Estudi de la fotodescomposició de l'àcid 4-clor-2-metilfenoxiacètic (MCPA)

Photodegradation of MCPA in aqueous solutions has been studied using UN. radiation and simulated sunlight with sensitizers. The main photoproducts have been characterized and a possible sequence of hotodecomposition leas been postulated. The kinetic study has been carried out in both processes for initial reaction times. It has been proved that the riboflavine, contained in husk rice is one of the most effective sensitizers to degrade MCPA

Screening of plant peptidases for the synthesis of arginine-based surfactants

Partially purified preparations with proteolytic activity, obtained from South American native plants, were used as biocatalysts in condensation reactions of N-protected arginine alkyl ester derivatives with decylamine and dodecylamine in low-water content systems. The final products are cationic surfactants with potential application as emulsifiers and preservatives. Most of the proteolytic extractswere obtained from latex of species belonging to the Asclepiadaceae family (araujiain from Araujia hortorum, asclepain c from Asclepias curassavica and funastrain from Funastrum clausum). Hieronymain was obtained from unripe fruits of Bromelia hieronymi (Bromeliaceae). Plant proteases from commercial sources (papain and bromelain) were also tested as catalysts in the same reactions. Araujiain and funastrain furnished good reaction conversions (60–84%, with a ratio synthesis/hydrolysis of 2–5) similar to those obtained with commercial papain. Moreover, araujiain was the biocatalyst which rendered the best conversions (60%) for the synthesis of the two novel Bz-Arg-NH-dodecylamide (Bz-Arg-NHC₁₂) and Bz-Arg-NH-decylamide (Bz-Arg-NHC₁₀) derivatives. Moderate to poor conversions (10–50%, showing a ratio synthesis/hydrolysis of 0.5–1) were achieved with asclepain c, hieronymain and bromelain. The screening presented in this work revealed that, although these are structurally similar, their behavior for the synthesis of this kind of products differ among them.Centro de Investigación de Proteínas Vegetale

Biocatalytic synthesis, antimicrobial properties and toxicity studies of arginine derivative surfactants

Two novel arginine-based cationic surfactants were synthesized using as biocatalyst papain, an endopeptidase from Carica papaya latex, adsorbed onto polyamide. The classical substrate Nα-benzoyl-arginine ethyl ester hydrochloride for the determination of cysteine and serine proteases activity was used as the arginine donor, whereas decyl- and dodecylamine were used as nucleophiles for the condensation reaction. Yields higher than 90 and 80 % were achieved for the synthesis of Nα-benzoyl-arginine decyl amide (Bz-Arg-NHC10) and Nα-benzoyl-arginine dodecyl amide (Bz-Arg-NHC12), respectively. The purification process was developed in order to make it more sustainable, by using water and ethanol as the main separation solvents in a single cationic exchange chromatographic separation step. Bz-Arg-NHC10 and Bz-Arg-NHC12 proved antimicrobial activity against both Gram-positive and Gram-negative bacteria, revealing their potential use as effective disinfectants as they reduced 99 % the initial bacterial population after only 1 h of contact. The cytotoxic effect towards different cell types of both arginine derivatives was also measured. Bz-Arg-NHCn demonstrated lower haemolytic activity and were less eye-irritating than the commercial cationic surfactant cetrimide. A similar trend could also be observed when cytotoxicity was tested on hepatocytes and fibroblast cell lines: both arginine derivatives were less toxic than cetrimide. All these properties would make the two novel arginine compounds a promising alternative to commercial cationic surfactants, especially for their use as additives in topical formulations.Centro de Investigación de Proteínas Vegetale

Biocatalytic synthesis, antimicrobial properties and toxicity studies of arginine derivative surfactants

