Reversible and covalent binding of 5-(hydroxymethyl)-2-furaldehyde (HMF) with lysine and selected amino acids

The chemical reactivity of 5-(hydroxymethyl)-2-furaldehyde (HMF) with lysine, glycine, and proline was studied using isotope labeling technique. To confirm the formation of HMF adducts in glucose amino acid model systems, a useful strategy was developed in which products simultaneously possessing six glucose (HMF moiety) and any number of amino acid carbon atoms in addition to nitrogen were targeted using specifically labeled precursors such as [(15)N(α)]lysine·2HCl, [(15)N(ε)]lysine·2HCl, [U-(13)C(6)]lysine·2HCl, [(13)C(6)]lysine·2HCl, and [U-(13)C(6)]glucose in the case of lysine model system. In addition, model systems containing HMF and amino acids were also studied to confirm specific adduct formation. Complete labeling studies along with structural analysis using appropriate synthetic precursors such as HMF Schiff base adducts of piperidine and glycine have indicated that HMF generated in the glucose/amino acid model systems initially forms a Schiff base adduct that can undergo decarboxylation through an oxazolidin-5-one intermediate and form two isomeric decarboxylated Schiff bases. Unlike the Schiff bases resulting from primary amines or amino acids such as glycine or lysine, those resulting from secondary amino acids such as proline or secondary amines such as piperidine can further undergo vinylogous Amadori rearrangement, forming N-substituted 5-(aminomethyl)furan-2-carbaldehyde derivatives.     

Hydrolysis of naptalam and structurally related amides: inhibition by dissolved metal ions and metal (hydr)oxide surfaces.

In metal ion-free solutions, the secondary amide naptalam hydrolyzes more rapidly as the pH is decreased; intramolecular nucleophilic attack by a carboxylate side group is very likely involved. Millimolar levels of dissolved Cu(II) and Zn(II) inhibit hydrolysis between pH 3.6 and pH 6.5. Metal ion-naptalam complex formation is important since addition of the competitive ligand citrate lessens the inhibitory effect. The metal (hydr)oxide surfaces Al(2)O(3) and FeOOH inhibit naptalam hydrolysis to a lesser degree; inhibition is proportional to the extent of naptalam adsorbed. Secondary amides (propanil, salicylanilide, and N-1-naphthylacetamide) and tertiary amides (N-methyl-N-1-naphthylacetamide, furalaxyl, and N, N-diethylsalicylamide) that lack carboxylate side groups do not hydrolyze within 45 days of reaction, even when millimolar Cu(II) concentrations are present. Tertiary amides possessing carboxylate side groups (N,N-diethyl-3,6-difluorophthalamic acid and N, N-dimethylsuccinamic acid) do hydrolyze but are insensitive to the presence or absence of Cu(II). The inhibitory effect is believed to occur via metal coordination of (1) the carbonyl group of naptalam, which induces deprotonation of the amide group and makes the substrate less reactive toward nucleophilic attack; (2) the free carboxylate group of naptalam, which blocks intramolecular nucleophilic attack; or (3) a combination of the two.     

The extraction and characterization of soil polysaccharide by whole soil methylation

A soil of the Countesswells series was repeatedly methylated by the Hakomori procedure and a chloroform-soluble product isolated after each methylation. Ninety-two per cent of the material engendered by seven methylations was released during the first four methylations. This had a methoxyl content of about 20% and contained 2% N. Later fractions had lower methoxyl and N contents. Residual carbohydrate in the soil had reducing sugar content on hydrolysis, equivalent to about 3% of the original value. The extracted material had the infrared spectrum of a methylated soil polysaccharide and, on hydrolysis by 2 m trifluoracetic acid, released methylated sugar derivatives of which 68 were characterised by GC-MS. Derivatives corresponding to (1→4) linked sugars predominated for both hexose and pentose sugars but there was also a large proportion of (1→3) linkages, (1→3) linkages predominated for the deoxyhexose sugars. There were more sugars with only one or two methylated hydroxyl groups than could be accounted for as branching points because of the relatively small numbers of end groups. Prior reduction of the soil with sodium borohydride had no measurable effect on the nature or yield of the methylated product. This indicates that amino acid sugar linkages susceptible to β-elimination reactions can have only a very small influence on the reaction. The isolated sugar derivatives accounted for 70% of the total soil sugars. The methylated material before hydrolysis had a low nominal molecular weight on diafiltration, with 68% < 10000. Some of the sugars unaccounted for were probably lost during the dialysis stage necessary to remove dimethyl sulphoxide.     

