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Optimization of enzymatic synthesis of eugenol ester using statistical approaches
Abstract
Eugenol caprylate was synthesized using Lipozyme TLIM as the biocatalyst for the reaction. A two level Plackett–Burman (PB) experimental design was used for finding the significant reaction parameters. Response surface methodology (RSM) with a three-factor-five-level central composite rotatable design (CCRD) was further employed to study and optimize the reaction conditions. A good correlation between the predicted and actual responses showed that the generated model could adequately predict the conversion yield. The maximum conversion yield (72.2%) was obtained at the optimal condition of 65 °C, 250 rpm, 259 min, 100 mg enzyme, and 2:1 M ratio of eugenol/caprylic acid in solvent-free system.
... The oven temperature program was 60-250 °C using a ramp of 3 °C/min. The eugenol and eugenyl acetae were identified by comparing their mass spectra and retention indices (IR relative to C8-C20) with those in the system library (NIST-11, FFNSC-2) and in the literature [5,11,15,[37][38][39][40]. The spectra were scanned within the range m/z 40-300. ...
... Cleavage of the ester gave the fragment peak at m/z 164 related to the eugenol part [M + H] + . Other fragments ions were also observed at m/z 41, 57, 91, 103, 131 and 149 [5,11,15,[37][38][39][40] (Table S1). ...
... In order to verify the integrity of the catalyst in successive reactions, after the fourth reuse cycle, the catalyst was characterized by the FTIR, XRD and EDS techniques. The FTIR spectrum (Fig. S9a) of MF4W15 R showed bands at 2932, 1765, 1513 cm -1 , which were attributed to the stretch vibration of the CH, CH 2 /CH 3 , C=O and aromatic ring [5,[37][38][39][40] which demonstrates the binding of esterification product on the surface of the reused catalyst [32,57,58]. Fig. S9b shows X-ray diffractograms for the catalyst before use (MF4W15) and after reuse cycle (MF4W15 R), no significant differences were observed in X-ray diffractograms for the catalyst even after the fourth cycle of use. ...
Eugenyl acetate has been investigated because of its beneficial bioactive antioxidant, antimicrobial and potential properties against the development of Aedes aegypti larvae. Here, we report, for the first time, the use of a catalyst prepared from flint kaolin with microwave irradiation for the acetylation of eugenol. A few kinetic parameters were evaluated in the experiments used for eugenol ester synthesis. High conversions (98%) were obtained after 1 h of reaction. The prepared material shows good activity (over 90%) even after 4 cycles of use. Therefore, the use of microwave radiation made it possible to prepare a catalyst in a very short time using a low-cost industrial by-product as a raw material that proved to be highly active, in addition to the additional advantage of being reusable, which would reduce possible environmental impacts caused by its disposal in the environment.
... Eugenol (4-allyl-2-methoxyphenol) is a fragrant compound typically found in clove leaf oil, nutmeg, cinnamon oil, bay, and basil leaf. [1] It is primarily used as a flavoring agent in temporary dental cements and fillings, in cosmetics and some food products, as well as a precursor to produce vanillin. [2] Eugenol is also sold in varying forms of dimers due to the lower cytotoxic effects as compared to the pure eugenol. ...
... Chaibakhsh et al. investigated the use of Lipozyme TLIM to produce eugenyl caprylate, and attained 72.2% of the ester under optimal conditions (65°C, 4 hr 19 min, 250 rpm). [1] However, a large amount of the costly commercial enzyme was used, i.e., 100 mg/mL, for the esterification reaction which could potentially add to increasing the cost of preparing the ester. [1] Our recent work assessed the use of another binary support that consisted of MWCNTs as nanofillers, conjugated via EDAC to CS (CS/MWCNTs) as support for RML. ...
... [1] However, a large amount of the costly commercial enzyme was used, i.e., 100 mg/mL, for the esterification reaction which could potentially add to increasing the cost of preparing the ester. [1] Our recent work assessed the use of another binary support that consisted of MWCNTs as nanofillers, conjugated via EDAC to CS (CS/MWCNTs) as support for RML. However, maximum yield obtained for the produced eugenyl benzoate was marginally lower (56.1%) ...
An alternative environmentally benign support was prepared from chitosan-chitin nanowhiskers (CS/CNWs) for covalent immobilization of Rhizomucor miehei lipase (RML) to increase the operational stability and recyclability of RML in synthesizing eugenyl benzoate. The CS/CNWs support and RML-CS/CNWs were characterized using X-ray diffraction (XRD), fluorescent microscopy and Fourier transform infrared spectroscopy (FTIR). Efficiency of the RML-CS/CNWs was compared to the free RML to synthesize eugenyl benzoate for parameters: reaction temperature, stirring rate, reusability and thermal stability. Under optimal experimental conditions (50 °C, 250 rpm, catalyst loading 3 mg /mL), a 2-fold increase in yield of eugenyl benzoate was observed for RML-CS/CNWs as compared to free RML, with the former achieving maximum yield of the ester at 62.1% after 5 h. Results demonstrated that the strategy adopted to prepare RML-CS/CNWs was useful, producing an improved and prospectively greener biocatalyst that supported a sustainable process to prepare eugenyl benzoate. Moreover, RML-CS/CNWs are biodegradable and carry out esterification reactions under ambient conditions as compared to the less eco-friendly conventional acid catalyst. This research provides a facile and promising approach for improving activity of RML in which the resultant RML-CS/CNWs demonstrated good operational stability for up to eight successive esterification cycles to synthesize eugenyl benzoate.
... Eugenol (4-allyl-2-methoxyphenol) is a member of phenylpropanoids, a large family of organic chemicals that contain a phenyl ring and a C 3 side chain [1]. It is commonly found in essential oils, especially in clove leaf oil, cinnamon oil, nutmeg, bay and basil leaf [2] in the form of a clear to pale yellow oily liquid [3]. It is commonplace in cosmetics and food products as well as flavoring agent in temporary dental cements and fillings. ...
... The current conventional method for optimizing biosynthetic processes requires screening of large number of variables, a large number of experiments as well as time and resources consuming [2]. Therefore, the statistical method of response surface methodology (RSM) has been suggested for applied enzymatic processes; considering it is a fast and economical means for determining the optimal conditions for a multivariable system. ...
... Contour plots were generated to illustrate the main and interactive effects of the independent variables on the dependent ones. The optimum combination of parameters can be determined on the basis of the ridge maximum analysis and the canonical analysis using the optimization function of the software [2]. ...
