Hog Liver Research Articles

High performance liquid chromatography to determine animal drug clenbuterol in pork, beef and hog liver

A semi-micro high performance liquid chromatography (HPLC) was developed to determine clenbuterol in pork, beef and hog liver. The procedure included extraction with 0.4 N perchloric acid, partitionally separation with diethyl ether, and then back-extraction with 0.2 M sulphuric acid. Analytical procedure was performed by HPLC with a Waters Cosmosil column 5C18-MS (2.0 × 150 mm), a mobile phase of 0.05 M NaH2PO4 (pH3.0)/acetonitrile solution (80/20, v/v) and absorbance at 212 nm. The recoveries of clenbuterol in pork, beef and hog liver spiked with standards of 0.0005-0.01 ppm were 80.9-90.6 %. The detection limit of clenbuterol in tested samples was 0.0001 ppm, which is lower than the officially allowed level. The equation was linear for detecting 0.0002-0.001 ppm clenbuterol. The method was validated to be usable for market samples. Three out of 150 samples were detected to contain clenbuterol (0.0001-0.00015 ppm), which were less than both JECFA and Department of Health regulation levels (hog liver 0.0006 ppm and beef 0.0002 ppm).

Review: Peran Enzim dalam Meningkatkan Kualitas Kopi

Indonesia is the third largest coffee producing nation in the world after Brazil and Vietnam. The types and the characteristics of Indonesian coffee are different in each area but the main important factor of consumer acceptance depends on its bitterness level. Chlorogenic acid lactone is a compounds that play an important role as contributor to the coffee bitterness that are formed during the roasting process of coffee bean because of its precursor chlorogenic acid. Chlorogenic acid is commonly found in many plants. One of them can be found in coffee with high concentration. Chlorogenic acid lactone (bitter compound) can be hydrolyzed to chlorogenic acid (non-bitter compound) using hog liver esterase and chlorogenate esterase. This study aimed to analyze the use of these enzymes to decrease the level of bitterness in coffee. The results indicated that HLE and chlorogenate esterase effectively hydrolyzed chlorogenic acid lactones in coffee. Based on the sensory test, coffee extracts treated with enzymes were less bitter than the untreated coffee extracts. If it was associated with Indonesian local coffee then the method can be done with chlorogenate esterase that was in accordance with the legal guarantee of halal product.

Selective enzymatic hydrolysis of chlorogenic acid lactones in a model system and in a coffee extract. Application to reduction of coffee bitterness

Chlorogenic acid lactones have been identified as key contributors to coffee bitterness. These compounds are formed during roasting by dehydration and cyclization of their precursors, the chlorogenic acids (CGAs). In the present study, we investigated an approach to decompose these lactones in a selective way without affecting the positive coffee attributes developed during roasting. A model system composed of (3-caffeoylquinic acid lactone (3-CQAL), 4- caffeoyl quinic acid lactone (4-CQAL), and 4-feruloylquinic acid lactone (4-FQAL)) was used for the screening of enzymes before treatment of the coffee extracts. Hog liver esterase (HLE) hydrolyzed chlorogenic acid lactones (CQALs, FQALs) selectively, while chlorogenate esterase hydrolyzed all chlorogenic acids (CQAs, FQAs) and their corresponding lactones (CQALs, FQALs) in a non-selective way. Enzymatically treated coffee samples were evaluated for their bitterness by a trained sensory panel and were found significantly less bitter than the untreated samples.