Two novel arginine-based cationic surfactants were synthesized using as biocatalyst papain, an endopeptidase from Carica papaya latex, adsorbed onto polyamide. The classical substrate Nα-benzoyl-arginine ethyl ester hydrochloride for the determination of cysteine and serine proteases activity was used as the arginine donor, whereas decyl- and dodecylamine were used as nucleophiles for the condensation reaction. Yields higher than 90 and 80 % were achieved for the synthesis of Nα-benzoyl-arginine decyl amide (Bz-Arg-NHC10) and Nα-benzoyl-arginine dodecyl amide (Bz-Arg-NHC12), respectively. The purification process was developed in order to make it more sustainable, by using water and ethanol as the main separation solvents in a single cationic exchange chromatographic separation step. Bz-Arg-NHC10 and Bz-Arg-NHC12 proved antimicrobial activity against both Gram-positive and Gram-negative bacteria, revealing their potential use as effective disinfectants as they reduced 99 % the initial bacterial population after only 1 h of contact. The cytotoxic effect towards different cell types of both arginine derivatives was also measured. Bz-Arg-NHCn demonstrated lower haemolytic activity and were less eye-irritating than the commercial cationic surfactant cetrimide. A similar trend could also be observed when cytotoxicity was tested on hepatocytes and fibroblast cell lines: both arginine derivatives were less toxic than cetrimide. All these properties would make the two novel arginine compounds a promising alternative to commercial cationic surfactants, especially for their use as additives in topical formulations.Centro de Investigación de Proteínas Vegetale

Comparative behaviour of proteinases from the latex of Carica papaya and Funastrum clausum as catalysts for the synthesis of Z-Ala-Phe-OMe

The proteolytic extract obtained from the latex of Funastrum clausum (Jacq.) Schlechter (Asclepiadaceae), a South American climbing plant, was assayed as a novel catalyst for peptide synthesis and compared with commercial papain under the same conditions. After immobilization on polyamide, the synthesis of the bitter peptide precursor Z-Ala-Phe-OMe was performed and different conditions were tried. Acetonitrile and ethyl acetate with low water content were tested as organic solvents. Equilibrium- and kinetically-controlled synthesis were tried by using either Z-Ala-OH or Z-Ala-OMe as acyl donors, respectively. The best conditions for the synthesis of the desired product varied according to the catalyst used. For papain, thermodynamic control in acetonitrile (aw ∼= 0.12) in the presence of triethylamine (TEA) or boric acid–borate buffer (40 mM), and equilibrium- and kinetic-controlled synthesis in ethyl acetate (aw ∼= 0.75) proved to be the best conditions. The thermodynamic control in either acetonitrile with aw ∼= 0.12 (40mM TEA or Na₂CO₃) or ethyl acetate (aw ∼= 0.75) were the best conditions found for funastrain. In all cases, the formation of oligopeptides up to three Phe was observed. The proteolytic extract of F. clausum latex showed more selectivity than papain towards the conversion to Z-Ala-Phe-OMe leading to less proportion of oligopeptides.Centro de Investigación de Proteínas Vegetale

Combining aldolases and transaminases for the synthesis of 2‑amino-4-hydroxybutanoic acid

Amino acids are of paramount importance as chiral building blocks of life, for drug development in modern medicinal chemistry, and for the manufacture of industrial products. In this work, the stereoselective synthesis of (S)- and (R)-2-amino-4-hydroxybutanoic acid was accomplished using a systems biocatalysis approach comprising a biocatalytic one-pot cyclic cascade by coupling of an aldol reaction with an ensuing stereoselective transamination. A class II pyruvate aldolase from E. coli, expressed as a soluble fusion protein, in tandem with either an S- or R-selective, pyridoxal phosphate dependent transaminase was used as a catalyst to realize the conversion, with formaldehyde and alanine being the sole starting materials. Interestingly, the class II pyruvate aldolase was found to tolerate formaldehyde concentrations of up to 1.4 M. The cascade system was found to reach product concentrations for (S)- or (R)-2-amino-4-hydroxybutanoic acid of at least 0.4 M, rendering yields between 86% and >95%, respectively, productivities of >80 g L–1 d–1, and ee values of >99%.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 635595 (CarbaZymes), the Ministerio de Economía y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (FEDER) (grant no. CTQ2015-63563-R to P.C.), and COST action CM1303 Systems Biocatalysis.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Production of an antimicrobial agent with potential surfactant activity by means of eco-friendly technologies

