Free Amino Compounds Research Articles

Detection and quantification of free amino compounds in selected agricultural by-products with derivatization followed by liquid chromatography-tandem mass spectrometry analysis

Recuperating bioactive compounds and nutrients from agricultural by-products for livestock feed is a potential solution for their reuse. Three of the agricultural by-products whose potential needs to be further explored are hempseed (Cannabis sativa L.) hull and sea buckthorn (Hippophae rhamnoides) pomace and leaves. Free amino compounds content has not yet been explored for these samples and they were compared to oat (Avena sativa) bran and apple (Malus domestica Borkh.) pomace, since they have already been employed as livestock feed. For the analysis of amino compounds, the samples were derivatized with diethyl ethoxymethylenemalonate (DEEMM) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, in an approach called derivatization-targeted analysis. Overall, 46 free amino compounds were quantified, and a correlation matrix revealed that amino compounds’ profile of sea buckthorn leaves resembles that of oat bran, indicating that it is the most suitable agricultural by-product to be employed as feed supplement.

Analysis of Main Components in Jujube and Mulberry Extracts by High-Sensitive HPLC-ESI-Q-TOF-MS/MS.

In order to comprehensively reflect the cigarette quality, a method combining direct injection of diluted sample with high sensitive high-performance liquid chromatography (HPLC)- electrospray (ESI)- quadrupole (Q)- time of flight (TOF)- tandem mass spectrometry (MS/MS) was developed for the identification of major components of cigarette essences (jujube and mulberry extracts). Based on the observed relative molecular mass, MS/MS fragmentation behavior, MS/MS database and related literatures, the components of the jujube extract and mulberry extract were identified. The result shows that the composition of jujube extract and mulberry extract has some similarity. They all mainly contain amino acids, free amino compounds and Maillard reaction products, which are the main constituents of a cigarette essence.

Targeted ultra-performance liquid chromatography/tandem mass spectrometric quantification of methylated amines and selected amino acids in biofluids.

Methylated amino compounds and basic amino acids are important analyte classes with high relevance in nutrition, physical activity and physiology. Reliable and easy quantification methods covering a variety of metabolites in body fluids are a prerequisite for efficient investigations in the field of food and nutrition. Targeted ultra-performance liquid chromatography/tandem mass spectrometric (UHPLC/MS) analysis was performed using HILIC separation and timed ESI-MRM detection, combined with a short sample preparation. Calibration in urine and blood plasma was achieved by matrix-matched standards, isotope-labelled internal standards and standard addition. The method was fully validated and the performance was evaluated using a subset from the Karlsruhe Metabolomics and Nutrition (KarMeN) study. Within this method, a total of 30 compounds could be quantified simultaneously in a short run of 9 min in both body fluids. This covers a variety of free amino compounds which are present in very different concentrations. The method is easy, precise and robust, and has a broad working range. As a proof of principle, literature-based associations of certain metabolites with dietary intake of respective foods were clearly confirmed in the KarMeN subset. Overall, the method turned out to be well suited for application in nutrition studies, as shown for the example of food intake biomarkers in KarMeN. Application to a variety of questions such as food-related effects or physical activity will support future studies in the context of nutrition and health.

Direct measurement of the in situ decomposition of microbial-derived soil organic matter

Soil organic matter (SOM) is the dominant reservoir of terrestrial organic carbon and nitrogen, and microbial necromass represents a primary input to it. However, knowledge of stabilization mechanisms and direct measurements of the decomposition of microbial-derived SOM are lacking. Here we report a novel 15N isotope pool dilution approach using labeled amino sugars and muropeptides as tracers to quantify the decomposition of proteins and microbial cell walls, which allows to estimate in situ decomposition rates of microbial-derived SOM. Our results demonstrate that microbial cell walls are as recalcitrant as soil protein, exhibiting comparable turnover times across various ecosystems. The bacterial peptidoglycan in soils was primarily decomposed to muropeptides which can be directly utilized by microbes without being further depolymerized to free amino compounds. Moreover, bacterial peptidoglycan decomposition was correlated with soil microbial biomass while fungal chitin and soil protein decomposition were correlated with high soil pH and fine soil texture. This approach thereby provides new insights into the decomposition pathways and stabilization mechanisms of microbial-derived SOM constituents pertaining to SOM persistence.