4‐Acetylthio‐2,2‐dimethyl‐3‐oxobutyl Group as an Esterase‐ and Thermo‐Labile Protecting Group for Oligomeric Phosphodiesters

Abstract(4‐Acetylthio‐2,2‐dimethyl‐3‐oxobutyl)‐protected oligomeric phosphodiesters 1 and 2 were synthesized and removal of the protecting groups in the presence and absence of hog liver esterase was followed at pH 7.5 and 37 °C. Phosphotriesters 1 and 2 were successfully converted into the desired fully deprotected phosphodiesters 3 and 4, respectively. Some cleavage of internucleosidic P–O bonds took place, which reduced the yield of 3 and 4. Non‐enzymatic removal of the protecting group was only modestly retarded by accumulation of negative charge on the molecule. With 1, the half‐lives for the departure of the first and second protecting groups were 7.8 and 10.7 h, respectively, and with 2, 6.2 and 7.2 h, respectively. After 4 d, 70 % of both starting materials 1 and 2 were converted into the unprotected phosphodiester. The presence of hog liver esterase (2.6 units mL–1) resulted in fast removal of the first protecting group (τ1/2 2.7 min and 36 min with 1 and 2, respectively), but the appearance of fully deprotected 3 and 4 was accelerated only by a factor of 2, consistent with dramatic retardation of the enzymatic reaction upon accumulation of the negative charge.

2‐[(Acetyloxy)methyl]‐4‐(acetylsulfanyl)‐2‐(ethoxycarbonyl)‐3‐oxobutyl Group: A Thermolabile Protecting Group for Phosphodiesters

AbstractThe phosphodiester linkage of 3′‐O‐levulinoylthymidine 5′‐methylphosphate (5) has been protected with 2‐[(acetyloxy)methyl]‐4‐(acetylsulfanyl)‐2‐(ethoxycarbonyl)‐3‐oxobutyl group (to give 1) to study the potential of this group as an esterase‐ and thermolabile protecting group. The group turned out to be unexpectedly thermolabile, being removed as ethyl 3‐(acetyloxy)‐4‐(acetylsulfanyl)‐2‐methylidenebut‐3‐enoate (10) without accumulation of any intermediates. The half‐life of this reaction at pH 7.5 and 37° is 14 min. Hog liver esterase (HLE), in turn, removes the protecting group as ethyl 4‐(acetylsulfanyl)‐2‐methylidene‐3‐oxobutanoate (12). On using 2.6 units of HLE in 1 ml, the rate of the enzymatic deprotection was still only one third of that of the nonenzymatic reaction. The mechanisms of both reactions have been studied and discussed. The crucial step seems to be removal of the O‐bound Ac group, either by esterase or by migration to the neighboring 3‐oxo group (nonenzymatic removal). This triggers the removal by retro‐aldol condensation/elimination mechanism. No alkylation of glutathione (GSH) upon the deprotection of 1 could be detected.

2,2-Disubstituted 4-Acylthio-3-oxobutyl Groups as Esterase- and Thermolabile Protecting Groups of Phosphodiesters

Five different 2,2-disubstituted 4-acylthio-3-oxobutyl groups have been introduced as esterase-labile phosphodiester protecting groups that additionally are thermolabile. The phosphotriesters 1-3 were prepared to determine the rate of the enzymatic and nonenzymatic removal of such groups at 37 °C and pH 7.5 by HPLC-ESI-MS. Additionally, (1)H NMR spectroscopic monitoring was used for structural characterization of the intermediates and products. When treated with hog liver esterase, these groups were removed by enzymatic deacylation followed by rapid chemical cyclization to 4,4-disubstituted dihydrothiophen-3(2H)-one. The rate of the enzymatic deprotection could be tuned by the nature of the 4-acylthio substituent, the benzoyl group and acetyl groups being removed 50 and 5 times as fast as the pivaloyl group. No alkylation of glutathione could be observed upon the enzymatic deprotection. The half-life for the nonenzymatic deprotection varied from 0.57 to 35 h depending on the electronegativity of the 2-substituents and the size of the acylthio group. The acyl group evidently migrates from the sulfur atom to C3-gem-diol obtained by hydration of the keto group and the exposed mercapto group attacks on C1 resulting in departure of the protecting group as 4,4-disubstituted 3-acyloxy-4,5-dihydrothiophene with concomitant release of the desired phosphodiester.

