Acid Methanolysis Research Articles

Gas Chromatography–Mass Spectrometry (GC–MS) Study of the Archaeological Plant Mixture from an Elite Burial Mound of the Sargat Culture in the Middle Irtysh River Basin

The article deals with the results of a study of a plant mixture from an ancient vessel found in the rich burial of the Isakovka I burial ground (the Gorkovsky district of the Omsk region, the right bank of the Irtysh River). According to archaeological material, the estimated date of the complex might be not earlier than the 1st–2nd centuries AD. The analysis of the substance was carried out by gas chromatography with mass spectrometric detection (GC–MS) after acid methanolysis. The mixture contains aliphatic lipids (fatty acids, phytosterol), terpenes (monoterpenes, sesquiterpenes, diterpenes and triterpenes) derived apparently from the large amounts of essential oils and resins of plant origin. The presence of a number of diagnostic compounds in the mixture composition (boswellic acid derivatives, amyrins, lupeol) suggests that frankincense from Boswellia resin is included in the mixture. Since psychotropic substances (cannabinoids and nicotinoids) have not been found, this combination may be characteristic of an aroma mixture or incense based on frankincense from Boswellia.

Novel Intact Polar and Core Lipid Compositions in the Pyrococcus Model Species, P. furiosus and P. yayanosii, Reveal the Largest Lipid Diversity Amongst Thermococcales.

Elucidating the lipidome of Archaea is essential to understand their tolerance to extreme environmental conditions. Previous characterizations of the lipid composition of Pyrococcus species, a model genus of hyperthermophilic archaea belonging to the Thermococcales order, led to conflicting results, which hindered the comprehension of their membrane structure and the putative adaptive role of their lipids. In an effort to clarify the lipid composition data of the Pyrococcus genus, we thoroughly investigated the distribution of both the core lipids (CL) and intact polar lipids (IPL) of the model Pyrococcus furiosus and, for the first time, of Pyrococcus yayanosii, the sole obligate piezophilic hyperthermophilic archaeon known to date. We showed a low diversity of IPL in the lipid extract of P. furiosus, which nonetheless allowed the first report of phosphatidyl inositol-based glycerol mono- and trialkyl glycerol tetraethers. With up to 13 different CL structures identified, the acid methanolysis of Pyrococcus furiosus revealed an unprecedented CL diversity and showed strong discrepancies with the IPL compositions reported here and in previous studies. By contrast, P. yayanosii displayed fewer CL structures but a much wider variety of polar heads. Our results showed severe inconsistencies between IPL and CL relative abundances. Such differences highlight the diversity and complexity of the Pyrococcus plasma membrane composition and demonstrate that a large part of its lipids remains uncharacterized. Reassessing the lipid composition of model archaea should lead to a better understanding of the structural diversity of their lipidome and of their physiological and adaptive functions.

Methodology optimization for the analysis of phenolic compounds in chestnut (Castanea sativa Mill.).

Phenols are bioactive substances of great interest because of their involvement in plant physiology, their use in many industrial processes, and their impact on human health. This work aims to summarize the varied approaches to the phenolic analysis of chestnut (bark and wood of trunk and branches, leaves, catkins, burs, and fruit) and to collate the optimal conditions into an easy to follow and execute protocol. Phenolic compounds were extracted by solid-liquid extraction and separated by liquid-liquid extraction. Total phenols content was determined by Folin-Ciocalteu assay, condensed tannins by vanillin assay, and hydrolyzable tannins (gallotannins and ellagitannins) by high-performance liquid chromatography quantification of methyl gallate and ellagic acid following acid methanolysis. The lowest temperature for conservation (-80 ℃), lyophilization, and milling (liquid N2) were the most effective pretreatments for samples. For quantification of tannins, the use of water clearly reduced the sensitivity of the analysis of condensed tannins, whilst the more efficient degradation capacity of sulfuric acid improved the methanolysis of hydrolyzable tannins. These findings were validated using a range of chestnut tissues, and thus confirm the utility and effectiveness of this easy to implement, cost-effective, and efficient protocol.

