Determination of lycopene and beta-carotene by high-performance liquid chromatography using sudan I as internal standard

A reverse-phase HPLC method based on ion-pair formation with UV detection was set up for the simultaneous determination of gemcitabine diphosphate (dFdCDP) and triphosphate (dFdCTP) in human cells. The separation was achieved on a Tracer Excel ODSA column (100 mm x 4.6mm i.d., 3 microm particle size) at room temperature. Nine nucleotides were separated by isocratic elution in 26 min. Accuracy, linearity, sensitivity and precision studies for dFdCDP, dFdCTP, adenosine diphosphate (ADP) and triphosphate (ATP) validated this method. This assay was used to provide data from gemcitabine treated patients and in vitro grown human cancer cells.     

Determination of ribonucleoside triphosphates and deoxyribonucleoside triphosphates in Novikoff hepatoma cells by high-performance liquid chromatography

A rapid, specific, and sensitive method has been developed for the determination of ribonucleoside and deoxyribonucleoside triphosphates in Novikoff hepatoma cells. A simple three-step procedure was used. Extraction of the biological material with 5% cold trichloroacetic acid (TCA); elimination of TCA by ethilic ether wash and concentration of the sample by lyophilization; and separation of CTP, dCTP, ATP, dATP, UTP, dTTP, GTP, dGTP and their quantitation by anionic-exchange high-performance liquid chromatography under isocratic conditions. All the compounds were identified by comparing their retention times with those of pure compounds, by cochromatography with single pure ribonucleoside triphosphates (NTPs) or deoxyribonucleoside triphosphates (dNTPs), and by comparing the 280 nm:254 nm spectral ratios of the peaks with those of known NTP and dNTP standards. The specific activity of all the above mentioned nucleotides also was determined in Novikoff hepatoma cells labeled with [32P]orthophosphate.     

Ion-pair reversed-phase high-performance liquid chromatography of adenine nucleotides and nucleoside using triethylamine as a counterion

An isocratic HPLC method for the simple and selective determination of adenine nucleoside and nucleotides has been developed. The separation is achieved at room temperature by reversed-phase chromatography (Shiseido, Capcell Pak C18). A mixture of 0.1 M triethylamine (TEA) phosphate buffer and methanol (95:5, v/v) is used as a standard eluent. Influence of pH and concentrations of organic modifiers and TEA ion on capacity factors of adenine compounds has been investigated. It has been also found that the TEA ion in the eluent is adsorbed onto the reversed-phase surface. The results clearly demonstrate that ion-pair formation with TEA ion occurs probably both in the mobile phase and on the stationary phase and governs the retention of adenine and nucleotides in the present system. The HPLC system is applied to the analysis of adenine nucleotides formed as intermediates in the synthesis of 3′-phosphoadenosine 5′-phosphosulphate (PAPS) and to the assays of ATPases and 5′-nucleotidase activities in rat liver plasma membrane. This method is a new type of ion-pair reversed-phase HPLC system and is suitable for the separation of highly polar organic anions, especially for adenine nucleotides.     

Analysis by high-performance liquid chromatography of radioactively labeled carbohydrate components of proteoglycans

Methods were developed for the separation of radioactively labeled carbohydrate components of proteoglycans by isocratic ion-moderated partition HPLC. Neutral sugars were separated after hydrolysis in trifluoroacetic acid with baseline separation between glucose, xylose, galactose, fucose, and mannose. N-Acetylneuraminic acid, N-acetylated hexosamines, glucose, galactose, and xylitol were likewise well separated from each other under isocratic elution conditions. Glucuronic acid, iduronic acid, and their lactones were separated after hydrolysis in formic acid and sulfuric acid. Glucosamine, galactosamine, galactosaminitol, and glucosaminitol were separated by HPLC on a cation exchanger with neutral buffer after hydrolysis in hydrochloric acid. The separation techniques also proved useful in fractionation of exoglycosidase digests of O- and N-linked oligosaccharides. Separations of aldoses, hexosamines, and uronic acids were adapted to sensitive photometric detection.     