Synthesis and Enzymatic Deprotection of Fully Protected 2′‐5′ Oligoadenylates (2‐5A): Towards a Prodrug Strategy for Short 2‐5A

Fully protected pA2'p5'A2'p5'A trimers 1a and 1b have been prepared as prodrug candidates for a short 2'-5' oligoadenylate, 2-5A, and its 3'-O-Me analog, respectively. The kinetics of hog liver carboxyesterase (HLE)-triggered deprotection in HEPES buffer (pH 7.5) at 37° has been studied. The deprotection of 1a turned out to be very slow, and 2-5A never appeared in a fully deprotected form. By contrast, a considerable proportion of 1b was converted to the desired 2-5A trimer, although partial removal of the 3'-O-[(acetyloxy)methyl] group prior to exposure of the adjacent phosphodiester linkage resulted in 2',5'→3',5' phosphate migration and release of adenosine as side reactions.

Synthesis and evaluation of biodegradable copolyesters of octadecane-1,18-dicarboxylic acid and poly(ε-caprolactone) diol

Copolyesters of poly(ε-caprolactone) diol and 1,18-octadecane dicarboxylic acid were synthesized by polyaddition. The copolymers have a "mixed" structure of ’polyester-polyethylene’. Characterization was carried out by using 1H and 13C NMR, FT-IR, viscosities, DSC, and GPC. The tensile strength varied from 11.9 to 19.9 MPa, and elongation at break varied from 370 to 660 %, respectively. Biodegradability was evaluated by enzymatic hydrolysis (lipases from Rhizopus arrhizus and Candida cylindracea and an esterase form hog liver) and by soil burial test. Both tests showed that the copolyesters were characterized by enhanced biodegradability.

Supercritical carbon dioxide biocatalysis as a novel and green methodology for the enzymatic acylation of fibrous cellulose in one step

Aliphatic esters of cellulose have recently raised the interest on the field of biopolymers. The objective of this work is to develop a methodology for the enzymatic acylation of cellulose with long chain fatty groups in one step. Therefore we designed a system at which fibrous cellulose was enzymatically acylated with vinyl laurate in supercritical carbon dioxide (scCO2) and as a result cellulose laurate was formed. The biocatalysts used for this reaction were immobilized lipase Candida antarctica, immobilized esterase from hog liver and the immobilized cutinase Fusarium solani. The ester content of the product varied on the specificity of the biocatalyst used, reaching a maximum of 4.1% after 9h of reaction. In our knowledge, it is the first time where fibrous cellulose is enzymatically acylated by a long chain aliphatic group in one step, without the necessity of any pretreatment.

Synthesis and Enzymatic Deprotection of Biodegradably Protected Dinucleoside‐2′,5′‐monophosphates: 3‐(Acetyloxy)‐2,2‐bis(ethoxycarbonyl)propyl Phosphoesters of 3′‐O‐(Acyloxymethyl)adenylyl‐2′,5′‐adenosines

As a first step towards a viable prodrug strategy for short oligoribonucleotides, such as 2-5A and its congeners, adenylyl-2',5'-adenosines bearing a 3-(acetyloxy)-2,2-bis(ethoxycarbonyl)propyl group at the phosphate moiety, and an (acetyloxy)methyl- or a (pivaloyloxy)methyl-protected 3'-OH group of the 2'-linked nucleoside have been prepared. The enzyme-triggered removal of these protecting groups by hog liver carboxyesterase at pH 7.5 and 37° has been studied. The (acetyloxy)methyl group turned out to be too labile for the 3'-O-protection, being removed faster than the phosphate-protecting group, which results in 2',5'- to 3',5'-isomerization of the internucleosidic phosphoester linkage. In addition, the starting material was unexpectedly converted to the 5'-O-acetylated derivative. (Pivaloyloxy)methyl group appears more appropriate for the purpose. The fully deprotected 2',5'-ApA was accumulated as a main product, although, even in this case, the isomerization of the starting material takes place.

