Toxicity and larvicidal activity on Aedes aegypti of citronella essential oil submitted to enzymatic esterification / Toxicidade e atividade larvicida sobre Aedes aegypti de óleo essencial de citronella submetido à esterificação enzimática

Abstract The essential oil of citronella (Cymbopogon winterianus) has several biological activities, among them the insect repellent action. Some studies showed that cinnamic acid esters can be applied as natural pesticides, insecticides and fungicides. In this context, the objective of the present work was to evaluate the production of esters from citronella essential oil with cinnamic acid via enzymatic esterification. Besides, the essential oil toxicity before and after esterification against Artemia salina and larvicidal action on Aedes aegypti was investigated. Esters were produced using cinnamic acid as the acylating agent and citronella essential oil (3:1) in heptane and 15 wt% NS 88011 enzyme as biocatalysts, at 70 °C and 150 rpm. Conversion rates of citronellyl and geranyl cinnamates were 58.7 and 69.0% for NS 88011, respectively. For the toxicity to Artemia salina LC50 results of 5.29 μg mL-1 were obtained for the essential oil and 4.36 μg mL-1 for the esterified oils obtained with NS 88011. In the insecticidal activity against Aedes aegypti larvae, was obtained LC50 of 111.84 μg mL-1 for the essential oil of citronella and 86.30 μg mL-1 for the esterified oils obtained with the enzyme NS 88011, indicating high toxicity of the esters. The results demonstrated that the evaluated samples present potential of application as bioinsecticide.

Resumo O óleo essencial de citronela (Cymbopogon winterianus) possui diversas atividades biológicas, entre elas a ação repelente a insetos. Alguns estudos mostraram que os ésteres do ácido cinâmico podem ser aplicados como pesticidas naturais, inseticidas e fungicidas. Nesse contexto, o objetivo do presente trabalho foi avaliar a produção de ésteres a partir do óleo essencial de citronela com ácido cinâmico via esterificação enzimática. Além disso, foi investigada a toxicidade do óleo essencial antes e após a esterificação contra Artemia salina e a ação larvicida sobre Aedes aegypti. Os ésteres foram produzidos utilizando ácido cinâmico como agente acilante e óleo essencial de citronela (3: 1) em heptano e 15% em peso da enzima NS 88011 como biocatalisadores, a 70 ° C e 150 rpm. As taxas de conversão de cinamatos de citronelil e geranil foram 58,7 e 69,0% para NS 88011, respectivamente. Para a toxicidade sobre Artemia salina foram obtidos CL50 de 5,29 μg mL-1 para o óleo essencial e 4,36 μg mL-1 para os óleos esterificados com NS 88011. Na atividade inseticida contra larvas de Aedes aegypti, obteve-se CL50 de 111,84 μg mL-1 para o óleo essencial de citronela e 86,30 μg mL-1 para os óleos esterificados com a enzima NS 88011, indicando alta toxicidade dos ésteres. Os resultados demonstraram que as amostras avaliadas apresentam potencial de aplicação como bioinseticida.

Process conditions for a rapid in situ transesterification for biodiesel production from oleaginous yeasts

BACKGROUND: Microbial oils produced by diverse microorganisms are being considered as alternative sources of triglycerides for biodiesel production. However, the standalone production of biodiesel from microorganisms is not currently economically feasible. In case of yeasts, the use of low-value nutrient sources in microbial production and the implementation of cost-efficient downstream processes could reduce costs and make microbial lipids competitive with other commodity-type oils in biodiesel production. Industrial biodiesel synthesis from oleaginous seeds is currently based on a multistep process. However, a simple process called in situ transesterification (ISTE), which takes place within the biomass without a previous lipid extraction step, is receiving increasing interest. In this work, the optimal conditions for an ISTE process to obtain biodiesel from previously selected oleaginous yeast (Rhodotorula graminis S1/S2) were defined using the response surface methodology (RSM). RESULTS: Using the RSM approach, the optimal conditions for the maximum yield with minimum reaction time included a methanol-to-biomass ratio of 60:1, 0.4 M H2SO4, and incubation at 70°C for 3 h. The optimized in situ process yield was significantly higher (123%) than that obtained with a two-step method in which fatty acids from saponifiable lipids were first extracted and then esterified with methanol. The composition of the fatty acid methyl ester mixture obtained from R. graminis S1/S2 by ISTE met Uruguayan standards for biodiesel. CONCLUSION: The characteristics achieved by the optimized method make microbial oil a potential alternative for biodiesel production from yeast at an industrial scale.