Effects of non-protein-type amino acids of fine particulate matter on E-cadherin and inflammatory responses in mice

Exposure to particulate matter less than 2.5μm (PM2.5) in size is an urgent issue for the protection of human health. Chemicals with PM2.5 collected during a period of intensive haze episodes in Beijing (BJ), Xian (XA) and Hong Kong (HK) were characterised for organic carbon (OC), elemental carbon (EC), total carbon (TC) and free amino acids. BALB/c mice underwent aspiration exposure of 50 or 150μg of PM2.5/mouse (BJ, XA and HK) on days 1 and 7 and were euthanised on day 14. The effects of these exposures on E-cadherin and inflammatory responses in the mouse lungs were analysed. The PM2.5 chemicals consisted of significant amounts of OC: 36.6±17.2μg/m3 for BJ, 38.8±3.8μg/m3 for XA and 7.2±1.4μg/m3 for HK. A total of 23 free amino compounds for the PM2.5 samples were analysed: 4075±1578pmol/m3 for BJ, 4718±2190pmol/m3 for XA and 1145±213pmol/m3 for HK. Exposure to PM2.5 resulted in the suppression of E-cadherin levels in the lung tissues and increased IFN-γ, IL-2, IL-4, IL-6 and IL-10 in the bronchoalveolar lavage fluid. The alterations in E-cadherin, IFN-γ, IL-6 and IL-10 were associated with OC, TC and some amino acids, particularly non-protein-type amino acids. These data emphasised the deleterious health effects of PM2.5.

Ethanol Production from Extruded Thermoplastic Maize Meal by High Gravity Fermentation with Zymomonas mobilis

A comparative study of extruded and ground maize meals as raw materials for the production of regular (12°P) and high gravity (20°P) worts was devised. Extruded water solubility index (WSI) was higher (9.8 percentage units) and crude fat was lower (2.64 percentage units) compared to ground maize. Free-amino nitrogen compounds (FAN), pH, and glucose were evaluated in regular and high gravity worts produced from ground or extruded maize. Extrusion improved glucose content and ethanol yield. In 20°P mashes, extrusion is enhanced by 2.14% initial glucose compared with regular ground mashes. The 12°P and 20°P extruded treatments averaged 12.2% and 8.4% higher ethanol, respectively, compared to the uncooked counterpart. The 20°P worts fermented with Zymomonas mobilis produced 9.56% more ethanol than the 12°P counterpart. The results show that the combination of extrusion and fermentation of 20°P worts improved ethanol yield per kg flour until 20.93%. This pretreatment stimulates Z. mobilis fermentation efficiency.

The effects of salt stress on growth and biochemical parameters in two maize varieties

The main objective of this study was to examine the influence of salinity on growth and biochemical parameters (NR activity, amino compound accumulation, protein content, some inorganic ion concentrations) of two varieties of maize (Limko and Koka). Salinity (75.0 mol • m<sup>-3</sup> NaCl and 37.5 mol • m<sup>-3</sup> Na<sub>2</sub>SO<sub>4</sub>) significantly reduced fresh and dry weights of the investigated maize varieties. NaCl induced higher reduction in biomass production than Na<sub>2</sub>SO<sub>4</sub>. Differences in salt tolerance between Limko and Koka were small.It was found that in both maize varieties the nitrate reductase activity decreased under salt stress (100 mol • m<sup>-3</sup> NaCl). This effect was more marked in the Koka variety than Limko. Decrease in nitrate reductase activity had no inhibitory effect on accumulation of protein and free amino compounds. Salinity treatment (100 mol • m<sup>-3</sup> NaCl) led to an increase in free amino compound contents in roots and shoots of both investigated maize varieties, but these changes were not very large. The highest increase in amino compound level was observed in roots of Koka and it was 2-fold higher than in control plants. Salt stress did not change soluble protein contents in Limko and Koka varieties with the exception of Limko leaves. There was significant increase in soluble protein content on leaves of Limko and it amounted 128% of the control. Salinity caused a great increase in leaf and root Na<sup>+</sup> concentration and a decrease in case of Ca<sup>2+</sup> and K<sup>+</sup> contents. The declines in Ca<sup>2+</sup> content in maize roots were 76 and 70% respectively for Koka and Limko roots. The fall in K<sup>+</sup> concentration was high, but not so drastic as in Ca<sup>2+</sup>. In roots of Koka and Limko the reduction in K<sup>+</sup> content was approximately 30%. Higher reduction in K<sup>+</sup>content showed shoots of Limko. In this case K<sup>+</sup> content lowered to 49% of control.