3-Acetyloxy-2-cyano-2-(alkylaminocarbamoyl)propyl Groups as Biodegradable Protecting Groups of Nucleoside 5´-mono-Phosphates

Thymidine 5´-bis[3-acetyloxy-2-cyano-2-(2-phenylethylcarbamoyl)propyl]phosphate (1) has been prepared and the removal of phosphate protecting groups by hog liver carboxyesterase (HLE) at pH 7.5 and 37 °C has been followed by HPLC. The first detectable intermediates are the (RP)- and (SP)-diastereomers of the monodeacetylated triester 14, which subsequently undergo concurrent retro-aldol condensation to diester 4 and enzyme-catalyzed hydrolysis to the fully deacetylated triester 15. The former pathway predominates, representing 90% of the overall breakdown of 14. The diester 4 undergoes the enzymatic deacetylation 700 times less readily than the triester, but gives finally thymidine 5´-monophosphate as the desired main product. To elucidate the potential toxicity of the electrophilic 2-cyano-N-(2-phenylethyl)acrylamideby-product 17 released upon the deprotection, the hydrolysis of 1 has also been studied in the presence of glutathione (GSH).

Direct enzymatic acylation of cellulose pretreated in BMIMCl ionic liquid

Cellulose esters are an important class of functional biopolymers with great interest in the chemical industry. In this work the enzymatic acylation of Avicel cellulose with vinyl propionate, vinyl laurate and vinyl stearate, has been performed successfully in a solvent free reaction system. At first cellulose was putted into the ionic liquid BMIMCl (1-n-butyl-3-methylimidazolium chloride) in order to facilitate the unwrap of the structure of the polysaccharide molecule and make it accessible to the enzyme. Thus, after this pretreatment the enzymatic esterification reaction was performed using various hydrolases. The enzymes capable of catalyzing the acylation of cellulose were found to be the immobilized esterase from hog liver and the immobilized cutinase from Fusarium solani, while the lipases used did not show any catalytic activity. Cellulose esters of propionate, laurate and stearate were synthesized with a degree of esterification of 1.9%, 1.3% and 1.0%, respectively. It is the first successful direct enzymatic acylation of cellulose with long chain fatty acids.

Phosphoramidates of 2′-β-d-arabinouridine (AraU) as phosphate prodrugs; design, synthesis, in vitro activity and metabolism

2′-β-d-Arabinouridine (AraU), the uridine analogue of the anticancer agent AraC, was synthesized and evaluated for antiviral activity and cytotoxicity. In addition, a series of AraU monophosphate prodrugs in the form of triester phosphoramidates (ProTides) were also synthesized and tested against a range of viruses, leukaemia and solid tumour cell lines. Unfortunately, neither the parent compound (AraU) nor any of its ProTides showed antiviral activity, nor potent inhibitory activity against any of the cancer cell lines. Therefore, the metabolism of AraU phosphoramidates to release AraU monophosphate was investigated. The results showed carboxypeptidase Y, hog liver esterase and crude CEM tumor cell extracts to hydrolyse the ester motif of phosphoramidates with subsequent loss of the aryl group, while molecular modelling studies suggested that the AraU l-alanine aminoacyl phosphate derivative might not be a good substrate for the phosphoramidase enzyme Hint-1. These findings are in agreement with the observed disappearance of intact prodrug and concomitant appearance of the corresponding phosphoramidate intermediate derivative in CEM cell extracts without measurable formation of araU monophosphate. These findings may explain the poor antiviral/cytostatic potential of the prodrugs.