The simultaneous determination of muramic acid and glucosamine in soil by high-performance liquid chromatography with precolumn fluorescence derivatization

Summary The optimal release and quantitative estimation of muramic acid and glucosamine were studied simultaneously in soil samples. The effect of hydrolysis conditions, HCl concentration, hydrolysis time, the ratio of soil dry weight to acid, and the recovery of reference substances were investigated. Derivatization of the fluorogenic reagent o-phthalaldehyde, in the presence of 2-mercaptoethanol with the residue of a soil hydrolysate, was achieved by optimizing the relative amounts of o-phthalaldehyde to hydrolysate in the reaction mixture, the pH of both, and the incubation period. A linear relationship was found between the fluorescence response and the concentration of the test substances. The muramic acid, as well as the glucosamine (o-phthalaldehyde) derivatives gave single peaks, and complete separation from interfering substances at the picomol level was achieved in a short time (3 h preparation and 30 min for chromatography) by using high-performance liquid chromatography.     

应用15N核磁共振技术对苯聚合物结合蛋白中氮形态的研究

Phenolic polymers synthesized by reactions by reactions of p-benzoquinone with 15N-labelled protein or (15NH4)2SO4 were studied by using 15N CP-MAS NMR technique in combination with chemical approaches.Results showed that more than 80% of nitrogen in quinone-protein polymers was in the form of amide with some present as aromatic and /or aliphatic amine and less than 10% of nitrogen occurred as heterocyclic N.The nitrogen distribution in the non-hydrolyzable residue of the quinone-protein polymers was basically similar to that of soil humic acid reported in literature with the exception that a higher proportion of N as heterocyclic N and aromatic amine and a lower proportion of N as amide and aliphatic amine were found in the former than in the latter,More than 70% of total nitrogen in quinone-(NH4)2OS4 polymer was acid resistant ,of which about 53% occurred as pyrrole,nitrile and imion type N.The possible roles of the reactions of phenols or quinones with proteins in the formation of humic acid.especially the non-hydrolyzable nitrogen in humicacid,are discussed.     

Isolation and identification of alpha-CEHC sulfate in rat urine and an improved method for the determination of conjugated alpha-CEHC

2,5,7,8-Tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC), the water-soluble metabolite of alpha-tocopherol (alpha-TOH) with a shortened side chain but an intact hydroxychroman structure, has been identified in human urine and are thought to be produced in significant amount at excess intake of alpha-TOH. In previous studies, CEHCs in biological specimens were measured by HPLC, GC-MS or LC-MS, preceded by a hydrolysis procedure using either enzyme or methanolic HCl. In an attempt to analyze alpha-CEHC in rat urine accordingly, we observed that enzyme hydrolysis was relatively inefficient in releasing alpha-CEHC compared to high concentrations of HCl. The HCl releasable alpha-CEHC conjugate was isolated and chemically identified as 6-O-sulfated alpha-CEHC (alpha-CEHC sulfate). Using the synthetic alpha-CEHC sulfate standard, it was found that sulfatase could not hydrolyze to a significant extent. On the other hand, pretreatment with HCl at 60 degrees C in the presence of ascorbate, followed by a one-step ether extraction, not only hydrolyzed the sulfate conjugate completely but also extracted alpha-CEHC with high recovery. The inclusion of ascorbate minimized the conversion of alpha-CEHC to alpha-tocopheronolactone in the HCl pretreatment. A complete procedure for the quantitative analysis of alpha-CEHC including HCl hydrolysis, ether extraction and reverse phase isocratic HPLC-ECD was thus established. In conclusion, alpha-CEHC sulfate was isolated and identified as the HCl-releasable conjugate of alpha-CEHC in rat urine. A rapid and sensitive method with high reproducibility for the determination of free, conjugated and total alpha-CEHC is then established.     