Drought and air warming affect the species-specific levels of stress-related foliar metabolites of three oak species on acidic and calcareous soil

Climate change as projected for Central Europe will lead to prolonged periods of summer drought and enhanced air temperature. Thus, forest management practices are required to take into account how species performance is adapted to cope with these climate changes. Oak trees may play a major role in future forests because of their relative drought-tolerance compared with other species like beech. Therefore, this study investigated the stress responses (i.e., anti-oxidants, free amino acids) in the leaves of three widely distributed oak species in Central Europe (i.e., Quercus robur L., Q. petraea [Matt.] Libel., Q. pubescens Willd.) to drought, air warming and the combination of drought plus air warming under controlled conditions after periods of spring drought, a short rewetting and summer drought. We quantified foliar levels of thiols, ascorbate, and free amino compounds in Q robur, Q. petraea and Q. pubescens. Our study showed that oak saplings had increased levels of γ-glutamylcysteine and total glutathione and proline with drought and air warming. Foliar ascorbate, glutathione disulfide and dehydroascorbic acid levels were not affected. The comparison of stress responses to drought and/or air warming between the three species showed higher foliar thiol levels in Q. robur and Q. pubescens compared with Q. petraea. For total and reduced ascorbic acid and γ-aminobutyric acid, the highest levels were found in Q. robur. In conclusion, our study showed that foliar anti-oxidant and free amino acid levels were significantly affected by drought plus air warming; however, this effect was species-dependent with the drought-tolerant species of Q. pubescens having the highest reactive oxygen species scavenging capacity among three tested oak species. Furthermore, stress responses as shown by increased levels of foliar anti-oxidants and free amino acids differ between calcareous and acidic soil indicating that the capacities of anti-oxidative defense and osmotic stress adjustment developed better on calcareous compared with acidic soil; however, this effect was metabolite- as well as species-specific.

Response of maize (Zea mays L.) to rimsulfuron under salt conditions

<p>Investigations were carried out to determine the possible interaction between salinity (60 mmol*dm<sup>-3</sup> NaCl) and phytotoxicity of herbicide Titus 25 DF (sulfonylurea herbicide containing active ingredient rimsulfuron). The herbicide was added to the nutrient solution at two concentrations - 1 or 100 nmol*dm<sup>-3</sup>. After 7 days of cultivation in the nutrient solution determined were the growth parameters and some biochemical compounds (photosynthetic pigments, total protein and free amino compounds content). The combined action of 1 nmol*dm<sup>-3</sup> rimsulfuron and salt caused a reduction in plant biomass accumulation, but this reduction was due to the salt itself. In the presence of 100 nmol*dm<sup>-3</sup> rimsulfuron, growth inhibition of maize roots was very high and salinity did not modify herbicide toxicity. However, reduction in maize shoots growth equalled the sum of the reductions caused by each particular factor applied separately (additive effect). The reduction in shoot fresh weight reached 64%.</p><p>The investigated stress factors induced a significant increase in amino compounds, with the exception of maize roots grown under NaCl plus 100 nmol-dm<sup>-3</sup> rimsulfuron. The concentration of total protein in maize roots diminished under NaCl and 100 nmol*dm<sup>-3</sup> rimsulfuron, although in the other cases, it did not change distinctly in comparison to the control. All factors, with the exception of NaCl, induced a slight increase in protein contents in maize leaves. Stress factors did not change significantly the total chlorophyll concentration, however, carotenoid content was markedly reduced. Nevertheless, the combined action of 100 nmol*dm<sup>-3</sup> rimsulfuron and NaCl caused a 10% increase in carotenoid content as compared to the control plants.</p><p>In conclusion, salinity did not change the toxicity of the herbicide applied in low dose (1 nmol*dm<sup>-3</sup>), but it did increase herbicide toxicity at high concentration (100 nmol*dm<sup>-3</sup>) regarding the maize shoots.</p>