... Each assessed factor was highly significant (p < 0.0001) to increase the percentage conversion of EV, although stirring rate (F-value 232.28) was more impacting than the (Table 4a). Increasing the biocatalyst loading and stirring rate from 1.5 to 3 mg/mL and 150 rpm to 300 rpm significantly elevated EV conversion from 66.81 to 84.63% [71]. This has to do with the reaction system needing a higher stirring rate to cater to the higher presence of the CRL/ SiO 2 /FeO 3 O 4 /GO and overcome the crowding effect and reactants' diffusional restriction interaction [30]. ...
... The broad peak centred at 3386 cm À1 (Fig. 9a), allotted to the O À H bonds stretching vibration of ethanol, was shifted to 3318 cm À1 with reduced intensity after 3 h (Fig. 9b). This peak completely disappeared after purification to obtain EV (Fig. 9c), producing a spectrum that matched EV, described in the literature [71]. Peaks for COOH were noted for the C ¼ O stretching (1708 cm À1 ), O À H bending (1410 cm À1 ), and C À O stretching (1266 cm À1 ), while the C À O stretching (1044 cm À1 ) described ethanol (Fig. 9a). ...
Biobased ternary nanocomposites can stabilize enzymes for greater stability, catalytic activity and easy recovery. This study aimed to optimize biogenic silica/magnetite/graphene oxide nanocomposite supported Candida rugosa lipase (CRL/SiO2/Fe3O4/GO) for ethyl valerate (EV) synthesis and characterize the biocatalysts’ physicochemical properties and operational stability. CRL conjugated-oil palm leaves-derived biogenic SiO2/Fe3O4/GO nanocomposite showed a maximum immobilized protein of 44.13 ± 2.1 mg/g with a specific activity (534.87 ± 9.5 U/mg), than free CRL (≥700 U/mg). GL-A-SiO2/Fe3O4/GO exhibited the highest surface area (260.87 m²/g) alongside superior thermal stability in TGA/DTG. XRD revealed an amorphous SiO2 (crystallinity = 26.7%), while Fe3O4 existed as cubic spinel crystal (crystallinity = 90.2%). Taguchi Design-optimization found that CRL/SiO2/Fe3O4/GO best catalyzed the EV synthesis (90.4% in 3 h) at 40 ℃ using 3 mg/mL of biocatalyst, valeric acid/ethanol molar ratio of 1:2, in 10% (m/v) molecular sieves with stirring in heptane at 200 rpm. EV production was confirmed by FTIR- (C=O: 1738 cm⁻¹ and C–O–C: 1174 cm⁻¹) and GC–MS ([M]⁺ m/z = 130, C7H14O2). CRL/SiO2/Fe3O4/GO’s reusability for 11 successive esterification cycles demonstrated the SiO2/Fe3O4/GO’s exceptional hyperactivation and stabilization properties on immobilized CRL. These findings conveyed the SiO2/Fe3O4/GO’s efficacy to alter CRL's physicochemical properties and operational stability for catalyzing higher yields EV.
... This condition was optimum to give good yield of 72%. 33 Eugenyl benzoate (9) was synthesized by an enzymatic reaction between benzoic acid and eugenol (6) using S. aureus lipase [24] and Rhizomucormiehei lipase as a biocatalyst. 34,35 The reaction mixture was incubated and shaken with heating. ...
... Reagents, conditions and yield in esterification reactions of resveratrol en-19-oat(39) have been synthesized from kaurenoic acid. These compounds were obtained through the esterification reaction of kaurenoic acid with suitable alkyl halides namely CH 3 I for(33), C 4 H 9 Br for (34), PhCH 2 Br for (35), 4-ClPhCH 2 Br for (36), ...
Secondary metabolite compounds have a very diverse structure that is widely used as a source of new drug discovery because they have a variety of bioactivity. But in its development, there are several problems related to these compounds including low bioavailability, low solubility and instability in the metabolic process. Modification of the structure of secondary metabolites is used to answer all these problems. One of the processed was by synthesising the ester derivative compounds through the chemical and enzymatic esterification reaction. Esters derivatives of secondary metabolite compounds can increase the diversity of structures, allow for increased biological activity and even new biological activity of these compounds. This review will discuss various processes of modification of the structure of secondary metabolite compounds through chemical and enzymatic esterification reactions that have been reported from 1994-2019.
... The presence of prominent bands of organic groups is clearly noted from the FTIR result. The FTIR Spectrum (Figure 12b) of (3)SO3H/AlSiM R showed prominent bands in 2932, 1765, 1513 cm −1 which were attributed to the stretching vibration of CH, CH2/CH3, C=O and presence of aromatic ring (C=C) [4,[73][74][75][76] demonstrating the binding of the esterification product to the surface of the reused catalyst. However, these characterizations showed that there were many differences between new and used catalysts, partially indicating that the catalyst exhibited good structural stability and activity for the eugenol reaction process. ...
... Cleavage of the ester gave the fragment peak at m/z 164 related to the eugenol part [M+H] + . Other fragments ions were also observed at m/z 41, 57, 91, 103, 131 and 149 [4,[73][74][75][76] ( Figure S3 and Table S1, see Supplementary Material). ...
The present work was aimed to investigate the catalytic activity of a mesoporous catalyst synthesized from 3-mercaptopropyltrimethoxysilane (MPTS) functionalized Amazonian flint kaolin in the acetylation of eugenol with acetic anhydride. Materials were characterized by thermogravimetry (TGA), N2 adsorption (BET), X-ray dispersive energy spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and acid-base titration. The results presented proved the efficiency of flint kaolin as an alternative source in the preparation of mesoporous materials, since the material exhibited textural properties (specific surface area of 1071 m2 g−1, pore volume of 1.05 cm3 g−1 and pore diameter of 3.85 nm) and structural properties (d100 = 4.35 nm, a0 = 5.06 nm and Wt = 1.21 nm) within the required and characteristic material standards. The catalyst with the total amount of acidic sites of 4.89 mmol H+ g−1 was efficient in converting 99.9% of eugenol (eugenol to acetic anhydride molar ratio of 1:5, 2% catalyst, temperature and reaction time 80 °C and 40 min reaction). In addition, the reused catalyst could be successfully recycled with 92% conversion activity under identical reaction conditions.
... Hence, this biphasic system gradually becomes larger over time. When in excess, water can re-direct the reaction equilibrium towards the counterproductive hydrolysis of the ester product (Chaibakhsh et al., 2012). Considering the use of immobilized RML, the adsorption of water on the support is one of the most important reasons contributing to biocatalyst inactivation, as phenomenon previously described by an earlier study (Fallavena et al., 2014). ...