Papaína es una endopeptidasa extraída del látex de frutos de Carica papaya ampliamente empleada en las industrias alimentaria y farmacéutica. Es muy utilizada como biocatalizador en la síntesis de péptidos y otros derivados. Los surfactantes derivados de arginina son una familia de tensioactivos catiónicos con propiedades antimicrobianas interesantes como preservativos para formulaciones farmacéuticas y alimentarias. El objetivo del presente trabajo fue la obtención, purificación y determinación del poder antimicrobiano de un compuesto derivado de arginina con potencial actividad tensioactiva, sintetizado mediante el empleo de papaína como biocatalizador.Papain is an endopeptidase obtained from Carica papaya latex which is widely used in food and pharma industries. It has been successfully applied as biocatalyst in the synthesis of peptide and other related compounds. Arginine-based surfactants consist of a family of cationic surfactants with interesting antimicrobial properties as preservatives for pharmaceutical and food formulations. The aim of the present work was to study the production, purification and determination of antimicrobial activity of an arginine-based compound with potencial surfactant activity synthetized using papain as biocatalyst.Comité de Medio Ambient

Screening of plant peptidases for the synthesis of arginine-based surfactants

Partially purified preparations with proteolytic activity, obtained from South American native plants, were used as biocatalysts in condensation reactions of N-protected arginine alkyl ester derivatives with decylamine and dodecylamine in low-water content systems. The final products are cationic surfactants with potential application as emulsifiers and preservatives. Most of the proteolytic extractswere obtained from latex of species belonging to the Asclepiadaceae family (araujiain from Araujia hortorum, asclepain c from Asclepias curassavica and funastrain from Funastrum clausum). Hieronymain was obtained from unripe fruits of Bromelia hieronymi (Bromeliaceae). Plant proteases from commercial sources (papain and bromelain) were also tested as catalysts in the same reactions. Araujiain and funastrain furnished good reaction conversions (60–84%, with a ratio synthesis/hydrolysis of 2–5) similar to those obtained with commercial papain. Moreover, araujiain was the biocatalyst which rendered the best conversions (60%) for the synthesis of the two novel Bz-Arg-NH-dodecylamide (Bz-Arg-NHC₁₂) and Bz-Arg-NH-decylamide (Bz-Arg-NHC₁₀) derivatives. Moderate to poor conversions (10–50%, showing a ratio synthesis/hydrolysis of 0.5–1) were achieved with asclepain c, hieronymain and bromelain. The screening presented in this work revealed that, although these are structurally similar, their behavior for the synthesis of this kind of products differ among them.Centro de Investigación de Proteínas Vegetale

D-Fagomine lowers postprandial blood glucose and modulates bacterial adhesion

d-Fagomine is an iminosugar originally isolated from seeds of buckwheat (Fagopyrum sculentum Moench), present in the human diet and now available as a pure crystalline product. We tested d-fagomine for activities connected to a reduction in the risk of developing insulin resistance, becoming overweight and suffering from an excess of potentially pathogenic bacteria. The activities were: intestinal sucrase inhibition in vitro (rat mucosa and everted intestine sleeves), modulation of postprandial blood glucose in rats, bacterial agglutination and bacterial adhesion to pig intestinal mucosa. When ingested together with sucrose or starch, d-fagomine lowered blood glucose in a dose-dependent manner without stimulating insulin secretion. d-Fagomine reduced the area under the curve (0-120 min) by 20 % (P < 0•01) and shifted the time to maximum blood glucose concentration (T max) by 15 min at doses of 1-2 mg/kg body weight when administered together with 1 g sucrose/kg body weight. Moreover, d-fagomine (0•14 mm) agglutinated 60 % of Enterobacteriaceae (Escherichia coli, Salmonella enterica serovar Typhimurium) populations (P < 0•01), while it did not show this effect on Bifidobacterium spp. or Lactobacillus spp. At the same concentration, d-fagomine significantly (P < 0•001) inhibited the adhesion of Enterobacteriaceae (95-99 % cells in the supernatant) and promoted the adhesion of Lactobacillus acidophilus (56 % cells in the supernatant) to intestinal mucosa. d-Fagomine did not show any effect on bacterial cell viability. Based on all this evidence, d-fagomine may be used as a dietary ingredient or functional food component to reduce the health risks associated with an excessive intake of fast-digestible carbohydrates, or an excess of potentially pathogenic bacteria. © 2011 The Authors