Spreadable 돼지 간제품의 영양학적 품질

This study was carried out to evaluate the nutritional properties of spreadable liver product. The composition of fresh hog liver used as raw material was 70.5% moisture, 5.2% fat, 20.3% protein and 1.2% ash. The composition of the spreadable liver product was 55.3% moisture, 19.4% protein, 21.6% fat and 3.7% ash. The total amino acid content of fresh liver was 18.69 g/100 g with glutamic acid at the highest level of 2.57 g/100 g. The total amino acid content of liver product was 18.03 g/100 g with glutamic acid at 2.28 g/100 g. The essential amino acid content was found to be 42% of total amino acids. The fatty acid analysis of fresh liver revealed oleic acid to be present at the highest level of 28% in the unsaturated fatty acid portion, and palmitic acid to be highest at 20.7% in the saturated fatty acid portion. The oleic acid content of the liver product was 40%, and the palmitic acid content was 20.4%. The level of cholesterol in fresh liver was 178.0 mg/100 g compared to 118.0 mg/100 g in the liver product. Regarding mineral analysis, the K and P contents of fresh liver were 362.2 mg/100 g and 339.1 mg/100 g, respectively, and 336.1 mg/100 g and 213.3 mg/100 g in the liver product, respectively. Many other minerals including Na, Mg, Ca and Fe were present in the product. Based on these results, the spreadable liver product made with hog liver was found to be a quality food with nutritional benefits and that is easy to consume.

Spreadable 간 제품의 저장온도별 품질변화

돼지 도축부산물의 하나인 돼지 간의 활용도 증진을 위하여 퍼짐형 간 제품을 제조하여 저장온도별 품질변화를 알아보고자 본 실험을 실시하였다. 저장시험은 <TEX>$-2^{\circ}C,\;5^{\circ}C$</TEX> 및 <TEX>$20^{\circ}C$</TEX>에서 30일간 저장하면서 pH, TBA, VBN, 색도, 일반세균, 대장균군 및 관능검사를 분석하였다 pH는 저장온도별에 따른 유의적 차이를 보이지 않았으며, TBA는 <TEX>$-2^{\circ}C$</TEX> 저장구에서 30일째에 0.6 MA mg/kg의 값을 보이고, <TEX>$5^{\circ}C$</TEX> 저장구에서는 21일째 0.80 MA mg/kg 이상을 나타냈으며, <TEX>$20^{\circ}C$</TEX>저장구는 14일째 0.91 MA mg/kg를 보였다. VBN함량의 변화는 저장기간이 길어짐에 따라 계속적인 증가 경향을 보였으나 그 중 <TEX>$20^{\circ}C$</TEX> 저장구가 10일째 가식권을 벗어났다. 색깔변화는 각 저장구간 전체적으로 명도가 증가하는 경향을 보였으며 적색도는 감소하였다. 관능검사 결과 저장온도별에 따라 유의적 차이는 있었지만 퍼짐성은 높은 온도에서 좋은 결과를 보였다. 일반세균수 및 대장균군의 변화는 <TEX>$-2^{\circ}C$</TEX>저장구에서는 저장기간이 경과함에 따라 크게 세균 증식이 일어나지 않아 저장 30일째에도 3.31 log CFU/g의 수준을 보였다. <TEX>$5^{\circ}C$</TEX> 저장구 30일까지 저장 후에도 3.56 log CFU/g 정도였다. 반면 <TEX>$20^{\circ}C$</TEX> 저장구에서는 저장 14일에 8.74 log CFU/g까지 증식하였다. 대장균군에서는 <TEX>$-2^{\circ}C$</TEX>와 <TEX>$20^{\circ}C$</TEX> 저장구에서는 전 저장기간 동안 검출되지 않았으며 <TEX>$5^{\circ}C$</TEX> 저장구 3일째에만 검출되었다. 따라서 종합적으로 돼지 간을 이용한 제조된 퍼짐형 간 제품은 이하에서 14일까지는 식용가능하다고 할 수 있겠다. In order to expand the use of hog liver by the food industry, spreadable liver product was manufactured and quality changes were investigated depending on storage temperature at <TEX>$-2^{\circ}C,\;5^{\circ}C\;and\;20^{\circ}C$</TEX> for 30 days. pH, thiobarbituric acid (TBA), volatile basic nitrogen (VBN), color, microbiological and sensory evaluation were carried out. Changes in pH values were not significantly different at different storage temperatures. TBA values were 0.6 mg MA/kg at <TEX>$-2^{\circ}C$</TEX> after 30 days, 0.80 mg MA/kg at <TEX>$5^{\circ}C$</TEX> after 21 days and showed 0.91 mg MA/kg at <TEX>$20^{\circ}C$</TEX> after 14 days. The change in VBN content tended to increase during prolonged storage periods regardless of storage temperature. The product color tended to lighten over time, although there was no difference in a value of color during storage periods. Also, sensory evaluation results showed that the optimal storage temperature for the liver product was <TEX>$5^{\circ}C$</TEX>. The numbers of general bacteria increased to a level of 7.38 log CFU/g on storage 7 days in <TEX>$20^{\circ}C$</TEX>. This study showed that a viable spreadable liver product could be manufactured using hog liver and remains edible for at least 14 days when stored at temperatures below <TEX>$5^{\circ}C$</TEX>.