Xylan accessibility of bleached eucalypt pulp in alkaline solutions

AbstractThe accessibility of glucuronoxylan from a refined, bleached Eucalyptus globulus industrial kraft pulp in 0–18% aqueous NaOH solution at room temperature (25°C) was studied. The extraction profile revealed a maximum extraction of xylan in the pulp at about 10–12% NaOH concentration and was explained by the maximum swelling of the pulp according to the Gibbs-Donnan equilibrium. The kinetics of xylan removal and the monitoring of its structural features were performed at 5 and 10% NaOH concentrations. The maximum yields of xylans with 10% and 5% NaOH were as high as 90% and 60% for 2 h extraction, respectively. The structural features of xylan were assessed by acid methanolysis and one-dimensional (1D)/two-dimensional (2D) nuclear magnetic resonance (NMR), and the molecular weight by size exclusion chromatography (SEC). The xylan extracted with 10% NaOH had a slightly higher molecular weight and a lower branching with uronic moieties than the xylan extracted with 5% NaOH. The former was less pure (contained more β-cellulose) than the latter. Structural studies by NMR resulted in the conclusion that there are at least two types of xylans removed from the pulp: one xylan with relatively high 4-O-methyl-α-D-glucuronosyl [MeGlcA-(1→] and [→2)-MeGlcA-(1→] substituents and another xylan with a much lower substitution with uronic residues.

Separation and characterization of products from acidic methanolysis of plasmalogenic lipids by two-dimensional gas chromatography with online reduction

The complexity of determining the composition of animal tissue lipids is greatly increased by the presence of plasmalogens in which the alkyl chain is linked to glycerol by an enol ether bond instead of being esterified. Acidic methanolysis of animal tissue lipids provides the simultaneous scission of acyl and alkenyl ether moieties, but the complexity of the products of reaction poses a great challenge in their gas chromatographic analysis. Two-dimensional gas chromatography with online reduction (GC-OR × GC) provided the resolution of all components contained in acid methanolyzed animal lipids, taking advantage of the selective hydrogenation of alkenyl ether methanolysis products prior to the second-dimension separation (2D). In this study, we also studied the chemical transformations occurring during the acidic methanolysis of animal lipids and the subsequent gas chromatographic analysis. In particular, we observed that using methanolysis reagents contaminated with water resulted in the undesired formation of fatty aldehydes, and we made recommendations on how to avoid these side reactions using proper methanolysis conditions. Products of acidic methanolysis were studied by GC-OR × GC, GC-MS, NMR spectroscopy, and GC with flame ionization detection (GC-FID). We defined the GC-FID elution order of animal lipid acidic methanolysis products using 100 m × 0.25 mm 100% bis(cyanopropyl)siloxane columns and two different set of elution conditions: isothermal elution at 180°C, and a temperature program optimized for dairy fats. A simple procedure for isolating dimethyl acetals (DMA) prior to GC analysis is also described.

Biodiesel Production by Acid Methanolysis of Slaughterhouse Sludge Cake.

Simple SummaryExcessive sludge in the wastewater treatment basins has to be removed periodically to ensure good water quality of the effluent. This study aims to evaluate the feasibility of biodiesel production by acid methanolysis of slaughterhouse sludge cake. Experimental and analytical results showed that acid methanolysis of sludge cake was one of the feasible and practical options to recycle sludge waste and produce renewable energy.Biosludge is a normal form of accumulating microbial populations inside the sewage or wastewater treatment facilities. Excessive sludge in the wastewater treatment basins has to be removed periodically to ensure good water quality of the effluent. This study aims to evaluate the feasibility of biodiesel production by transesterification of slaughterhouse sludge cake. The sludge cake was collected from a selected commercial slaughterhouse and transesterified with methanol, n-hexane, and acids (e.g., sulfuric acid or hydrochloric acid) at 55 °C. Three acid concentrations (2%, 4%, and 8%, v/v) in methanol under four reaction time periods (4, 8, 16, and 24 h) were applied. Results showed that the highest accumulated fatty acid methyl ester (FAME) yields of 2.51 ± 0.08% and 2.27 ± 0.09% were achieved when 8% (v/v) of H2SO4 or HCl were added in a 4 h reaction time, respectively. Methyl esters of palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), and oleic acid (C18:1n9c) were the major components of biodiesel from acid methanolysis of slaughterhouse sludge cake. Experimental and analytical results of acid methanolysis of slaughterhouse sludge cake showed that acid methanolysis of sludge cake was one of the feasible and practical options to recycle sludge waste and produce renewable energy.