Physiological Activities of Policosanol Extracted from Sugarcane Wax

Policosanol extracted from sugarcane wax is a generic term used for total fatty alcohols obtained from esterification of fatty acids. It has been approved as a health functional food by the Ministry of Food and Drug Safety of Korea in 2006. Policosanol is well-known to aid in lowering blood cholesterol level. Recently, several studies have reported the physiological activities of policosanol, such as anti-inflammatory effects, antioxidant effects, and lowering of the incidence of ageing-related diseases, for example, hypertension, stroke, among others. This review describes the physiological activities of policosanol and its applications in the field of health functional foods.

Toxicity of clove essential oil and its ester eugenyl acetate against Artemia salina / Toxicidade do óleo essencial de cravo e seu éster acetato de eugenila contra Artemia salina

Abstract The production of compounds via enzymatic esterification has great scientific and technological interest due to the several inconveniences related to acid catalysis, mainly by these systems do not fit to the concept of “green chemistry”. Besides, natural products as clove oil present compounds with excellent biological potential. Bioactives compounds are often toxic at high doses. The evaluation of lethality in a less complex animal organism can be used to a monitoring simple and rapid, helping the identification of compounds with potential insecticide activity against larvae of insect vector of diseases. In this sense, the toxicity against Artemia salina of clove essential oil and its derivative eugenyl acetate obtained by enzymatic esterification using Novozym 435 as biocatalyst was evaluated. The conversion of eugenyl acetate synthesis was 95.6%. The results about the evaluation of toxicity against the microcrustacean Artemia salina demonstrated that both oil (LC50= 0.5993 µg.mL–1) and ester (LC50= 0.1178 µg.mL–1) presented high toxic potential, being the eugenyl acetate almost 5 times more toxic than clove essential oil. The results reported here shows the potential of employing clove oil and eugenyl acetate in insecticide formulations.

Resumo A produção de compostos via esterificação enzimática possui grande interesse científico e tecnológico devido às inúmeras inconveniências relacionadas com a catálise ácida, principalmente por estes sitemas não se adequarem ao atual termo “tecnologias limpas”. Além disso, produtos naturais como o óleo de cravo, apresentam compostos com excelentes potenciais biológicos. Compostos bioativos são quase sempre tóxicos em altas doses. A avaliação da letalidade em um organismo animal menos complexo pode ser usada para um monitoramento simples e rápido, servindo também para a identificação de compostos com potencial atividade inseticida contra larvas de insetos vetores de doenças. Neste sentido, foi determinada a toxicidade frente a Artemia salina do óleo essencial de cravo e do seu derivado acetato de eugenila obtido por esterificação enzimática com lipase Novozym 435. A conversão da reação de síntese de acetato de eugenila foi de 95,6%. Os resultados referentes à avaliação da toxicidade frente ao microcrustáceo Artemia salina demonstraram que tanto o óleo (LC50= 0,5993 µg.mL–1) quanto o éster (LC50= 0,1178 µg.mL–1) apresentam elevado potencial toxicológico, sendo que o éster apresenta aproximadamente 5 vezes mais toxicidade em relação ao óleo. Estes resultados demonstram o potencial emprego do óleo de cravo e de acetato de eugenila em formulações de inseticidas.