Biochemical Characterization of a Flavin Adenine Dinculeotide-Dependent Monooxygenase, Ornithine Hydroxylase fromPseudomonas aeruginosa, Suggests a Novel Reaction Mechanism

Pyoverdin is the hydroxamate siderophore produced by the opportunistic pathogen Pseudomonas aeruginosa under the iron-limiting conditions of the human host. This siderophore includes derivatives of ornithine in the peptide backbone that serve as iron chelators. PvdA is the ornithine hydroxylase, which performs the first enzymatic step in preparation of these derivatives. PvdA requires both flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide phosphate (NADPH) for activity; it was found to be a soluble monomer most active at pH 8.0. The enzyme demonstrated Michaelis-Menten kinetics in an NADPH oxidation assay, but a hydroxylation assay indicated substrate inhibition at high ornithine concentration. PvdA is highly specific for both substrate and coenzyme, and lysine was shown to be a nonsubstrate effector and mixed inhibitor of the enzyme with respect to ornithine. Chloride is a mixed inhibitor of PvdA with respect to ornithine but a competitive inhibitor with respect to NADPH, and a bulky mercurial compound (p-chloromercuribenzoate) is a mixed inhibitor with respect to ornithine. Steady-state experiments indicate that PvdA/FAD forms a ternary complex with NADPH and ornithine for catalysis. PvdA in the absence of ornithine shows slow substrate-independent flavin reduction by NADPH. Biochemical comparison of PvdA to p-hydroxybenzoate hydroxylase (PHBH, from Pseudomonas fluorescens) and flavin-containing monooxygenases (FMOs, from Schizosaccharomyces pombe and hog liver microsomes) leads to the hypothesis that PvdA catalysis proceeds by a novel reaction mechanism.

Lactones 29. Enzymatic resolution of racemic γ-lactones

Studies on the application of commercially available enzymes to resolution of the racemic unsaturated γ-lactones: 5-(3-methylbutylidene)-4-methyl-tetrahydrofuran-2-one (1a) and 5-(3,3-dimethylbutylidene)-4-methyl-tetrahydrofuran-2-one (2a) are presented. Lipase PS, Rhizopus niveus lipase, Rhizopus arrhizus lipase, porcine pancreas lipase and hog liver esterase transformed substrates into their respective γ-keto acids with good efficiency (50–75%). Three of them hydrolysed the studied lactones with moderate enantioselectivity. Enantiomeric excesses determined by GC for the unreacted lactones were in the range of 20–60%. Lipase PS preferentially hydrolysed the (+) enantiomers of lactones 1a and 2a whereas R. niveus lipase hydrolysed the (−) enantiomers, respectively.

