Hydroxy Analogue Research Articles

Transport of l-leucine hydroxy analogue and l-lactate in rabbit small-intestinal brush-border membrane vesicles

Substitution of the alpha-amino group of amino acids by hydroxyl groups yields hydroxy analogues (HA), which have been ascribed beneficial effects in nitrogen-sparing diets for uremic patients. In this study, intestinal uptake of L-leucine HA (L-LeuHA) and L-lactate into rabbit jejunal brush-border membrane vesicles was investigated. An inward-directed H+ or Na+ gradient stimulated uptake of both labelled substrates in a voltage-clamped assay. The H+ gradient was the major driving force of uptake as compared with the Na+ gradient, and it led to a transient accumulation of both L-LeuHA and L-lactate. The proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) reduced the initial H(+)-gradient-driven uptake rates of both substrates, but was without effect on Na(+)-gradient-driven uptakes. The H(+)-gradient-driven L-LeuHA uptake was saturable (apparent Kt = 15.4 mM). Alpha-HA of L-leucine, L-isoleucine, L-valine, D-leucine, D-valine or L-lactate inhibited the H(+)-gradient-driven L-LeuHA or L-lactate uptakes whereas free branched-chain amino acids had no effect. Preloading the vesicles with one of the L- or D-HA of branched-chain amino acids or with L-lactate stimulated tracer L-LeuHA and also tracer L-lactate uptakes in the presence of a H+ gradient. It is concluded that H(+)-gradient-driven transport of L- and D-stereoisomeric HA of branched-chain amino acids as well as of L-lactate across rabbit intestinal brush-border membranes is mediated by the same carrier. Furthermore, there exists a Na+ gradient-driven L-lactate transport system in the rabbit intestinal brush-border membrane.

Influence of Forage Type, Ratio of Forage to Concentrate, and Methionine Hydroxy Analog on Performance of Dairy Cows

In a 2-yr study, 44 primiparous and 77 multiparous cows were assigned to one of 12 dietary treatments (2 × 3 × 2 factorial). Treatments were two forages (alfalfa or smooth bromegrass), three percentages of grain (40, 50, or 60% of diet DM), and two percentages of methionine hydroxy analog (0 or .15% of diet DM). Feeds were offered as total mixed diets. Data collection began 4 d postpartum and continued through 116 d postpartum. Dry matter intake was not affected by percentage of concentrate or forage source even though NDF of the diets ranged from 25.6 to 48.8% and ADF ranged from 15.7 to 36.8%. Cows fed bromegrass hay produced 1.5 kg/d more FCM and 1.2 kg/ d more SCM than those fed alfalfa hay. Concentrate percentage in the diet increased milk yield (28.9, 30.4, and 31.3 kg/d at 40, 50, and 60%, respectively). Methionine hydroxy analog increased milk fat percentage and yield for cows fed diets of 50 and 6096 concentrate with alfalfa hay but not for those fed diets of 50 and 60% concentrate with bromegrass hay. Effect of methionine hydroxy analog was not significant for milk fat or yield when diets of 40% concentrate were fed.

An Evaluation of Methionine Hydroxy Analog Free Acid Using A Nonlinear (Exponential) Bioassay

Two experiments were conducted to determine the bioefficacy of methionine hydroxy analog free acid (MHA-FA) using the nonlinear (exponential) bioassay method. Male broiler chicks were fed a low methionine diet composed primarily of ground yellow corn and soybean meal for the 1st wk. The experimental diets, which varied in eight levels of DL-methionine and in eight equimolar levels of MHA-FA, were fed from 7 to 21 days of age. The source of protein was soybean meal and isolated soybean meal (15% of each) in the first experiment and soybean meal and peanut meal (23 and 21%, respectively) in the second experiment with glucose as the primary source of energy. Compared with DL-methionine on an equimolar basis, the bioefficacy of the MHA-FA was 72 ± 5 and 73 ± 7% using weight gains and feed conversions, respectively, from the first experiment and 85 ± 11 and 79 ± 8% using weight gain and feed conversion from the second experiment. These results clearly show that DL-methionine is much superior to MHA-FA on an equimolar basis.