Esterificación transesterificación de aceites residuales para obtener biodiesel / Esterificationannd transesterification of waste oils for biodiesel obtaining

El biodiesel es un biocombustible producido a partir de grasas y aceites, y debido a las desventajas del uso de los combustibles fósiles, su producción y consumo ha aumentado en los últimos años. En este trabajo fue estudiada la esterificación por catálisis ácida y la transesterificación alcalina de aceites residuales para obtener biodiesel. Las condiciones de relación aceite-metanol (6:1 y 5:1) y concentración de catalizador fueron variadas para seleccionar las más favorables para el proceso. Los aceites usados fueron recolectados en restaurantes de la ciudad de Cartagena. Se encontró que la variable con mayor efecto en el rendimiento de la reacción fue la relación aceite-metanol, favoreciéndose para bajas concentraciones de metanol (6:1), a las cuales se obtienen rendimientos superiores al 93%. La concentración de catalizador no influyó de manera significado la eficiencia de la esterificación. El biodiesel obtenido presentó buenas características de acidez y bajo contenido de azufre. Adicionalmente, se evidenció la necesidad de un pretratamiento a los aceites y una purificación del biodiesel para lograr el cumplimiento de estándares internacionales.

Biodiesel is a biofuel produced from fats and oils and because of the disadvantages of fossil oils use, its production and consumption has increased in recent years. In this work the esterification of waste oil by acid catalysis and alkaline transesterification to obtain biodiesel was studied. The oil-methanol (6:1 and 5:1) ratio conditions and catalyst concentration were varied to select the most favorable for the process. The oils used were collected in restaurants in the city of Cartagena. It was found that the variable to greater effect on the reaction yield was the oil-methanol ratio, favoring low concentrations of methanol (6:1), from which yields higher than 93% are obtained. The catalyst concentration did not affect significantly the efficiency of esterification. The biodiesel obtained had good acidity characteristics and low sulfur content. Additionally the need for a pretreatment to oils and biodiesel purification to achieve compliance of international standards was evidenced.

Preparative resolution of gatifloxacin enantiomers with pre-column esterification strategy and comparing their enantioselectivity to bacteria and antibody / 生物医学与环境科学（英文）

Gatifloxacin (GFX) is a kind of chiral fluoroquinolones compound due to the methyl group at the C-3 position of the piperazine ring[1]. Although the enantiomers of GFX show similar levels of antimicrobial activity and pharmacokinetics[2], the other biological activities (i.e., toxicity or enantioselective recognition to various receptors in vivo) of GFX enantiomers have not yet been studied. With this in mind, we developed a rapid and cost-effective high performance liquid chromatographic (HPLC) separation procedure for GFX enantiomers with a pre-column esterification strategy. With significant enhancement of drug solubility and optimization for chromatographic conditions, the proposed method was scaled up to preparative HPLC to obtain optical active S-(-)- and R-(+)-GFX. The antibacterial activities of GFX enantiomers after preparative separation were further verified by measuring the Minimum Inhibitory Concentration (MIC) values against Escherichia coli ATCC 25922. In addition, the binding selectivity of GFX enantiomers to protein receptor were evaluated by antibody using enzyme-linked immunosorbent assay (ELISA) for the first time.

Production and characterization of an extracellular lipase from Candida guilliermondii

Extracellular lipases from the endophytic yeast Candida guilliermondii isolated from castor leaves (Ricinus communis L.) were produced using low-cost raw materials such as agro-industrial residues and applying them in the esterification of oleic acid for evaluating their potential use in biodiesel production. After partial purification using ammonium sulfate, the enzyme was characterized and presented higher activity (26.8 ± 1.5 U mL-1) in the presence of 5 mmol L-1 NaCl at 30 ºC and pH 6.5. The production through submerged fermentation was formerly performed in 150 mL erlenmeyer flasks and, once the enzyme production was verified, assays in a 14 L bioreactor were conducted, obtaining 18 ± 1.4 U mL-1. The produced enzyme was applied in the oleic acid esterification under different solvents: hexane, cyclohexane or cyclohexanone) and different acid:alcohol molar ratios. Higher ester conversion rate (81%) was obtained using hexane and the molar ratio of 1:9 was the best conditions using methanol. The results suggest the potential for development of endophytic yeast in the production of biocatalyst through submerged fermentation using agroindustrial residues as culture medium.