Separation and quantitation of oxypurines by isocratic high-pressure liquid chromatography: application to xanthinuria and the Lesch-Nyhan syndrome

An isocratic HPLC technique has been developed for the separation and measurement of urine and plasma oxypurines in a patient with xanthinuria. The case history and laboratory data are presented. Xanthine excretion was 172 mg/g creatinine and hypoxanthine was 45 mg/g creatinine. Uric acid was too small to be measured but uricase determination showed only 3 mg/24 hr. Serum oxypurine analysis showed hypoxanthine 0.87 mg/dl and xanthine 0.35 mg/dl. Uric acid was not seen in this patient's serum but could be readily measured in normal control subjects. The technique can also be used to separate nucleotides from purine bases, and we have demonstrated its application to the measurement of erythrocyte hypoxanthine guanine phosphoribosyl transferase and adenine phosphoribosyl transferase in a kindred associated with the Lesch-Nyhan syndrome.     

Separation and analysis of 4'-epimeric UDP-sugars by borate high-performance liquid chromatography

Separation of UDP-glucose from UDP-galactose, of UDP-N-acetylglucosamine from UDP-N-acetylgalactosamine, of UDP-glucuronate from UDP-galacturonate, or of UDP-glucosamine from UDP-galactosamine was achieved within 10-45 min by isocratic anion-exchange high-performance liquid chromatography (HPLC) using a flow rate of 2 ml/min. The eluants were composed of borate as complex-forming and eluting agent and of glycerol for protection of the alkali-labile silica packing of the column. This borate HPLC was suitable for the analysis of 4'-epimeric UDP-sugars in the range of 2 to 100 nmol. The applicability of this technique was demonstrated by determination of the relative amounts of 4'-epimeric UDP-amino sugars formed in rat liver after administration of D-galactosamine. Since a high salt content of UDP-sugar samples can interfere with borate HPLC, desalting was performed on a 1-ml C18 cartridge using triethylammonium hydrogen carbonate buffer. This procedure enabled the complete separation of various nucleotides from salts within 10 min prior to HPLC.     

A new highly selective physicochemical assay to measure NAD+ in intact cells

A simple, fast, and highly specific chromatographic method for measuring the content of NAD+ in intact cells has been developed. This procedure involves the separation of NAD+ from the bulk of acid-soluble nucleosides, nucleotides, and other pyridine containing molecules by affinity chromatography on dihydroxyboronyl-Bio-Rex. The boronate purified preparations were utilized for the quantification of NAD+ by strong anion exchange high-pressure liquid chromatography under isocratic conditions using a low salt buffer system. The overall recovery of the method exceeded 80%. This new method was applied to determine the extent of NAD+ consumption in intact hepatocytes following treatment with two different DNA damaging agents. A major advantage of this method is that it allows for the simultaneous determination of poly(ADP-ribose) in the acid-insoluble fraction of the same sample.     

Separation of nucleotides in homogenates of octopus retina by ion-pair reversed-phase liquid chromatography and identification by mass spectrometry

An isocratic ion-pair reversed-phase liquid chromatographic method has been developed for the determination of thirteen nucleotides including cyclic AMP and cyclic GMP. The resolution capability of this method was evaluated successfully using homogenates of octopus retina, the aim being to elucidate the role of nucleotides (particularly ADP and ATP) in the control of oxidative metabolism. To overcome the inherent lack of specificity of ultraviolet detection we used the coupling of liquid chromatography with mass spectrometry, via a thermospray interface, to confirm the identity of the nucleotides of interest in the biological samples.     

Purine metabolism in human lymphocytes.

In peripheral human blood lymphocytes the uptake and metabolism of adenine, guanine, and hypoxanthine was investigated. This was achieved by incubation of purified lymphocytes with 14C-purine bases, separation of cells from the incubation medium by a rapid filtration technique, and subsequent separation of the acid soluble material by thin-layer chromatography. No perferential uptake for one of the purine bases was observed. In all cases only traces of 14C-purine bases not added originally and labeled nucleosides could be demonstrated. Approximately 2/3 of adenine and 1/2 of guanine or hypoxanthine were converted to nucleotides. Separation of formed nucleotides showed that adenine and guanine were metabolized mainly to their corresponding nucleotides; hypoxanthine was converted to a considerable amount to adenine nucleotides and only to a small proportion into its own nucleotides. These results demonstrate the predomonance of adenine nucleotide formation in normal human lymphocytes.     

