Structures and pesticidal activities of derivatives of dinitrophenols. IX. Effects of substitution of dinitrophenols with C4 to C13 alpha-branched alkyl groups and of esterification on the eradication of apple mildew

The eradication of apple mildew caused by Podosphaera leucotricha (Ell. and Everh.) Salm. with 2-(C₄ to C₁₃ α-branched alkyl)-4,6-dinitrophenols and 4-(C₄ to C₁₃ α-branched alkyl)-2,6-dinitrophenols was examined. 4-(1-Ethylbutyl)- and most 4-(C₇ to C₁₂ α-branched alkyl)-2,6-dinitrophenols were significantly more active than their 2-alkyl-4,6-dinitrophenol analogues. Compounds containing 4-C₁₃ alkyls did not show significant activity. Activity generally increased as the α-alkyl branch lengthened. Methyl carbonates did not show lower activity than the parent phenols, but esterification of 4-(C₁₂ or C₁₃ α-branched alkyl)-2,6-dinitrophenols to ethyl carbonates or crotonates gave compounds with reduced activity. Methyl-, ethyl- or isopropyl-carbonates and crotonates of 4-(1-ethylhexyl)-2,6-dinitrophenol had much higher activity than the corresponding esters of the 4-(1-methylheptyl) isomer or of 2-(1-ethyl-hexyl)-4,6-dinitrophenol. Compounds containing long ester chains (C₇ or C₈) had less activity than 4-(1-ethylhexyl)-2,6-dinitrophenol. O-Methylation produced compounds with less activity than the parent 4-(1-ethylhexyl)- and 4-(1-propyl-pentyl)-2,6-dinitrophenols.     

Structures and pesticidal activities of derivatives of dinitrophenols. XI. Effects of substitution of dinitrophenols with C3 to C13 alpha-branched alkyl groups and of esterification on the eradication of cucumber mildew

The eradication of cucumber mildew caused by Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll. with 2-(C₄ to C₁₃ α-branched alkyl)-4,6-dinitrophenols and 4-(C₄ to C₁₃ α-branched alkyl)-2,6-dinitrophenols was examined. 2-(C₈ to C₁₃ α-Branched alkyl)-4,6-dinitrophenols were highly active, but O-methylation produced compounds with no activity. 4-(C₇ to C₁₀ and several C₁₁ to C₁₃ α-branched alkyl)-2,6-dinitro-phenols gave a significant degree of eradication. 2-(C₆ to C₁₃ α-Branched alkyl)-4,6-dinitrophenols were significantly more active than their 4-alkyl-2,6-dinitrophenol analogues. Esterification of C₄ to C₇ α-branched alkyl dinitrophenols to methyl- or ethyl- carbonates or crotonates gave compounds with enhanced activity. Generally, the methyl- or ethyl- carbonates or 2-C₈-alkyl-4,6-dinitrophenols were as active as the parent phenols, but the higher alkyl carbonates or crotonates had lower activity. Esterification of 2-(C₉ to C₁₃ α-branched alkyl)-4,6-dinitrophenols to ethyl carbonates and crotonates gave compounds with reduced activity.     

Structures and pesticidal activities of derivatives of dinitrophenols. XII.—In vitro activity of C3 to C13 α-branched alkyldinitro-phenols and their esters and ethers against the spores of Venturia inaequalis and other fungi

The activity in vitro of 2-(C₃ to C₁₃ α-branched alkyl)-4,6-dinitrophenols and 4-(C₄ to C₁₃ α-branched alkyl)-2,6-dinitrophenols and of their various esters and ethers was determined against the spores of Venturia inaequalis (Cooke) Wint., Botrytis cinerea Pers., Fusarium bulbigenum, Cooke & Massee, var. lycopersici (Brushi) Wollenw. and Cercospora melonis Cooke. Several alkyldinitrophenols were highly active against Venturia and the 2-alkylphenols were generally more active than the 4-alkylphenols. The alkyldinitrophenols were not effective against the spores of Botrytis, Fusarium and Cercospora.. Esterification of several lower alkyldinitrophenols to methyl carbonates gave compounds with enhanced activity, but methyl carbonates of C₇ to C₁₁ alkyl dinitrophenols showed considerably reduced activity. Esterification to ethyl- or other alkyl-carbonates gave compounds with considerably reduced activity against Venturia. Esterification of 2-isopropyl- and 2-t-butyl-4,6-dinitrophenols to crotonates gave compounds with enhanced activity against Venturia, but crotonates of other phenols showed reduced activity. The acrylates of several C₆ to C₈ alkyl dinitrophenols proved highly active. Ethers of active phenols showed considerably reduced activity.     