Determination of Free Amino Compounds in Betalainic Fruits and Vegetables by Gas Chromatography with Flame Ionization and Mass Spectrometric Detection

Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

Free and combined amino compounds in atmospheric fine particles (PM 2.5) and fog waters from Northern California

Atmospheric fine particles (PM 2.5) collected during August 1997–July 1998 and wintertime fog waters collected during 1997–1999 at Davis, California were analyzed for free and combined amino compounds. In both PM 2.5 and fog waters, the average concentrations of combined amino compounds (CAC, e.g., proteins and peptides) were generally 4–5 times higher than those of free amino compounds (FAC, i.e., amino acids and alkyl amines). Concentrations of total amino compounds (TAC=FAC+CAC) ranged from 1260 to 3650 pmol m −3 air in PM 2.5, and from 1620 to 5880 pmol m −3 air in fog waters. Average values (±1 σ) were 2500±879 and 3400±1430 pmol m −3 air, respectively. Concentrations of amino compounds in PM 2.5 varied seasonally, with a peak during late winter and early spring. Ornithine was a major FAC component in both PM 2.5 and fog waters (typically accounting for ∼20% of FAC), but these sample types otherwise had fairly different FAC distributions. FAC in PM 2.5 were enriched in protein-type amino species such as glycine/threonine, serine and alanine, while fog water FAC had significantly higher levels of non-protein species such as methylamine, γ-aminobutyric acid and ethanolamine. The compositions of CAC in PM 2.5 and fogs were fairly similar and were mainly protein-type. Mass concentrations of TAC in PM 2.5 and fog waters were, on average, 302 and 399 ng m −3 air, respectively. Amino compounds were an important component of the organic carbon pool for both fog and particles, with TAC accounting for an average of 13% of the dissolved organic carbon in fog waters and ∼10% of the water-soluble organic carbon in PM 2.5. At these levels amino compounds likely play important roles in the chemistry of fog drops and fine particles, for example by influencing their buffering capacity and basicity.

Synthesis and Screening of New Chiral Ligands for the Copper-Catalysed Enantioselective Allylic Substitution

The synthesis of the new chiral ligands 6ae, 8ae, 9ae, and 11ae starting from the chiral β-[(Boc)amino]sulfonamide 3ae is reported. The β-amino group of 3ae was deprotected and condensed with 3,5-dichlorosalicylaldehyde (4) to yield the known Schiff base 5ae, which was then reduced to the amino compound 6ae (Scheme 3). Alternatively, condensation of the free amino compound with 2-(diphenylphosphanyl)benzaldehyde (7) afforded the imino ligand 8ae which upon reduction yielded the amino ligand 9ae (Scheme 4). The free amino compound derived from 3ae was also coupled with 2-(diphenylphosphanyl)benzoic acid (10) to give ligand 11ae (Scheme 5). These ligands were tested in the copper-catalysed allylic substitution reaction of cinnamyl (=3-phenylprop-2-enyl) phosphate 12 with diethylzinc as a nucleophile. Ligands 5ae, 6ae, 8ae, and 11ae gave excellent ratios (100 : 0) of the SN2′/SN2 products (Scheme 6 and Table 1). Ligand 11ce, identified from the screening of a small library of ligands of general formula 11, promoted the allylic substitution reaction with moderate enantioselectivity (40% for the SN2′ product 13 (Scheme 8 and Table 3)).

Sulphur signature in the hydrothermal vent mussel Bathymodiolus azoricus from the Mid-Atlantic Ridge

The sulphur compound composition of the hydrothermal vent mussel Bathymodiolus azoricus (Bivalvia: Mytilidae) was analysed in order to determine the specific biochemical characteristics of a thiotrophic mode of nutrition. In specimens collected from two contrasting vent fields on the Mid-Atlantic Ridge (Menez Gwen and Lucky Strike), substantial differences in the sulphur composition were observed between tissues and sampling sites. Total sulphur content was higher for samples from Lucky Strike than for those from Menez Gwen. The amount of elemental sulphur in the gill of B. azoricus was in the same range as values previously reported for the vesicomyid clam Calyptogena phaseoliformis and the lucinid clam Lucinoma annulata. Rings of orthorhombic sulphur or compounds such as polythionates or organopolysulphides excreted in the cytoplasm by the symbionts may account for the large amounts of elemental sulphur evidenced for the first time in an hydrothermal vent mussel. A large proportion of the tissue-sulphur was incorporated into free amino compounds such as taurine, hypotaurine, thiotaurine and cysteine, and in a lesser extent to the tripeptide glutathione. In mantles, sulphur seems to be contained mainly in organic compounds such as proteins, mucopolysaccharides and lipids. However, the occurrence of specific compounds such as thiotaurine and elemental sulphur in gills indicate that in this tissue a large proportion of the sulphur might be involved in specific pathways related to transport, storage and detoxification of sulphide. Moreover, our results suggest a greater reliance on thiotrophy of mussels from Lucky Strike as compared to specimens from Menez Gwen.

Contribution of amino compounds to dissolved organic nitrogen in forest soils

Dissolved organic nitrogen (DON) may play an important role in plantnutrition and nitrogen fluxes in forest ecosystems. In spite of the apparentimportance of DON, there is a paucity of information concerning its chemicalcomposition. However, it is exactly this chemical characterization that isrequired to understand the importance of DON in ecosystem processes. Theprimaryobjective of this study was to characterize the distribution of free aminoacidsand hydrolyzable peptides/proteins in the DON fraction of Oa horizon leachatesalong an extreme edaphic gradient in northern California. Insitu soil solutions were extracted by centrifugation from Oahorizonscollected beneath Pinus muricata (Bishop pine) andCupressus pygmaea (pygmy cypress) on slightlyacidic/fertile and highly acidic/infertile sites. DON accounted for 77 to99% of the total dissolved nitrogen in Oa horizon leachates. Nitrogen infree amino acids and alkyl amines ranged from 0.04–0.07 mgN/L on the low fertility site to 0.45–0.49 mg N/L onthe high fertility site, and accounted for 1.5 to 10.6% of the DON fraction.Serine, glutamic acid, leucine, ornithine, alanine, aspartic acid andmethylamine were generally the most abundant free amino compounds. Combinedamino acids released by acid hydrolysis accounted for 48 to 74% of theDON, suggesting that proteins and peptides were the main contributor to DON inOa horizon leachates. Together, nitrogen from free andcombined amino compounds accounted for 59 to 78% of the DON. Most of theDON was found in the hydrophobic fraction, which suggests the presence ofprotein/peptide-polyphenol complexes or amino compounds associated withhumic substances. Because free and combined amino acids can be an importantnitrogen source for some plants, soil DON may play an important role in plantnutrition and ecosystem function.

Chemistry of fog waters in California's Central Valley—Part 3: concentrations and speciation of organic and inorganic nitrogen

Although organic nitrogen (ON) has been found to be a ubiquitous and significant component in wet and dry deposition, almost nothing is known about its concentration or composition in fog waters. To address this gap, we have investigated the concentration and composition of ON in fog waters collected in Davis, in California's Central Valley. Significant quantities of dissolved organic nitrogen (DON) were found in these samples, with a median concentration of 303 μM N (range=120–1630 μM N). DON typically represented approximately 16% of the total dissolved nitrogen (inorganic+organic) in Davis fog waters. The median concentration of nitrogen in free amino acids and alkyl amines was 16 μM N (range=3.8–120 μM N), which accounted for 3.4% of the DON in Davis fogs. Thus, although the absolute concentrations of free amino compounds were significant, they were only a minor component of the DON pool. Combined amino nitrogen (e.g., proteins and peptides) was present at higher concentrations and accounted for 6.1–29% (median=16%) of DON. Overall, free and combined amino compounds typically accounted for a median value of 22% of DON in the fog waters. The high concentrations of DON found, and the fact that amino and other N-containing organic compounds can serve as nitrogen sources for microorganisms and plants, indicate that atmospheric ON compounds likely play an important role in nitrogen cycling in the Central Valley. In addition, due to the basicity of some N functional groups, ON compounds likely contribute to the previously observed acid buffering capacity of Central Valley fog waters. Finally, a comparison of fog waters with fine particles (PM 2.5) collected from the same site during the same period of time indicated that the median concentrations (mol N m −3-air) of total water-soluble ON, free amino nitrogen and total amino nitrogen were very similar in the fog water and PM 2.5. Given the high water solubility of many organic N compounds, this result suggests that ON might contribute to the hygroscopic properties of atmospheric particles.