Characterization of residual oils for biodiesel production

Background: Residual oils were characterized according to their physicochemical properties, i.e. acidity, iodine value, peroxide value and saponification number, to evaluate the degradation level and viability for biodiesel production. Results: The methyl esters of fatty acids (FAME) from samples of residual bovine, chicken and soybean oils were quantified by using four transesterification methods, using acidic and basic catalysis and, gas chromatography with flame ionization detector (GC-FID). Methods that used acidic catalysis at a lower temperature were the most efficient. Methyl biodiesel samples were synthesized by basic catalysis (KOH) for all quantified oils and the physicochemical properties of the biofuel were evaluated, i.e. viscosity, flash and fire points, density, water content, iodine and acidity numbers. Conclusions: The obtained results suggesting that it is possible to take advantage of these residues for biodiesel production as the obtained products were approved according to the rules established by the National Association of Petroleum (ANP); the bovine samples were the exception regarding moisture and acidity.

Study of reaction parameters and kinetics of esterification of lauric acid with butanol by immobilized Candida antarctica lipase.

Esterification of lauric acid with n-butanol, catalyzed by immobilized Candida antarctica lipase (CAL) in aqueous-organic biphasic solvent system was studied. Effects of various reaction parameters on esterification were investigated, such as type and amount of solvent, amount of buffer, pH, temperature, speed of agitation, amount of enzyme, butanol and lauric acid. The most suitable reaction conditions for esterification were observed at 50ºC and pH 7.0 using 5000 μmoles of lauric acid, 7000 μmoles of butanol, 0.25 ml phosphate buffer, 1 ml of isooctane as the solvent and 50 mg of immobilized enzyme in the reaction medium at agitation speed of 150 rpm. Maximum esterification of 96.36% was acheived in 600 min of reaction time at n-butanol to lauric acid molar ratio of 1: 0.7. Kinetic study for the esterification of lauric acid with n-butanol using immobilized CAL was carried out and the kinetic constants were estimated by using non-linear regression method. The estimated value of Michaelis kinetic constants for butanol (KmBt) and acid (KmAc) were 451.56 (M) and 4.7 × 10-7(M), respectively and the value of dissociation constant (KBt) of the butanol-lipase complex was 9.41 × 107(M). The estimated constants agreed fairly well with literature data.

Obtención de biodiesel a partir de diferentes tipos de grasa residual de origen animal / Extractin biodieesel from different types of animal origin residual fat

Se estudian diferentes posibilidades de obtención de biodiesel a partir de residuos grasos generados en la explotación pecuaria: grasa de pollo, cerdo, y vacuna, para ello se analizan las variables relación molar alcohol/grasa animal y cantidad de catalizador, puesto que son las que más inciden en la calidad del biodiesel, al evaluar sus características y rendimientos de la reacción de transesterificación. El rendimiento en el proceso de extracción de la grasa de material de desecho de pollo es del 70,5%, y de la grasa de cerdo del 90%, por lo que se plantean como alternativas viables desde el punto de vista técnico, permitiendo la valorización de estos desechos orgánicos y aliviando la contaminación generada en este tipo de industrias. De la caracterización realizada a la grasa de pollo y cerdo se pudo establecer que ambas materias primas son de baja acidez lo cual garantiza un alto grado de transesterificación, teniendo en cuenta que tuvo un rendimiento del 96% a partir de la grasa de pollo y del 91,2% a partir de la grasa de cerdo. Del análisis cromatográfico del biodiesel sintetizado se obtuvo que el ácido graso más común fue el del ácido oleico.