Structures and pesticidal activities of derivatives of dinitrophenols. 8. Effects of substitution with C5 to C13-s-alkyl groups and of esterification on the acaricidal activity of dinitrophenols

38 methyl-, 37 ethyl- and 19 other alkyl-carbonates, 37 crotonates, 10 acrylates and 17 other esters, and 15 methyl ethers of 2-(C₅ to C₁₃-s-alkyl)-4,6-dinitro- and 4-(C₄ t4 to C₁₃-s-alkyl)-2,6-dinitrophenols were synthesised, and their activities against Tetranychus telarius (greenhouse red spider mite) were investigated. 2-s-Alkyl-4,6-dinitrophenols and esters were more active than their 4-s-alkyl-2,6-dinitro- analogues, acaricidal activity remaining high with the 4,6-dinitrophenols up to 2-(C₁₁-s-alkyl). Generally compactness of the 2-s-alkyl group aided activity. Methyl ethers had very low activity. Esters of 2-(C₃ to C₇-s-alkyl)-4,6-dinitrophenols were more acaricidal than the parent phenols, but the reverse was the case with C₈ to C₁₃-s-alkyl compounds. Crotonates and other esters were generally less active than methyl carbonates. The methyl carbonates of 2-(1-ethylhexyl)- and 2-(1-propylpentyl)-4,6-dinitrophenols were found to be of particular economic interest as acaricides.     

Structures and pesticidal activities of derivatives of dinitrophenols. I. Structure and acaricidal activity of certain carbonates of dimitrophenols

The activities against Tetranychus telarius (greenhouse red spider mite) of alkyl, aralkyl and aryl 2-substituted-4,6-dinitrophenyl and 4-substituted-2,6-dinitrophenyl carbonates have been investigated. Alkyl carbonates of 2-s-butyl-, 2-(l-methyl-n-butyl)- and 2-t-butyl-4,6-dinitrophenols were highly active. The carbonates of the first two phenols were more active than the phenols themselves. A detailed study of the structure–activity relation revealed that increase in length of the ester chain caused decrease in acaricidal activity. The branched alkyl carbonates of 2-s-butyl- and 2-(l-methyl-n-butyl)-4,6-dinitrophenol were as active as, whereas those of 2-t-butyl-4,6-dinitrophenol were less active than, the corresponding n-alkyl carbonates. The thiolo-, thiono-, and dithio-carbonates were less active than their oxy-analogues and the aralkyl and aryl carbonates less active than their alkyl analogues.     

Structure and pesticidal activities of derivative of dinitrophenols. 3. Structure and acaricidal activity of certain carbonates of 2-alkyl-5-methyl-4,6-dinitrophenols and related compounds

The activities of alkyl 2-alkyl-5-methyl-4,6-dinitrophenyl carbonates and of related compounds against Tetranychus telarius (greenhouse red spider mite) were examined. The 5-methyl substituent slightly reduced the toxicity to mites, but not to mammals. The carbonates of 2-isopropyl- and 2-s-butyl-5-methyl 4,6-dinitrophenols were more acaricidal than the parent phenols. The increase in chain length of the alkoxyl group in the carbonates caused a decrease in acaricidal activity. In contrast to the branched carbonates of 2-t-butyl-4,6-dinitrophenol their 5-methyl-analogues were as active as the normal homologues. The cyclohexyl and phenyl carbonates of the 5-methyl-analogues had better activity than those without the 5-methyl substituent. The thiolo- and dithio-carbonates were found to be less active than their oxy-analogues.     

Structures and pesticidal activities of derivatives of dinitrophenols. VI. Structure and pre-emergence herbicidal activity of certain alkyldinitrophenols and their esters

The activities of DNOC, dinoseb, dinoterb and dinosam and the 5-methyl analogues (I; R = Bu^s, Bu^t, or CHMePrⁿ and R' = Me) of these phenols against Capsella bursa-pastoris, Chenopodium album, Senecio vulgaris, Stellaria media and Rumex spp., and their effects on peas, oats, beet, cabbage and carrots, were investigated by pre-emergence application to soil. The effects of esterification of these phenols with aliphatic acids, of esterification of dinoterb with dibasic acids, aromatic acids, substituted carbonic acids, and of etherification on activity were investigated. 2-t-Butyl phenols and their aliphatic esters proved more active than the corresponding compounds of the other phenols. Acetylation improved the activity of dinoterb and medinoterb. Halogenation reduced the activity of the acetate of dinoterb, but unsaturation of the ester chain enhanced the activity of dinoterb esters. Esterification of dinoterb with aromatic acids, substituted carbonic acids, oxalic and adipic acids, and etherification led to compounds of low activity. In general, all compounds caused little damage to peas and oats. Dinoterb esters damaged cabbage plants. Esters of medinoterb were generally less damaging to crops than were dinoterb esters.     