Early diagenetic sequestration of microbial mat lipid biomarkers through covalent binding into insoluble macromolecular organic matter (IMOM) as revealed by sequential chemolysis and catalytic hydropyrolysis

Analyses of lipids in modern microbial mat ecosystems provide valuable insights into the taxonomic affinities of the dominant biological producers and consumers as well as carbon flow within the mat community. Such microbial mat biomarker assemblages also provide a window into the ancient biomarker record, facilitating paleobiological and paleoenvironmental reconstructions of analogous ecosystems on early Earth. Our focus was to investigate the covalent binding of lipid biomarkers into insoluble macromolecular organic matter (IMOM) during diagenesis in the well-studied hypersaline microbial mat ecosystems and underlying sediments at Guerrero Negro, Baja California Sur, Mexico. Following exhaustive solvent extraction, three different chemical degradation reagents of varying reactivity (acid methanolysis, trichloroacetic acid extraction, and periodate oxidation) were applied to two shallow sedimentary layers prior to fragmentation of the recalcitrant insoluble residues using catalytic hydropyrolysis (HyPy). The hydrocarbons released by HyPy included a complex variety of linear, branched and polycyclic alkane structures, including hopanes, methylhopanes and steranes. Our findings indicate that a significant fraction of the bound biomarker pool was strongly linked by covalent binding through functional groups into IMOM but that a portion of this bound pool was not recoverable by chemolysis treatment. These results provide new insights about the mode and timing of chemical binding of steroids and hopanoids, and their early diagenetic transformation products, into IMOM. The formation of sedimentary IMOM from the earliest stages of organic matter diagenesis, commencing on a timescale of only years, aids the long-term preservation of biomarker lipids in the geological record.

Extracted ulvans from green algae Ulva linza of Lebanese origin and amphiphilic derivatives: evaluation of their physico-chemical and rheological properties

Over the last years, different seaweeds have raised considerable interest as sources of valuable and biodegradable materials from renewable and environmental sources in order to limit the use of the traditional non-renewable petroleum/chemical-based ones. For instance, the exploitation of algae as a source of carbohydrate polymers has been the target of special attention and specifically research on the unexploited green algae, including their polysaccharide ulvan. In this study, a simple method for extraction of ulvan from the green alga Ulva linza of Lebanese origin is demonstrated successfully without enzymatic treatment. The isolated ulvan (yield = 21.7%) was characterized in terms of composition and structure by elemental analysis, turbidimetric method of barium sulfate, size exclusion chromatography, HPLC after acidic methanolysis of ulvan, FTIR, and NMR spectroscopy. An ulvan with a relatively low content of protein (2.56%), high amount of sulfate (17.2%), and a molecular weight of 565,100 g mol−1 was identified as a sole polysaccharide. This ulvan was rich in rhamnose (26.2%) and glucuronic acid (11.5%) while a low amount of iduronic acid (3.5%), xylose (5.8%), and glucose (1.2%) was detected. Rheological properties of ulvan revealed a shear-thinning pseudoplastic behavior for a concentration range between 0.5 and 3% in a solution of 7 mM CaCl2 and 7 mM H3BO3. Also, storage (G′) and loss (G″) moduli were studied for ulvan solution (1%). Besides, an original hydrophobically modified uronamide ulvan (HM-ulvan) was elaborated in aqueous medium using the coupling agent EDC-HCl in the presence of octylamine. The linkage between carboxylic groups of ulvan uronic acid and octylamine via amide functions was demonstrated chemically by FTIR and NMR (1D and 2D). In conclusion, the introduction of octyl fatty chains on the ulvan backbone increased the dynamic viscosity and improved the rheological properties by creating hydrophobic associations in the solution of HM-ulvan. The low degree of substitution (0.42) influenced dramatically the critical aggregation concentration (CAC) and no foam properties of HM-ulvan were detected.

