Methyl Phenylacetate Research Articles

Chiral Bioelectrocatalytic Oxidations Driven By Electrocatalytic Oxygen Reduction and Horseradish Peroxidase or Cytochrome P450

Biocatalysis, the use of enzymes for synthesis, has emerged as a powerful tool for synthesis of chiral molecules in pharmaceutical and fine chemical industries. Natural enzymes offer inherent stereoselectivity, making them attractive catalysts for this purpose. Peroxidases and cytochrome P450s enzymes utilize an iron-heme cofactor to perform a diverse array of chemical transformations including CH2 hydroxylation, epoxidations, and sulfur-oxidations. Here, we report chiral biocatalytic oxidations in microemulsion media driven by horseradish peroxidase (HRP) coupled with a synthetic Cu2+-polymer electrocatalyst to convert O2 to H2O2. This tandem system uses crosslinked layer-by-layer (LBL) films of polyelectrolytes with Cu2+- poly(2-hydroxy-3-dipicolylamino) propyl methacrylate (Py-PGMADPA) to drive O2 reduction. Peroxide in turn activates HRP crosslinked in LbL films on magnetic beads (MB) to biocatalytically oxidize styrene, ethylbenzene, and methyl phenylacetate to chiral products. R-stereoisomers of these reactants were selectively formed with a high enantiomeric excess of > 80%. Conductive microemulsion reaction media are used to provide solubility to the non-polar reactants and water to hydrate the enzymes to function. The enzyme films show high thermal stability and high chiral selectivity up to 90 °C. A second synthetic goal was to compare chiral products of reactions catalyzed by cyt P450’s natural catalytic pathway mimicked by electrocatalysis versus via electrochemical generation of H2O2. We immobilized baculosome-P450s in LBL films with polystyrene sulfonate for the natural catalytic pathway, and for peroxide activation crosslinked P450 LbL on magnetic beads. These synthetic hybrid approaches open new doors to designing biocatalytic syntheses using an electrochemical driving force. Keywords: Biocatalysis, organic syntheses, cytochrome P450, horseradish peroxidase, regioselective and stereoselective oxidation

Chiral Biocatalytic Oxidations at 90 °C in Microemulsions Driven by Electrocatalytic Oxygen Reduction to Hydrogen Peroxide

AbstractChirality plays a significant role in the manufacture of pharmaceuticals and fine chemicals. The use of chemical catalysts to control stereoselectivity relies on the use of chiral catalysts with labor–intensive synthesis and purification. Natural enzymes offer inherent stereoselectivity, making them attractive catalysts for this purpose. We report here chiral biocatalytic oxidations in microemulsions driven by horseradish peroxidase coupled with a synthetic Cu2+‐polymer catalyst. This hybrid system features crosslinked layer–by–layer (LBL) films composed of polyions with Cu2+‐containing pyrene–labelled poly(2‐hydroxy‐3‐dipicolylamino) propyl methacrylate (Py−PGMADPA) to drive oxygen reduction to form hydrogen peroxide. Peroxide in turn activates horseradish peroxidase (HRP) crosslinked in LbL films on magnetic particle beads to biocatalytically oxidize styrene, ethylbenzene, and methyl phenylacetate to chiral products. R‐stereoisomers of these reactants were selectively formed with a high enantiomeric excess of ≥80 % at 90 °C. The enzyme films show high thermal stability at 90 °C in cetyltrimethylammonium bromide microemulsion. Reactions at 90 °C were essentially complete in 2 hr. This hybrid approach opens a door to new designs of biocatalytic syntheses using a separate electrocatalyst for enzyme activation.

Volatiles from nutritional fungal symbiont influence the attraction of Anisandrus maiche (Coleoptera: Curculionidae) to ethanol-baited traps.

Anisandrus maiche Stark (Coleoptera: Curculionidae: Scolytinae) is a non-native ambrosia beetle from central Asia that has been spreading throughout the eastern United States since 2005. Preferred hosts of A. maiche are not well characterized within its currently invaded range, but it is established in managed and natural forests throughout Indiana. Current monitoring and detection efforts for this beetle rely on ethanol-baited traps, but fungal volatiles may alter the attraction of A. maiche to ethanol. In this study, we conducted trapping experiments in Indiana to determine the extent to which a suite of common fungal alcohols influences the response of A. maiche to ethanol-baited traps. We then evaluated isoamyl and isobutyl alcohol as potential attractants for A. maiche and their ability to enhance attraction to ethanol. Lastly, we used SPME-GC-MS to identify volatiles from Ambrosiella cleistominuta (Mayers & Harr.), the fungal symbiont of A. maiche, grown for 7 and 14 days on malt extract agar. Benzyl alcohol, isobutyl alcohol, hexanol, methyl phenylacetate, phenethyl alcohol, and piperitone reduced the attraction of A. maiche to ethanol-baited traps in the field. Moreover, adding methyl benzoate and isoamyl alcohol individually to ethanol-baited traps did not further increase A. maiche capture. When paired with ethanol, isoamyl alcohol repelled beetles in the early flight period but did not significantly increase trap capture during the fall flight. These results represent a first step in understanding the role of fungal volatiles in the colonization behavior of A. maiche and may ultimately inform management strategies for this species.

Update to RIFM fragrance ingredient safety assessment, methyl phenylacetate, CAS Registry Number 101-41-7

Update to RIFM fragrance ingredient safety assessment, methyl phenylacetate, CAS Registry Number 101-41-7

The Tungsten-Promoted Synthesis of Piperidyl-Modified erythro-Methylphenidate Derivatives.

Due to its efficacy as a dopamine receptor agonist, methylphenidate (MPH) is of interest as a potential therapeutic for cocaine addiction. While numerous derivatives of MPH have been investigated for their potential medicinal value, functionalization of the piperidine ring has not been explored. The pyridine borane ligand in WTp(NO)(PMe3)(η2-pyBH3) is dearomatized by the metal and can be elaborated to the analogous η2-mesylpyridinium complex. Installing a methyl phenylacetate moiety at the C2' position via a Reformatsky reaction followed by a tandem protonation/nucleophilic addition sequence results in a library of erythro MPH analogues functionalized at the piperidyl C5' position. The functional group is added chemoselectively to C5', cis to the methyl phenylacetate. Repeating this procedure with an enantioenriched source of the tungsten reagent results in enantioenriched MPH derivatives. All identities of the newly reported compounds are supported by comprehensive 2D NMR and HRMS data or crystallographic data.

Untersuchung von aromaaktiven Biosyntheseprodukten von Basidiomyceten auf Reststoffströmen der Lebensmittelindustrie

Biotechnological production of flavors is economically relevant and a key to enable a tasty and diverse food supply. Fungi are suitable biocatalysts for the production of flavor compounds and often more efficient than the classical flavor extraction from plants and foods. Fungi from the department of Basidiomycota have a powerful enzymatic toolbox to generate flavor compounds.Based on a broad screening of Basidiomycota, media optimization was performed to find suitable conditions for an efficient biotransformation of black currant pomace. During fermentation, the scents were investigated on a sensory and instrumental level via gas chromatography‐mass spectrometry (GCMS). W. cocos was grown on a solid‐state medium composed of 30 g kg‐1 pomace, 6.24 g kg‐1 sodium aspartate‐monohydrate and 30 g kg‐1 agaragar for 10 days. Tue flavor was characterized by means of a self‐validated aroma dilution analysis (ADA), quantified, and proven with recombination experiments.Solid‐state fermentation of pomace and aspartate led to a pleasant odor reminiscent of wild strawberries. Methyl anthranilate (2,206 μg kg‐1, flavor dilution factor 210), (R)‐linalool (1,879 μg kg‐1, 211), 2‐amino benzaldehyde (771 μg kg‐1, 25), and geraniol (138 μg kg‐1, 25) were determined as aromarelevant for the wild strawberry like flavor in recombination experiments. Tue substrate‐fungus combination made use of the nutrients provided by the black currant pomace leading to an appealing natural flavoring for food.In a second approach, 80 g L‐1 pomace and 60 g L‐1 sucrose (pH 4.4) were fermented in a submerged culture until the medium reached a pH‐value of 3.5. Supernatants of the fermented product were evaluated for a potential use as a beverage. Submerged fermentation of black currant pomace and sucrose led to a pleasant flowery and honey‐like odor and a fruity, slightly sour taste. Tue produced fruit acids and flavor compounds were characterized and quantified. Tue scaled‐up fermentation product was processed and carbonized in cooperation with the Geisenheim University. A panel evaluated the carbonated fermented beverage on a hedonic scale, ranging from O to 10, with 8.0 ± 1.4, whereas the value for the non‐inoculated medium was 2.5 ± 2.5. A rise of the oxalic acid concentration was detected, which led to the characteristic fruity taste in combination with citric acid (935 mg L‐1 citric acid and 192 mg L‐1 oxalic acid). Linalool (23 μg L‐1), geraniol (42 μg L‐1), phenylacetic acid (950 μg L‐1), eugenol (23 μg L‐1) and methyl phenylacetate (94 μg L‐1) were detected with odor activity values above one, which imparted fruity and honey‐like odors. Fermentation of black currant pomace led to a tasty beverage, which suits the current beverage trends. Upcycling of pomace with its physiologically valuable nutrients as a fermented beverage could contribute to a healthy human nutrition.In a third study, 28 potentially aroma active non‐canonical terpenes were investigated in cooperation with the Dechema Research Institute. For twelve especially potent compounds, the odor thresholds (OT) were determined in comparison to their non‐methylated equivalents. In addition to the classical approach according to Ullrich and Grosch (1987), a novel method including the individual OT determination of the internal standards was established. Tue odors of several non‐canonical terpenes were described for the first time. Twelve compounds were identified as highly intense flavors, e.g., the flowery smelling 2‐methyllinalool with an OT of 1.8 ng L‐1 air, the earthy smelling 2‐ methyl‐a‐fenchol (3.6 ng L‐1 air), and the flowery scent 2‐methylgeraniol (5.4 ng L‐1 air). The newly developed method for the OT determination appeared as an improvement compared to the method used so far. Methylated derivatives of linalool, citronellol, and geraniol were highly attractive due to their flowery and citruslike scents, which are highly interesting for the cosmetic industry.

Upcycling of black currant pomace for the production of a fermented beverage with Wolfiporia cocos

Pomace as a side stream from black currant juice production is mostly discarded, even though it is rich in nutrients like protein, fiber, sugars, anthocyanins, polyphenols, and other secondary metabolites. Fungi from the division of Basidiomycota have a great enzymatic toolbox to recycle these complex mixtures of nutrients. In particular, the edible medicinal fungus Wolfiporia cocos has been described as a suitable biocatalyst to form pleasant aroma compounds in fermentation processes. Therefore, medium optimization, upscaling, and filtration were performed to produce a beverage based on black currant pomace fermented with W. cocos. A trained panel described the beverage as highly pleasant, reminiscent of honey, flowers and berries with a well-balanced sour and sweet taste. The flavor compounds linalool (citrus), geraniol (flowery), phenylacetic acid (honey), methyl phenylacetate (honey), eugenol (clove), and 2-phenylethanol (rose) were produced during fermentation and the concentrations exceeded their respective odor thresholds. The produced beverage was evaluated with 8.0 ± 1.4 from 10 for the question of whether panelists would buy the product. Fungal fermentation with the edible fungus W. cocos enabled the production of a highly pleasant beverage and additionally may reduce waste by using pomace and table sugar as sole ingredients.

Optimization and Control for Separation of Ethyl Benzene from C8 Aromatic Hydrocarbons with Extractive Distillation

Extractive distillation has great significance for the separation of ethylbenzene from C8 aromatic hydrocarbons. Herein, a distillation process for the separation of ethylbenzene was designed using methyl phenylacetate as an extractant. A genetic algorithm (GA) was used to evaluate the economic and environmental factors of the process, and Aspen Dynamic was used to assess the dynamic performance. The sequential optimization method was used to obtain the initial process parameters. Then, the total annual cost and CO2 emissions were minimized by NSGA-III to increase the economic and environmental benefits. To enhance the search performance of GA, the mutation probability and crossover probability were studied and adjusted. The optimal total annual cost and CO2 emissions were 11.7% and 23.7% lower than those of the initial process. Based on a steady process, two control strategies, which were the flow rate of the recycling solvent controlled by entrainer makeup flow rate (CS1) and the bottom flow rate of the extractant recovery column (CS2), were designed. The results showed that the temperature deviation of CS2 was smaller than that of CS1, and the temperature of the process was more stable under the control of CS2.

Applying the Crystalline Sponge Method to Agrochemicals: Obtaining X-ray Structures of the Fungicide Metalaxyl-M and Herbicide S-Metolachlor.

The crystalline sponge method is a technique that provides the ability to elucidate the absolute structure of noncrystalline or hard to crystallize compounds through single-crystal X-ray diffraction by removing the need to obtain crystals of the target compound. In this study the crystalline sponges {[(ZnX2)3(2,4,6-tris(4-pyridyl)-1,3,5-trazine)2].x(solvent)}n (X = I, Br) were used to obtain X-ray structures of the agrochemical active ingredients metalaxyl-M and S-metolachlor. The effect of the temperature used during guest uptake and the influence of changing the host framework ZnX2 nodes on guest encapsulation were investigated. Additionally, three compounds containing chemical fragments similar to those of metalaxyl-M and S-metolachlor (phenylacetaldehyde, N-ethyl-o-toluidine, and methyl phenylacetate) were also encapsulated. This allowed for the effect of guest size on the position that guests occupy within the host frameworks to be examined. The disorder experienced by the guest compounds was documented, and an analysis of the intermolecular host–guest interactions (CH···π and π ···π) used for guest ordering within the host frameworks was also undertaken in this study.

The Bacteriostatic Activity of 2-Phenylethanol Derivatives Correlates with Membrane Binding Affinity.

The hydrophobic tails of aliphatic primary alcohols do insert into the hydrophobic core of a lipid bilayer. Thereby, they disrupt hydrophobic interactions between the lipid molecules, resulting in a decreased lipid order, i.e., an increased membrane fluidity. While aromatic alcohols, such as 2-phenylethanol, also insert into lipid bilayers and disturb the membrane organization, the impact of aromatic alcohols on the structure of biological membranes, as well as the potential physiological implication of membrane incorporation has only been studied to a limited extent. Although diverse targets are discussed to be causing the bacteriostatic and bactericidal activity of 2-phenylethanol, it is clear that 2-phenylethanol severely affects the structure of biomembranes, which has been linked to its bacteriostatic activity. Yet, in fungi some 2-phenylethanol derivatives are also produced, some of which appear to also have bacteriostatic activities. We showed that the 2-phenylethanol derivatives phenylacetic acid, phenyllactic acid, and methyl phenylacetate, but not Tyrosol, were fully incorporated into model membranes and affected the membrane organization. Furthermore, we observed that the propensity of the herein-analyzed molecules to partition into biomembranes positively correlated with their respective bacteriostatic activity, which clearly linked the bacteriotoxic activity of the substances to biomembranes.

Fatty Acid Methyl Esters From the Coral-Associated Bacterium Pseudomonas aeruginosa Inhibit Virulence and Biofilm Phenotypes in Multidrug Resistant Staphylococcus aureus: An in vitro Approach.

In an attempt to study the antibacterial, antivirulence and antibiofilm potentials of bacteria residing the tissue and surface mucus layers of the pristine corals, we screened a total of 43 distinct bacterial morphotypes from the coral Favites sp. Among the isolates, Pseudomonas aeruginosa strain CBMGL12 with showed antibacterial, antivirulence and antibiofilm activity against multidrug resistant pathogenic strains of Staphylococcus aureus (reference strain: MTCC96; community-acquired methicillin resistant strain: CA-MRSA). Extracellular products (ECP) from the coral-associated bacterium P. aeruginosa were solvent extracted, fractionated by chromatographic techniques such as silica column and HPLC-UV with concomitant bioassays guiding the fractionation of metabolites. Identification of bioactive chemical moieties was performed by FT-IR analysis, GC-MS/MS equipped with NIST library, 1H and 13C NMR spectral studies. We report the differential production of extracellular and cell-associated virulence and biofilm phenotypes in multi-drug resistant strains of S. aureus, post-treatment with the ECP containing aromatic fatty acid methyl esters (FAME) such as methyl benzoate and methyl phenyl acetate produced by a coral-associated bacterium. In conclusion, this study has identified antibacterial, antibiofilm and antivirulent FAME from the coral-associated P. aeruginosa for its ability to attenuate virulence and biofilms phenotypes in multi-drug resistant pathogenic strains of S. aureus.

Brønsted Acid‐Catalyzed Cyclopropanation of Indoles Using α‐Aryl‐α‐diazoacetates

AbstractMetal‐free cyclopropanation of N‐protected indoles with α‐aryl‐α‐diazoacetates proceeded by using a catalytic amount of triflic imide as a Brønsted acid catalyst. The use of a catalytic amount of methyl phenylacetate improved the efficiency of the Brønsted acid‐catalyzed cyclopropanation. A reaction mechanism including C‐protonation of diazoacetates with HNTf2, followed by formal [3+2] cycloaddition with indoles and 1,3‐rearrangement was proposed for the cyclopropanation.

Phenylacetic Acid and Methylphenyl Acetate From the Biocontrol Bacterium Bacillus mycoides BM02 Suppress Spore Germination in Fusarium oxysporum f. sp. lycopersici

Bacillus mycoides strain BM02 originally isolated from the tomato rhizosphere was found to have beneficial functions in tomato by promoting plant growth and reducing the severity of Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol). Cytological experiments demonstrated B. mycoides BM02 reduced Fol invasion by reducing spore attachment and increasing hyphal deformation in hydroponics-grown tomato root tissues. Two volatile antifungal compounds, phenylacetic acid (PAA) and methylphenyl acetate (MPA), were identified from the culture filtrates of B. mycoides BM02 by GC-MS analysis. Chemically synthesized PAA, and to a lower extent MPA, suppressed spore germination but have no effects on the hyphal growth of Fol. Our results indicated that the biocontrol agent B. mycoides BM02 produced an array of bioactive compounds including PAA and MPA to suppress plant diseases caused by Fol and other pathogenic microorganisms.

Effects of Dimethyl Anthranilate-Based Repellents on Behavior, Plumage Condition, Egg Quality, and Performance in Laying Hens.

Feather pecking is a behavior that occurs in order to cope with a constrained environment and is a serious problem in the egg production industry. This longitudinal study was conducted under commercial conditions to investigate whether the application of two repellent mixtures, previously suggested as aversive to wild birds, to the plumage of Prelux-R hybrid egg layers is a viable alternative to beak trimming as a solution to discourage feather pecking among laying hens. A total of 180 untrimmed hybrid layers was reared together in a floor pen. At 18 weeks of age they were allocated randomly to three treatments (repellent P, repellent T, control), each consisting of 6 replicated enriched cages with 10 hens in each cage. Hens were evenly sprayed once every 2 weeks for 54 weeks with solution P (dimethyl anthranilate and methyl phenylacetate), solution T (dimethyl anthranilate and geraniol), or distilled water (control). Body weight, plumage condition, behavior, feed intake, and egg quality measurements were taken at five time periods from 26 to 76 weeks of age. Egg production and mortality were recorded daily. The treatments did not affect feather pecking behavior. Hens treated with repellent T tended to perform less cage pecking than the control hens. The use of the repellents did not reduce feather pecking, the plumage was even more significantly damaged in the hens given the repellents compared to the control hens. This suggests the chemicals in the repellents worsened the plumage. No differences in feed intake and daily egg production between treatments were found. Raw and hard-boiled eggs were highly uniform in odor/flavor/taste and no offensive odor absorption related to the chemicals in the repellents was detected. In conclusion, in the present study we did not find any beneficial effect of dimethyl anthranilate-based repellents on feather pecking frequency and plumage/feather condition. Therefore, we do not encourage their use in wider commercial settings.

Characterization of a Self-Sufficient Cytochrome P450 Monooxygenase from Deinococcus apachensis for Enantioselective Benzylic Hydroxylation.

A self-sufficient cytochrome P450 monooxygenase from Deinococcus apachensis (P450DA) was identified and successfully overexpressed in Escherichia coli BL21(DE3). P450DA would be a member of the CYP102D subfamily and assigned as CYP102D2 according to the phylogenetic tree and sequence alignment. Purification and characterization of the recombinant P450DA indicated both NADH and NADPH could be used by P450DA as a reducing cofactor. The recombinant E. coli (P450DA) strain was functionally active, showing excellent enantioselectivity for benzylic hydroxylation of methyl 2-phenylacetate. Further substrate scope studies revealed that P450DA is able to catalyze benzylic hydroxylation of a variety of compounds, affording the corresponding chiral benzylic alcohols in 86-99 % ee and 130-1020 total turnover numbers.

Phenolic derivatives from Garcinia multiflora Champion ex Bentham and their chemotaxonomic significance

A phytochemical investigation of the leaves and twigs of Garcinia multiflora Champion ex Bentham led to the isolation of eleven phenolic derivatives, including a new polycyclic polyprenylated acylphloroglucinol (PPAP, 1), five known PPAPs (2–6), three xanthones (7–9), a benzophenone (10), and a methyl phenyl acetate derivative (11). Their structures were established by extensive spectroscopic analysis, including HR-ESI-MS and NMR. Five compounds (1, 2, 4, 5, and 11) were first found in the genus Garcinia, of which compounds 1 and 11 were reported from the family Guttiferae for the first time. The chemotaxonomic significance of the isolated compounds was discussed. Furthermore, six PPAPs showed good cytotoxicities with IC50 values ranging from 1.79 to 9.40 μM.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF SOME NOVEL 3,4-DISUBSTITUTED PYRAZOLE DERIVATIVES

Objective: The objective of the current work was to synthesize a series of 3,4-substituted pyrazoles from the cyclization of substituted aryl ethanone and hydrazine hydrate in a two-step process and screen the derivatives for their antimicrobial activity.
 Methods: The title compounds were derived from the condensation of ethanone intermediate with N, N-Dimethyl formamide-dimethyl acetal and hydrazine hydrate. Ethanone intermediate synthesized from substituted methyl phenylacetate in the presence of potassium t-butoxide with 6-methyl pyridine-2-carboxylic acid methyl ester.
 Results: The final products were characterized by detailed spectral analysis using Mass, Nuclear Magnetic Resonance, and Infra Red spectroscopy. All the compounds (4a-4j) showed significant antibacterial properties on both Gram-positive and Gram-negative bacteria. Interestingly, the selected microbes were found to be highly sensitive for compound 4a, 4c, 4d, 4h, and 4i. The molecules are also antifungal in nature, and they have a significant inhibitory effect on the growth of Candida albicans and Aspergillus niger.
 Conclusion: The results suggest that the developed derivatives bearing the pyrazole nucleus could be the lead structures for the development of antimicrobial agents for fatal infections.