Concentrations of bisphenol a, bisphenol a diglycidyl ether, and their derivatives in canned foods in Japanese markets

Bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE), and their derivatives in 38 canned foods sold in Japan were measured using high-performance liquid chromatography-mass spectrometry (LC-MS) and LC-tandem mass spectrometry (LC-MS/MS). BPA, BADGE, BADGE.2H 2O, BADGE.HCl.H2O, BADGE.HCl, and BADGE.2HCl were 0-235.4, 0-3.4, 0-247.2, 0.2-196.4, 0-3.0, and 0-25.7 ng/g, respectively, which did not exceed acceptable daily intake for BPA and specific migration limit for BADGEs. BADGE was degraded by 58, 100, 46, and 58% in water (pH 7), 0.01 N HCl (pH 2), 0.01 N NaCl (pH 6.8), and 0.01 N NaCl with acetic acid (pH 2.5), respectively, when it was allowed to stand at 120 degrees C for 30 min. The prominent derivatives formed were BADGE.2H 2O and BADGE.HCl.H2O, which was formed not only in BADGE with added HCl but also in that with NaCl. Acetic acid accelerated the formation of both BADGE.2H2O and BADGE.HCl.H2O in NaCl. No BPA was detected in any simulation samples started from BADGE. The results suggest that BPA and BADGE are independently leached into canned foods and that BADGE is easily changed to more stable compounds such as BADGE.2H2O and BADGE.HCl.H2O by sterilization.     

Potential of Chemically Labile Fractions to Measure Mineralizable Soil Nitrogen

Nitrogen (N) in the soil is largely organic and is available to crops only after it is mineralized to inorganic N by microbial or enzyme action. To develop a soil test for guiding N applications, a method to predict the relative amount of organic N that will mineralize in a growing season is necessary. Several chemical analysis methods proposed in the literature to measure mineralizable N were examined for chemical interference, measurement precision, response to procedure modifications, and ability to distinguish differences among soils. The chemical analyses examined involved various acid or alkaline hydrolysis, with the resulting inorganic ammonium N measured by steam distillation and manual or automated diffusion. A gelatinous precipitate in the filtered and neutralized 6 M hydrochloric acid (HCl) hydrolysis solution interfered with magnesium oxide (MgO) diffusion traditionally used to measure inorganic ammonium N. Removing the precipitate appeared to circumvent the interference. The precipitate did not appear to interfere with the sodium hydroxide (NaOH) diffusion. The 6 M HCl hydrolysis extracted 34 to 103% of clay‐fixed ammonium in the soils. Steam distillation was shown to be an acceptable alternative to diffusion for measuring NaOH‐labile N. The vigor of NaOH measurement conditions caused differences in results, showing that precise and reproducible conditions are necessary. Several methods were closely correlated (r² > 0.62) with N mineralized during aerobic incubations and could be considered for further evaluation for soil N testing. This study showed that modifications are required to several proposed analytical methods to improve their potential to estimate mineralizable N for fetilizer or other amendment recommendations for crop production     