Evaluation of cerebrospinal fluid heparan sulfate as a biomarker of neuropathology in a murine model of mucopolysaccharidosis type II using high-sensitivity LC/MS/MS

Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS), an enzyme that catabolizes glycosaminoglycans (GAGs) including heparan sulfate (HS) and dermatan sulfate (DS). GAG accumulation leads to severe neurological and somatic impairments. At present, the most common treatment for MPS II is intravenous enzyme replacement therapy; however, the inability of recombinant IDS to cross the blood-brain barrier (BBB) restricts therapeutic efficacy for neurological manifestations. We recently developed a BBB-penetrating IDS fusion protein, JR-141, and demonstrated its ability to reduce GAG accumulation in the brain of human transferrin receptor knock-in and Ids knock-out mice (TFRC-KI/Ids-KO), an animal model of MPS II, following intravenous administration. Given the impossibility of measuring GAG accumulation in the brains of human patients with MPS II, we hypothesized that GAG content in the cerebrospinal fluid (CSF) might serve as an indicator of brain GAG burden. To test this hypothesis, we optimized a high-sensitivity method for quantifying HS and DS in low-volume samples by combining acidic methanolysis and liquid chromatography-tandem mass spectrometry (LC/MS/MS). We employed this method to quantify HS and DS in samples from TFRC-KI/Ids-KO mice and revealed that HS but not DS accumulated in the central nerve system (CNS). Moreover, concentrations of HS in CSF correlated with those in brain. Finally, intravenous treatment with JR-141 reduced levels of HS in the CSF and brain in TFRC-KI/Ids-KO mice. These results suggest that CSF HS content may be a useful biomarker for evaluating the brain GAG accumulation and the therapeutic efficacy of drugs in patients with MPS II.

A novel heterocyst glycolipid detected in a pelagic N2-fixing cyanobacterium of the genus Calothrix

Previous studies have shown that heterocyst glycolipids (HGs) are unique markers for N2-fixing heterocystous cyanobacteria. In this study, the HGs of a marine pelagic Calothrix sp. CCY1611 isolated from the tropical western North Atlantic were analyzed by ultra-high pressure liquid chromatography–high resolution mass spectrometry and it was shown that this organism contains an unusual C28 triol HG with a methylated C6 sugar (methyl-HG28 triol) head group. Gas chromatography–mass spectrometry analysis of the sugar released from the novel HG by acid methanolysis revealed that the sugar is likely 6-O-methyl-β-d-glucopyranose. We propose that this methyl-HG28 triol is a potential biomarker for pelagic members of the genus Calothrix.