Different possibilities of extracting biodiesel from fat residues generated on farm livestock: chicken, pork, and bovine fat, were studied. To do this, the variables molar ratio alcohol/animal fat and amount of catalyst are analyzed, since those are the ones which most affect the quality of biodiesel when assessing the characteristics and efficiency of the transesterification reaction. The efficiency in the poultry waste material extraction process is 70.5%, and in pork fat is 90%, reason why they are proposed as feasible alternatives from the technical standpoint, allowing the recovery of this organic waste, thus alleviating the pollution generated by this type of industry. From the characterization performed on chicken and pork fat, it has been established that this raw material has low acidity which ensures a high degree of transesterification, taking into account that it had 96% efficiency from chicken fat and 91.2% from pork fat. From the synthesized biodiesel Chromatographic analysis it was found that the most common fatty acid was oleic acid.

Synthesis and hypoglycemic activity of esterified-derivatives of mangiferin / 中国天然药物

AIM@#To synthesize three novel esterified-derivatives of mangiferin and evaluate their hypoglycemic activities.@*METHODS@#Acetic, propionic, and butyric anhydride were reacted with mangiferin, respectively. The hypoglycemic activity of the derivatives was evaluated using a hyperglycemic mouse model induced by streptozotocin (STZ), and the islet cells were checked by biopsy inspection.@*RESULTS@#7, 2', 3', 4', 6'-penta-acetyl-mangiferin (PAM), 3, 6, 7, 2', 3', 4', 6'-hepta-propionyl-mangiferin (HPM) and 3, 6, 7, 2', 3', 4'-hexa-butyryl-mangiferin (HBM) were synthesized and their structures were identified by MS,(1)H, (13)C NMR, and 2D NMR. These three compounds were reported for the first time. PAM group (0.5, 0.25 mmol·kg(-1)), HPM group (0.5, 0.25 mmol·kg(-1)), and HBM group (0.5, 0.25, 0.125 mmol·kg(-1)) mice showed strong hypoglycemic activity (P < 0.01); mangiferin group (1, 0.5 mmol·kg(-1)), PAM group (0.125 mmol·kg(-1)) and HPM group (0.125 mmol·kg(-1)) showed marginal hypoglycemic activity (P < 0.05); mangiferin group (0.25 mmol·kg(-1)) had the potential for a hypoglycemic effect, although it did not demonstrate that statistically. In histological examination, the islet cells of the PAM, HPM, and HBM groups could recover from the STZ damage; islet cells of the mangiferin group could recover also, but less than the esterified-derivative groups.@*CONCLUSION@#Derivatives could repair the damaged islet cells, and had higher lipid-solubility and stronger hypoglycemic activity than mangiferin itself. There existed a structure activity effect, and a solubility effect relationship: the larger esterification moieties, or the higher lipid-solubility, the stronger the hypoglycemic activity (no ester → acetyl → propionyl → butyryl). Esterified derivatives of mangiferin are potential compounds for new anti-diabetes drugs.

The Role of Androgen in the Adipose Tissue of Males

Adipose tissue, where various metabolic hormones are secreted, plays a role in metabolizing different substances including androgen. Within fat tissue, enzymes such as aromatase and aldo-keto reductase 1C are responsible for metabolizing testosterone into estrogen and 5-dihydrotestosterone into inactive metabolites. Adipose tissue can also affect the secretion of gonadotropin, which influences the formation of androgen in the testes. At the same time, androgen has an impact on the distribution and proliferation of adipose tissue. The adrenoreceptors for catecholamines, which have been proven to play an essential role in controlling lipolysis, function by being up-regulated by androgens. Furthermore, androgens regulate the activity of lipoprotein lipase, a key enzyme involved in intracellular esterification of adipose tissue.

