularly in palm kernel meal producing countries, not only for increasing bird productivity but also to improve chicken health. Selective enzyme addition increases feed efficiency and digestibility as well as decreasing the moisture content of faeces.
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The separation performance of a semicontinuous counter-current chromatographic refiner (SCCR7), consisting of twelve 5.4 cm id x 75cm long columns packed with calcium charged cross-linked polysytrene resin (KORELA VO7C), was optimised. An industrial barley syrup was used containing 42% fructose, 52% glucose and 6% maltose and oligosaccharides. The effects of temperature, flow rates and concentration on the distribution coefficients were evaluated and quantified by deriving general relationships. The effects of flow rates, feed composition and concentration on the separation performance of the SCCR7 were identified and general relationships between them and the switch time, which was found to be the controlling parameter, were developed. Fructose rich (FRP) and glucose rich (GRP) product purities of 99.9% were obtained at 18.6% w/v feed concentrations. When a 66% w/v feed concentration was used and product splitting technique was employed, the throughput was 32.1 kg sugar solids/m3 resin/hr. The GRP contained less than 4.5% fructose, the FRP was over 95% pure, and the respective concentrations were 22.56 and 11.29% w/v. Over 94% of the glucose and 95.78% of the fructose in the feed were recovered in the GRP and FRP respectively. By recycling the dilute product split fractions, the GRP and FRP concentrations were increased to 25.4 and 12.96% w/v; the FRP was 90.2% pure and the GRP contained 6.69% w/v fructose. A theoretical link between batch and semicontinuous chromatographic equipments has been determined. A computer simulation was developed predicting successfully the purging concentration profiles at `pseudo-equilibrium', and also certain system design parameters. An important further aspect of the work has been to study the behaviour of chromatographic bioreactor-separators. Such batch systems of 5.4cm id and lengths varying between 30 and 230cm, were used to investigate the effect of scaling up on the conversion of sucrose into dextran and fructose in the presence of the dextransucrase enzyme. Conversions of over 80% were achieved at 4 hr sucrose residence times. The crude dextransucrase was purified using centrifugation, ultrafiltration and cross-flow microfiltration techniques. Better enzyme stability was obtained by first separating the non-solid impurities using cross-flow microfiltration, and then removing the cells from the enzyme immediately before use by continuous centrifugation.
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Human milk is the ideal nutrition source for healthy infants during the first six months of life and a detailed characterisation of the composition of milk from mothers that deliver prematurely (<37 weeks gestation), and of how human milk changes during lactation, would benefit our understanding of the nutritional requirements of premature infants. Individual milk samples from mothers delivering prematurely and at term were collected. The human milk metabolome, established by (NMR) spectroscopy, was influenced by gestational and lactation age. Metabolite profiling identified that levels of valine, leucine, betaine, and creatinine were increased in colostrum from term mothers compared with mature milk, while those of glutamate, caprylate, and caprate were increased in mature term milk compared with colostrum. Levels of oligosaccharides, citrate, and creatinine were increased in pre-term colostrum, while those of caprylate, caprate, valine, leucine, glutamate, and pantothenate increased with time postpartum. There were differences between pre-term and full-term milk in the levels of carnitine, caprylate, caprate, pantothenate, urea, lactose, oligosaccharides, citrate, phosphocholine, choline, and formate. These findings suggest that the metabolome of pre-term milk changes within 5-7 weeks postpartum to resemble that of term milk, independent of time of gestation at pre-mature delivery.
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Bifidobacteria constitute a specific group of commensal bacteria, typically found in the gastrointestinal tract (GIT) of humans and other mammals. Bifidobacterium breve strains are numerically prevalent among the gut microbiota of many healthy breast-fed infants. In the current study, we investigated glycosulfatase activity in a bacterial nursling stool isolate, B. breve UCC2003. Two putative sulfatases were identified on the genome of B. breve UCC2003. The sulfated monosaccharide N-acetylglucosamine-6-sulfate (GlcNAc-6-S) was shown to support growth of B. breve UCC2003, while, N-acetylglucosamine-3-sulfate, N-acetylgalactosamine-3-sulfate and N-acetylgalactosamine-6-sulfate, did not support appreciable growth. Using a combination of transcriptomic and functional genomic approaches, a gene cluster, designated ats2, was shown to be specifically required for GlcNAc-6-S metabolism. Transcription of the ats2 cluster is regulated by a ROK-family transcriptional repressor. This study represents the first description of glycosulfatase activity within the Bifidobacterium genus. Bifidobacteria are saccharolytic organisms naturally found in the digestive tract of mammals and insects. Bifidobacterium breve strains utilize a variety of plant and host-derived carbohydrates which allow them to be present as prominent members of the infant gut microbiota as well as being present in the gastrointestinal tract of adults. In this study, we introduce a previously unexplored area of carbohydrate metabolism in bifidobacteria, namely the metabolism of sulfated carbohydrates. B. breve UCC2003 was shown to metabolize N-acetylglucosamine-6-sulfate (GlcNAc-6-S) through one of two sulfatase-encoding gene clusters identified on its genome. GlcNAc-6-S can be found in terminal or branched positions of mucin oligosaccharides, the glycoprotein component of the mucous layer that covers the digestive tract. The results of this study provide further evidence of this species' ability to utilize mucin-derived sugars, a trait which may provide a competitive advantage in both the infant and adult gut.
