Geciane Toniazzo

Enzymatic synthesis of ascorbyl palmitate in ultrasound-assisted system: Process optimization and kinetic evaluation

This work is focused on the optimization of reaction parameters for the synthesis of ascorbyl palmitate catalyzed by Candida antarctica lipase in different organic solvents under ultrasound irradiation. The sequential strategy of experimental design proved to be useful in determining the optimal conditions for reaction conversion in tert-butanol system using Novozym 435 as catalyst. The optimum production was achieved at 70°C, ascorbic acid to palmitic acid molar ratio of 1:9, enzyme concentration of 5 wt% at 3h of reaction, resulting in an ascorbyl palmitate conversion of about 27%. Reaction kinetics for ascorbyl palmitate production in ultrasound device showed that satisfactory reaction conversions (∼26%) could be achieved in short reaction times (2h). The empirical kinetic model proposed is able to satisfactorily represent and predict the experimental data.

Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae).

BACKGROUND The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains. RESULTS The essential oils chemical composition showed that the E. benthamii presents the cis-ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 microL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD(50) values were calculated and E. dunnii was shown to be the most efficient (25.03 microL), followed by E. saligna (37.93 microL) and E. benthamii (121.09 microL). Using the previously calculated LD(50) values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter. CONCLUSION The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment.

Produção de carotenoides: microrganismos como fonte de pigmentos naturais

Carotenoids are natural dyes synthesized by plants, algae and microorganisms. Application in many sectors can be found, as food dyeing and supplementation, pharmaceuticals, cosmetics and animal feed. Recent investigations have shown their ability to reduce the risks for many degenerative diseases like cancer, heart diseases, cataract and macular degeneration. An advantage of microbial carotenoids is the fact that the cultivation in controlled conditions is not dependent of climate, season or soil composition. In this review the advances in bio-production of carotenoids are presented, discussing the main factors that influence the microbial production of these dyes in different systems.

Ultrasound-assisted enzymatic transesterification of methyl benzoate and glycerol to 1-glyceryl benzoate in organic solvent.

The aim of this work is to report the enzymatic transesterification production of 1-glyceryl benzoate under ultrasound irradiation, using a commercial immobilized lipase, Novozym 435. Firstly, a preliminary evaluation was carried out at 2, 4 and 6h, at constant temperature of 50 °C, methyl benzoate to glycerol molar ratio of 1:1 and 5.5 wt% of enzyme concentration. After analyzing the results obtained, the experimental design technique was used to evaluate the effects of temperature, substrates molar ratio, enzyme concentration, solvent volume and ultrasonic power on the 1-glyceryl benzoate production. The highest conversion, around 16%, was obtained at 65 °C, 1:1 of methyl benzoate to glycerol molar ratio, 15 wt% of enzyme concentration, 7 mL of solvent and 40% ultrasonic power in 4h of reaction. A preliminary kinetic experiment carried out varying the enzyme concentration (15 and 20 wt%) keeping fixed the temperature at 35 °C, 1:1 of substrates molar ratio, 3 mL of solvent and 40% of maximum ultrasonic power led to lower (around 15% after 12 h of reaction) conversions compared to that achieved in the experimental design.

SUCCESSIVE CYCLES OF UTILIZATION OF NOVOZYM 435 IN THREE DIFFERENT REACTION SYSTEMS

The main focus of this work was to investigate the residual esterification activity and the product conversion after 10 successive cycles of utilization of a commercial lipase in three systems: esterification of 2-ethyl hexanol and palmitic acid in a solvent-free system; esterification of ascorbic acid and palmitic acid in tert-butanol; and transesterification of glycerol and methyl benzoate in 2-propanol. These systems were chosen based on previous results by our research group in terms of product conversion. Before scale-up, there is a need for evaluating several cycles of utilization of the biocatalyst. The esterification of 2-ethyl hexanol showed that after 10 cycles the enzyme retained 90% of its activity. The system consisting of ascorbic acid, palmitic acid, Novozym 435 and tert-butanol showed that a reduction in enzyme activity was accompanied by a reduction in reaction conversion; the same behavior was not observed for the third system.

Biotransformation of (−)β-Pinene by Aspergillus niger ATCC 9642

The main objective of this work was to investigate the biotransformations of (−)β-pinene, (−)β-pinene, and (+) limonene by Aspergillus niger ATCC 9642. The culture conditions involved—concentration of cosolvent (EtOH), substrate applied, and sequential addition of substrates—were investigated. Adaptation of the precultures with small amounts of substrate was also studied. The experiments were performed in conical flasks with liquid cultures. This strain of A. niger was able to convert only (−)β-pinene into α-terpineol. An optimum conversion of (−)β-pinene into γ-terpineol of about 4% was obtained when the substrate was applied as a diluted solution in EtOH and sequential addition of substrate was used.

Perfil da composição química e atividades antibacteriana e antioxidante do óleo essencial do cravo-da-índia (Eugenia caryophyllata Thunb.)