A new labdane diterpene from the limpet Trimusculus peruvianus / Un nuevo diterpeno labdano aislado del molusco Trimusculus peruvianus

The family Trimusculidae produces labdane diterpenes, which differ in the degree and type of esterification with acetoxy and isovaleroyl ester predominantly. Here we describe the isolation from the marine pulmonate Trimusculus peruvianus, collected on intertidal rocks of Chilean coasts, of a new diterpene closely related to the above mentioned characteristics. It structure was determined by spectroscopic data. The compounds were subjected to toxicity tests using nauplii and cysts of Artemia salina. The known compounds isolated in this study have shown an ability to inhibit egg hatch of A. salina.

La familia Trimusculidae produce diterpenos tipo labdano, que difieren en el grado y tipo de esterificación con esteres acetato e isovalérico predominantemente. En este trabajo describimos el aislamiento de un nuevo diterpeno con las características ya mencionadas y de otros ya conocidos desde el molusco marino pulmonado Trimusculus peruvianus, recolectado en la zona intermareal del litoral chileno. Su estructura fue determinada a través de métodos espectroscopicos. Los compuestos fueron sometidos a ensayos de toxicidad y eclosión de los huevos de Artemia salina.

Whey upgrading by enzyme biocatalysis

Whey is a co-product of processes for the production of cheese and casein that retains most of the lactose content in milk. World production of whey is estimated around 200 million tons per year with an increase rate of about 2 percent/per year. Milk production is seasonal, so surplus whey is unavoidable. Traditionally, whey producers have considered it as a nuisance and strategies of whey handling have been mostly oriented to their more convenient disposal. This vision has been steadily evolving because of the upgrading potential of whey major components (lactose and whey proteins), but also because of more stringent regulations of waste disposal. Only the big cheese manufacturing companies are in the position of implementing technologies for their recovery and upgrading, so there is a major challenge in incorporating medium and small size producers to a platform of whey utilization, conciliating industrial interest with environmental protection within the framework of sustainable development. Within this context, among the many technological options for whey upgrading, transformation of whey components by enzyme biocatalysis appears as prominent. In fact, enzymes are green catalysts that can perform a myriad of transformation reactions under mild conditions and with strict specificity, so reducing production costs and environmental burden. This review pretends to highlight the impact of biocatalysis within a platform of whey upgrading. Technological options are shortly reviewed and then an in-depth and critical appraisal of enzyme technologies for whey upgrading is presented, with a special focus on newly developed enzymatic processes of organic synthesis, where the added value is high, being then a powerful driving force for industrial implementation.

Kinetic analysis of batch ethanol acetylation in isothermal non-stationary multiphase systems by lyophilized mycelium of Aspergillus oryzae

A relatively complex network of reactions has been investigated, using as a network model the isothermal batch esterification of acetic acid with ethanol in n-heptane catalyzed by lyophilized mycelium of Aspergillus oryzae. The kinetic analysis was firstly carried out on the whole system, without any simplification, by means of the well-known integral method. Owing to the poor results obtained by this way, we developed an alternative approach, combining initial rates and integral analysis and reducing the number of empirical parameters to be determined by the use of equilibrium data. All the values of the parameters calculated according to this "composite" approach to kinetic analysis well correlate with experimental data.

Looking for a More Useful Atherogenic Index for Nigerians

Researchers have divided opinion as to which lipid fraction or cholesterol ratio can effectively be used to predict the chances of an individual developing heart disease or can best describe the atherogenic index of an individual. In this study the atherogenic risk of Nigerian hypertensives and normotensives was examined by different parameters in an attempt to find out which one best separates the high risk individual from the one with low risk of atherogenicity. Lipid profile and lipid ratios were examined by standard methods in 330 untreated hypertensives and 110 age snd sex matched normotensives in Nigerian hypertensives and normotensives respectively in UBTH; Benin City; Nigeria. Statistical analysis was used to determine which lipid parameter(s) gave a better reflection of the atherogenic index. The mean of serum lipids and lipid ratios were significantly higher in the hypertensives than in the normotensives. The mean of the atherogenic index of plasma (AIP); log (Tg/HDL-C) was significantly positive for the hypertensives but significantly negative for the study population and for the normotensives; p

