Butyrate Esters Research Articles

Catalytic profiles of lipolytic biocatalysts produced by filamentous fungi

The aim of this work is to propose and evaluate a catalytic profile of biocatalysts with lipase activity based on four characteristic reactions of lipases. For that, the catalytic profiles of three lipolytic biocatalysts from strains of the genus Rhizopus produced by solid-state fermentation (SSF) were determined based on acyl-, regio-, enantio- and chemoselectivity. Four commercial lipases were also evaluated according to their catalytic selectivity. p-nitrophenol esters from C-4 to C-16 were used to evaluate the acyl selectivities of the biocatalysts. The three biocatalysts produced by SSF presented the highest hydrolytic activity on triglycerides of medium chain length (C-8). The use of high performance thin layer chromatography (HPTLC) allowed us to demonstrate the biocatalysts produced by SSF presented sn-1,3-regioselectivity. Based on the Quick E method, the biocatalysts preferentially acted on the S-enantioisomer of glycidyl butyrate esters. Although their E values were insufficiently high (< 5), they demonstrated 1,3-sn selectivity hydrolytic activity, and the ability to synthesise ester and amide bonds (benzyl oleate and N-benzyloleamide, respectively), validating them as promising biocatalysts for these types of applications.

Glucose and Glucose Esters in the Larval Secretion of Chrysomela Lapponica; Selectivity of the Glucoside Import System from Host Plant Leaves

Larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) sequester characteristic O-glucosides from the leaves of their food plants, namely Betula and/or Salix The present study focuses on birch-feeding larvae of C. lapponica from the Altai region in East Kazakhstan. As in other sequestering leaf beetle larvae, the compounds are transported intact via different membrane barriers into the defensive system, followed by glucoside cleavage and subsequent transformations of the plant-derived aglycones. Unlike previous studies with model compounds, we studied the sequestration of phytogenic precursors by analyzing the complex pattern of glucosides present in food plant Betula rotundifolia (39 compounds) and compared this composition with the aglycones present as butyrate esters in the defensive secretion. In addition to the analytic approach, the insect's ability, to transport individual glucosides was tested by using hydrolysis-resistant thioglucoside analogs, applied onto the leaf surface. The test compounds reach the defensive system intact and without intermediate transformation. No significant difference of the transport capacity and selectivity was observed between larvae of birch-feeding population from Kazakhstan, and previous results for larvae of birch-feeding population from the Czech Republic or willow-feeding populations. Overall, the transport of the phytogenic glucosides is highly selective and highly efficient, since only minor compounds of the spectrum of phytogenic glucoside precursors contribute to the limited number of aglycones utilized in the defensive secretion. Interestingly, salicortin 44 and tremulacin 60 were found in the leaves, but no aldehyde or esters of salicylalcohol. Surprisingly, we observed large amounts of free glucose, together with small amounts of 6-O-butyrate esters of glucose (27a/b and 28a/b).

Toxicities of 31 Volatile Low Molecular Weight Compounds AgainstAedes aegyptiandCulex quinquefasciatus

This research studied 31 volatile compounds for indoor control of the medically important mosquitoes Aedes aegypti L. and Culex quinquefasciatus Say. Only adult female mosquitoes were tested. The test compounds were from six families that included five heterobicyclics, eight formate esters, formic acid (a hydrolyzed metabolite of formate esters), eight acetate esters, four propionate esters, three butyrate esters, and two valerate esters. Also, the organophosphate compound dichlorvos (DDVP) was tested as a positive control. Cx. quinquefasciatus was generally more susceptible than Ae. aegypti. Cx. quinquefasciatus was most susceptible to a subset of heterobicyclics and formate esters (rank: n-butyl formate > hexyl formate = dihydrobenzofuran = menthofuran = heptyl formate = ethyl formate). Ae. aegypti was most susceptible to a subset of formate esters (rank: methyl > n-butyl > propyl = ethyl = hexyl). The most active materials against both species had LC50s of 0.4-1 mg active ingredient per 0.5 liter of air volume (0.8-2 mg/liter), which is 50- to 60-fold less toxic than dichlorvos (an organophosphate insecticide that is being phased out from indoor use). In relation to Drosophila melanogaster Meigen, both mosquito species were generally more susceptible to formate esters but more tolerant of heterobicyclics. Generally, the most toxic compound against all dipterans tested to date is n-butyl formate, whereas menthofuran is additionally toxic against Cx. quinquefasciatus and D. melanogaster. Finally, the toxicity differences between species point to the potential for differential toxicity among mosquito general/species, suggesting that further studies of a number of mosquito species might be warranted.