Chemical characterization of Pinus halepensis sapwood and heartwood

ABSTRACTThis paper describes the chemical composition of sapwood (SW) and heartwood (HW) of Pinus halepensis Mill stem. Extractives were first isolated by accelerated solvent extraction and then analysed by gas chromatography-mass spectrometry (GC-MS). The cellulosic polysaccharide content present in the pre-extracted wood samples was determined with acid hydrolysis and GC. The hemicelluloses content was determined with acid methanolysis and GC. Free monomers were additionally analysed by GC. The amount of lignin was determined gravimetrically by the Klason lignin method and the acid-soluble lignin was determined by a UV method. Formic and acetic acids in wood were determined after alkaline hydrolysis and analysed by HP-SEC. It was found that lipophilic and hydrophilic extractives were more abundant in heartwood (1.6% and 2.5%) than in sapwood (1.1% and 1.8%). Celluloses content was higher in sapwood (42.5%) than in heartwood (39.7%), whereas lignin, hemicelluloses and sugar monomer contents were more abundant in heartwood (28.9%, 26.8% and 0.3%) than in sapwood (28.0%, 24.5% and 0.2%). The variation in acetic and formic acids and ash contents between sapwood (0.7%, 0.2% and 0.5%) and heartwood (0.6%, 0.1% and 0.4%) was small. The acetylation degrees were found to be slightly similar in sapwood (0.4) and heartwood (0.3).

Functionality of spruce galactoglucomannans in oil-in-water emulsions

For a sustainable food chain, the demand for plant-based, functional, and cost-effective food hydrocolloids is on a high-rise. Hemicelluloses from the renewable lignocellulosic biomass are available in abundance from side-streams of the forestry industry to fulfill this demand. Their effective valorization requires a safe, economic extraction method that can be up-scaled to an industrial scale and, simultaneously, understanding of their functionality to develop applications. In this study, an aqueous-based extraction method, pressurized hot water extraction (PHWE) of spruce saw meal was used to obtain galactoglucomannans (GGM), “spruce gum”. Ethanol precipitation was performed to remove non-polysaccharide extractives such as free phenolic compounds, and the emulsion component ratio-dependent interfacial saturation capacity of the remaining purified fraction was studied to understand its functionality. GGM resulted in good to excellent emulsification and stabilization of oil-in-water emulsions and exhibited adsorption at the oil droplet interface, which depended on the amount of oil and droplet size of emulsions. The adsorbed GGM content was determined by gas chromatography after acid methanolysis, and their macromolecular characteristics were studied by size-exclusion chromatography. At GGM to oil ratios 2, 1, and 0.4, stable emulsions with predicted several months of shelf life at room temperature were achieved. The results indicated mechanisms affecting the physical stabilization and breakdown of emulsions containing spruce gum, a novel sustainable hydrocolloid.

Determination of Polyhydroxybutyrate (PHB) Content in Ralstonia eutropha Using Gas Chromatography and Nile Red Staining.

Ralstonia eutropha H16 produces and mobilizes (re-utilizes) intracellular polyhydroxybutyrate (PHB) granules during growth. This protocol describes the visualization of intracellular Nile red stained PHB granules and the quantification of PHB by gas chromatography. Our first method describes how to analyze PHB granules by fluorescence microscopy qualitatively. Our second approach enables the conversion of PHB to volatile hydroxycarboxylic acid methyl esters by acidic methanolysis and their quantification by gas chromatography. Through this method, it is possible to obtain an absolute quantification of PHB, e.g., per cell dry weight.

Antiproliferative hydroxy-fatty acids from the fodder legume Stylosanthes guianensis

Stylosanthes guianensis is a fodder legume native from South America and widely grown worldwide. Dried plant material was purchased on the web and taxonomically identified by light and SEM microscopy, and morphological analysis of plants germinated from seeds. The plant was extracted with dichloromethane:2-propanol (9:1). Bioguided fractionation using calcein-AM cytotoxicity assay on HeLa and A431 tumor cells allowed to isolate a lipophilic fraction, endowed with strong cytotoxicity. By means of 1- and 2-D NMR, HPLC–MS, and HR-ESIMS it could be seen that the fraction was an inseparable mixture of complex lipids, mainly consisting of esterified 3-hydroxy fatty acids. Acidic methanolysis of the mixture yielded 3-OH C10 and C12 carboxylic acids, together with palmitic, stearic, and arachidonic acids. Mass values indicate the presence of dimeric and trimeric combinations of 3-hydroxy, C10/C12 acids, and C16/C18/C20 acids, linked via ester bond. Monomeric hydroxyl-fatty acids were also observed, in particular derivatives of mono-hydroxy and di-hydroxy linolenic, linoleic, and oleic acids. 3-O-acylated, esterified fatty acids are unusual in higher plants, and recall motifs of Gram-negative endotoxin lipid A. These oxylipins are likely to be responsible for the antiproliferative activity of S. guianensis, suggesting possible use of the plant in the development of antitumor drugs.

Lipid profiles of Mediterranean moray, Muraena helena, European conger, Conger conger, and European eel, Anguilla anguilla (Actinopterygii: Anguilliformes)

Background. The current topics in fish fatty acid (FA) research include qualitative comparisons, trophic transfer as nutritive sources of FA, evolutionary comparison of synthesis pathways, and potential application of most efficient fish desaturases and elongases. FA are scarcely investigated in Elopomorpha and Anguilliformes, except for common- and Japanese eels. In this study determines the differences in lipid composition of FA between species of the order Anguilliformes, representing three families, Mediterranean moray, Muraena helena Linnaeus, 1758; European conger, Conger conger (Linnaeus, 1758); and European eel Anguilla anguilla (Linnaeus, 1758) (thereafter moray, conger, and eel, respectively). These are the first results on FA for the moray. Materials and methods. The fishes were collected in September 2011 on the Croatian coast of the Adriatic Sea, including the Neretva River estuary. Total lipids were extracted and the fatty acid profile in total lipid isolates were determined by gas chromatography of the corresponding methyl esters, obtained by acid methanolysis. A Hewlett Packard HP 5890A capillary gas chromatograph equipped with flame ionization detector (FID) was used. Results. Both moray and conger were less fatty than eel but had higher ω FA content, especially ω-3. Moray and conger, contained more proteins than lipids, while in eel, lipids exceeded the crude protein content. Conger was the leanest fish among the three. The qualitative SFA, MUFA, and PUFA were species specific (myristic FA characteristic for moray). PUFA were higher in moray and conger, due primarily to DHA. Moray showed the most favourable qualitative lipid content and profile and best ratio of ω-3 to ω-6 FA. Moray had 7.6- and conger 11-fold more DHA than eel. Approximate ratios along ω-3 biosynthesis pathway, show that there was 6-fold more EPA than α-LNA in moray and conger, and only 1.64- in eel, 5.63-fold, and 11.27-fold more DHA than DPA in Mediterranean moray and conger, respectively, and only 1.03-fold more in eel Approximate ratios along ω-3 biosynthesis pathway, show that there was 6-fold more EPA than α-LNA in moray and conger, and only 1.64-fold in eel. DHA was 5.63-fold, and 11.27-fold more abundant than DPA in moray and conger, respectively. In comparison, eel had only 1.03-fold more DHA than DPA. Conclusion. Although trophic status and environment are the most determined, the differences in individual FA ratios might indirectly suggest different physiological utilization of elongation pathways in each species. Presently reported results draw focus on Muraena helena and Conger conger to be included in the studies elongase and desaturase pathways in teleost fish.

A convenient method for the preparation of 20-[18O]-labeled ingenol

A short and efficient protecting group-free synthesis of isotopically labeled 20-[18O]-ingenol has been developed. Based on a highly selective (only one out of four hydroxy groups) Mitsunobu reaction of ingenol with 18O2-acetic acid and subsequent methanolysis, this route yielded the desired 20-[18O]-ingenol in high yield and chemical and isotopic purity.

ChemInform Abstract: Flavonoid Glycosides from Siparuna gigantotepala Leaves and Their Antioxidant Activity.