Oxidation of the Supplemental Methionine Source L-2-Hydroxy-4-Methylthiobutanoic Acid by Pure L-2-Hydroxy Acid Oxidase from Chicken Liver

The peroxisomal enzyme L-2-hydroxy acid oxidase A (EC 1.1.3.1) was isolated from chicken liver to better evaluate its part in the utilization of the L isomer of supplemental DL-hydroxy-4-methylthiobutanoic acid by birds fed diets containing the methionine hydroxy analogue. The 650-fold purified enzyme, a 169 kDa protein composed of four apparently identical subunits, exhibited a specific activity of 1.3 mumol glycolate oxidized.min-1.mg protein-1. Glycolate (Km = 0.10 mmol/L) was actually a better substrate than L-2-hydroxyisocaproate (Km = 0.63 mmol/L), L-2-hydroxy-4-methylthiobutanoate (Km = 1.73 mmol/L) and L-lactate (Km = 10.13 mmol/L). Under all substrate concentrations tested, the enzyme activity toward L-2-hydroxyisocaproate and L-2-hydroxy-4-methylthiobutanoate was 55 and 17%, respectively, of that toward glycolate. Although the highly purified enzyme was unable to oxidize D-lactate, D-methionine, L-methionine, L-mandelate and beta-phenyl-L-lactate, the latter two aromatic substrates were significantly oxidized by the first ammonium sulfate precipitate obtained during the isolation procedure, supposedly because of the presence of L-2-hydroxy acid oxidase isozyme B. Because the hepatic tissue concentration of glycolate, the physiological substrate for the enzyme, was rather low (10 mumol/L) as compared to the concentration of the methionine hydroxy analogue, one can expect that the conversion of L-2-hydroxy-4-methylthiobutanoate to 2-keto-4-methylthiobutanoate prior to L-methionine formation might proceed at a substantial rate in chickens fed the supplemental methionine source.

Potential antipsychotic agents. 5. Synthesis and antidopaminergic properties of substituted 5,6-dimethoxysalicylamides and related compounds

A series of 3-substituted 5,6-dimethoxysalicylamides III (9-13 and 15) has been synthesized from the corresponding 2,5,6-trimethoxybenzoic acids. Relaxation times T1 and carbon chemical shifts of the methoxy groups in III showed that the 6-methoxy group adopts a nearly perpendicular orientation and the 5-methoxy group takes on a more coplanar orientation with respect to the ring plane in solution. The salicylamides III display a very high and stereoselective affinity for the [3H]spiperone and [3H]raclopride binding sites in vitro. Regioisomeric salicylamides IV also exhibit pronounced, but lower than III, affinity for the [3H]spiperone binding site. The structural requirements were further assessed by studies of the related amino analogues 23 and 24 and hydroxy analogue 27. The 3-bromo compound 11 (FLB 463) was studied in various in vivo models and compared with the dopamine-D2 antagonists sulpiride, raclopride, eticlopride, and haloperidol. The high potency of 11 to selectively block dopamine-D2 receptors in vitro and in vivo combined with indications on a low potential for motor side effects makes it a very interesting new member of the class of substituted salicylamides.

Absorption and Bioavailability of DL-Methionine Hydroxy Analog Compared to DL-Methionine