Antioxidant activity of O-protected derivatives of (-)-epigallocatechin-3-gallate: inhibition of soybean and rabbit 15-lipoxygenases

Epigallocatechin-3-gallate (EGCG) was protected at all eight phenolic groups as the methyl ether or acetate, propionate or butyrate esters. The synthetic derivatives were examined for antioxidant activities. The compounds were tested as potential diphenylpicrylhydrazyl (DPPH) radical scavengers and as inhibitors of 15-lipoxygenase (15-LO) enzymes from soybeans and rabbit reticulocytes. The O-protected EGCG derivatives were essentially inactive as DPPH scavengers but showed profound inhibiting effects on both types of 15-LO, and the inhibitory effects towards the two enzymes were significantly correlated. The O-protected EGCG derivatives inhibited 15-LO more strongly that EGCG itself. EGCG and its O-protected derivatives were also screened for antibacterial activity against M. tuberculosis.

Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)

The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.

A validated gas chromatographic method for the evaluation of enzymatic enantioselectivity in kinetic resolution applications

An enantioselective gas chromatography (GC) method has been developed and validated for determination of the enantiomers of citronellol in kinetic resolution experiments. S-(-)-beta-Citronellol is a precursor of rose oxide. After solid-phase extraction (SPE) with ethyl acetate, the enantiomers of R-(+)-beta-citronellol and S-(-)-beta-citronellol and their corresponding acetate- and butyrate esters were separated through enantioselective GC respectively. The method was validated and found to be reproducible, specific, accurate, and precise. Analyte recoveries and detection limits were also determined. The applicability of this method was shown in a kinetic resolution experiment using lipase A of Bacillus subtilis.

EFFECT OF REARING CONDITIONS ON PRODUCTION OF STERNAL GLAND SECRETION, AND IDENTIFICATION OF MINOR COMPONENTS IN THE STERNAL GLAND SECRETION OF THE PREDATORY STINK BUG Eocanthecona furcellata

Production of the male specific compound, 6,10,13-trimethyltetradecyl isovalerate by the predatory stink bug Eocanthecona furcellata (Wolff) was dramatically affected by rearing conditions. Male bugs kept isolated after eclosion produced an average of 1,948 ng of 6,10,13-trimethyltetradecyl isovalerate per bug, whereas male bugs reared in groups of 5-8 bugs produced an average of only 4 ng of 6,10,13-trimethyltetradecyl isovalerate per bug. Same-sex or mixed-sex pairs of bugs produced less than 50 ng per bug. Male bugs kept isolated for 1 wk and then grouped for 1 wk produced 3 ng of 6,10,13-trimethyltetradecyl isovalerate per bug, whereas male bugs grouped first and then isolated produced 135 ng of 6,10,13-trimethyltetradecyl isovalerate. A total of 11 minor components in relative amounts of less than 1% of the major 6,10,13-trimethyltetradecyl isovalerate were found in the sternal gland secretion. These included 6,10,13-trimethyltetradecanol, acetate, propionate, and butyrate esters of 6,10,13-trimethyltetradecanol, and isovalerate or valerate esters of homologs of 6,10,13-trimethyltetradecanol.

Presence of Acetyl-CoA Synthetase in Ripened Bananas

Acetyl-CoA synthetase (ACS) activity in fully ripened bananas was determined by HPLC. The ACS activity was higher for acetate as a substrate than for butyrate. The higher substrate specificity for acetate than for butyrate evidences that banana produces a great amount of acetate esters and a less amount of butyrate esters. The Km for MgCl2 for butyryl-CoA formation was 5-fold higher than that for acetyl-CoA formation. ACS activity was assayed in mitochondrial, microsomal, and cytosol fractions isolated from ripened banana pulp and the highest total enzyme activity was detected in the cytosol fraction. This is the first report on the presence of this enzyme, ACS, in fruit pulp.