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Fasciola hepatica, commonly known as liver fluke, is a trematode which causes Fasciolosis in ruminants and humans. The outer tegumental coat of F. hepatica (FhTeg) is a complex metabolically active biological matrix that is continually exposed to the host immune system and therefore makes a good vaccine target. F. hepatica tegumental coat is highly glycosylated and helminth-derived immunogenic oligosaccharide motifs and glycoproteins are currently being investigated as novel vaccine candidates. This report presents the first systematic characterisation of FhTeg glycosylation using lectin microarrays to characterise carbohydrates motifs present, and lectin histochemistry to localize these on the F. hepatica tegument. We discovered that FhTeg glycoproteins are predominantly oligomannose oligosaccharides that are expressed on the spines, suckers and tegumental coat of F. hepatica and lectin blot analysis confirmed the abundance of N- glycosylated proteins. While some oligosaccharides are widely distributed on the fluke surface other subsets are restricted to distinct anatomical regions. We selectively enriched for FhTeg mannosylated glycoprotein subsets using lectin affinity chromatography and identified 369 proteins by mass spectrometric analysis. Among these proteins are a number of potential vaccine candidates with known immune modulatory properties including proteases, protease inhibitors, paramyosin, Venom Allergen-like II, Enolase and two proteins, nardilysin and TRIL, that have not been previously associated with F. hepatica Furthermore, we provide a comprehensive insight regarding the putative glycosylation of FhTeg components which could highlight the importance of further studies examining glycoconjugates in host-parasite interactions in the context of F. hepatica infection and the development of an effective vaccine.
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Carbohydrates are a major source of energy in the diet. Classified according to their chemistry, carbohydrates can be divided into sugars (monosaccharides and disaccharides), polyols, oligosaccharides (malto-oligosaccharides and non-digestible oligosaccharides) and polysaccharides (starch and non-starch polysaccharides). However, this classification does not allow a simple translation into nutritional effects since each class of carbohydrates has overlapping physiological properties and effects on health. Carbohydrates can also be classified according to their digestion and absorption in the human small intestine. Digestible carbohydrates are absorbed and digested in the small intestine; non-digestible carbohydrates are resistant to hydrolysis in the small intestine and reach the large intestine where they are at least partially fermented by the commensal bacteria present in the colon. There is no universal definition of the term ‘dietary fibre’; broadly speaking, it refers to some or all of the constituents of non-digestible carbohydrates and may also include other quantitatively minor components (e.g.lignin) that are associated with non-digestible carbohydrates in plant cell walls.
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Infant formula is consumed by the majority of infants in the United States for at least part of the first year of life. Infant formula lacks many of the bioactive compounds that are naturally occurring in breast milk. Because of this, there has been an increased interest by the companies that manufacture infant formula to include additives that would potentially allow formula to more closely mimic breast milk activity. One such ingredient currently being added to infant formula is prebiotics. Prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth of specific healthful bacteria in the colon. It is speculated that prebiotics replicate the activity of breast milk oligosaccharides, which through the production of butyrate by intestinal microbiota, may interact with the Wnt/BMP pathways. The Wnt/BMP pathways regulate intestinal stem cells, which determine the growth, development and maintenance of the intestine. Therefore, the objective of this study was to explore the effects that the addition of prebiotics to formula have on the regulation of the Wnt/BMP pathways when fed to neonatal piglets, a model commonly used in the study of infant nutrition. Piglets (n=5) were randomized into sow-reared (SR), fed control formula (F), or fed formula with added prebiotics (F+P). Fructooligosaccharides (FOS) (2 g/L) and polydextrose (PDX) (2 g/L) were chosen as the prebiotics for this study, because this combination had been less studied than other combinations. Ileum and ascending colon were collected at 7 and 14 days-of-age. Dry matter content, pH, and short chain fatty acid (SCFA) content was measured. The mRNA expression of β-catenin, sFRP3, sFRP4, frizzled 6, DKK1 (Wnt pathway), gremlin (BMP pathway), TNF-a, HNF-4α and osteopontin (OPN) was measured by RT-qPCR. Piglets fed the F+P diet had greater acetate concentration and lower pH in the ileum at day 14 and in the colon at day 7 and day 14 than F piglets. Butyrate concentrations were highest in SR with F+P not differing from F in ileum at day 14 and colon at day 7 and day 14. Effects of age were seen in all genes, with