... Eugenyl benzoate produced from the enzymatic esterification was purified and characterized. The FTIR spectrum showed wavenumber that matches those reported by a similar study (Chaibakhsh et al., 2012). A band for the vibrational stretching of C=O (ester) at 1703.9 cm -1 and the characteristic multiple stretching vibrations for C O (ester) between wavenumbers 1300 1000 cm -1 were observed. ...
To overcome drawbacks in the conventional chemical route to synthesize eugenyl benzoate, immobilized Rhizomucor miehei lipase (RML) as the biocatalyst was proposed. The RML conjugated to a hybrid support consisting of biopolymers, chitosan (CS) and chitin nanowhiskers (CNWs). 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDAC) was used as the crosslinker to bind the lipase. Immobilization of RML was the highest on crosslinked CS/CNWs which gave a protein loading of ~8.12 mg/g, corresponding to specific and residual activity of 537 U/g and 137%, respectively. Fourier transform infrared spectroscopy, thermogravimetric analysis-differential thermogravimetry, field emission scanning electron and atomic force microscopy of RML-CS/CNWs revealed that RML was successfully attached to the surface of crosslinked CS/CNWs. Under an optimized condition, the highest yield of eugenyl benzoate (56.3 %) was attained after 5 h using 3 mg/mL of RML-CS/CNWs with molar ratio of eugenol: benzoic acid of 3:1, as compared to only 47.3 % for the free RML. Analyses of FTIR and NMR on purified eugenyl benzoate affirmed that the ester was successfully produced in the enzymatic esterification. Therefore, the use of the RML-CS/CNWs biocatalysts appears promising to afford good yields of eugenyl benzoate within a relatively shorter reaction time.
... Several researchers reported enzymatic synthesis of esters in organic solvent-free systems in an attempt to make the processes feasible (Bezbradica et al., 2007;Graber et al., 2007;Vossman et al., 2008;Chaibakhsh et al., 2012). Catalysis in a solvent-free system offers the benefits of minimizing environmental impact by avoiding the use of flammable organic and toxic solvents. ...
... For assessing the optimization technique, the actual and predicted values were compared and the results were depicted in Figure 2.1. The predicted values of the response from the model agreed with the observed values and could be properly applied to navigate the design space (Zhang et al., 2008;Chaibakhsh et al., 2012). According to the ANOVA of factors, the F-value for the lack of fit was 1.15 which was lower than the tabulated value of F 0.05 (10,4) = 5.964, which implied that the lack of fit was not significantly relative to the pure error (Table 2.3). ...
... Following the successful employment as desiccant in many enzymatic esterification reactions [22,23], in this present study too, molecular sieves (4Å) were chosen. They act as absorbents that are replaceable with new ones when saturated with water [24]. By removing water in media, the reaction equilibrium would shift toward the synthesis of the desired ester hence, higher conversion of ester products [24]. ...
... They act as absorbents that are replaceable with new ones when saturated with water [24]. By removing water in media, the reaction equilibrium would shift toward the synthesis of the desired ester hence, higher conversion of ester products [24]. The effects of desiccant on the free CRL and CRL-MWCNTs were evaluated in the presence (1.0 g) or absence (0 g) of molecular sieves. ...
... A more recent work in this field [10] relates the optimization of enzymatic synthesis of eugenol ester using statistical approaches. Eugenol and caprylic acid were used as substrates and Lipozyme TL IM as catalyst. ...
... Lower conversions were obtained compared to our work and is also important to observe that the authors used chloroform as organic solvent, what can enhance the cost of process, due to need of solvent separation after the reaction completeness. A recent work [10] relates the optimization of enzymatic synthesis of eugenol ester using statistical approaches. Eugenol and caprylic acid were used as substrates and Lipozyme TL IM as catalyst. ...
Enzymatic esterification of eugenol is a matter of great scientific and technological interest due to the well-known drawbacks of the chemical-catalyzed route as well as the potential use of produced compounds as natural antimicrobials. This work reports the maximization of eugenil acetate production by esterification of eugenol and acetic anhydride in a solvent-free system using Novozym 435 as catalyst. The antimicrobial activity of eugenol and eugenil acetate was also determined. The operating conditions that maximized eugenil acetate production were 50 °C, eugenol to acetic anhydride of 1:3, 150 rpm, and 5.5 wt% of enzyme, with a conversion of 99 %. A kinetic study was performed to assess the influence of substrates molar ratio, enzyme concentration, and temperature on eugenil acetate yield. Results show that an excess of anhydride, low enzyme concentration (1 wt%), and 60 °C afforded nearly complete conversion after 6 h of reaction. The highest antimicrobial activity of eugenil acetate was observed against Acinetobacter sp. (48.66 mm) at concentration of 20 μL. Results indicate that the esterification of eugenol improved its antimicrobial properties. New experimental data on enzymatic esterification of eugenol and acetic anhydride are reported in this work, showing a promising perspective to overcome the inconvenient of the chemical-catalyzed route for obtaining antimicrobial natural compounds.
... Z przeglądu literatury przedmiotu wynika, że eugenol oraz estry otrzymane na drodze estryfikacji eugenolu, takie jak: octan eugenylu, propionian eugenylu, maślan eugenylu oraz 4-etylo-, 4-fluoro-, 4-chloro-i 4-bromobenzoesan eugenylu, charakteryzują się również działaniem antymikrobiologicznym [21][22][23]. ...
... However, in high concentrations, it has an adverse effect of provoking inflammatory and allergic reactions, possibly due to its low instability, which favors the formation of phenoxyl radicals via its pro-oxidant activity [2,9]. Despite the fact that its structure is polyfunctional and readily accessible, eugenol is considered as a useful starting material for producing valuable derivatives through chemical synthesis [2,[10][11][12][13][14][15] or biochemistry [1,4,9,[16][17][18]. ...
A new prepared catalyst, 12-molybdophosphoric acid (HPMo) anchored to the mesoporous aluminosilicate AlSiM, synthesized from Amazon kaolin, was characterized and used as a heterogeneous acid catalyst for the production of eugenyl acetate by acetylation of eugenol with acetic anhydride. The effect of various reaction parameters, such as catalyst concentration, eugenol/acetic anhydride molar ratio, temperature and reaction time, was studied to optimize the conditions of maximum conversion of eugenol. The kinetics studies showed that in eugenol acetylation, the substrate concentration follows a first order kinetics. The results of activation energy was 19.96 kJ mol −1 for HPMo anchored to AlSiM. The reuse of the catalyst was also studied and there was no loss of catalytic activity after four cycles of use (from 99.9% in the first cycle to 90% in the fifth cycle was confirmed), and an excellent stability of the material was observed. Based on catalytic and kinetic studies, HPMo anchored to AlSiM is considered an excellent catalyst.