Intestinal absorption of crystalline DL-methionine (DL-MET) and DL-methionine hydroxy analog calcium (DL-HMA) were determined in a true-digestibility-balance assay using cecectomized (CEC) and sham-operated conventional (CONV) cockerels. The treatments consisted of fasted birds and birds crop-intubated (CI) with 30 g of a corn-soybean meal basal diet (16% CP) supplemented with 0, .2, or .4% of DL-MET or equimolar levels of DL-HMA. There was no detectable free D-MET or L-MET or HMA in the excreta of fasted birds or of those fed the unsupplemented basal diet. The intestinal absorption of DL-HMA was 95.9 ± .8% (χ̄ ± SE) for CEC and 98.8 ± .8% for the CONV cockerels. The absorption of DL-MET was approximately 99.7 ± .2% for the CEC and the CONV cockerels.In a second experiment procedures were developed for a bioavailability assessment by comparing the growth responses to CI and intraperitoneal-injected (IP) DL-MET or DL-HMA in chicks fed a crystalline-amino-acid diet deficient in methionine. Graded increments of pH-adjusted DL-MET or DL-HMA (in water solutions) were administered twice daily in a 7-day growth assay. Slope-ratio analysis indicated that bioavailability (± SE) of CI DL-HMA was 91.3 ± 11.8% relative to the CI DL-MET on an equimolar basis. The bioavailability of CI DL-HMA was similar to that of IP DL-HMA, indicating that the intestinal absorption of DL-HMA was highly efficient.The conclusion reached from these experiments was that the DL-HMA was well absorbed by the chickens and that any differences in bioavailability between DL-HMA and DL-MET must be related to the in vivo conversion of DL-HMA into L-MET.

Simultaneous liquid chromatographic determination of methionine hydroxy analogue and dl-methionine in feed formulations

A liquid chromatographic method for the simultaneous determination of methionine hydroxy analogue and dl-methionine in compounded feed samples is described. Samples are subjected to a simple extraction procedure followed by quantification on a LiChrospher reversed-phase column with ultraviolet detection at 214 nm. The reproducibility and recovery were determined for a range of typical European feed formulations. An excellent correlation was found between the data obtained by this method and by conventional methods.

Responses of finishing broilers at high temperatures to dietary methionine source and supplementation levels

The methionine requirements of 3-6-week-old broilers kept at a constant 30�C or at diurnally cycling temperatures of 25-35�C were reduced compared with broilers kept at 21�C. The methionine requirements varied from 0.29 g/MJ of metabolizable energy (ME) at 2 1�C to 0.26 g/MJ of ME at 25-35�C to 0.22 g/MJ of ME at 30�C with total sulfur amino acid requirements of between 0.51 and 0.55 g/MJ of ME. The estimate at 21�C is similar to recommendations made by others for moderate temperatures. Differences in response to DL-methionine and methionine hydroxy analogue free acid were small.

Structures of minor ether lipids isolated from the aceticlastic methanogen, Methanothrix concilii GP6.

Structures were determined for two phospholipids and three glycolipids purified from chloroform-methanol extracts of Methanothrix concilii GP6. Together they accounted for 14% of the total lipid and were based on a C20,20-diether core structure consisting of either 2,3-di-O-phytanyl-sn-glycerol or its 3'-hydroxy analog, namely, 2-O-[3,7,11,15-tetramethylhexadecyl]-3-O-[3'- hydroxy-3',7',11',15'-tetramethylhexadecyl]-sn-glycerol. These two core lipids formed phosphodiester bonds to ethanolamine and glycosidic bonds to beta-D-galactopyranose. A third glycolipid consisted of the triglycosyl head group beta-D-galactopyranosyl-(1----6)-[beta-D-glucopyranosyl-(1----3)]-beta-D - galactopyranose in glycosidic linkage to the 3'-hydroxydiether core lipid.

Total synthesis of acarbose and adiposin-2

The first total synthesis is described of the α- d-glucosidase inhibitor acarbose ( 1a). 1,6-Anhydro-4′- O-(3,4-anhydro-6-deoxy-α- d-galactopyranosyl)-β-maltose ( 21), prepared from 1,6-β-maltotriose ( 3a), and (+)-4,7:5,6-di- O-isopropylidenevalienamine ( 28) gave two pseudo-tetrasaccharide derivatives separable as the per- O-acetyl derivatives ( 29 and 31) by chromatography, and their structures were established on the basis of 1H-n.m.r. spectroscopy. On acetolysis followed by acetylation, 29 afforded the peracetate ( 1b), which was O-deacetylated to give 1a. Likewise, adiposin-2 ( 2a), the 6″-hydroxy analogue of 1a, isolated from fermentation broth of Streptomyces calvus TM-521, was synthesised.

18-cycloalkyl analogues of enisoprost.

By use of standard cuprate methodology, a series of 18-cycloalkyl analogues of enisoprost was prepared in an effort to impede omega chain metabolism and prolong duration of gastric antisecretory activity. An initial product of omega chain oxidation, the C-20 hydroxy analogue, was also synthesized for pharmacological comparison. The cyclopropyl, cyclobutyl, and cyclopentyl analogues were approximately one-fourth as potent as enisoprost in inhibiting gastric acid secretion, while the cyclohexyl and cycloheptyl analogues showed very weak activity, and the 20-hydroxy compound was inactive at a dose 100 times the ED50 of enisoprost. The cyclobutyl compound had a longer duration of antisecretory action than enisoprost and the other cycloalkyl analogues. The cycloalkyl analogues unexpectedly possessed low diarrheogenic activity in rats.

Methionine Hydroxy Analog (Free Acid) Reduces Avian Kidney Damage and Urolithiasis Induced by Excess Dietary Calcium

Urinary acidification previously was shown to be an effective treatment for calcium-induced urolithiasis in domestic fowl, but diuresis caused by the acidifying agent (ammonium chloride) was an undesirable side effect. Because supplemental dietary methionine reportedly acidifies mammalian urine, an experiment was conducted to evaluate the efficacy of the free acid form of methionine hydroxy analog (MHA) as an acidifying agent for treating avian urolithiasis. From 5 to 17 wk of age, immature Single Comb White Leghorns were fed diets containing normal calcium (1%) or high calcium (3.5%). Diets were supplemented with 0, 0.3 or 0.6% MHA. Relative to birds fed the normal calcium diets, birds fed the high calcium diet without added MHA were in a state of metabolic alkalosis and excreted more alkaline urine containing high levels of calcium. Birds fed the high calcium diet without MHA also had significantly higher kidney asymmetry ratios, a higher incidence of gross kidney damage, and a higher incidence of urolith formation when compared with birds fed normal calcium diets. When compared with the high calcium diet without MHA, the high calcium diet supplemented with 0.6% MHA significantly acidified the urine without causing detectable metabolic acidosis, significantly reduced kidney asymmetry and gross kidney damage, and reduced the incidence of urolith formation without increasing water consumption or urine flow. These data demonstrate that MHA effectively prevents calcium-induced kidney damage in domestic fowl without causing undesirable side effects. MHA did increase both fractional and absolute calcium excretion during calcium loading.

Effect on Days of Lactation and Methionine Hydroxy Analog on Incorporation of Plasma Fatty Acids into Plasma Triglycerides

Methionine hydroxy analog has been proposed to stimulate hepatic lipoprotein synthesis and incorporation of plasma fatty acids into plasma triglyceride. Seven cows were fed diets containing 0 or 30g analog/d starting 14 d prepartum. At approximately 30 and 60 d postpartum, cows were continuously infused intravenously with 1-[14C] palmitic acid for 160min to achieve steady-state labeling of plasma fatty acid and triglyceride. Turnover of fatty acid and transfer quotients for triglyceride and CO2 were 3.3 and 2.7 mmol min−1; 13.0 and 10.0%; and 8.0 and 5.0%, for control and analog, respectively. Proportion of fatty acid turnover incorporated into triglyceride and CO2 were 14.0 and 15.0%; and 21.0 and 18.0, respectively, for control and analog. Analog increased 14C recovered in milk fat (52 vs. 36%). Plasma concentration of fatty acids, percent oxidized to CO2, and percent of CO2 from fatty acids decreased with increasing lactation days. Milk fat percent and yield, fatty acid turnover, and oxidation were positively correlated with concentration of plasma fatty acids, whereas fatty acid incorporated into plasma triglyceride was negatively correlated with fatty acid concentration. The data suggest that hepatic triglyceride secretion is not increased in early lactation; further, no effects of analog on lipid metabolism were detected.

Na +-independent and nonstereospecific transport of 2-hydroxy 4-methylthiobutanoic acid by brush border membrane vesicles from chick small intestine

1. 1. The transport of l-and dl-2-hydroxy 4-methylthiobutanoic acid (HMB), the methionine hydroxy analogue, by brush border membrane vesicles (BBMV) from chick small intestine was the sum of a saturable Michaelian component and a diffusive term. 2. 2. Unlike that of l- and dl-MET, uptake was Na + independent and electroneutral. 3. 3. The inhibition of l-HMB transport by l-lactate, a structural analogue, and d-HMB as well, was of the competitive type. 4. 4. Preloading of BBMV with d-HMB but not with l-lactate or l-MET trans-stimulated the influx of labelled l-HMB. 5. 5. HMB uptake by rat and chick intestinal BBMV exhibited similar characteristics but the chick nonstereospecific transport system appeared to be unable to carry out l-lactate translocation.

Metabolism of DL-Methionine and Methionine Analogs by Rumen Microorganisms1,2

Rates of degradation of DL-methionine and a number of methionine derivatives by rumen microorganisms were studied in vitro. Methionine hydroxy analog, the ammonium salt, and the amide derivative of methionine hydroxy analog were degraded more slowly than was methionine. Methyl and ethyl esters of methionine hydroxy analog were rapidly converted to methionine hydroxy analog, which was then degraded. Whole rumen contents were separated into protozoal and bacterial fractions, and rates of disappearance of [14C]carboxyl-labeled methionine and methionine hydroxy analog were determined. Disappearance of the label tended to be slower in the bacterial fraction; however, incorporation into cellular material tended to be higher for the bacterial than for the protozoal fraction. Disappearance of labeled methionine hydroxy analog was slower than labeled methionine in all fractions. Addition of unlabeled methionine inhibited disappearance of labeled methionine hydroxy analog, but unlabeled methionine hydroxy analog did not affect disappearance of labeled methionine. The effect of either Na2SO4, methionine, or methionine hydroxy analog on neutral detergent fiber digestion was related to amount of sulfur in the medium and not source of sulfur.

Effects of parasitism and of supplementing ewes with methyl methionine hydroxy analogue on the wool production of their lambs as adults.

Australian Veterinary JournalVolume 65, Issue 11 p. 358-359 Effects of parasitism and of supplementing ewes with methyl methionine hydroxy analogue on the wool production of their lambs as adults JL WHEELER, JL WHEELER CSIRO Division of Animal Production, Pastoral Research Laboratory, Armidale, New South Wales 2350Search for more papers by this authorAJ WILLIAMS, AJ WILLIAMS Agricultural Research and Veterinary Centre, NSW Department of Agriculture, Orange, New South Wales 2800Search for more papers by this authorWH SOUTHCOTT, WH SOUTHCOTT CSIRO Division of Animal Health, Pastoral Research Laboratory, Armidale, New South Wales 2350Search for more papers by this author JL WHEELER, JL WHEELER CSIRO Division of Animal Production, Pastoral Research Laboratory, Armidale, New South Wales 2350Search for more papers by this authorAJ WILLIAMS, AJ WILLIAMS Agricultural Research and Veterinary Centre, NSW Department of Agriculture, Orange, New South Wales 2800Search for more papers by this authorWH SOUTHCOTT, WH SOUTHCOTT CSIRO Division of Animal Health, Pastoral Research Laboratory, Armidale, New South Wales 2350Search for more papers by this author First published: November 1988 https://doi.org/10.1111/j.1751-0813.1988.tb14267.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume65, Issue11November 1988Pages 358-359 RelatedInformation

Basis of the Stereospecific Preference of Porcine Kidney Fibroblasts for D-2-Hydroxy-4-Methylthiobutanoic Acid as a Source of Methionine , ,