A busca por substâncias antibacterianas e antioxidantes naturais tem sido alvo de diversos estudos cientificos. Foi objetivo determinar as atividades antibacteriana e antioxidante e a concentracao inibitoria minima do oleo essencial do cravo-da-india, obtido por hidrodestilacao. O estudo por CG-EM identificou o eugenol como o constituinte majoritario do oleo essencial e os testes de atividade antibacteriana mostraram bons resultados para quase todos os microorganismos avaliados. Os valores de concentracao inibitoria minima variaram de 0,2 mg.mL-1 a 0,6 mg.mL-1. Aatividade antioxidante demonstrou uma correlacao linear com a concentracao de oleo essencial. Os resultados demonstraram potencial antibacteriano e antioxidante do oleo essencial de Eugenia caryophyllata, constituindo-se uma opcao para a formulacao de novos produtos alimenticios.

Screening of microorganisms for production of carotenoids Selección de microorganismos para la producción de carotenoides

This work aimed at screening microorganisms capable of producing carotenoids. Microorganisms were isolated from soil, leaves, fruits, flowers, agro-industrial wastes, and processed product in decomposition and then grown in an orbital shaker, using 10% (w/v) of inoculum (25 °C, 180 rpm for 48 h) and incubated for 120 h in a dark room. A total of 116 microorganisms were isolated and screened: 16 yeasts, 65 bacteria, and 35 fungi. Three yeasts demonstrated great potential to produce red carotenoids, with a total carotenoid content of 707–818 μg L−1 (99–263 μg g−1). One filamentous fungus and two bacteria produced mostly yellow pigments in a final concentration ranging from 1063 to 2563 μg L−1 (239–2310 μg g−1). From 116 isolated microorganisms, several of them showed potential for production of carotenoid-synthesizing activity. RAPD analysis was used to check the genetic differences between the screened strains, showing that all microorganisms were from different species. El objetivo de este trabajo fue examinar los microorganismos capaces de producir carotenoides. Microorganismos de tierra, hojas, frutos, flores, residuos agro-industriales y producto procesado en descomposición se aislaron y se cultivaron en un agitador orbital, usando 10% (w/v) de inóculo (25 °C, 180 rpm durante 48 horas) e incubados durante 120 h en una habitación oscura. Se aislaron y examinaron un total de 116 microorganismos, 16 levaduras, 65 bacterias y 35 hongos. Tres levaduras demostraron un gran potencial para producir carotenoides rojos, con un contenido total de carotenoides de entre 707 a 818 μg L−1 (de 99 a 263 μg g−1). Un hongo filamentoso y dos bacterias produjeron en su mayoría pigmentos amarillos en una concentración final de entre 1063 a 2563 μg L−1 (239 a 2310 μg g−1). De 116 microorganismos aislados, varios de ellos mostraron potencial para la producción de actividad sintetizadora de carotenoides. Se usó el análisis RAPD para revisar las diferencias genéticas entre las cepas examinadas, mostrando que todos los microorganismos eran de diferentes especies.

Atividade antimicrobiana e antioxidante do óleo essencial de ho-sho (Cinnamomum camphora Ness e Eberm Var. Linaloolifera fujita)

Este trabalho teve como objetivo determinar a atividade antimicrobiana e antioxidante do oleo essencial de Ho-Sho. O principal componente do oleo essencial obtido a partir de folhas da planta submetidas ao processo de hidrodestilacao foi o linalol (80 a 95% m/m). O oleo essencial mostrou atividade antimicrobiana para todos os microrganismos testados, com excecao de Pseudomonas aeruginosa. A maior atividade antimicrobiana do oleo essencial sobre as bacterias testadas foi observada sobre Xanthomonas campestris (33,0 mm) e a menor sobre Yersinia enterocolitica (10,5 mm). Para a concentracao inibitoria minima (CIM), observou-se que todos os microrganismos apresentaram-se susceptiveis ao oleo essencial de Ho-Sho. A variacao das CIM para as bacterias Gram-positivas foi de 1,00 mg.mL-1 (Streptococcus mutans) a 1,75 mg.mL-1 (Staphylococcus epidermidis). Ja a variacao das CIM para as bacterias Gram-negativas foi de 0,625 mg.mL-1 (Citrobacter freundii) a 2,50 mg.mL-1 (Shigella flexneri). Os resultados obtidos na determinacao da atividade antioxidante do oleo essencial demonstram que o percentual antioxidante aumenta proporcionalmente a concentracao de oleo essencial adicionado, atingindo o valor maximo de 97,49% de atividade antioxidante para a concentracao de 50000 μg.mL-1.

Enzyme-catalyzed production of 1-glyceryl benzoate in compressed n-butane.

The aim of this work is to report the enzymatic transesterification production of 1-glyceryl benzoate in compressed n-butane, using a commercial immobilized lipase, Novozym 435. For this purpose, reaction experiments were performed on the basis of phase equilibrium data of the system methyl benzoate/n-butane, measured using the static synthetic method with a variable-volume view cell in the temperature range of 313.15-343.15K and pressures up to 12MPa, in the entire compositional range of n-butane. Results indicate the existence of a relatively complex phase behavior for all temperatures investigated with the occurrence of vapor-liquid and liquid-liquid phase transitions. Reaction results showed that the strategy adopted for the experimental design proved to be useful in optimizing the reaction conversion in pressurized n-butane and Novozym 435. The optimum conditions were found to be 5.5wt% of enzyme, methyl benzoate to glycerol molar ratio of 3:1, 50°C and 6h of reaction, affording about 6% of 1-glyceryl benzoate yield.