... Conversely, the plateauing of the ester yield after 3 h was likely due to substantial presence of water molecules in the reaction system as a by-product from the esterification process, as reported in literature (Ozyilmaz and Gezer, 2010). With regards to the CRL/Gl-A-SiO 2 -MNPs, the adsorption of water on the nanosupports may constitute one of the crucial reasons that contributed to biocatalyst inactivation as mentioned in another similar study (Fallavena et al., 2014) as well as the re-direction of the reaction equilibrium towards hydrolysis (Chaibakhsh et al., 2012;Elias et al., 2017;Manan et al., 2018) These reasons may also account for the inability to achieve a 100% conversion of butyric acid to butyl butyrate. For the subsequent investigations, 3 h was adopted as the optimum esterification time for CRL/Gl-A-SiO 2 -MNPs. ...
The study reports the preparation of a composite consisting of magnetite coated with nanosilica extracted from oil palm leaves (OPL) ash as nanosupports for immobilization of Candida rugosa lipase (CRL) and its application for the synthesis of butyl butyrate. Results of immobilization parameters showed that ~ 80 % of CRL (84.5 mg) initially offered was immobilized onto the surface of the nanosupports to yield a maximum protein loading and specific activity of 67.5 ± 0.72 mg/g and 320.8 ± 0.42 U/g of support, respectively. Surface topography, morphology as well as information on surface composition obtained by Raman spectroscopy, atomic force microscopy, field emission scanning electron microscopy and transmission electron microscopy showed that CRL was successfully immobilized onto the nanosupports, affirming its biocompatibility. Under optimal conditions (3.5 mg/mL protein loading, at 45 ℃, 3 h and molar ratio 2:1 (1-butanol:n-butyric acid) the CRL/Gl-A-SiO2-MNPs gave a maximum yield of 94 ± 0.24 % butyl butyrate as compared to 84 ± 0.32 % in the lyophilized CRL. CRL/Gl-A-SiO2-MNPs showed an extended operational stability, retaining 50 % of its initial activity after 17 consecutive esterification cycles. The results indicated that OPL derived nanosilica coated on magnetite can potentially be employed as carrier for lipase immobilization in replacement of the non-renewable conventional silica sources.
... The conventional method of optimization requires screening of a large number of variables, many experiments, with plenty time and resources. Experimental design A.G.A. S approach provides an easy and efficient evaluation of the main reaction variables, such as temperature, time reaction, enzyme amount and the molar ratio of substrates, which improves the biocatalyst activity and the conversion in the esters synthesis (Chaibakhsh, Basri, Anuar, & Rahman, 2012;Narwal et al., 2016;Shinde & Yadav, 2014, 2015. ...
Background
Many sectors of industry, mainly food, cosmetics and pharmaceutics, have increased their interest in esters due to their flavor property. Flavor esters that possess an aromatic ring in their molecular structure are also known as aromatic esters. These esters are widely found in nature (fruits and plants) and the synthetic (i.e. via chemical) and natural routes (i.e. via direct extraction from nature or via biotechnology) are suitable for their biocatalysis.
Scope and approach
In this context, from the industrial point of view, enzyme-catalyzed reactions are the most economical approach to reach final green products with no toxicity and no harm to human health. The present article gives an overview of the aromatic esters synthesis, considering the main effects in the reaction media conditions and enzymes used. This review also describes applied trends in enzymatic-catalyzed reactions, pointing alternatives to production, like ultrasound-assisted reactions and process optimization of aromatic esters. Furthermore, this work presents perspectives concerning the biological potential of these esters and recent advances in their encapsulation.
Key findings and conclusions
Lipases play an important role in the aromatic esters production, with several advantages over synthetic route. Lipase-catalyzed reactions usually follows Ping-Pong Bi-Bi or ternary complex (order Bi-Bi) mechanism. The study of the process parameters and their interaction are very important to understand the system optimization and achieve the maximum reaction yield to scale up. Aromatic esters can present some biological activities, in addition to their fragrances, which increases the interest in the encapsulation of these compounds.
... Bu bileşik gıda ve kozmetik ürünlerinde ve ilaç sektörlerinde aroma maddesi olarak kullanılmaktadır [19]. Ayrıca, Eugenol türevleri antioksidan, antimikrobiyal, antiinflammatuvar, antidepresan, antigenotoksik ve antibakteriyel özellik gibi yaygın farmakolojik aktivitelere sahiptir [20][21][22]. ...
Bu calismada, karbamat grubu iceren 14 yeni eugenol turevleri sentezlenmis ve bunlarin asetilkolinesteraz (AChE) ve butirilkolinesteraz (BuChE) enzimleri uzerine inhibitor etkileri incelenmistir. 4-allil-2-metoksifenil-(3,4-diklorofenil)karbamat (3f) 71.6 µM’lik IC 50 degeri ile en iyi AChE inhibitoru olarak b elirlenmistir . 4-allil-2-metoksifenil(3-metoksifenil)karbamat (3a) 0.58 µM’lik IC 50 degeri ile BuChE’ye karsi en guclu inhibisyonu sergilemistir. Ayrica sentezlenen bilesikler icin yapi-aktivite iliskileri de incelenmistir.
... Chiaradia et al. (2012) achieved a conversion of about 99% in the esterification of eugenol and acetic anhydride using a commercial immobilized lipase from Candida antarctica as catalyst, at acetic anhydride to eugenol molar ratio of 3:1, enzyme concentration of 5.5 wt% (based on the total mass of substrates), 50 °C in 6 hours of reaction. Chaibakhsh et al. (2012) synthesized eugenyl caprylate using Lipozyme TL IM as catalyst in solvent-free system, and obtained a maximum reaction yield of 72.2% at 65 °C, 250 rpm, 100 mg of enzyme, caprylic acid do eugenol molar ratio of 1:2 after 4.5 hours of reaction. ...
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.
... The predicted values of the response from the model agreed with the observed values and could be properly applied to navigate the design space. [27,28] Mutual effects of factors on the production of geranyl propionate Effect of solvent log P and time Figure 2 shows the effect of the reaction time and solvent and their mutual interaction on the CRL-MWCNTs catalysed production of geranyl propionate at constant conditions of geraniol:propionic acid molar ratio of 3:1 and 50 C. The F-value for time versus solvent (log P) showed that the effect of time on the percentage conversion of geranyl propionate was more significant than the used solvent (log P) (Table 3). ...