Natural flavor ester synthesis catalyzed by lipases

AbstractIn spite of the fact that several flavors and fragrances are obtained either by chemical synthesis or by extraction from plants, the application of biocatalysis for the sake of a safe and productive pathway by more sustainable chemical processes is the main alternative. The current study focuses on the synthesis of three flavor esters, namelycis‐3‐hexen‐1‐yl acetate, 2‐phenylethyl acetate, and methyl phenylacetate,viatransesterification and esterification of the natural corresponding alcohols or acids. The impact of optimizing variables that influence this lipase‐catalyzed synthesis, such as enzyme formulations, solvent‐free media, and acetylating agents, is crucial to achieving higher conversions. The enzymatic transesterification using Novozym 435 affordedcis‐3‐hexen‐1‐yl, and 2‐phenylethyl acetates with high yields (>90%) in green solvents. Similar results were obtained in solvent‐free system, which is more economic for the scaling up of this synthesis. In the case of esterification reactions, the removal of water, formed as a by‐product, with the use of Aquasorb enhanced the conversions as in the case of methyl phenylacetate attained with a conversion of 89% in the presence of Novozym 435. However, this effect was not observed in the larger scale reaction (with 0.85 mol ofcis‐3‐hexen‐1‐ol). Instead, the efficient strategy of gradual addition of acetic acid has proven to significantly improve the yield ofcis‐3‐hexen‐1‐yl acetate (from 2% up to about 80% in the case of the preparative reaction with 100 mL substrate). Box‐Behnken analysis was also performed to identify the lowest amount of acetylating agent and the shorter time to obtain the highest conversion ratio. This analysis showed that a triacetin/alcohol molar ratio of 1 and 1.75 can be sufficient to obtain a conversion >90% and up to 95%, forcis‐3‐hexen‐1‐yl acetate and 2‐phenylethyl acetate, respectively, similarly to what is obtained with higher triacetin/alcohol molar ratios and comparable reaction time.

Comparison Analysis of Volatile Components in Two Kinds of Rattan Pepper Oil Produced from Different Processing

The volatile components of two kinds of rattan pepper oil produced from different processing was analyzed by HS-GC-MS (headspace gas chromatography-mass spectrometry). The volatile components were qualitatively analyzed by matching the mass spectral database NIST14 and were quantified by peak area normalization. The results were as follows:33 volatile components were identified from the two rattan pepper oils by traditional oil immersion method and supercritical CO2 extraction method. 16 components in total existed in both the two oils, of which 4 components (D-limonene, linalool, sabinene and myrcene) were the main parts (relative content ≥ 4.5%). There were 6 kinds of volatile components (β-elemene, 1-caryophyllene, germacrene D, humulene, octyl aldehyde and decanal) peculiar to traditional oil immersion method, and 11 kinds of volatile components (3-methyl-2-butenonitrile, 5-cyanol-1-pentene, (1S)-(1) -β-Pinene, alpha-terpinene, trans-β.-Ocimene, 3, 3-dimethylcyclohexanol, 4-terpinenyl acetate, methyl phenylacetate, 2, 4-Hexadienal, (E, E) -, (+) -citronellal and 1-methyl-isohexanoic acid) peculiar to supercritical CO2extraction. Alkenes and alcohols were main volatile components in the two kinds of oil, but the relative contents were different. The latter oil contained traces of acid compounds (1-methyl-isohexanoic acid). The results above provided theoretical basis for both processing and quality improvement of rattan pepper oil.

Different strategies to immobilize lipase from Geotrichum candidum : Kinetic and thermodynamic studies

Abstract The use of different strategies to immobilize lipase from Geotrichum candidum (GCLI) produced through submerged fermentation was evaluated in order to obtain a biocatalyst with a high stability and activity. Crude and purified GCLI were immobilized by different protocols such as interfacial activation, ionic adsorption and multipoint covalent attachment. The biocatalyst prepared using purified GCLI immobilized on MANAE-agarose exhibited the highest hydrolytic activity (45.40 ± 0.19 IU/g of support) among all the supports used, therefore it was selected for kinetic and thermodynamic studies and the influence of the pH and the protein loading was investigated. The maximum adsorption capacity of 4.51 ± 0.21 mg/g of support was observed at pH 7.0 and 25 °C with a hydrolytic activity of 81.10 ± 2.11 IU/g. GCLI immobilization on MANAE-agarose also reduced the apparent activation energy by 50% compared to the soluble enzyme and increased the amount of product formed in hydrolysis reactions, which was verified by calculating the apparent kinetic parameters Vmax (46.30 IU/mL) and Km (261.77 mmol/L). All thermodynamic apparent parameters determined from thermal stability assays showed that immobilized GCLI allowed a great increase in thermostability. Also, the prepared biocatalyst was able to hydrolyze methyl phenylacetate better than methyl mandelate.