Synthesis of aroma compounds by apples supplied with alcohols and methyl esters of fatty acids

Ester synthesis by apples supplied with alcohols (C2–C8) and methyl esters of short chain fatty acids (C4–C8) was studied using gas chromatographic analysis of the products. The substrates were supplied as vapours to whole fruits stored in 2% O₂ at 3°C. The alcohols were converted to the corresponding acetate ester; butanol, pentanol and hexanol were converted most rapidly. The methyl esters of short chain fatty acids (C_n) were converted to esters with an alkyl group (C_n-2, C_n-4) confirming the presence in whole fruits of an active β-oxidation pathway for fatty acids. Ester synthesis was stimulated when apples were supplied with methyl octanoate at different periods during long term storage in 2% O₂. Treatment of the fruit immediately postharvest did not enhance ethylene synthesis.     

Proteinaceous Surfactants Produced from Gelatin by Enzymatic Modification: Evaluation for Their Functionality

Proteinaceous surfactants were prepared by applying the “one-step process” which permitted covalent incorporation of amino acid esters directly into proteins during treatment with papain. Gelatin was used as a hydrophile and n-alkyl esters of L-leucine as lipophiles. Each of the hydrophile-lipophile mixtures was incubated with papain under the following conditions: medium, 1M carbonate (pH 9) or a 20:80 mixture of acetone-1M carbonate (pH 9) containing 2 mM 2-mercaptoethanol; concentration of gelatin in the medium, 33% (w/w); L-leucine ester vs gelatin ratio, 0.1 mole/100g; papain vs gelatin, 1% (w/w); incubation period, 15 min; and temperature, 37°C. The enzymatic reaction was stopped by adding 1N HCl and the product purified by dialysis followed by washing with hot acetone or dichloromethane to remove low-molecular species. Each product was found to be a mixture of peptides having a wide range of molecular weight, with an average at approximately 7,500 daltons. The amounts of the alkyl moieties covalently incorporated were in a range 1.1–1.2 moles per 7,500g of the products. Their surfactancy varied depending particularly on the carbon number of the alkyl moiety; the products resulting from the incorporation of C₄–C₆ alkyl esters of leucine showed greater whippability, whereas the incorporation of the C₁₀–C₁₂ alkyl esters gave products having a higher ability to stabilize an o/w type emulsions.     

Binding of aroma compounds with legumin. III. Thermodynamics of competitive binding of aroma compounds with 11S globulin depending on the structure of aroma compounds

This paper considers the prominent features in competitive binding of aroma esters from their mixtures to 11S globulin of broad beans (legumin) in aqueous medium at pH 7.2 and ionic strength of 0.05 mol dm⁻³. Series of alkyl acetates (C₄–C₈) and methyl esters of carbonic acids (C₅–C₉), differing in the length of hydrocarbon chain, have been under our studying. To accomplish the ends of the study, a combination of ultrafiltration and gas–liquid chromatography (GC) has been used. An increase in the length of hydrocarbon chain of the aroma esters brought about greater binding affinity for the protein, the occurrence of some structural restrictions in the interior of the protein molecule, preventing binding, and the change in the binding mechanism of the aroma compounds at the specific critical length of hydrocarbon chain. Differential scanning microcalorimetry data suggested that the revealed changes in the binding mechanism of the studied aroma compounds were attributable to the conformational modification of the protein globule as a result of binding with the aroma compounds. A distinguishing feature in binding of methyl esters of carbonic acids with legumin was their greater binding affinity for the protein as compared with alkyl acetates. The mutual effect of aroma compounds on binding from their equimolar mixtures to the protein made itself evident, firstly, as a drastic increase in the binding extent of aroma esters, having rather long hydrocarbon chain and, secondly, as a dramatic change in the binding mechanism of the aroma esters with relatively short hydrocarbon chain.     

ESTERASES OF BAKER'S YEAST. II. SUBSTRATE SPECIFICITIES TOWARDS ESTERS FORMED DURING SUGAR FERMENTATIONS

Ethyl esters of fatty acids (C₂–C₁₂), isoamyl acetate and 2-phenethyl acetate were studied as substrates for yeast esterases and compared with the synthetic substrates, p-nitrophenyl esters and β-naphthyl esters. Intact yeast, the 55% and 55–75% ammonium sulphate precipitate of centrifuged yeast homogenate, and partly purified esterases were used for the determination of the hydrolysation activity towards the esters. The results showed that the yeast esterases prefer to hydrolyse the ethyl esters with acyl chain length of C₅ to C₁₂. The acetate esters, ethyl acetate, isoamyl acetate and 2-phenethyl acetate are only very slowly hydrolysed or remain unaffected. The substrate specificity of different esterases varies and can be used for their characterisation. Investigating pH optimum curves using intact yeast and a crude esterase preparation and different substrates confirmed the earlier result that there are esterases on both sides of the plasma membrane. The specificity of intracellular and periplasmically located esterases is, however, different.     

Relationship between the physical properties of chlorogenic acid esters and their ability to inhibit lipid oxidation in oil-in-water emulsions

In oil-in-water emulsions, the physical location of antioxidants has been postulated to be one of the most important factors impacting activity. The purpose of this research was to examine how the esterification of various hydrocarbon chains (C₄, C₈, or C₁₂) onto chlorogenic acid (CGA) influenced physical properties and antioxidant activity in menhaden oil-in-water emulsions. Both surface activity and partitioning of CGA and its hydrocarbon esters into the lipid phase of oil-in-water emulsions increased with increasing size of the hydrocarbon chain. When CGA and its esters were added to a menhaden oil-in-water emulsion at concentration that resulted in equal free radical scavenging activity, CGA, butyl CGA and octyl CGA had similar antioxidant activity while dodecyl CGA was ineffective. These results suggest that phenolic antioxidants conjugated with hydrocarbon chains are more highly associated with lipid emulsions droplets, but these changes in physical properties did not increase antioxidant activity.     

Eco-friendly methodologies for the synthesis of some aromatic esters, well-known cosmetic ingredients

Solid-liquid solvent-free phase transfer catalysis (PTC) and acidic catalysis in dry media were applied, with noticeable improvement and simplification over classical procedures in a Green Chemistry context, to the synthesis of some aromatic esters useful as cosmetic ingredients: 3-methylbutyl 4-methoxycinnamate, 2-ethylhexyl 4-methoxycinnamate, 2-ethylhexyl 4-(dimethylamino)benzoate and 2-ethylhexyl salicylate, well-known ultraviolet B sunscreen filters; 4-isopropylbenzyl salicylate, UV absorber and cutaneous antilipoperoxidant; propyl 4-hydroxybenzoate and butyl 4-hydroxybenzoate (parabens), antimicrobial agents. The reactions were performed under microwave (MW) activation and conventional heating. The best results for the synthesis of cinnamic, salicylic and 4-(dimethylamino)benzoic esters were achieved by in situ preformed carboxylates alkylation with alkyl bromides using PTC. The 4-hydroxybenzoates were obtained in good yields by classical esterification of the acid with alcohols using a simple heterogeneous mixture of reagents with catalytic amounts of p-toluenesulfonic acid (PTSA). The comparisons of yields and thermal profiles under either MW or conventional heating were studied and reported.     

Determination of volatile fatty acids C1–C6, and lactic acid in silage juice

A method for the determination of volatile fatty acids, C₁–C₆, and lactic acid in silage juice is described. The procedure is simple and capable of application to large numbers of samples. It involves separation of the free acids by ion exchange, formation of their benzyl esters by the addition of benzyl bromide to a solution of the tetrabutylammonium salts in acetone and ultimate determination by gas liquid chromatography.     

Characterization of wax esters,free fatty alcohols and free fatty acids of crude wax from sunflower seed oil refineries

The sunflower seed wax (10–12%) from oil refineries was purified through two steps, namely, extraction using solvents and precipitation with chilled acetone. Fatty esters, free fatty alcohols and free fatty acids were separated by thin-layer chromatography (TLC). The fractions of fatty esters and free fatty alcohols were separated and identified by gas chromatography (GC) using a Dexil-300 column and OV-101 column, respectively, at temperatures from 150–290 °C and were further confirmed by Gas chromatography–mass spectrometry (GC–MS), using a capillary silica column SPB™-1 coated with polydimethyl siloxane. Among the long chain fatty esters (C₃₈–C₅₄), comprised of one unit of fatty alcohol and one unit of fatty acid through an ester linkage, the major esters were C₄₀–C_44, of which C₄₂ was predominant. These fatty esters, upon hydrolysis, followed by methylation and subsequent GC–MS analysis, showed the presence of C₁₆–C₃₀ fatty acids in the bound form, whereas methylation of native wax indicated the presence of C₁₈–C₃₀ fatty acids in the free form. Acetylation of hydrolysis product showed the presence of C₁₈–C₃₀ fatty alcohols in the bound form, where as acetylation of native wax indicated that the C₁₈–C₃₂ fatty alcohols were in the free form. n-Triacontanol (C₃₀), a plant growth regulator, was found in both free and bound forms.     

Lipase Mediated Production of Flavor and Fragrance Esters from Fusel Oil

Mixtures of C₃, C₄ and C₅ chain length aliphatic alcohols found in fusel oil were converted to their acetic acid and butyric acid esters using a lipase (from Candida cylindracea) mediated process in a water immiscible fluid (hexane). Incubation temperature was 30°C with shaking (150 rpm). Maximum production of the mixed butyric acid ester product (0.62 mol/L; yield = 65.8%) and acetic acid ester product (0.052 mol/L; yield = 46.4%) were obtained in 48 hr. Enzyme could be reused three times before loss of activity for acetic acid ester synthesis but enzyme activity decreased after one use for butyric acid ester synthesis.     

Proteinaceous Surfactants Produced from Gelatin by Enzymatic Modification: Application to Preparation of Food Items

Proteinaceous surfactants produced from gelatin by papain-catalyzed incorporation of L-leucine n-alkyl esters were used as ingredients replacing conventional surfactants for food use. The incorporation of leucine Cz-C6 alkyl esters gave surfactants effective in making snow jelly. In ice cream making, a leucine C₁₂ alkyl ester-incorporated product used as the surfactant gave a high degree of overrun even in a few minutes from the start of whipping. This surfactant was applicable also to making mayonnaise, with formation of a tine emulsion having favorable hardness and adhesiveness. In bread making as well, the same surfactant was usable and found preferable to monostearin. The use of this surfactant resulted in satisfactory loaf quality as well as slow staling of bread over a long period of storage.     

Inhibition ofIn VitroHuman LDL Oxidation by Phenolic Antioxidants from Grapes and Wines

Current research suggests that wine contains substances that may reduce the mortality rate from coronary diseases. The oxidation of low-density lipoprotein (LDL) is thought to be a key step in the development of atherosclerosis. Phenolic fractions of a Petite Syrah wine were evaluated for their antioxidant activity in inhibiting LDL oxidation in vitro . The more active fractions contained components of the catechin family. The catechin oligomers and the procyanidin dimers (B₂, B₃, B₄, B₆, B₈) and trimers (C₁, C₂) were extracted, isolated and purified from grapes seeds. These compounds were tested for their inhibition of LDL oxidation, along with other monomeric wine phenolics. The procyanidin dimers B₂ and B₈, and trimer C₁, and the monomers catechin, epicatechin and myricetin had the highest antioxidant activity. The procyanidin dimers B₃, B₄ and C₂ and the monomers gallic acid, quercetin, caffeic acid, and rutin, and a group of compounds that included the dimer B₆, ellagic acid, sinapic acid, cyanidin had lower antioxidant activity and α-tocopherol had the least activity. Thus, the numerous phenolic compounds found in wine are potent antioxidants in inhibiting LDL oxidation in vitro .     

Tyrosinase inhibitory effects and antioxidative activities of novel cinnamoyl amides with amino acid ester moiety

Nine cinnamoyl amides with amino acid ester (CAAE) moiety were synthesized by the conjugation of the corresponding cinnamic acids (cinnamic acid, 4-hydroxy cinnamic acid, ferulic acid and caffeic acid) with amino acid esters, and their inhibitory effects on the activities of mushroom tyrosinase were investigated, using l-3,4-dihydroxyl-phenylalanine (l-DOPA) as the substrate. Among these CAAE amides, ethyl N-[3-(4-hydroxy-3-methoxyphenyl)-1-oxo-2-propen-1-yl]-l-phenylalaninate (b₄) showed the strongest inhibitory activity; the IC₅₀ was 0.18 μM. The IC₅₀ values, inhibition types, inhibition mechanisms and kinetics of all these CAAE amides were evaluated. A structure–activity relationship (SAR) study found that the inhibitory effects were potentiated with the increasing length of hydrocarbon chains at the amino acid esters and also influenced by the substituents at the styrene groups. Furthermore, the hydroxyl radical scavenging and anti-lipid peroxidation activities of four CAAE derivatives were also investigated. Among these compounds, b₃ (ethyl N-[3-(3,4-dihydroxyphenyl)-1-oxo-2-propen-1-yl]-l-phenylalaninate) and b₄ exhibited potential antioxidant activities.