Terpene esters of short-chain fatty acids are essential oils that have big importance in food, cosmetic and pharmaceutical industries as flavours and fragrances. Geraniol and citronellol are the most important substances. Considering the everincreasing demand for such products, their enzymatic production from natural raw materials by using environmentally friendly and economically attractive processes may prove advantageous. In this contribution, we would like to present an alternative option for the production of geranyl propionate using nanobioconjugates consisting of Candida rugosa lipase adsorbed onto multi-walled carbon nanotubes (CRL-MWCNTs). We investigated the effects of incubation time, temperature, solvent log P and substrate molar ratio, and determined the optimum conditions. The yield of geranyl propionate catalysed by CRL-MWCNTs nanobioconjugates was significantly influenced by two factors, namely, temperature and time of the reaction. Under the optimum reaction conditions of 55 _C, solvent n-heptane (log P D 4.0), geraniol to propionic acid molar ratio of 5:1 and reaction time of 6 h, the use of CRL-MWCNTs resulted in 51.3% production of geranyl propionate. Therefore, the investigation revealed that geranyl propionate was successfully synthesized under mild conditions with reasonably high yield within a short period of time. The CRL-MWCNTs nanobioconjugates demonstrated a potential as economical and environmentally smarter biocatalysts for the production of geranyl propionate.
... Lower conversions were obtained compared to our work, and it is also important to observe that the authors used chloroform as organic solvent, what can enhance the cost of the process, due to need of solvent separation after the reaction completion. A recent work [19] relates the optimization of enzymatic synthesis of eugenol ester using statistical approaches. Eugenol and caprylic acid were used as substrates and Lipozyme TL IM as catalyst. ...
This work reports the maximization of eugenyl acetate production by esterification of essential oil of clove in a solvent-free system using Novozym 435 as catalyst. The antimicrobial and antioxidant activities of clove essential oil and eugenyl acetate produced were determined. The conditions that maximized eugenyl acetate production were 60 °C, essential oil of clove to acetic anhydride ratio of 1:5, 150 rpm, and 10 wt% of enzyme, with a conversion of 99.87 %. A kinetic study was performed to assess the influence of substrates' molar ratio, enzyme concentration, and temperature on product yield. Results show that an excess of anhydride, enzyme concentration of 5.5 wt%, 50 °C, and essential oil of clove to acetic anhydride ratio of 1:5 afforded nearly a complete conversion after 2 h of reaction. Comparing the antibacterial activity of the essential oil of clove before and after esterification, we observed a decrease in the antimicrobial activity of eugenyl acetate, particularly with regard to minimum inhibitory concentration (MIC). Both eugenyl acetate and clove essential oil were most effective to the gram-negative than gram-positive bacteria group. The results showed a high antioxidant potential for essential oil before and particularly after the esterification reaction thus becoming an option for the formulation of new antioxidant products.
Eugenol is a phenolic monoterpenoid, emplyed in this study to obtain bio-based antimicrobial and antioxidant methacrylate polymers.
The aim of the study was to determine the antioxidant activity and assess the lipophilicity and skin penetration of eugenyl chloroacetate (EChA), eugenyl dichloroacetate (EDChA), and eugenyl trichloroacetate (ETChA). Identification of the obtained products was based on gas chromatography (GC), infrared spectroscopy (FTIR/ATR), gas chromatography coupled with mass spectrometry (GC-MS), and the analysis of 13 C-NMR and 1 H-NMR spectra. The antioxidative capacity of the derivatives obtained was determined by the DPPH free radical reduction method, while the octanol/ water partition coefficient (shake-flask method) was tested to determine the lipophilicity of these compounds. In the next stage of testing EDChA and ETChA-(compounds characterized by the highest degree of free radical scavenging), the penetration of DPPH through pig skin and its accumulation in the skin were evaluated. For comparison, penetration studies of eugenol alone as well as dichloroacetic acid (DChAA) and trichloroacetic acid (TChAA) were also carried out. The antioxidant activity (DPPH, ABTS, and Folin-Ciocalteu methods) of the fluid that penetrated through pig skin was also evaluated. The in vitro pig skin penetration study showed that eugenol derivatives are particularly relevant for topical application. The obtained derivatives were characterized by a high level of antioxidant activity estimated after 24 h of conducting the experiment, which indicates long-term protection against reactive oxygen species (ROS) in the deeper layers of the skin.
A new prepared catalyst, 12-molybdophosphoric acid (HPMo) anchored to the mesoporous aluminosilicate AlSiM, synthesized from Amazon kaolin, was characterized and used as a heterogeneous acid catalyst for the production of eugenyl acetate by acetylation of eugenol with acetic anhydride. The effect of various reaction parameters, such as catalyst concentration, eugenol/acetic anhydride molar ratio, temperature and reaction time, was studied to optimize the conditions of maximum conversion of eugenol. The kinetics studies showed that in eugenol acetylation, the substrate concentration follows a first order kinetics. The results of activation energy was 19.96 kJ mol −1 for HPMo anchored to AlSiM. The reuse of the catalyst was also studied and there was no loss of catalytic activity after four cycles of use (from 99.9% in the first cycle to 90% in the fifth cycle was confirmed), and an excellent stability of the material was observed. Based on catalytic and kinetic studies, HPMo anchored to AlSiM is considered an excellent catalyst.
The chemical route of producing geranyl propionate involves the use of toxic chemicals, liberation of unwanted by-products as well as problematic separation process. In view of such problems, the use of Rhizomucor miehei lipase (RML) covalently bound onto activated chitosan-graphene oxide (RML/CS/GO) support is suggested. Following analyses using Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetry, properties of the RML-CS/GO were characterized. A response surface methodological approach employing a 3-level-four-factor (incubation time, temperature, substrate molar ratio, and stirring rate) Box-Behnken design was used to optimize the experimental conditions to maximize yield of geranyl propionate. Results revealed that 76 ± 0.02 % of recovered protein had yielded 7.2 ± 0.04 mg·g−1 and 211 ± 0.3% U/g of the maximum protein loading and esterification activity, respectively. The actual yield of geranyl propionate (49.46 %) closely agreed with the predicted value (49.97 %) under optimum reaction conditions (temperature: 37.67°C, incubation time: 10.20 h, molar ratio (propionic acid:geraniol) 1:3.28 and stirring rate: 100.70 rpm) and hence, verifying the suitability of this approach. Since the method is carried out under mild conditions, the RML-CS/GO biocatalyst may prove to be an environmentally benign alternative for producing satisfactory yield of geranyl propionate.