Metabolism of [(14)c]chlorantraniliprole in the lactating goat

Metabolism of [(14)C]chlorantraniliprole {3-bromo-N-[4-chloro-2-methyl-6-[(methylamino)carbonyl]phenyl]-1- (3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxamide} was investigated in a lactating goat following seven consecutive daily single oral doses. Each dose was equivalent to 10.4 mg/kg of feed. There was no significant transfer of residues of either chlorantraniliprole or its metabolites into fat, meat, or milk. Chlorantraniliprole and its metabolites accounted for 93.57% of the administered dose and were eliminated primarily in the excreta. Residues in meat, milk, liver, and kidney together accounted for ca. 1.5% of the administered radioactivity. A total of 19 metabolites including 3 glucuronide conjugates and intact chlorantraniliprole were identified in the feces, urine, or tissues by comparison of their HPLC retention times, mass spectral fragments (LC-MS/MS), or multiple reaction monitoring (MRM) transitions to authentic synthesized standards. The major metabolic pathways of [(14)C]chlorantraniliprole in the goat were N-demethylation, methylphenyl hydroxylation, and further oxidation to the carboxylic acid; loss of water from the N-hydroxymethyl group to yield various cyclic metabolites; and hydrolysis of N-methyl amides to form benzoic acid derivatives. Minor metabolic reactions involved cleavage of the amide bridge between the phenyl and heterocyclic rings of chlorantraniliprole.     

Rapid detection of meso-diaminopimelic acid in lactic acid bacteria by microwave cell wall hydrolysis

Two innovative microwave hydrolysis procedures for rapidly detecting meso-diaminopimelic acid in lactic acid bacteria have been developed. Whole-cell hydrolysis was performed both in liquid phase and vapor phase with 6 N HCl in sealed vessels using a microwave oven equipped with pressure and temperature probes. The presence or absence of meso-diaminopimelic acid determined by TLC, after the application of liquid- and vapor-phase microwave hydrolysis procedures, gave the same qualitative results as those obtained by traditional hydrolysis. These standardized microwave hydrolysis procedures permit a drastic reduction in hydrolysis time, from 16-20 h to less than 10 min and, consequently, in the total time of meso-diaminopimelic acid analysis (less than 90 min). Microwave hydrolysis in vapor phase is particularly convenient because, besides reducing hydrolysis time, it also eliminates the successive troublesome step of HCl removal.     

Phaseolin in vitro pepsin digestibility: role of acids and phenolic compounds

Great Northern bean (Phaseolus vulgaris L.) phaseolin proteolysis at 37 degrees C, varying HCl concentrations (10 mM to 1 M), phaseolin:pepsin ratios ranging from 5:1 to 100:1 (w/w), and incubation times up to 24 h was investigated. The results suggest that phaseolin is not resistant to in vitro pepsin hydrolysis. At a phaseolin-to-pepsin ratio of 100:1 (w/w), native phaseolin was completely digested in 24 h when incubated in 50 mM HCl, while heat-denatured phaseolin (30 min at 100 degrees C, boiling water bath) was digested in 1 h under similar conditions. When incubated at 37 degrees C for 24 h, acid alone, even at as low a concentration as 10 mM, caused a partial breakdown of native phaseolin. The degree of phaseolin hydrolysis by HCl was dependent on the acid concentration used. The rate of native phaseolin hydrolysis increased with increasing HCl concentration rather than pepsin concentration. Common food acids were able to partially hydrolyze phaseolin. Among the food acids tested, oxalic acid was the most effective in hydrolyzing phaseolin. Spectroscopic studies revealed a significant change in secondary and tertiary structures when native phaseolin was incubated in dilute HCl. None of the tested phenolic compounds adversely affected phaseolin hydrolysis by pepsin.     