Emission patterns of wound volatile compounds following injury of ripe strawberry fruit

AbstractVolatile compounds emitted from plants following wounding influence the growth of fungal pathogens, including Botrytis cinerea (grey mould), which causes serious economic loss of strawberry fruit. In the present study the patterns of volatile compound emission from ripe strawberry fruit, comprising store‐purchased fruit and two known cultivars, were determined following injury, using solid phase microextraction analysis to sample a stream of air continuously flowing over the fruit. The principal compounds produced from all fruits comprised C6 aldehydes, alcohols and acetate and butyrate esters derived from the lipoxygenase–hydroperoxide lyase pathway. There was an initial burst of production of aldehydes, including t‐2‐hexenal, following wounding and then a gradual decline, which in one cultivar continued for 3 h. t‐2‐Hexenal is of special interest, since it has been shown to inhibit or promote Botrytis growth in vitro depending on concentration. The acetate esters t‐2‐hexenyl acetate, c‐3‐hexenyl acetate and hexyl acetate were major wound compounds released by the fruit and were produced for 3 h after wounding. The production of relatively large quantities of wound‐derived esters is markedly different from the patterns observed for most vegetative tissue. Knowledge of the wound compounds produced by strawberry fruit and their profiles of emission after injury provides a basis for studies of the potential roles of these compounds in pathogen development on fruit.© 2003 Society of Chemical Industry

Effect of 1-methylcyclopropene on volatile emission and aroma in cv. Anna apples.

The rapidly ripening summer apple cultivar Anna was treated with 0.1 micro L(-1) and 1 microL L(-1) 1-methylcyclopropene (MCP) at harvest and kept at 20 degrees C, or stored for 5 weeks at 0 degrees C and then transferred to 20 degrees C. Total volatiles were not reduced by treatment with 0.1 microL L(-1) MCP, but were 70% lower in fruits treated with 1 microL L(-1) MCP than in untreated fruits. Ethylene production was 50% and 95% inhibited by 0.1 microL L(-1) and 1 microL L(-1) MCP, respectively. The volatiles produced by fruit at harvest were predominantly aldehydes and alcohols, with some acetate esters as well as 2-methyl butyl acetate and beta-damascenone. During ripening, the acetate and butyrate esters increased greatly and alcohols and aldehydes decreased. MCP-treated apples retained more alcohols, aldehydes, and beta-damascenone volatiles than did untreated apples. Sensory evaluation found that control and 0.1 microL L(-1) treated apples developed more fruity, ripe, and overall aromas, but the preference was for the 1 microL L(-1) treated apples with a less ripe aroma.

Propionate and butyrate esters of camptothecin and 9-nitrocamptothecin as antileukemia prodrugs in vitro.

Six camptothecin (CPT) alkyl esters and four 9-nitrocamptothecin (9NC) alkyl esters were assayed for ability to inhibit proliferation and induce programmed cell death (apoptosis) in human leukemia HL-60 and U-937 cells, which exhibit differential sensitivity to CPT and 9NC. In general, CPT-propionate and CPT-butyrate demonstrated activities, while the other esters were practically inactive. Similarly, 9NC-propionate and 9NC-butyrate were active, while the other 9NC esters exhibited little or no activity. The biologically active esters required metabolic conversion (i.e., de-esterification) to their parental compounds as demonstrated by the conversion of CPT-propionate to CPT in mouse liver homogenate, and the topoisomerase I-inhibition assay. In conclusion, the propionate and butyrate esters of CPT and 9NC are CPT and 9NC prodrugs, that can develop to important chemotherapeutic agents for the effective treatment of human leukemias and other malignancies.

The determination of lipase and phospholipase activities in gut contents of turbot (Scophthalmus maximus) by fluorescence-based assays

To study the potential of fluorescence based assays in the study of lipid digestion in fish, acyl esters of 4-methylumbelliferone and 1-acyl-2-[6 (7 nitro-1,3 benzoxadiazol-4-yl)amino]caproyl labeled phosphatidylcholine compounds (NBD-PC) were used as substrates for the assay of neutral lipase and phospholipase, respectively, in the gut contents of turbot. 4-Methylumbelliferyl hepatanoate (4-MUH) was hydrolysed at a higher rate than the butyrate or oleate esters whilst the hexanoic (C6) ester of NBD-PC was a more convenient substrate for the phospholipase assay than the dodecanoic (C12) ester. Neutral lipase activity was almost 10% higher when 50 mm potassium phosphate buffer pH 7.8 was used instead of 0.01 m citrate/sodium phosphate buffer pH 7.2. Both assays were very sensitive: neutral lipase and phospholipase activities were detectable at a minimum protein concentration in the digesta of 0.04 and 1.25 mg/ml, respectively. When the variations in lipolytic activities with gut segment and with size of fish were examined neutral lipase activity was always found to be higher in the hindgut and rectum segments than in the foregut. Although phospholipase activity was also found to be highest in the hindgut of the largest fish examined (av. wt. 182.3g), in fish of average weight 8g fish the activity was similar in all three segments. In the digesta from the whole gut of smaller fish (av. wt. 0.2, 0.6 and 1.43g) neutral lipase and phospholipase activities increased with increasing body mass when expressed as per ml of digesta. It is concluded that fluorescence-based assays are applicable to the study of lipid digestion in fish of different size.

Cellulose Derivatives Membranes as Supports for Immobilisation of Enzymes

Cellulosic derivatives (cellulose acetate, cellulose propionate and cellulose acetate-butyrate) as membranes, were prepared in different ways. These were then characterised by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contact angle evaluation. Subsequently, catalase (H2O2:H2O2 oxireductase; EC 1.11.1.6), alcohol oxidase (Alcohol:oxygen oxireductase; EC 1.1.3.13) and glucose oxidase (β-D- Glucose:oxygen 1-oxireductase; EC 1.1.3.4) were covalently linked to these membranes. The catalytic activity and stability of these enzymes, when immobilised, were examined. The results obtained showed that the immobilisation efficiency and the stability of the coupled enzymes could be correlated with the studied properties of the supports. The cellulose acetate membrane which was prepared by evaporation gave the more active conjugate support-enzyme. Membranes prepared by the immersion technique were more crystalline and therefore less suitable for enzyme immobilisation. The highly hydrophobic membranes, obtained from the propionate and the butyrate esters of cellulose reduced the activities but gave better storage stability.

Effect of Acylation on the Ocular Disposition of Acyclovir I: Synthesis, Physicochemical Properties, and Antiviral Activity of 2′-Esters

A series of aliphatic 2'-esters of acyclovir ([9-(2-hydroxyethoxymethyl)guanine]) were synthesized by direct acylation in a pyridine-N,N-dimethylformamide solution. The prodrugs were characterized as to their aqueous solubility in phosphate buffer (pH 7.4), partition coefficients in 1-octanol/phosphate buffer (pH 7.4), bioreversion kinetics by the soluble ocular esterases, and in vitro effectiveness against Herpes group viruses. The compounds exhibit an expected decrease in aqueous solubility upon esterification with a corresponding increase in the 1-octanol/water partition coefficient. The butyrate ester shows good aqueous stability in the neutral pH ranges. The apparent first order rate constants of bioreversion varied with the steric nature and polarity of the acyl substituent. The butyrate and pivalate esters were evaluated for their anti-herpesvirus activity and cellular toxicity. The butyrate ester possesses similar anti-herpesvirus activity to acyclovir and has a very high selectivity index. The pivalate ester shows poor anti-herpes simplex virus activity; however, it is unique in its effectiveness against the Epstein-Barr virus.

Studies of Australian Soft Corals. XLIII. The Structure Elucidation of a New Diterpene From Alcyonium molle

The isolation of a new cladiellin based diterpene (6), (1S,2R,3S,4R,SR,6S,8E,11S,12R,13S,14S)-3-acetoxy-2,12-dibutanoyloxycladiell-8-ene-4,11-diol is reported from the soft coral Alcyonium molle (Octocorallia, Alcyonacea, Alcyoniidae). The structure was deduced by high-field n.m.r. spectroscopy including 13C-lH shift correlated 2D n.m.r. experiments and n.O.e. measurements. The absolute configuration was based on the kinetic resolution method of Horeau. This highly derivatized diterpene (6) is the first alcyonacean derived metabolite to possess hydroxy functionalities protected as butyrate esters, although this feature is relatively common among gorgonacean metabolites. Gorgosterol (7), which cooccurs with (6) in A. molle was identified and its 13C n.m.r. spectrum reported for the first time.

Volatile components of scent material from cotton-top tamarin (Saguinus o. oedipus)

The first chemical analysis of the volatile components of scent material from the cotton-top tamarin,Saguinus o. oedipus is presented. In contrast to our previous findings in saddle-back tamarins (Saguinus fuscicollis), the chemical composition of the scent marks is quite variable. Analysis of secretion expressed manually from different areas of the scent pads of sedated animals shows individual and regional variability. Only three components (squalene, cholesterol, andp-methoxybenzaldehyde) were found in all scent mark samples analyzed. However, suprapubic secretions obtained from one sedated female contained, in addition, 12 butyrate esters as well as five acetate esters which were homologous to the butyrates. The butyrate esters have been previously identified in scent material fromSaguinus fuscicollis. The variability of the composition of the scent material is discussed in relation to the scent-marking behavior of the cotton-top tamarins. Behavioral studies tested the ability of the cotton-top tamarins to discriminate between scent marks from conspecifics and scent marks from saddle-back tamarins. The group of 12 subjects discriminated between the scent marks from both species in choice tests during which they could freely contact the scent samples. However, when scent marks were presented under a screen, so that the subjects could smell but not contact the stimuli, no discrimination was shown. Four individuals displayed more interest in the screened scent stimuli than all other subjects. When these animals were tested in a second experiment for their ability to discriminate between material from the two species on the basis of only volatile cues, it became evident that they were able to do so. These results indicate that volatile cues alone enable the tamarins to recognize scent marks from conspecifics, but that additional cues perceived during contact with the scent are important for its full attractiveness and/or informational content.

Purification and properties of carboxylesterase B of Escherichia coli

Carboxylesterase B produced by Escherichia coli was purified 1,350-fold with a recovery of 12% by successive gel filtrations, DEAE-trisacryl, phenyl-Sepharose chromatography and preparative electrophoresis. The purified enzyme was found to be homogeneous, as judged by a single precipitation line in Ouchterlony double diffusion in an experiment with homologous antiserum. The apparent molecular weight determined by gel filtration and the isoelectric point determined by electrofocusing were 57,000 and 4.6, respectively. Using acetate, propionate and butyrate esters of 1-naphtol, it was observed that elongation of the acyl carbon chain resulted in a progressive increase in velocity of ester hydrolysis. The apparent Km for 1-naphtyl acetate was found to be 0.25 mM. The enzyme was maximally active at pH 7.4 and was found to be unstable below pH 5. Hydrolytic activity was preserved after heat treatment for 30 min at 60 degrees C, but was abolished by heating for 10 min at 70 degrees C. The enzyme was strongly inhibited by low concentrations of di-isopropyl fluorophosphate. This suggested that a serine residue is required for catalytic activity. Esterase was unaffected by tosyl-L-lysin chloromethylketone, iodoacetamide, 4-hydroxy-mercuribenzoate and EDTA. Using antiserum against purified carboxylesterase B of E. coli, significant immunological cross-reactions were observed between this antigen and carboxylesterase B produced by Shigella flexneri, S. boydii and S. sonnei.

Trypanosoma cruzi: Carboxylesterase activity in intact epimastigotes

1. 1. Carboxylesterase activity corresponding to types A and B has been demonstrated in intact T. cruzi epimastigotes as shown by the hydrolysis of several esters of p-nitrophenol and the effect of suitable inhibitors. 2. 2. The in situ carboxylesterase activity was described by the Michaelis-Menten kinetic approach. The apparent V max for the acetate and butyrate esters were 66.5 and 165.3 nmol hydrolysed per min and mg of protein respectively. 3. 3. An Arrhenius plot of the temperature dependent activity showed two sharp linear regions with a transition temperature of 31.6°C and energies of activation of 6.2 and 14.1 kcal/mol. 4. 4. The in situ carboxylesterase activity was inhibited 26% by paraoxon and 56% by N-ethylmaleimide, but not by p-chloromercuribenzoate.

Gas chromatography of homogolous esters: XVIII. Polychlorinated propionate and butyrate esters

Gas chromatography of homogolous esters: XVIII. Polychlorinated propionate and butyrate esters

Inhibition of Clostridium botulinum 62A by Saturated n-Aliphatic Acids, n-Alkyl Formates, Acetates, Propionates and Butyrates

Saturated aliphatic acids (C1 to C20) and n-alkyl formate, acetate, propionate and butyrate esters (C1 to C20) were evaluated to determine the minimum inhibitory concentrations (MIC) necessary to inhibit the growth of Clostridium botulinum 62A in a bacteriological medium. The C1 to C7 and C16 to C20 acids and esters were relatively inactive (MIC > 200 μg/ml). The C8 to C15 acids exhibited some antibotulinal acitivity (MIC = 100 μg/ml), whereas C8 to C15 esters were substantially more inhibitory. The n-alkyl formates, acetates and propionates having C13 to C14 groups gave the highest inhibition, with MIC's of 3.1, 6.3 and 6.3 μg/ml, respectively. The maximum inhibition for the butyrates (MIC = 12.4 μg/ml) was associated with C11 to C12 alkyl groups. A mathematical relationship between activity and alkyl group chain length was derived.