Green chemistry - also called sustainable chemistry - as the cost-effective and environmentally friendly techniques have been gaining more attention recent years. Here, we introduced a fast, non-toxic and sustainable method to synthesize Ag nanoparticles. Various parameters are involved in the bio-synthesis of Ag nanoparticles/multi-walled carbon nanotubes (Ag/MWf-CNT) composites, including silver nitrate concentration, initial pH, temperature, CNT concentration, agitation time, biomass and stirring rate. The Plackett–Burman Design (PBD) approach indicated that the initial pH, the carbon nanotube concentration and the weight of biomass are the major effects of the Ag/MWf-CNT biosynthesis. A quadratic polynomial model was developed using Central Composite Design (CCD) to statistically evaluate the effect of the initial pH (3.5-7), the carbon nanotubes concentration (0.2-1 g/L) and the weight of wet biomass (6-16 g) on the response- reduction percentage of Ag ions. The significant factors and their interactions in the biosynthesis process were examined by means of analysis of variance (ANOVA). The results showed that the wet biomass weight has the most significant effect on the response compared to the other variables. Additionally, the model predicted that up to 89% of Ag+ reduction to Ag nanoparticles were obtained at the optimum range conditions– weight of biomass 13 g, the initial pH range 5.5-6.2 and concentration of carbon nanotubes 0.6 g/L.
BACKGROUND
Essential oils are complex mixtures of a variety of volatile molecules which can easily be decomposed depending on the industrial application. Geraniol is a terpene alcohol found in many essential oils from aromatic plants and its antimicrobial property increases its use as an important additive for the food industry.
RESULTS
Through experimental design 75% of geranyl cinnamate was obtained under reaction conditions of 70 °C, 15 wt% of immobilized C. antarctica NS88011, and 3:1 geraniol to cinnamic acid molar ratio. Kinetic assay showed it was possible to improve the enzymatic esterification reaction (97%) under reaction conditions of 80 °C, 20 wt% of immobilized NS88011 lipase and 5:1 geraniol to cinnamic acid molar ratio. The antimicrobial activity of the geranyl cinnamate ester was tested on bacteria Staphylococcus aureus and Escherichia coli by determining the minimum inhibitory concentration (MIC) and agar diffusion and the compound showed excellent antimicrobial activity for the two bacteria, with a bactericidal effect.
CONCLUSION
The results showed the promise of a technique to overcome the well‐known drawbacks of the chemical‐catalyzed route to obtain a high‐value compound. © 2016 Society of Chemical Industry
Essential oils are produced by plants for many reasons including protection against various bacterial and fungal. This study provides a dose-response analysis for antibacterial activity assessment using Escherichia coli DH5 as indicator microorganism. In this work it has been shown that it is possible to extract antibacterial activities using a simple process.
Phenylpropenes are produced by plants as part of their defense strategy against microorganisms and animals, and also as floral attractants of pollinators. Eugenol, the main component of clove's essential oil, is an inexpensive and easily available phenylpropene that has been known by humankind since antiquity, and used as a medicinal agent, but also for food flavoring and preservation. The review includes the most relevant results obtained during the last 15 years with regard to the synthetic uses of eugenol. Discussed here are the multiple applications of eugenol in organic synthesis, including its use as starting material or building block for the total synthesis of natural products, their analogs and derivatives, as well as other structurally interesting or bioactive compounds. The preparation technologically relevant macrocycles and polymeric derivatives of eugenol, is included, and the impact of biotechnology on the use of eugenol as feedstock for biotransformations, leading to other valuable small molecules is also addressed.
The ability of commercial immobilized lipase from Thermomyces lanuginosus (Lipozyme TL IM) to catalyze the acetylation of essential clove oil with acetic anhydride in a solvent-free system was studied, and the antimicrobial activity of the ester formed was evaluated as well. Experimental design based on two variables (eugenol to acetic anhydride molar ratio and temperature) was employed to evaluate the experimental conditions of eugenyl acetate ester production. The maximum conversion yield (92.86 %) was obtained using Lipozyme TL IM (5 wt%, based on the total amount of substrates), with eugenol to acetic anhydride molar ratio of 1:5 at 70 °C. The chemical structure of the eugenyl acetate ester obtained at the optimized condition, and purified, was confirmed by the proton nuclear magnetic resonance ((1)H-NMR) analysis. The antimicrobial activity of eugenyl acetate ester was proven effective on Gram-positive and Gram-negative bacteria, with means of 16.62 and 17.55 mm of inhibition halo.
In this study, we used plackett-burman design (PBD) and response surface methodology (RSM) methods to optimize media and culture conditions for expression of recombinant human basic fibroblast growth factor (rhbFGF) in Pichia pastoris in order to effectively enhance the production of rhbFGF. PBD was used to screen the most significant factors from nine important factors, which were fermentation time, methanol, temperature, initial pH, OD600 for inducement, concentrated volume, YNB peptone, and casein. Then RSM was further used to optimize the significant parameters. Our results had shown that three significant factors selected by PBD were temperature, fermentation time, and methanol. Base on the 3-factor-3-level central composite design (CCD) of RSM, the final optimized conditions were fermentation time 126.7h, methanol 1.3%, temperature 21.3°C, initial pH 6.0±0.1, OD600 for inducement 26, concentrated volume 100 ml, YNB 13.4%, peptone 4%, and casein 0.1%. The maximum production of rhbFGF was 302.4mg/L, which was 2 times higher than the production of rhbFGF reported in the previous studies. Those results provided the foundation for further researches on higher density cultivation condition of rhbFGF explored in the fermenter and accelerate the industrialization development of rhbFGF.
There are very chemical reactions with very slow rates which can be catalyzed by enzymes. These biocatalysts need to moderate conditions for their catalytic activity and are stable in low temperature (between 15-50A degrees C), average pH (5-10) and aqueous media. One of important things in enzymatic synthesis which has been recently noticed is the yield of reactions. Nowadays wide application of response surface methodology (RSM) was observed in organic chemistry. In one-variable-at-a-time technique only one parameter is changed and other parameters are kept at a constant level. It does not study the interactive effects among the variables, and does not illustrate the complete effects of the parameters on the process. Increasing the yield of product without increase in casts is carried out by modeling and optimization of reaction variables through statistical techniques such as RSM. In this paper, we reviewed some articles that used the RSM for optimization in the enzymatic synthesis.