Nucleophilic reactions of phorate and terbufos with reduced sulfur species under anoxic conditions

The reactions of phorate and terbufos with bisulfide (HS-), polysulfide (Sn2-), thiosulfate (S2O32-), and thiophenolate (PhS-) were examined in well-defined aqueous solution under anoxic conditions to investigate their role in the degradations of phorate and terbufos. Reactions were monitored at various concentrations of reduced sulfur species to obtain the second-order rate constants. The reactivity of the reduced sulfur species decreased in the order Sn2- > PhS- > HS- > S2O32-. Hydrolysis products, formaldehyde and diethyl disulfide/di-tert-butyl disulfide, indicated that OH-/H2O attacked the carbon atom between the two sulfur atoms, the so-called thioacetal carbon, which is very reactive due to the presence of the two neighboring sulfur atoms. The reaction of phorate and terbufos with PhS- was investigated to study the transformation products in the reactions with reduced sulfur species. The transformation products demonstrated that the observed increase in rate constants in the reaction with reduced sulfur species compared to hydrolysis could result from the nucleophilic attack of reduced sulfur species at the alpha-carbon of the ethoxy group and at the thioacetal carbon atom. The temperature dependence of measured second-order rate constants of the reaction of phorate and terbufos with HS- over 25-50 degrees C was investigated to explore activation parameters, which are not significantly different for phorate and terbufos. All of the observations may imply similar pathways in the degradation of phorate and terbufos in the presence of reduced sulfur species. Slightly higher hydrolysis rates of terbufos and second-order reaction rate constants for the reactions with sulfur species of terbufos compared with those for phorate are observed, which could be attributed to the slightly different substituents.     

生物质热解过程中氮迁移转化机理研究进展

生物质热解产物中热解气和热解油具有较高能源利用价值,可作为替代燃料或化工原料,但伴随热解过程迁移至热解气/油中的氮元素不仅会影响其品质,热解气/油进一步利用后也会污染大气环境。该研究围绕生物质资源制备清洁能源的总目标,系统分析生物质热解过程中氮迁移转化机理,重点论述气相氮、液相氮和焦炭氮的生成与转化机理。通过总结前人研究,得出生物质热解气中的含氮物质主要为HCN、NH3等,其中NH3主要来源于氨基酸热解释放的氨基以及HCN在焦炭表面的水解转化;HCN主要来源于腈、含氮杂环等一次热解产物的二次裂解;热解油中的含氮物质主要为含氮杂环、腈与酰胺,其中含氮杂环主要由部分氨基酸片段或氨基酸间的脱水缩合反应产生;腈主要来源于氨基酸分子脱H2反应以及酰胺脱H2O反应;酰胺主要来源于NH3与羧基的置换反应。不同生物质种类与热解工况下氮的迁移转化特性复杂多样,生物质种类以及热解过程中的压力、停留时间、升温速率、温度、热解气氛、粒径、催化剂等因素均会影响热解过程中氮的迁移转化路径,最终影响生物质热解气/油中含氮物质的组成及分布。进一步提出生物质热解过程中氮排放控制未来研究方向,以期为实现农村生物质资源高效清洁利用提供参考。     

Chemical estimation of nitrogen mineralization in paddy rice soils: I. Comparison to laboratory indices

Abstract

A reliable, rapid procedure for estimating native soil nitrogen (N) mineralization potential in paddy rice (Orysa sativa L.) has eluded researchers. While several have been proposed, no technique has been sufficiently reproducible to be implemented in any soil testing program. Therefore, the objective was to develop a chemical extraction procedure as an index to estimate N mineralization in silt.loam rice soils of the Southern United States Rice Belt. Samples of silt loam soils were collected from strategic locations throughout the rice‐growing region of Arkansas during 1990 and 1991. Anaerobic incubations were performed as an index of potentially mineralisable N. Extraction with acidified potassium permanganate (KMnO₄), acidified potassium dichromate (K₂Cr₂O₇), hydrochloric acid (HCl), and oxalic acid [(COOH)₂], were evaluated at extractant:soil ratios ranging from 5:1 to 1:1. Also, distillation of centrifuged extracts (SUP) was compared to distilling the entire soil‐solution suspension (TOT). The acidified KMnO₄ and acidified K₂CnO₇ extractions gave the best overall indices of N availability. The acidifed KMnO₄ and acidified K₂Cr₂O₇ sucessfully predicted N mineralization at all ratios evaluated. A significant relationship with anaerobic incubation was observed for all HCl TOT ratios evaluated, except the 3:1 in 1991. The HCl SUP methods were not significant for all soils evaluated. The oxalic acid TOT extractable ammonium‐nitrogen (NH₄+‐N) was significantly related to anaerobic incubation. More N was extracted with the TOT methods than SUP methods, probably due to alkaline hydrolysis during distillation of TOT methods. Oxidation with KMnO₄ released the most N, while HCl and oxalic acid extracted the least.     