In previous studies we have found that porcine kidney fibroblasts will grow in medium containing D-2-hydroxy-4-methylthiobutanoic acid (D-methionine hydroxy analogue, D-MHA) as the sole source of methionine but not in medium containing the L-isomer (L-MHA) alone. The fibroblasts have been found to have both D-2-hydroxy acid dehydrogenase (EC 1.1.99.6), which uses D-MHA as substrate (Km = 6.0 mM) and L-2-hydroxy acid oxidase (EC 1.1.3.1), which uses L-MHA as substrate (Km = 7.1 mM). These two activities should make it possible for the fibroblasts to grow on either isomer. Only one protein band with L-2-hydroxy acid oxidase activity can be detected with enzyme-specific staining of protein profiles obtained after polyacrylamide gel electrophoresis. The enzyme L-2-hydroxy acid oxidase from porcine kidney has properties that are different from the two porcine isozymes reported previously by others. Passage of DL-[14C]MHA at tracer levels into the porcine kidney fibroblasts in culture is reduced to 31% of control in the presence of 3.75 mM D-MHA, 86% of control with 3.75 mM L-MHA and 65% with 3.75 mM D-lactate but is not affected by up to 3.75 mM L-lactate. It appears that the transport specificity is the basis for the growth promotion of kidney fibroblasts by the D-isomer of MHA as opposed to L-MHA when each is used as the sole source of methionine.

Degradation of Methionine Hydroxy Analog in the Rumen of Lactatina Cows

Four lactating cows fitted with T-type cannulae in the proximal duodenum were utilized in a 4×4 Latin square design to study rumen microbial degradation of methionine hydroxy analog, a methionine supplement. A diet consisting of 55% concentrate and 45% corn silage was fed ad libitum four times daily. The four treatments were 1) control, no methionine hydroxy analog, 2) methionine hydroxy analog in the form of a calcium salt, 3) methionine hydroxy analog in the acid form, and 4) DL-methionine. The amino acids were incorporated into a grain mix, which was top-dressed. All diets were isonitrogenous. Twelve samples of duodenal digesta and fecal matter were collected during the last 3 d of each of the four 14-d periods. Samples were composited for analysis. Microbes either altered or degraded 99% of the methionine hydroxy analog in the rumen, since recovery of the analog in duodenal digesta was less than 1% of the amount fed for both the acid form and the calcium salt.

Theoretical investigations of methanesulphonamide as a hydroxy group equivalent in drugs. Examples from possible β-adrenergic agents and analysis of computational methods

Quantum chemical methods were used to analyse various physical chemical properties and interaction characteristics of methanesulphonamide. Comparison of β-methylsulphonylaminophenethylamine with its hydroxy analogue and certain structural fragments was used to examine the structure–activity relationships of arylhydroxyethylamines. The general role of methanesulphonamide as a hydroxy replacement was examined. In particular, based on the results of the calculations presented here, the differences in proton affinities, proton-donating abilities, or conformational properties do not account for the differences in activities of these compounds. Critical evaluation was made of several quantum chemical methods used in the study of these and other possible drugs, including the semiempirical MNDO and MINDO/3 methods and the ab initio Hartree–Fock method with the STO-3G, 3-21G, and 3-21G(*) basis sets.

Microbial transformation of 6-O-methylerythromycin derivatives.

Mucor circinelloides f. griseo-cyanus IFO 4563 was found to convert 6-O-methylerythromycin A (TE-031, A-56268) to (14R)-14-hydroxy-6-O-methylerythromycin A [14R)-14-hydroxy TE-031). The TLC and spectral data of the conversion product were perfectly identical with those of an active major metabolite of TE-031 in humans (M-5). A related antibiotic, 6-O-methylerythromycin B (TB-010), was able to be similarly transformed to its C-14 hydroxy analogue [14R)-14-hydroxy-6-O-methylerythromycin B, (14R)-14-hydroxy TB-010). The MICs of (14R)-14-hydroxy-6-O-methylerythromycin B against some Gram-positive bacteria were almost equal to those of 6-O-methylerythromycin B. It is suggested that the hydroxylation at C-14 of 6-O-methylerythromycins A and B scarcely reduces their in vitro activity.