The synthesis of wax ester using refined, bleached and deodorized (RBD) palm oil and oleyl alcohol catalyzed by lipozyme IM was carried out. Response surface methodology (RSM) based on a five-level, four-variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of synthesis, of reaction time (2.5–10 h), temperature (30–70 °C), amount of enzyme (0.1–0.2 g) and substrate molar ratio (palm oil to oleyl alcohol, 1:1–1:5) on the percentage yield of wax esters. The optimum conditions derived via RSM were: reaction time 7.38 h, temperature 53.9 °C, amount of enzyme 0.149 g, and substrate molar ratio 1:3.41. The actual experimental yield was 84.6% under optimum condition, which compared well to the maximum predicted value of 85.4%.
Cosmeceuticals are cosmetic-pharmaceutical hybrids intended to enhance health and beauty of the skin. Nanocosmeceuticals use nano-sized system for the delivery of active ingredients to the targeted cells for better penetration. In this work, nanoemulsion from palm oil esters was developed as a delivery system to produce nanocosmeceuticals. The stability of the resulting formulation was tested using various methods. In addition, the effect of components i.e. Vitamin E and Pluronic F-68 on the formulation was also studied.
Both vitamin E and Pluronic F-68 were found to co-emulsify and co-stabilized the formulations. The best formulation was found to be the one having the composition of 10% Palm Oil Esters (POEs), 10% vitamin E, 24% Tween 80, 2.4% Pluronic F-68 and 53.6% deionised water. Those compositions are considered to be the best as a nanocosmeceutical product due to the small particle size (94.21 nm), low occurrence of Ostwald ripening and stable at different storing temperatures (5, 25 and 45 degrees C) for four weeks.
Palm oil esters-in-water nanoemulsions loaded with vitamin E was successfully formulated and has the potential for the use as nanocosmeceuticals.
Objective: To evaluate the media components affecting the antimicrobial activity of alkaliphilic cyanobacteria using Plackett-Burman design. Material and Methods: Seven cyanobacterial cultures were isolated from alkaline-saline lake Lonar, MS, India. Cell extract of cyanobacteria in methanol, distilled water, acetone and isopropanol was evaluated for antibacterial activity against 5 bacterial cultures using disc diffusion method. Media components affecting the antibacterial activity of cyanobacteria were evaluated with the help of Plackett-Burman design. Results: Among cultures under test the unicellular cyanobacterium, Synechocystis aquatilis showed highest antibacterial activity against the test cultures. Acetone was found to be suitable extraction agent yielding maximum antibacterial activity for Synechocystis aquatilis From the Plackett-Burman experiment magnesium sulphate and ferric ammonium citrate were appeared to be the media components influencing antibacterial activity of Synechocystis aquatilis. Conclusion: Plackett-Burman design was useful in determining the media components affecting antibacterial activity of Synechocystis aquatilis significantly. 2010
The epoxidation of alkenes and other unsaturated hydrocarbon chains constitutes one of the most useful reactions in organic synthesis. As the epoxide group is an active intermediate, it can be readily transformed to the required functionality. Here, we report the synthesis of seven useful branched 2-ethylhexyl α-hydroxy stearate esters from commercially available oleic acid and common organic acids. The common organic acids used herein were octanoic, nananoic, lauric, myristic, palmitic, stearic and behenic acids. One of the products, the behenic ester of 2-ethylhexyl hydroxy stearate showed to have pour point, flash point and viscosity indices of -53 °C, 161 °C, and 215 cp, respectively, which is favourable properties in the synthesis of a bio-based lubrication base fluid. Overall, the data indicated that most of these synthesized derivative compounds have significant potential as lubricant base oil.
Our aim is to give a short introduction of the use of phase diagrams in order to rationalise general principles of surfactant self-assembly. These can be rationalised in terms of geometrical constraints: volume, surface and curvature. Binary (two components: surfactant and water) and ternary systems (surfactants, water, oil) are considered separately. Models for solubilisation, to be understood within the general principles and not as tabulated data, are presented. Finally, some examples of application of solubilisation in formulation are given. To cite this article: F. Testard, T. Zemb, C. R. Geoscience 334 (2002) 649–663.
Ethyl levulinate, produced through esterification of levulinic acid, is a ketoester with various applications. Synthesis of ethyl levulinate was carried out in solvent-free system using immobilized Candida antarctica lipase B (Novozym 435) as the biocatalyst for the reaction. Response surface methodology (RSM) with a four-factor-five-level central composite rotatable design (CCRD) was employed to study and optimize the reaction conditions in the synthesis of levulinate ester. The effect of four main reaction parameters including time, temperature, ethanol/levulinic acid molar ratio and amount of enzyme on the synthesis of ester were analyzed. A quadratic polynomial model was fitted to the data with an R 2 of 0.8993. Model validation experiments show good correspondence between actual and predicted values. A high conver-sion yield (96.2%) was obtained at the optimum conditions of 51.4 • C, 41.9 min, 292.3 mg enzyme amount and 1.1:1 alcohol:acid molar ratio.
The lipase-catalyzed synthesis of fatty alcohol esters of pyroglutamic acid (pGlu) was investigated. The results showed that, a strategy involving ethyl pyroglutamic ester intermediate was advantageous since this compound had a better solubility in the chosen solvent than the free pyroglutamic acid. The effects of the enzyme load, type of solvent, substrates molar ratio and fatty alcohol type were studied. It was shown that the most optimized reaction conditions were the ones using a 10% (w/w) quantities of Candida antarctica lipase with acetonitrile as solvent and a molar ratio of substrates corresponding to a 1:5 excess of fatty alcohols. Under such conditions, octyl, decyl and dodecyl esters of pyroglutamic acid were obtained in satisfactory yields between 65 and 70% with good reaction kinetics within 24 h.
Although it has not been explicitly recognized in the literature, biotransformations in organic media can be classified as
either solvent-based or solvent-free reactions. In the former systems, one or more substrates are dissolved in an inert organic
solvent that does not participate in the reaction in any respect, but to provide an environment for the enzyme to exert its
action on the dissolved substrate(s). In a solvent-free system, no other compounds but substrate(s) and enzyme are present
in a reactor. In principle, one substrate can be used in a large excess over another and, if so, it may also act as a solvent
for other reactants. Examples of such “neat” biotransformations can be found even in the early literature (1-3).
The orthogonal Plackett–Burman statistical experimental design was employed to study the efficacy of the lipase-mediated esterification of α-terpineol with a wide variety of organic acids. A two level design used to study the effect of eleven carboxylic acids of carbon chain length C2 to C18 identified all the acids to be significant, implying that corresponding esters of α-terpineol were produced in substantial amounts, 18.7–41.1%, on using lipase as catalyst. The Plackett–Burman design, not attempted in lipase catalysis before, is a reliable method to short-list the best organic acid from a wide range or understand the extent of esterification possible under a given set of conditions in a very small number of experiments.