Soil amino acid composition quantified by acid hydrolysis and anion chromatography-pulsed amperometry

Soil organic N accounts for 95-98% of the total soil N content with amino acids (AAs) and amino sugars (ASs) identified as the major soil organic N compounds, but traditional 6 M HCl with reflux or sealed digestions for 24 h and various detection systems have accounted for only 30-40% of soil total N content as AA-N. This study compared traditional HCl extraction methodology with methanesulfonic acid (MSA) hydrolysis and nonderivatized AA and AS quantification by ion chromatography with pulsed amperometric detection for determination of the AA composition of plant litter and soils. MSA (4 M) gave AA-N recovery comparable to or better than 6 M HCl for plant AA digestions (16 h, 121 degrees C, 104 kPa). Use of 4 M MSA (0.5-1.5 h, 136 degrees C, 112 kPa) increased the total recovery of organic N as AAs, ASs, and NH(4)(+) by 46% from soils (n = 22) compared with 6 M HCl (12 h, 110 degrees C, reflux) with a MSA recovery rate of 85.6% of the total N content (n = 22 soils). The shorter MSA soil digestions (0.5-1.5 h) suggested that the majority of soil organic N was not present as protein forms found in plant litter analysis (16 h of digestion). MSA ion chromatographic analysis for soil AA/AS composition is a robust nonderivatization method requiring little sample preparation that can distinguish between small changes in soil AA composition during one growing season due to vegetation and tillage managements.     

Kinetics and mechanism of the nucleophilic displacement reactions of chloroacetanilide herbicides: investigation of alpha-substituent effects

The ease with which alpha-chloroacetanilide herbicides undergo displacement reactions with strong nucleophiles, and their recalcitrance toward weak ones, is intimately related to their herbicidal properties and environmental chemistry. In this study, we investigate the kinetics and mechanisms of nucleophilic substitution reactions of propachlor and alachlor in aqueous solution. The role played by the alpha-amide group was examined by including several structurally related analogs of propachlor possessing modified alpha substituents. The overall second-order nature of the reaction, the negative DeltaS(double dagger) values, the weak influence of ionic strength on reactivity, and structure-reactivity trends together support an intermolecular S(N)2 mechanism rather than an intramolecular reaction for alpha-chloroacetanilides as well as the alpha-chlorothioacetanilide analog of propachlor. In contrast, the alpha-methylene analog exhibits kinetics and a salt effect consistent with anchimeric assistance by the aniline nitrogen. Electronic interactions with the alpha-anilide substituent, rather than neighboring group participation, can be inferred to govern the reactivity of alpha-chloroacetanilides toward nucleophiles.     

Lipase-assisted generation of 2-methyl-3-furanthiol and 2-furfurylthiol from thioacetates

Enzymatic hydrolysis of S-3-(2-methylfuryl) thioacetate and S-2-furfuryl thioacetate using lipase from Candida rugosa produced 2-methyl-3-furanthiol and 2-furfurylthiol, respectively. When reactions were carried out at room temperature and pH 5.8, 2-methyl-3-furanthiol was produced in a optimal yield of 88% after 15 min of reaction, whereas 2-furfurylthiol was obtained in a yield of 80% after 1 h of reaction time. Enzymatic hydrolysis was also performed in n-hexane, n-pentane, and water/propylene glycol mixture. The reaction rates in these media were slower as compared to those in aqueous medium; however, the reaction yields were quite similar. As expected, the stability of the generated 2-methyl-3-furanthiol and 2-furfurylthiol was better in n-hexane, n-pentane, and the water/propylene glycol mixture as compared to that in water or phosphate buffer.     