Analysis of the free nucleotide pools of mammalian tissues by high-pressure liquid chromatography

Perchloric acid extracts of tissues were neutralized with tri-N-octylamine and, after removal of ClO₄^?, subjected to preliminary purification on a Cu²⁺-loaded column of Chelex 100. A high-pressure liquid chromatographic (HPLC) anion-exchange procedure was developed and gave good resolution of the naturally occurring free nucleotides on a single column. Where heterogeneous peaks eluted, an effective supplementary analysis was achieved by reverse-phase HPLC. An HPLC paired-ion technique was also evaluated for use in nucleotide analysis. Although anion-exchange was best for overall separation of nucleotides, both reverse-phase and paired-ion chromatography gave excellent separation of cyclic nucleotides. Reduced pyridine nucleotides were detected and measured in the form of their acid-decomposition products. The recovery of nucleotides was examined throughout the described analytical techniques and shown to be quantitative.     

High performance liquid chromatography of phospholipids on modified silica gel

A sensitive method for the separation of phospholipids by a HPLC procedure is described. The separation was carried out on a 30 cm prepacked column with aminopropyl bonded silica under isocratic conditions. The effective separation of major phospholipid classes was carried out for less than 5 min. These chromatographic conditions were used for analysis of natural phospholipid mixtures.     

High-pressure liquid chromatography of polycyclic aromatic hydrocarbons and some of their derivatives.

The separation of polycyclic aromatic hydrocarbons and their derivatives by means of high-pressure liquid chromatography on Permaphase ODS is described. The method consists of the (isocratic) elution of compounds from the column with a methanol-water mixture of constant composition and is particularly suited to the identification of metabolic products of polycyclic hydrocarbons.     

A simple, inexpensive, high pressure liquid chromatographic method for separating cytokinins in plant extracts

Separation of a mixture of the main cytokinins occurring naturally in plant tissues was achieved by high pressure liquid chromatography using insoluble polyvinylpyrrolidone as the solid support. The separation of each cytokinin was first assessed over a range of salt and l-butanol concentrations and pH using a mixture of borate buffer and l-butanol as the mobile phase to determine the conditions necessary for optimum resolution. A discrete separation of zeatin, N-6-(Delta-2-isopentenyl)adenine, their related ribonucleosides, and kinetin was achieved using a simple isocratic elution with 0.025 m borate buffer at pH 6.8 and 4% (v/v) l-butanol. A number of cytokinin-active compounds were detected in cabbage extracts by the Amaranthus betacyanin bioassay using this separation technique.     

A rapid method for the determination of guanosine 5′-diphosphate-3′-diphosphate and guanosine 5′-triphosphate-3′-diphosphate by high-performance liquid chromatography

A method is described for the rapid analysis of the nucleotides, guanosine 5′-diphosphate-3′-diphosphate (ppGpp) and guanosine 5′-triphosphate-3′-diphosphate (pppGpp), by high-performance liquid chromatography. It has been found that the inclusion of magnesium acetate in the potassium phosphate buffer facilitates elution of these highly phosphorylated compounds from the Partisil strong anion-exchange resin and allows their determination under isocratic conditions. The application of this methodology to formic acid extracts of bacterial cells is demonstrated.     

High-performance liquid chromatographic analysis of cytosine arabinoside and metabolites in biological samples

A rapid, non-radioactive method to quantitate therapeutically realistic levels of 1-β- -arabinofuranosylcytosine (Ara-C) and its metabolites would be useful both in the clinic, for monitoring drug levels, and in the laboratory for correlating drug levels with cellular and molecular perturbations. Liquid chromatographic analysis of arabinose-nucleoside analogs in biological samples is complicated by the presence of interfering nucleosides and nucleotides. We report the development of two analytic procedures to measure Ara-C and metabolite levels in biological samples. One method uses a quaternary ammonium type anion-exchange resin to achieve isocratic separation in less than one hour. The second method utilizes a boronate-derivatized polyacrylamide column which binds cis-diols to selectively retain cytosine and uridine, while arabinose compounds are eluted with recovery approaching 100%. The eluted compounds are then easily quantitated on a reversed-phase C₁₅ column. The sensitivity of both procedures was sufficient to obtain pharmacokinetic data on Ara-C and uracil-arabinose levels in serum and urine and on Ara-C triphosphate levels in tumor cells.     