Relationship between fractional esterification rate of high density lipoprotein cholesterol and coronary artery disease / 中华心血管病杂志

<p><b>OBJECTIVE</b>To assess the relationship between fractional esterification rate of high density lipoprotein cholesterol (FER(HDL)) and coronary artery disease.</p><p><b>METHODS</b>A total of 131 hospitalized patients underwent coronary angiography due to chest pain were included in the study and patients were divided into CAD group (n = 76) and non CAD group (n = 55) according to coronary angiogram. Clinical and laboratory data including biochemical laboratory, FER(HDL) and lipid subclasses were analyzed.</p><p><b>RESULTS</b>The FER(HDL) value of CAD group was significantly higher than that of the non CAD group (21.70 ± 8.73 vs. 18.65 ± 6.26, P < 0.05). There was an increased trend of FER(HDL) with numbers of diseased coronary arteries, significant difference was evidenced between non CAD group and 3-vessel group (18.65 ± 6.26 vs. 24.00 ± 9.22, P < 0.05). FER(HDL) was positively correlated with TG (r = 0.647, P < 0.001), LDLb-C(r = 0.441, P < 0.001) and negatively correlated with HDL-C (r = -0.708, P < 0.001) and HDL(2)-C (r = -0.748, P < 0.001).</p><p><b>CONCLUSION</b>Our data showed that the values of FER(HDL) were significantly increased in CAD patients and correlated with the severity of the CAD.</p>

Rapeseed lipase catalyzed synthesis of butyl butyrate for flavour and nutraceutical applications in organic media

Butyl butyrate, a short chain ester with fine fruity pineapple odour, is a significant flavour compound. Recent investigations show that butyrate esters also have anticancer activity. Factors influencing the synthesis of butyl butyrate by organic phase biocatalysis were investigated. Maximum ester yield of 89% was obtained when 0.25 M butanol and butyric acid were reacted at 25 [degree sign] C for 48 h in the presence of 250 mg rape seed lipase acetone powder in hexane. Addition of water did not affect synthesis, while a water activity of 0.45 was found optimum. Of 15 different alcohols evaluated, isoamyl and [Z]-3-hexen-1-ol were esterified most effectively with molar conversion yields of 92.2 and 80.2%. Short chain primary alcohols such as methanol and medium-long chain alcohols, such as heptanol and octanol were esterified were slowly. The results show that rape see lipase is versatile catalyst for ester synthesis with temperature stability range 5-50 [degree sign] C

Fabrication of potential macromolecular prodrugs of aspirin and diclofenac with dextran

Aspirin and diclofenac conjugates with dextran were synthesized as potential macromolecular prodrugs under homogeneous reaction conditions by using 4-methyl-benzenesulfonyl chloride as an acylating agent in the presence of triethylamine as a base. Highly pure conjugates with good yields were synthesized by this acylation method. All of the products were found soluble in aqueous medium as well as in dimethylsulfoxide and N, N-dimethylacetamide. The UV/Vis spectrophotometry has indicated the incorporation of drugs in conjugates and extent of substitution of drug onto dextran polymer. Covalent attachment of the drug onto the drug carrier polymer [dextran] was verified by [1]H NMR and Fourier transform infrared [FTIR] spectroscopic analysis. The prodrugs were analysed by powder X-ray diffraction [XRD] measurements. Phase changes were noticed by powder XRD for all macromolecular prodrugs indicating the change of state of matter towards more crystallinity. Therefore, fabricated macromolecular prodrugs are potential candidates to show better pharmacokinetic profile. All of the products were thoroughly characterized by using different spectroscopic techniques

Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: batch and fluidized bed reactor study

Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99 percent) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g-1 dry support and in a relatively short time (24 hrs) at 37°C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2 percent yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale.