Secondary Acetate Research Articles

Isolasi Fungi Tanah Muara Mangrove Desa Katialada Gorontalo dan Skrining Aktivitas Antibakteri terhadap Pseudomonas aeruginosa

Pseudomonas aeruginosa is a bacterial pathogen that causes various kinds of infections. The use of antibiotics is usually done to treat the infection. However, Pseudomonas aeruginosa has various resistance abilities that can avoid the efficacy of antibiotics. The emergence of drug resistance events encourages the need for the discovery of new antibiotic drugs, one of which comes from fungals secondary metabolite. Soil fungi from mangrove ecosystems have not been studied much. Interestingly, these soil fungi have unique adaptive responses. This response also affects the secondary metabolites it contains. Knowing this information, mangrove soil samples were cultured on fungi media which were then tested against Pseudomonas aeruginosa through antagonist test and microdilution test. Three fungal cultures with yeast characteristics were obtained and each of the secondary metabolite ethyl acetate extracts of these three fungi had antibacterial activity. The antibacterial activity was indicated by the % inhibition parameter. The terpenoid content in fungal cultures may be responsible for the antibacterial activity against Pseudomonas aeruginosa. This research is an initial screening of the search for new antibiotic candidates, so further research study such as isolation and species determination needs to be done.

Synthesis of tetrahydrochromenes and dihydronaphthofurans via a cascade process of [3 + 3] and [3 + 2] annulation reactions: mechanistic insight for 6-endo-trig and 5-exo-trig cyclisation.

Substituted tetrahydrochromenes and dihydronaphthofurans are easily accessible by the treatment of β-tetralone with trans-β-nitro styrene derived Morita-Baylis-Hillman (MBH) acetates through a formal [3 + 3]/[3 + 2] annulation. The reaction proceeds through a cascade Michael/oxa-Michael pathway with moderate to good yields. A DFT study was carried out to account for the formation of the corresponding six and five-membered heterocycles via 6-endo-trig and 5-exo-trig cyclization.

Phytochemical investigation of Euphorbiatrigona

Euphorbia species (Family: Euphorbeaceae) have wide applicability in traditional medicines and biofuel sector, and are also rich sources of secondary metabolites, especially terpenoids, attributed with various pharmacological properties. Though 82 Euphorbia species are reported in India, most of the species are uninvestigated for their constituents or potential utilities. Present study reports the isolation and characterization of chemical constituents, estimation of major triterpenoids using a validated HPTLC method and cytotoxicity of plant and latex extracts of Euphorbia trigona. As the secondary metabolites epi-friedelinyl acetate, 3β-friedelinol, taraxerol, rhoiptlenone, stigmasterol and stearic acid were isolated and characterized from E. trigona. HPTLC estimation showed 3β-friedelinol at 0.91 ​± ​0.11% and taraxerol at 1.45 ​± ​0.12% was present in E. trigona plant powder (dry weight). Plant and latex extracts were found non toxic towards normal cell line H9C2 (cardiac myoblasts) and showed insignificant cytotoxic effects towards HeLa (cervical cancer cell line) upto 100 ​μg/ml concentration.

Effect of Lactate Fermentation Type on the Biochemical Methane Potential of Tequila Vinasse

In a two-stage anaerobic digestion (AD) process approach, the relation between the type of fermentation that occurs during the acidogenic stage and methane production potential from tequila vinasse (TV) remains unexplored. This study aimed to investigate the effect of lactate fermentation type on the biochemical methane potential (BMP) of TV. To this end, a series of batch cultures were carried out to perform two sequential lactate-type fermentations, i.e., first (carbohydrates → lactate + acetate) and second (lactate + acetate → butyrate + H2) fermentation, which were further tested for mesophilic BMP using an automatic gas measuring device. Raw TV was also included in the comparison as a control (single-stage AD). During the primary fermentation, 75% of the total fermentable sugars were metabolized into lactate (12.6 g/L) and acetate (6.6 g/L) by the bacterial cluster mainly encompassing Klebsiella, Enterobacter, and Streptococcus, as supported by Illumina MiSeq sequencing analysis. During the secondary fermentation, lactate and acetate were bioconverted into butyrate (5.1 g/L) and hydrogen (115.6 NmL/g VSadded) by Clostridium. During methanogenesis, all tested feedstocks resulted in different BMP performances. The primary lactate fermentation led to the highest BMP (435.9 NmL CH4/g VSadded), methane production rate (105.8 NmL CH4/day), and chemical oxygen demand removal efficiency (92.9%), which were 46.2%, 89.3%, and 8.8%, respectively, higher than those attained from raw TV. Methanobacterium and Methanolinea dominated in the starter granular sludge culture, suggesting the hydrogenotrophic pathway was key for methane formation. This study shows for the first time the viability of the lactate-type fermentation for designing enhanced two-stage TV-fed AD processes.

Selective Hydrogenolysis of Furfural Derivative 2-Methyltetrahydrofuran into Pentanediol Acetate and Pentanol Acetate over Pd/C and Sc(OTf)3 Cocatalytic System.

It is of great significance to convert platform molecules and their derivatives into high value-added alcohols, which have multitudinous applications. This study concerns systematic conversion of 2-methyltetrahydrofuran (MTHF), which is obtained from furfural, into 1-pentanol acetate (PA) and 1,4-pentanediol acetate (PDA). Reaction parameters, such as the Lewis acid species, reaction temperature, and hydrogen pressure, were investigated in detail. 1 H NMR spectroscopy and reaction dynamics study were also conducted to help clarify the reaction mechanism. Results suggested that cleavage of the primary alcohol acetate was less facile than that of the secondary alcohol acetate, with the main product being PA. A PA yield of 91.8 % (150 °C, 3 MPa H2 , 30 min) was achieved by using Pd/C and Sc(OTf)3 as a cocatalytic system and an 82 % yield of PDA was achieved (150 °C, 30 min) by using Sc(OTf)3 catalyst. Simultaneously, the efficient conversion of acetic esters into alcohols by simple saponification was carried out and led to a good yield.

Spatial Heterogeneity and Co-occurrence of Mucosal and Luminal Microbiome across Swine Intestinal Tract.

Pigs are one of the most important economic livestock. Gut microbiota is not only critical to the health but also the production efficiency of pigs. Manipulating gut microbiota relies on the full view of gut microbiome and the understanding of drive forces shaping microbial communities. 16s rDNA sequencing was used to profile microbiota along the longitudinal and radical axes to obtain the topographical map of microbiome in different intestinal compartments in young pigs. Alpha and beta-diversities revealed distinct differences in microbial compositions between the distal ileum and cecum and colon, as well as between the lumen and mucosa. Firmicutes and Proteobacteria dominated in the ileum, constituting 95 and 80% of the luminal and mucosa-attached microbiome. Transitioning from the small intestine to the large intestine, luminal Bacteroidetes increased from 1.69 to 45.98% in the cecum and 40.09% in the colon, while mucosal Bacteroidetes raised from 9 to 35.36% and 27.96%. Concurrently, luminal Firmicutes and Proteobacteria and mucosal-attached Proteobacteria remarkably decreased. By co-occurrence network analyses, Prevotellaceae, Ruminococcaceae, Lachnospiraceae and Veillonellaceae were recognized as the central nodes of luminal microbial network, and Prevotellaceae and Enterobacteriaceae, Caulobacteraceae, Enterococcaceae, Xanthomonadaceae, Pseudomonadaceae were identified as mucosal central nodes. Co-abundance was uncovered among Prevotellaceae, Lachnospiraceae, and Veillonellaceae in the luminal and mucosal microbiome, while opportunistic pathogens from γ-Proteobacteria in the mucosa. Strong co-exclusion was shown between Enterobacteriaceae with Prevotellaceae-centered microbial groups in the lumen. Redundancy analysis found bile acids and short chain fatty acids explained 37.1 and 41% of variations in the luminal microbial composition, respectively. Primary bile acid, taurine- and glycine- conjugated bile acids were positively correlated with Lactobacillaceae, Enterobacteriaceae, Clostridiaceae_1, Peptostreptococcaceae, whereas secondary bile acids, acetate, propionate, butyrate, and valerate were positively correlated with Prevotellaceae, Acidaminococcaceae, Ruminococcaceae, Lachnospiraceae, Desulfovibronaceae, Veillonellaceae. Functional analyses demonstrated that Prevotella, Veillonellaceae, Lachnospiraceae, and Ruminococcaceae were positively correlated with gene functions related to amino acids, energy, cofactors and vitamins metabolism, which are indispensable for the hosts. These results suggested site specific colonization and co-occurrence of swine gut microbiome closely relate to the microenvironment in each niche. Interactions of core gut microbiome greatly contributed to metabolism and/or immunity in the swine intestine.

Diastereoselective [4+1] Cycloaddition of Alkenyl Propargylic Tertiary Acetates with CO Catalyzed by [RhCl(CO)2]2

Alkenyl propargylic tertiary acetates were prepared by deprotonation of the corresponding enyne followed by nucleophilic addition to ketones and then treatment with acetic anhydride. The resulting acetates were then employed in diastereoselective [4+1] cycloadditions with CO catalyzed by [RhCl(CO)2]2 to form α‐benzylidene cyclopentenone derivatives. We found the cycloadditions of the tertiary acetates to be more diastereoselective than those of the corresponding secondary acetates, as a result of increased substitution at the propargylic carbon. When an electron‐donating meta substituent, such as Me and MeO, is introduced to the aryl group at the propargylic carbon of the tertiary acetate, the diastereoselectivity improved to >8:1 (E/Z).

Expression and specificity profile of the major acetate transporter AcpA in Aspergillus nidulans

AcpA has been previously characterized as a high-affinity transporter essential for the uptake and use of acetate as sole carbon source in Aspergillus nidulans. Here, we follow the expression profile of AcpA and define its substrate specificity. AcpA-mediated acetate transport is detected from the onset of conidiospore germination, peaks at the time of germ tube emergence, and drops to low basal levels in germlings and young mycelia, where a second acetate transporter is also becoming apparent. AcpA activity also responds to acetate presence in the growth medium, but is not subject to either carbon or nitrogen catabolite repression. Short-chain monocarboxylates (benzoate, formate, butyrate and propionate) inhibit AcpA-mediated acetate transport with apparent inhibition constants (Ki) of 16.89±2.12, 9.25±1.01, 12.06±3.29 and 1.44±0.13mM, respectively. AcpA is also shown not to be directly involved in ammonia export, as proposed for its Saccharomyces cerevisiae homologue Ady2p. In the second part of this work, we search for the unknown acetate transporter expressed in mycelia, and for other transporters that might contribute to acetate uptake. In silico analysis, genetic construction of relevant null mutants, and uptake assays, reveal that the closest AcpA homologue (AN1839), named AcpB, is the ‘missing’ secondary acetate transporter in mycelia. We also identify two major short-chain carboxylate (lactate, succinate, pyruvate and malate) transporters, named JenA (AN6095) and JenB (AN6703), which however are not involved in acetate uptake. This work establishes a framework for further exploiting acetate and carboxylate transport in filamentous ascomycetes.

Aldol reaction of kojic acid using alumina supported base catalyst and enzymatic resolution of the aldol adduct by CALB

An efficient and ecofriendly aldol reaction of kojic acid with aldehydes using a heterogeneous reusable catalyst (alumina modified with base) is developed. Enzymatic hydrolytic resolution of the racemic acetylated aldol adduct 2 was achieved using lipase from Candida antarctica type B (CALB). The key feature of this enzymatic resolution is that regioselective deacetylation of ester derived from the primary alcohol located away from the stereocentre occurred in the presence of adjacent secondary acetate.

Synthesis of (+)-perillyl alcohol from (+)-limonene

(+)-Perillyl alcohol (1) has been synthesised in four steps and 39% overall yield from commercially available limonene oxide (4). The sequence features, as its key step, a palladium(0)-mediated transformation of a secondary allylic acetate (6) into its primary isomer (7). An application of (+)-perillyl alcohol (1) in a formal synthesis of naturally occurring (−)-mesembrine (2) and (−)-mesembranol was demonstrated.

ChemInform Abstract: Nickel‐Catalyzed Reductive Coupling of Aryl Halides with Secondary Alkyl Bromides and Allylic Acetate.

AbstractEfficient methods for the condensation of aryl halides with secondary alkyl bromides and allylic acetate are reported.

ChemInform Abstract: Ireland—Claisen Rearrangement of Secondary Allyl Acetate Revisited: Inevitable C‐Silylation Circumvented by One‐Pot Application of Excessive LDA/TMSCl and TBAF.

AbstractOptimized conditions A) allow the preparation of mixtures which contain the desired unsaturated rearranged acids and silylated analogues of type (III), where the latter are generally formed with higher yields.

Nickel-Catalyzed Reductive Coupling of Aryl Halides with Secondary Alkyl Bromides and Allylic Acetate

A room-temperature Ni-catalyzed reductive method for the coupling of aryl bromides with secondary alkyl bromides has been developed, providing C(sp(2))-C(sp(3)) products in good to excellent yields. Slight modification of this protocol allows efficient coupling of activated aryl chlorides with cyclohexyl bromide and aryl bromides with allylic acetate.

Ireland-Claisen rearrangement of secondary allyl acetate revisited: inevitable C-silylation circumvented by one-pot application of excessive LDA/TMSCl and TBAF

Yield lowering C-silylation was found to be inevitable in all the six tested examples of stoichiometric LDA/TMSCl promoted Ireland-Claisen rearrangement of secondary allyl acetates. In order to circumvent this problem, a higher yielding protocol was devised after the isolated by-products were found to be excellent substrates for further rearrangement. Thus, excessive LDA/TMSCl was applied to achieve complete 3,3′-sigmatropic shift of the substrates, and the resulting mixtures of normal and α-silylated γ,δ-unsaturated carboxylic acids was then desilylated by one-pot application of TBAF.

Palladium-catalyzed cross-coupling reactions of organogold(i) phosphanes with allylic electrophiles

Aryl and alkenylgold(I) phosphanes react regioselectively with allylic electrophiles such as cinnamyl and geranyl halides (bromide, chloride and acetates) under palladium catalysis in THF at 80 °C to afford the α-substitution product with moderate to high yields. When the reaction is performed with a chiral enantiopure secondary acetate, the α-substituted cross-coupling product is obtained with complete inversion of the stereochemistry.

ChemInform Abstract: Hydrolytic Resolution of Tertiary Acetylenic Acetate Esters with the Lipase from Candida cylindracea.

The kinetic resolution of a series of tertiary acetylenic acetate esters using the lipase from Candida cylindracea has been explored. Compounds 6c and the trifluoromethyl acetate 6e have been resolved with high enantiomeric enrichments. Several other tertiary acetate esters carrying a CF3 group have been investigated which proved inert to enzymatic hydrolysis. From these results and published data, we are able to propose a predictive model for identifying the preferred enantiomer of secondary and tertiary trifluoromethyl acetate esters for this lipase.

(2S,12Z)-2-Acetoxy-12-heptadecene: Major Sex Pheromone Component of Pistachio Twig Borer, Kermania pistaciella

The sex pheromone of the pistachio twig borer, Kermania pistaciella (Lepidoptera: Oinophilidae), one of the most important insect pests of pistachio, Pistacia vera, in Turkey and Iran, was identified. In gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of pheromone gland extracts of female K. pistaciella from Turkey, (2S,12Z)-2-acetoxy-12-heptadecene was identified as the major candidate pheromone component. In field experiments in Turkey, lures containing synthetic (2S,12Z)-2-acetoxy-12-heptadecene attracted large numbers of male moths. Its attractiveness was significantly reduced by the presence of the R-enantiomer or of either enantiomer of the corresponding alcohol. (2S,12Z)-2-Acetoxy-12-heptadecene is the first pheromone component identified in the Oinophilidae and the first secondary acetate pheromone component identified in the Lepidoptera.

A Novel and Convenient Method for the Synthesis of Ubiquinone-10

A novel and convenient synthetic approach to ubiquinone-10 was reported via the SN2-type nucleophilic displacement reaction between copper-catalyzed Grignard reagent and the secondary allylic acetate, which was suitable for the large-scale production of ubiquinone-10. Keywords: SN2'-type reaction, copper-catalyzed, Grignard reagent, secondary allylic acetate, regioselectivity, stereoselectivity

A Practical and Stereoselective Synthesis of Cinnamyl Alcohols Bearing α‐Cyano or α‐Ester Functional Group from Baylis—Hillman Adducts.

Cinnamyl alcohols bearing ester, acid, or nitrile functional group at the 2-position are very useful synthons for the synthesis of various biologically important compounds. Synthesis of cinnamyl alcohol derivatives from the BaylisHillman adducts has been reported by us and other groups. The conversion can be carried out directly by using 20% aqueous sulfuric acid (for the Baylis-Hillman adducts derived from acrylonitrile) or trifluoroacetic acid (for the Baylis-Hillman adducts derived from acrylates). Recently, Basavaiah and coworkers have reported the two-step, onepot conversion method: TMSOTf-assisted conversion of Baylis-Hillman alcohol into the corresponding primary acetate with acetic anhydride and the following partial hydrolysis with K2CO3 in methanol. In the above chemical transformation, the conversion of secondary acetate into the primary one is the key step. Rearrangement of secondary acetate into the primary one was conducted by following reaction conditions such as DABCO/THF/reflux, montmorillonite K10 clay/microwave, and TMSOTf (cat.)/CH2Cl2. Direct conversion of BaylisHillman alcohol into the corresponding primary acetate can be carried out by the Basavaiahs method: acetic anhydride in the presence of TMSOTf. However, TMSOTf is a moisturesensitive and somewhat expensive reagent. During the preparation of Baylis-Hillman acetate, we found that the use of acetic anhydride in the presence of a catalytic amount of sulfuric acid in CH2Cl2 afforded directly the corresponding primary acetate in excellent yield. In these regards we envisioned that we could develop the more convenient and practical method to convert the BaylisHillman alcohol into the primary acetate or eventually to primary alcohol (Scheme 1 and Table 1). The reaction of Baylis-Hillman adducts with acetic anhydride (1.5 equiv.) in the presence of sulfuric acid (10 mol%) gave the corresponding rearranged cinnamyl acetates quantitatively in dichloromethane at room temperature within 30 min (Actually, the cinnamyl acetate derivatives could be isolated in 92-95% yields.). In order to obtain the corresponding cinnamyl alcohols in a one-pot we tried some reaction conditions for the next partial hydrolysis. Addition of water to the reaction mixture (two-phase system) afforded the hydrolyzed cinnamyl alcohols in trace amounts. The use of THF instead of CH2Cl2 showed better results in the hydrolysis step. However, neither the acetylation in THF nor the subsequent acidic hydrolysis in aq. THF was efficient. As a next choice, we used methanol as solvent after the formation of rearranged acetate in CH2Cl2 and added K2CO3. However, this process showed incomplete reaction and produced some side products. Thus, we finally adapted the two-step procedure involving the well-known hydrolysis protocol, K2CO3 in methanol, after simple workup process of the primary acetates (vide infra). The representative examples are shown in Table 1. As shown in Table 1, the method can be applicable to both of the Baylis-Hillman adducts derived from acrylates or acrylonitrile. The yields are higher than the reported in all cases. The formation of the cinnamyl alcohols is highly stereoselective (E for the ester and acetyl derivatives and Z for the nitrile analogs) as reported. The method has some advantages over the previous methods: (1) higher yields in

A Practical and Stereoselective Synthesis of Cinnamyl Alcohols Bearing α-Cyano or α-Ester Functional Group from Baylis-Hillman Adducts

Cinnamyl alcohols bearing ester, acid, or nitrile functional group at the 2-position are very useful synthons for the synthesis of various biologically important compounds. Synthesis of cinnamyl alcohol derivatives from the BaylisHillman adducts has been reported by us and other groups. The conversion can be carried out directly by using 20% aqueous sulfuric acid (for the Baylis-Hillman adducts derived from acrylonitrile) or trifluoroacetic acid (for the Baylis-Hillman adducts derived from acrylates). Recently, Basavaiah and coworkers have reported the two-step, onepot conversion method: TMSOTf-assisted conversion of Baylis-Hillman alcohol into the corresponding primary acetate with acetic anhydride and the following partial hydrolysis with K2CO3 in methanol. In the above chemical transformation, the conversion of secondary acetate into the primary one is the key step. Rearrangement of secondary acetate into the primary one was conducted by following reaction conditions such as DABCO/THF/reflux, montmorillonite K10 clay/microwave, and TMSOTf (cat.)/CH2Cl2. Direct conversion of BaylisHillman alcohol into the corresponding primary acetate can be carried out by the Basavaiahs method: acetic anhydride in the presence of TMSOTf. However, TMSOTf is a moisturesensitive and somewhat expensive reagent. During the preparation of Baylis-Hillman acetate, we found that the use of acetic anhydride in the presence of a catalytic amount of sulfuric acid in CH2Cl2 afforded directly the corresponding primary acetate in excellent yield. In these regards we envisioned that we could develop the more convenient and practical method to convert the BaylisHillman alcohol into the primary acetate or eventually to primary alcohol (Scheme 1 and Table 1). The reaction of Baylis-Hillman adducts with acetic anhydride (1.5 equiv.) in the presence of sulfuric acid (10 mol%) gave the corresponding rearranged cinnamyl acetates quantitatively in dichloromethane at room temperature within 30 min (Actually, the cinnamyl acetate derivatives could be isolated in 92-95% yields.). In order to obtain the corresponding cinnamyl alcohols in a one-pot we tried some reaction conditions for the next partial hydrolysis. Addition of water to the reaction mixture (two-phase system) afforded the hydrolyzed cinnamyl alcohols in trace amounts. The use of THF instead of CH2Cl2 showed better results in the hydrolysis step. However, neither the acetylation in THF nor the subsequent acidic hydrolysis in aq. THF was efficient. As a next choice, we used methanol as solvent after the formation of rearranged acetate in CH2Cl2 and added K2CO3. However, this process showed incomplete reaction and produced some side products. Thus, we finally adapted the two-step procedure involving the well-known hydrolysis protocol, K2CO3 in methanol, after simple workup process of the primary acetates (vide infra). The representative examples are shown in Table 1. As shown in Table 1, the method can be applicable to both of the Baylis-Hillman adducts derived from acrylates or acrylonitrile. The yields are higher than the reported in all cases. The formation of the cinnamyl alcohols is highly stereoselective (E for the ester and acetyl derivatives and Z for the nitrile analogs) as reported. The method has some advantages over the previous methods: (1) higher yields in