Detection scheme for bioassays based on 2,6-pyridinedicarboxylic acid derivatives and enzyme-amplified lanthanide luminescence

2,6-Pyridinedicarboxylic acid (PDC) and its derivatives are introduced as a new sensitizer system for enzyme-amplified lanthanide luminescence (EALL), a detection scheme for bioassays, which combines enzymatic amplification with time-resolved luminescence measurements of lanthanide chelates. Various PDC esters have been synthesized as esterase substrates that are cleaved to PDC in the presence of the enzyme. PDC forms luminescent complexes with Tb(III) or Eu(III), and the evaluation of the reaction is used for the selective and sensitive detection of esterases. For an esterase from hog liver a limit of detection of 10 −3 u/mL (equivalent to 10 −9 mol/L) and a limit of quantification of 3 × 10 −3 u/mL (equivalent to 3 × 10 −9 mol/L) could be achieved. As a second model reaction, xanthine oxidase (XOD) catalyzes the oxidation of 2,6-pyridinedicarboxaldehyde to PDC. Here, the limit of detection was 3 × 10 −3 u/mL and the limit of quantification 10 −2 u/mL for XOD from microorganisms. Major advantage of the tridentate PDC ligand is the possibility to perform all steps of the assay within or close to the physiological pH range, while the established EALL schemes based on bidentate salicylates or bisphenols have to be carried out at strongly alkaline pH to ensure sufficient complexation with the lanthanides.

Stereoselective synthesis of natural N-(1-Deoxy-D-beta-fructos-1-yl)-L-amino acids and their effect on lead decorporation.

N-(1-Deoxy-D-fructos-1-yl)-l-amino acids isolated from hog liver are endogenous lead decorporation substances with low toxicity and cell membrane crossing ability. To simulate the effect of the natural N-(1-deoxy-D-fructos-1-yl)-l-amino acids on lead decorporation, a series of the epimerically pure N-(1-deoxy-D-fructos-1-yl)-l-amino acids (6a-e beta) were synthesized, and their usefulness as antagonists of lead intoxication was investigated. The results suggest that after treatment with 6a-e beta the liver, kidney, bone, and brain, lead levels of mice were significantly reduced in comparison with the control group. Except for bone and brain lead levels of the mice after chelating treatment with 6d beta, all of the other tissue lead levels of mice after chelating treatment with 6a-e beta are significantly lower than those of mice after treatment with dl-penicillamine (p < 0.05). All fecal lead levels of mice after treatment with 6a-e beta are significantly higher than those of mice after treatment with 0.9% saline (controls) and dl-penicillamine (p < 0.05-0.01). The effects of all chelating agents on urinary excretion of lead in mice are clearly superior to the control (p < 0.05-0.01). The results of the present studies on repeated lead exposure indicated that at tested levels of i.p. injections, the fructose-amino acids were effective antagonists of lead poisoning under the experimental conditions. After treatment with the chelators, the concentration of essential metals in mice did not exhibit change as compared to the control. The effects of the compounds on cadmium decorporation were also investigated, and similar results were observed.

Biodegradability study of copolyesteramides based on diacid chlorides, diamines, and diols

AbstractCopolyesteramides were synthesized by polycondensation of diacid chlorides, diamines, and diols of varying methylene group chain length. The composition of the synthesized polymer was determined with nuclear magnetic resonance (NMR) analysis. The biodegradation of the polymers was evaluated both with enzymatic hydrolysis and activated sludge test. The polymers were hydrolyzed with lipases from Rhizopus arrhizus, Rhizopus delemar, Candida cylindracea, and an esterase from hog liver, whereas trypsin and α‐chymotrypsin did not have any apparent effect upon them. Enzymatic hydrolysis was found to be greatly affected by the polymer composition and structure. The degradation results obtained from the activated sludge test were in satisfactory agreement with those from enzymatic hydrolysis. The water‐soluble parts of hydrolyzed products were more susceptible to degradation of their ester bonds rather than their amide bonds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 774–784, 2002