Soil organic nitrogen composition in Pinus forest acid soils: variability and bioavailability

 The total N content in the acid forest soils studied ranged between 0.41% and 1.43%, and in more than 98% was composed of organic N. Total hydrolysable organic N, hydrolysable unknown N (HUN) and α-aminoacidic N represented around 70%, 34% and 20% of the organic N, respectively, and varied in wide ranges. The percentages of amidic N and of the organic N compounds solubilised to NH₄ ⁺ were approximately 6% and 5%, respectively, and ranged in narrow intervals. Aminoglucidic N reached a maximum of 3.8% of the organic N and was undetectable in some of the samples analysed. Most of the hydrolysable N, HUN and α-aminoacidic N was solubilised with 1 N and 3 N HCl, while a high amount of the compounds recovered as NH₄ ⁺ (60%) was obtained with 6 N HCl. The distribution of aminoglucidic N in the four fractions of increasing hydrolytic intensity was very irregular. The organic N composition in the 0 to 5-cm and 5 to 10-cm layers was not significantly different. The variation among samples was determined mainly by the organic N compounds less resistant to acid hydrolysis (hydrolysable N and HUN less resistant to acid hydrolysis, amidic N and labile ammoniacal N) and by all α-aminoacidic N fractions. Aminoacidic N was positively correlated with electrical conductivity and negatively correlated with exchangeable Al. The net N mineralisation over 10 weeks of incubation was positive in all the soil samples analysed. The inorganic N content after the incubation and the microbial N content were positively correlated with other variables – mainly with amidic N and α-aminoacidic N, as well as with HUN and the hydrolysable N less resistant to hydrolysis. Received: 13 July 1999     

Synthesis and antiviral activities of amide derivatives containing the alpha-aminophosphonate moiety

Starting from (substituted-)benzaldehydes, the title compounds 6 were synthesized through five step reactions. Benzaldehydes were treated with ammonium hydroxide, followed by dialkyl phosphite, to give dialkyl N-(arylmethylene)-1-amino-1-aryl methylphosphonates ( 3). Phosphonates 3 were then easily hydrolyzed to give dialkyl 1-amino-1-aryl-methylphosphonates 5. Target compounds 6 were then obtained by the reaction of 5 and substituted benzoic or cinnamic acid. Their structures were clearly verified by spectroscopic data (IR, 1H, 13C, and 31P NMR, and elemental analysis). These compounds were shown to be antivirally active in the bioassay. It was found that title compounds 6g, 6l, and 6n had the same inactivation effect of TMV (EC 50 = 54.8, 60.0, and 65.2 microg/mL, respectively) as commercial product Ningnanmycin (EC50 = 55.6 microg/mL). To the best of our knowledge, this is the first report on the synthesis and antiviral activity of amide derivatives containing an alpha-aminophosphonate moiety.     

Invertase storage stability and sucrose hydrolysis in solids as affected by water activity and glass transition

Research continues to differentiate the impact of water activity (a(W)) and the glass transition temperature (T(g)) on chemical reactions. Invertase with and without sucrose was incorporated into low and high molecular weight poly(vinylpyrrolidone) model systems (PVP-LMW and PVP-K30, respectively). Invertase activity and sucrose hydrolysis were monitored during storage at a(W) = 0.32-0.75 and 30 degrees C. Pseudo-first-order rate constants for activity loss in PVP-K30 were not different, regardless of the system being glassy or rubbery. In PVP-LMW, invertase stability decreased with increasing a(W). An a(W) > 0.62 was required for sucrose hydrolysis to occur in PVP-LMW. PVP molecular weight appeared to affect invertase stability and reactivity. No dramatic change around T(g) was found in either invertase stability or sucrose hydrolysis, suggesting that T(g)-dictated mobility has a minimal effect on these reactions in amorphous solids.