the exception of OPN, sFRP-3 and sFRP-4. On day 7, no effect of diet was observed in the ileum, however, mRNA expression of DKK1 and frizzled 6 were greater in F+P than SR (p≤0.05). On day 14, gremlin expression was lower and OPN was greater in the ileum of SR piglets compared to F and F+P. Also on day 14, HNF-4α mRNA expression was greater in both ileum and colon of F+P piglets and sFRP3 mRNA expression was greater in the colon than F or SR . In summary, differences were observed between gene expression of F+P and SR piglet intestines, but the supplementation of 2 g/L scFOS and 2 g/L PDX to formula did not shift expression of genes in the Wnt/BMP pathways to be more similar to SR than F. As the Wnt/BMP pathway is known to exist in a gradient along the crypt-villus axis, with Wnt expression dominating in the crypt region and BMP expression dominating in the villi, it was possible that pooling whole tissue reduced our ability to detect treatment effects that would be concentrated in either region. A method was therefore developed to remove intestinal epithelial cells along the villus-to-crypt axis. Twenty-five-day-old F and SR piglets were euthanized and ileal tissue was collected and placed in a dissociation buffer in a shaking water bath. Exfoliated cells were removed at increasing time points from 5 to 100 minutes in order to remove cells along the villus-to-crypt axis. After the final incubation, remaining mucosal tissue was removed using a sterile glass microscope slide and pooled with the final exfoliated cell isolation. After each cell collection, a section of tissue was fixed in formalin for histomorphological examination. Expression of genes in the Wnt/BMP pathways, along with crypt marker genes (CDK5 and v-myb), were measured in both whole ileal tissue, pooled epithelial cells, and separate epithelial cell isolations from the same piglet. The expression of β-catenin, HNF-4α, TNF-α, TGF-β and the crypt marker v-myb matched the expected villus-to-crypt pattern in cells collected after 10 (incubation 1), 30 (incubation 2) and 60 (incubation 3) minutes. However, expression of expression in cells collected after 100 minutes (incubation 4) was variable, which may be due to the fact that crypt cells were not efficiently removed and the presence of unwanted non-epithelial tissue. Gremlin, OPN, DKK1, sFRP3 and sFRP4 expression was not statistically different along the villus-to-crypt axis. Frizzled 6 and CDK5 did not express as we had predicted, with expression highest towards the villi. In summary, the epithelial cell collection method used was not entirely successful. While much of the gene data suggests that cells were removed along the villus-to-crypt axis through the first three incubations, the last incubation, which involved scraping the tissue, removed non-epithelial components of the mucosa, while leaving the crypts intact. In conclusion, the addition of 2 g/L PDX and 2 g/L scFOS did not cause gene expression of the Wnt/BMP pathways to mirror either F or SR expression. New isolation methods to extract cells along the crypt-villus axis should be considered, including the use of a laser capture microdissection. While this combination of prebiotics did not yield the intended effects, future research should be done on other combinations, such as the inclusion of galactooligosaccharides (GOS), which is commonly added to food products including infant formula.
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Somatic embryogenesis has been shown to be an efficient in vitro plant regeneration system for many crops such as the important ornamental plant Cyclamen persicum, for which this regeneration pathway of somatic embryogenesis is of interest for the vegetative propagation of parental lines as well as elite plants. However, somatic embryogenesis is not commercially used in many crops due to several unsolved problems, such as malformations, asynchronous development, deficiencies in maturation and germination of somatic embryos. In contrast, zygotic embryos in seeds develop and germinate without abnormalities in most cases. Instead of time-consuming and labor-intensive experiments involving tests of different in vitro culture conditions and plant growth regulator supplements, we follow a more directed approach. Zygotic embryos served as a reference and were compared to somatic embryos in metabolomic analyses allowing the future optimization of the in vitro system. The aims of this study were to detect differences in the metabolite profiles of torpedo stage somatic and zygotic embryos of C. persicum. Moreover, major metabolites in endosperm and testa were identified and quantified. Two sets of extracts of two to four biological replicates each were analyzed. In total 52 metabolites were identified and quantified in the different tissues. One of the most significant differences between somatic and zygotic embryos was that the proline concentration in the zygotic embryos was about 40 times higher than that found in somatic embryos. Epicatechin, a scavenger for reactive oxygen species, was found in highest abundance in the testa. Sucrose, the most abundant metabolite was detected in significantly higher concentrations in zygotic embryos. Also, a yet unknown trisaccharide, was significantly enriched in zygotic embryos.
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Este estudo envolve o controlo e a optimização das condições de culturas dos microrganismos: Saccharomyces cerevisiae CCMI 396, S. cerevisiae v. lab., Aspergillus oryzae CCMI 125, Aspergillus japonicus CCMI 443, Fusarium oxysporum CCMI 866, Aspergillus niger CCMI 296 com vista à produção de oligossacáridos. Determinaram-se os parâmetros característicos das culturas de duas diferentes estirpes de Saccharomyces com diferentes fontes de carbono e em diferentes condições ambientais. O perfil de crescimento da S. cerevisiae CCMI 396 foi semelhante nos diferentes meios de cultura estudados, sendo a velocidade específica de crescimento mais elevada no meio com glucose a pH 5 e a 30°C (0,36h-1). A S. cerevisiae v. lab. Teve velocidade específica de crescimento idêntica nas mesmas condições da outra estirpe, no entanto, o perfil de crescimento foi diferente nos outros meios de cultura. Estudou-se o efeito da adição de sumo de laranja ou de tomate ao meio de cultura com sacarose e avaliou-se a evolução glucídica no meio de cultura durante o ensaio por HPLC com detector RI. Determinou-se a frutosiltransferase no sobrenadante e na fracção intracelular e determinou-se a evolução dos oligossacáridos. Numa segunda parte deste trabalho efectuaram-se culturas dos quatro fungos filamentosos com vista a avaliar a capacidade de produção, nomeadamente, de frutooligassacáridos. Os resultados mostraram que a espécie Aspergillus japonicus CCMI 443 originou, nas mesmas condições de cultura, valores superiores, sendo a percentagem de produção FOStotais/GluCtotais de 61% para as enzimas intracelulares e 40% para as enzimas no sobrenadante. ABSTRACT; This study involves control and optimization of the cultures of microorganisms: Saccharomyces cerevisiae CCMI 396, S. cerevisiae v. lab., Aspergillus oryzae CCMI 125, Aspergillus japonicus CCMI 443, Fusarium oxysporum CCMI 866, Aspergillus níger CCMI 296 for oligosaccharides production. Were determined the parameters characteristic of the cultures of two different strains of Saccharomyces with different sources of carbon and in different environmental conditions. The growth profile of S. cerevisiae CCMI 396 was similar in different cultures media, but the highest specific growth was obtained in a medium with glucose, pH 5, at 30°C (0.36h-1). S. cerevisiae v. lab. had similar growth profile in a medium with glucose but with others culture media was different. We studied the effect of adding orange juice or tomato to the culture medium with sucrose and evaluated the evolution glucidic in the culture medium during the test by HPLC with RI detector. Fructosyltransferase was determined in the extracellular and the intracellular fractions and determined the evolution of oligosaccharides. ln the second part of this work were carried out cultures of four filamentous fungi in order to assess production capacity, in particular, fructoligosaccharides. The results showed that the specie Aspergillus japonicus CCMI 443 originated in the same culture conditions, higher values and the percentage of production FOStotal/Guctotal of 61% for intracellular enzymes and 40% for extracellular enzymes.
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The acquisition of oligosaccharides from chitosan has been the subject of several studies in the pharmaceutical, biochemical, food and medical due to functional properties of these compounds. This study aimed to boost its production of chitooligosaccharides (COS) through the optimization of production and characterization of chitosanolytic enzymes secreted by microorganisms Paenibacillus chitinolyticus and Paenibacillus ehimensis, and evaluating the antioxidant potential of the products obtained. In the process of optimizing the production of chitosanase were employed strategies Fractional Factorial Experimental Design and Central Composite Rotatable Design. The results identified the chitosan, peptone and yeast extract as the components that influenced the production of chitosanase by these microorganisms. With the optimization of the culture media was possible to obtain an increase of approximately 8.1 times (from 0.043 to 0.35 U.mL U.mL-1) and 7.6 times (from 0.08 U.mL-1 to 0.61 U.mL-1) in the enzymatic activity of chitosanase produced by P. chitinolyticus and P. ehimensis respectively. Enzyme complexes showed high stability in temperature ranges between 30º and 55º C and pH between 5.0 and 9.0. Has seen the share of organic solvents, divalent ions and other chemical agents on the activity of these enzymes, demonstrating high stability of these crude complexes and dependence of Mn2+. The COS generated showed the ability of DPPH radical scavenging activity, reaching a maximum rate of scavenging of 61% and 39% when they were produced with enzymes of P. ehimensis and P. chitinolyticus respectively. The use of these enzymes in raw form might facilitate its use for industrial applications