Two new flavonol glycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4'-O-α-rhamnopyranosyl-(1→2)-β-glucopyranoside (2). In addition, three known flavonol glycosides, rutin (3), kaempferol 3-O-rutinoside (4), and kaempferol 3,7-di-O-methyl-4'-O-rutinoside (5), and three flavonol aglycones, quercetin (6), kaempferol 3,7-dimethyl ether (7), and kaempferol 3,7,4'-trimethyl ether (8), were also isolated and are reported here for the first time in this species. The structures of compounds 1 and 2 were established on the basis of their LC-MS and one- and two-dimensional (1D)- and (2D)-NMR spectroscopic analyses, combined with acid methanolysis and silylation of sugar moieties for GC-MS. Evaluation of the antioxidant activity, conducted in the 96-well plate format, showed that the flavonoids isolated possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and moderate oxygen radical absorption capacity.

Flavonoid Glycosides from Siparuna gigantotepala Leaves and Their Antioxidant Activity.

Two new flavonol glycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4'-O-α-rhamnopyranosyl-(1→2)-β-glucopyranoside (2). In addition, three known flavonol glycosides, rutin (3), kaempferol 3-O-rutinoside (4), and kaempferol 3,7-di-O-methyl-4'-O-rutinoside (5), and three flavonol aglycones, quercetin (6), kaempferol 3,7-dimethyl ether (7), and kaempferol 3,7,4'-trimethyl ether (8), were also isolated and are reported here for the first time in this species. The structures of compounds 1 and 2 were established on the basis of their LC-MS and one- and two-dimensional (1D)- and (2D)-NMR spectroscopic analyses, combined with acid methanolysis and silylation of sugar moieties for GC-MS. Evaluation of the antioxidant activity, conducted in the 96-well plate format, showed that the flavonoids isolated possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and moderate oxygen radical absorption capacity.

Comparison of different types of pretreatment and enzymatic saccharification of Macrocystis pyrifera for the production of biofuel

In this work, the brown algae Macrocystis pyrifera were pretreated with dilute sulfuric acid, water and three different types of ionic liquids (ILs): 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc]) and 1,8-diazabicyclo-[5.4.0]–undec-7-ene–sulfurdioxide–monoethanolamine (DBU–MEA–SO2–SIL), to disassemble the complex polysaccharide structure. After each pretreatment procedure, enzymatic saccharification was performed to release the monosaccharides. The main building blocks of M. pyrifera were processed by derivatization via acid methanolysis and subjected to gas chromatographic analysis. It was found that the main constituents were alginate (60.6wt.%) and cellulose (22.6wt.%) of total carbohydrate content. The degradation of alginate requires the action of alginate lyase and oligoalginate lyase, which hydrolyze the main chain in a synergistic mechanism releasing uronic acid (unsaturated uronate). Upon saccharification of cellulose, cellulases and β-glucosidase were used allowing the release of glucose. It was found that the best pretreatment strategy for M. pyrifera consisted of a pretreatment with 2vol.% sulfuric acid, followed by saccharification of cellulose with a mixture of cellulases at pH5.2 for 4h at 50°C or by saccharification of alginate with the enzyme lyase/oligoalginate lyase at pH7.5 for 2h at 37°C. The process resulted in a release of 68.4wt.% of glucose (55.74±0.05mg glucose/g algae) whereas in the case of alginate 85.8wt.% of uronic acid (193.7±10.6mg uronic acid/g algae) was released. To the best of our knowledge this is the first time that saccharification of both cellulose and alginate from brown algae is reported.

Synthesis of Novel Thymine-β-lactam Hybrids and Evaluation of Their Antitumor Activity

Trimethylene-tethered thymine-β-lactam and thymine-bis-β-lactam chimeras were prepared as novel classes of hybrid systems through selective mono- or bis-N-alkylation of thymine with <i>cis</i>-1-(3-bromopropyl)-β-lactams. In addition, acidic methanolysis of the β-lactam nucleus in these systems provided an entry into the class of thymine-β-amino ester hybrids. A selection of the newly synthesized hybrid compounds was assessed for their antiviral activity, cytotoxicity, and cytostatic activity, revealing a significant cytostatic effect of one of the derivatives against murine leukemia and human T-lymphocyte tumor cells.