Lipozyme (Rhizomucor miehei lipase) was used to catalyze the acylation of the amino acid l-lysine (L) with the free fatty acids, palmitic (PA) and oleic (OA) acids, to synthesize N-ε-palmitoyllysine and N-ε-oleoyllysine, respectively. Response surface methodology (RSM) based on a five-level, five-variable design was employed, firstly, for studying the interactive effects of various parameters on the reactions, and secondly, for their optimization. Simultaneously increasing temperature and solvent hydrophobicity, fatty substrate concentration or enzyme amount improved yields in both reactions, as did increasing solvent hydrophobicity and substrate concentration or enzyme amount, and substrate concentration and enzyme amount together. Increasing desiccant amount in very non-polar solvents, at very high levels of enzyme, and in very concentrated substrate solutions led to higher yields in the PA reaction but compromised the OA reaction. The optimum conditions predicted for the two reactions were: temperature, 69.3 °C (PA) and 56.6 °C (OA); solvent log P=3.46 (PA) and log P=3.50 (OA); fatty substrate concentration, 98.0 mM (PA) and 99.9 mM (OA); enzyme amount, 186 mg (PA and OA); molecular sieves, 160 mg (PA) and 80 mg (OA). Reactions under optimized conditions yielded 16.1% of N-ε-palmitoyllysine and 33.1% of N-ε-oleoyllysine.
Glycerol-fatty acid esterification has been conducted with lipase from Penicillium camembertii lipase immobilized on epoxy SiO2-PVA in solvent-free media, with the major product being 1-monoglyceride, a useful food emulsifier. For a given set of initial conditions, the influence of reaction was measured in terms of product formation and selectivity using different fatty acids as acyl donors. Results were found to be relatively dependent of the chain length of the fatty acids, showing high specificity for both myristic and palmytic acids attaining final mixture that fulfills the requirements established by the World Health Organization to be used as food emulsifiers.
The effect of nonionic surfactants on the solubility and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase and in the soil slurry phase, as well as the fate of these surfactants, were investigated. The PAH solubility was linearly proportional to the surfactant concentration when above the critical micelle concentration (CMC), and increased as the hydrophile–lipophile balance (HLB) value decreased. Substantial amounts of the sorbed phenanthrene in the soil particles were desorbed by non-ionic surfactants into the liquid phase when the ratio of soil to water was 1:10 (g/ml). Brij 30 was the most biodegradable surfactant tested, showed no substrate inhibition up to a concentration of 1.5 g/l, and was definitely used as a C source by the bacteria. Naphthalene and phenanthrene were completely degraded by phenanthrene-acclimatised cultures within 60 h, but a substantial amount of naphthalene was lost due to volatilization. The limiting step in the soil slurry bioremediation was bioavailability by the micro-organisms for the sand slurry and mass transfer from a solid to aqueous phase in the clay slurry.
Eugenol, a phytochemical , is a pale yellow oil which is isolated from essential oil of Ocimum sanctum Rama.Eugenol has wide medicinal applications. It affects central nervous system and cardiovascular system. It is used indentistry and as an analgesic, antipyretic, antimicrobial, anti septic, antidepressant agent. Its analogues also showmany biological activities which prompted us to synthesize new analogues for their future application as bioactivemolecules.
Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM) approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme. A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60 degrees C, reaction time of 438 min, and agitation speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester.
The proteolytic enzymes are the most important group of commercially produced enzymes. The production of alkaline protease was optimized using a newly isolated Bacillus sp. RKY3. The fermentation variables were selected in accordance with the Plackett-Burman design and were further optimized via response surface methodological approach. Four significant variables (corn starch, yeast extract, corn steep liquor, and inoculum size) were selected for the optimization studies. The statistical model was constructed via central composite design (CCD) using three screened variables (corn starch, corn steep liquor, and inoculum size). An overall 2.3-fold increase in protease production was achieved in the optimized medium as compared with the unoptimized basal medium. Enzyme activity increased significantly with optimized medium (939 u ml(-1)) when compared with unoptimized medium (417 u ml(-1)).
Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, medicinal and cosmetic applications, especially nowadays in pharmaceutical, sanitary, cosmetic, agricultural and food industries. Because of the mode of extraction, mostly by distillation from aromatic plants, they contain a variety of volatile molecules such as terpenes and terpenoids, phenol-derived aromatic components and aliphatic components. In vitro physicochemical assays characterise most of them as antioxidants. However, recent work shows that in eukaryotic cells, essential oils can act as prooxidants affecting inner cell membranes and organelles such as mitochondria. Depending on type and concentration, they exhibit cytotoxic effects on living cells but are usually non-genotoxic. In some cases, changes in intracellular redox potential and mitochondrial dysfunction induced by essential oils can be associated with their capacity to exert antigenotoxic effects. These findings suggest that, at least in part, the encountered beneficial effects of essential oils are due to prooxidant effects on the cellular level.
A group of 4-allyl-2-methoxyphenol (eugenol) esters were designed, synthesized, and evaluated as potential inhibitors of soybean 15-lipoxygenase (SLO). Compounds 4c, 4d 4f, 4p, and 4q showed the best IC(50) in SLO inhibition (IC(50)=1.7, 2.3, 2.1, 2.2, and 0.017microM, respectively). All compounds were docked into SLO active site and showed that allyl group of compounds is oriented toward the iron atom in the active site of SLO. It is assumed that lipophilic interaction of ligand-enzyme would be in charge of inhibiting the enzyme activity. The selectivity of eugenol derivatives in inhibiting 15-HLOb was also compared with 15-HLOa by molecular modeling and multiple alignment techniques.
In an effort to optimize the reaction conditions of biodiesel production from lard, response surface methodology was applied, and the effects of five-level-three-factors and their reciprocal interactions were assessed. A total of 20 individual experiments were conducted, and were designed to study reaction temperature, catalyst amount, and oil-to-methanol molar ratio. A statistical model predicted that the highest conversion yield of lard biodiesel would be 98.6%, at the following optimized reaction conditions: a reaction temperature of 65 degrees C, a catalyst amount of 1.26%, and an oil-to-methanol molar ratio of 7.5:1, with a 20-min reaction time. Using these optimal factor values under experimental conditions in three independent replicates, an average content of 97.8+/-0.6% was achieved, and this value was well within the range predicted by the model. The quality of biodiesel produced from lard at the optimum reaction conditions satisfied the relevant quality standards, with the exception of cold filter plugging point.