Phytochemical and nutritional significance of cactus pear

This review discusses cactus pear fruit with special emphasis on its functional components. Besides their nutritional importance, their significance in plant physiology is also described. Opuntia sp. is characterized by high levels of amino acids, especially proline and taurine. The latter was recently re-evaluated in nutritional science as a conditional amino acid and was hitherto virtually unknown in plant tissues. Free amino compounds also take part in osmoregulation and play an important role in betaxanthin biosynthesis. In contrast to red beets, cactus pears offer a great palette of colour hues and therefore may be used as a food colouring free from certification. The mucilages in Opuntia sp. tissue are responsible for water retention and can be used as dietary fibre or food thickening agents. Low in acids, the fruit is suitable for use in dairy products. With readily absorbable sugars, high vitamin C and mineral content, as well as containing polyphenols, amino acids and having a pleasant flavour, cactus pear is tailor-made for functional food preparations.

Thiotaurine is a biomarker of sulfide‐based symbiosis in deep‐sea bivalves

A simple biochemical approach for demonstrating the presence of symbionts in deep‐sea bivalves and for discriminating between thiotrophic and methylotrophic symbioses is described. Correspondence analysis (CA) of the free amino compound composition of nine bivalve species living in hydrothermal vents and cold seeps successfully discriminates symbiotic species from nonsymbiotic ones, and sulfur‐oxidizing symbiont from methylotrophic symbionts. CA was also used to infer the metabolism of Bathymodiolus azoricus, B. boomerang, and two new species of Mytilid and Vesicomyid from the Barbados. These results were consistent with the evidence obtained by ultrastructural observations of the gills and enzymatic studies, and show that CA of amino acid profiles might be a useful tool to determine the type of endosymbionts present in deep‐sea bivalves. Among all the free amino acids, thiotaurine appears as the main discriminating one and is proposed as a biomarker of sulfide‐based endosymbiosis in deep‐sea bivalves from hydrothermal vents and cold seeps.

The tethered nitrogen in natural products synthesis

A variety of nitrogen-containing natural products, including aminosugars and aminocyclitols, have been synthesized by routes that feature the intramolecular delivery of a temporarily-tethered nitrogen nucleophile to an electrophilic site. This general tactic for amino group introduction frequently provides entropic advantages, as well as improved site selectivity and stereoselectivity, compared with the corresponding intermolecular approach. An occasional additional benefit is that the resulting cyclized products can be more easily manipulated toward the desired target than the corresponding free amino compounds. These aspects are illustrated in a discussion of several natural products syntheses from the author’s laboratory.

The synthesis of ethyl 2‐[(2,2‐dibenzoyl)ethenyl]amino‐3‐dimethyl‐aminopropenoate and its application to the synthesis of fused 3‐aminopyran‐2‐ones and 3‐aminoazolo‐ and ‐azinopyrimidin‐4(4H)‐ones

AbstractEthyl 2‐[(2,2‐dibenzoyl)ethenyl]amino‐3‐dimethylaminopropenoate (3) was prepared from dibenzoylmethane (1) in two steps, and used as a reagent for preparation of fused substituted 3‐aminopyranones 12–15 in over 90% yield, quinolizin‐4‐one 16 in over 79% yield, and fused pyrimidin‐4‐ones 17–19 in 40–50% yield. Deprotection of (2,2‐dibenzoyl)ethenyl group with either diethylamine or hydrazine hydrate produced free amino compounds 20, 21 and 22 in 35%, 91% and 71% yield, respectively.

Synthesis and Antibacterial Activities of New Carbapenems Having a Proline Reverse Amide Moiety at the C-2 Position

The synthesis of new 1 beta-methylcarbapenems (1a-l) having a proline reverse amide moiety at the C-2 position and their in vitro antibacterial activities are described. The compounds were evaluated by the Mueller-Hinton agar dilution method and compared with meropenem as control. Aliphatic amides (1a-h) are found to show greater antibacterial activity than aromatic amides (1i-l). Moreover, C-2 free amino compound (1m) reveals greater activity than any other amide compounds (1a-l).