Measurement of liver adenine nucleotides and S-adenosyl amino acids by one-step high-performance liquid chromatography

A reverse-phase isocratic HPLC method is described for direct simultaneous assay of ATP, ADP, AMP, S-adenosylmethionine, S-adenosylhomocysteine, S-adenosylethionine, and other adenine derivatives in liver microbiopsies. The procedure was tested in conditions which alter the hepatic content of adenine nucleotides and sulfur-adenosyl amino acids in humans, rats, and guinea pigs.     

Fluorometric determination of adenine nucleotides and adenosine by ion-paired, reverse-phase, high-performance liquid chromatography

A sensitive and specific assay for measurement of adenine nucleotides and adenosine by paired-ion high-performance liquid chromatography is described. The 1,N6-ethenoderivatives of ATP (epsilon-ATP), ADP (epsilon-ADP), AMP (epsilon-AMP), and adenosine (epsilon-Ado), formed by reaction with chloroacetaldehyde at 37 degrees C, were separated under isocratic conditions in 20 min. These compounds are strongly fluorescent at an emission wavelength of 280 nm, rendering a lowest detection limit of 2-5 pmol per injection. The detector responded linearly over the measured ranges (5-100 pmol for epsilon-Ado and 5-4000 pmol for nucleotides). Specificity was confirmed enzymatically. alpha, beta-Methyleneadenosine 5'-diphosphate could be used as an internal standard for measurement of the nucleotides. Significant amounts of NADH appeared as a separate peak in hypoxic tissue. Recoveries from snap-frozen kidney were 88, 92, 76, and 63% for AMP, ADP, ATP, and adenosine, with SD for recovery of 1.0, 10.5, 8.3, and 5.6%, respectively. This method was successfully used to measure adenine nucleotides and adenosine in oxygenated and hypoxic perfused rat kidneys.     

Alkaline extraction and reverse-phase high-performance liquid chromatography of adenine and pyridine nucleotides in human platelets

The levels of adenine (ATP, ADP, AMP) and pyridine (NAD, NADH) nucleotides in human platelets have been measured by a simple and reproducible method. A rapid alkaline extraction allows a complete recovery of the compounds concerned. The metabolic ATP and ADP in the cytosolic fraction, the amount released upon thrombin stimulation, and the ADP bound to F-actin have also been evaluated. Analysis was performed by reverse-phase, isocratic high-performance liquid chromatography on a 5-microns Lichrosorb RP-18 column with uv detection at 254 nm.     

Separation of tocopherol and tocotrienol isomers using normal- and reverse-phase liquid chromatography

This optimization study for tocopherols and tocotrienols involved both normal- and reverse-phase liquid chromatography using various columns and mobile phases. Normal-phase systems showed elution of the homologs in order of increasing polarity with separation based on methyl substituents on the chromanol moiety. Reverse-phase systems showed class separation based on the saturation of the phytyl side chain; the more saturated tocopherols were retained on the column longer. When the Zorbax ODS was used with an isocratic ternary acetonitrile:methanol:methylene chloride (60:35:5) mixture, the optimized resolution was greater than 2.0 and separation was achieved in less than 13 min, but there was no separation of beta- and gamma-tocopherols. The normal-phase silica and amino columns provided separation of all available isomers with resolution greater than 1.1 and separation times of less than 5.5 and less than 10 min, respectively. Optimized isocratic binary solvent mixtures of hexane:2-propanol were used for silica (99:1) and amino (98:2) columns. Derivative spectra showed differences depending on substituents in the chromanol moiety but not the phytyl side chain. Second- and fourth-derivative spectra gave the best differentiation of the vitamin E isomers.     

Regeneration of Mycelial Protoplasts from Lyophyllum shimeji

A new HPLC system for simultaneous analysis of NAD⁺, NADH, NADP⁺, and NADPH was developed and used to measure the transhydrogenase activity of spinach ferredoxin-N ADP ⁺ reductase (EC 1.18.1.2, FNR). The system is based on a reverse-phase HPLC with isocratic elution on an ODS column (4.6 × 50 mm). The four nucleotides were completely separated by developing the column with 0.15 m sodium phosphate/citrate buffer (pH 6.8) containing 1 mm EDTA at 40°C with a flow rate of 1 ml/min. The four nucleotides can be simultaneously assayed within 13 min by monitoring the effluents with a UV detector. It was also indicated that the transhydrogenase activity of spinach FNR can be advantageously assayed by measuring the nucleotides by this method.