Determination of 5,10,15,20-tetra-(m-hydroxyphenyl)chlorin in tissues by high performance liquid chromatography

A procedure for the extraction and high performance liquid chromatographic (HPLC) determination of the photodynamic therapeutic agent 5,10,15,20-tetra(m-hydroxyphenyl)chlorin in human, rat and mouse tissues following intravenous administration of the drug is described. The tissue (tumour, skin, muscle and liver) was homogenized and extracted into a mixture of methanol:dimethyl sulphoxide:water (32:8:1 by vol.) containing, 5,10,15,20-tetra(p-hydroxyphenyl)chlorin as the internal standard. The precipitated proteins were removed by centrifugation and the supernatant was separated by reversed phase HPLC on a Hypersil-ODS column with 77% (v/v) acetonitrile in 0.1% trifluoroacetic acid as the mobile phase. The solute was detected with high sensitivity and specificity by a UV-VIS detector set at 423 nm.

Order of uroporphyrinogen III decarboxylation on incubation of porphobilinogen and uroporphyrinogen III with erythrocyte uroporphyrinogen decarboxylase

The isomeric compositions of the heptacarboxylic, hexacarboxylic and pentacarboxylic porphyrinogens formed by incubation of porphobilinogen with human red-cell haemolysates have been analysed and compared with those derived from incubation with chemically prepared uroporphyrinogen III as substrate. The results indicated that when supplied with an excess (3.7 microM) of exogenous uroporphyrinogen III, uroporphyrinogen decarboxylase utilized the substrate at random and a mixture of isomers was produced; whereas with uroporphyrinogen III generated enzymically from porphobilinogen as substrate a clockwise decarboxylation sequence was observed, resulting in the formation of intermediates mainly with the ring-D, rings-AD and rings-ABD acetate groups decarboxylated. Using [14C]uroporphyrinogen III as substrate at low concentrations (0.01-0.5 microM) also led to preferential decarboxylation of the ring-D acetate group. It was concluded that the order of uroporphyrinogen III decarboxylation is substrate-concentration-dependent, and under normal physiological conditions enzymic decarboxylation is most probably orderly and clockwise, starting at the ring-D acetate group.

Effect of drug-light interval on photodynamic therapy with meta-tetrahydroxyphenylchlorin in malignant mesothelioma

The influence of the time interval (TI) between drug administration and laser activation on selectivity of meta-tetrahydroxyphenylchlorin(mTHPC)-mediated photodynamic therapy (PDT) for tumour tissue was assessed in BALB/c nude mice bearing human malignant mesothelioma xenografts. Following i.p. administration of 0.3 mg/kg mTHPC, a light dose of 10 J/cm2 and 0.1 W/cm2 was delivered at 650 nm on the tumour and an equal-sized area of the hind leg after 4, 12, 24 and 36 hr and 2, 3, 4, 5 and 6 days to groups of 6 animals (surface irradiance). Then, 72 hr after light delivery, the depth of necrosis was measured in the tumour and in the skin and underlying muscle of the hind leg. Photosensitized necrosis occurred in normal tissue at TI from 4 hr to 3 days and in the tumour at TI from 12 hr to 4 days. The therapeutic ratio of mTHPC-PDT varied significantly with the time interval between drug administration and laser activation and was greatest at an interval of 3 days. mTHPC concentration was measured in 3 control unirradiated animals at all time points in normal tissues and in tumour tissue, and found to be the same in both tissues. Thus the tissue concentration of mTHPC was of limited use as regards the prediction of photosensitizing effects in the tumour model.

Determination of 5,10,15,20-tetra-(m-hydroxyphenyl)chlorin in human plasma by high performance liquid chromatography

A high performance liquid chromatographic method for the determination of the photodynamic chemotherapeutic agent 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) in human plasma following intravenous infusion is described. The procedure involves extraction of the drug in plasma with methanol/dimethyl sulphoxide (4:1 v/v) containing 5,10,15,20-tetra(p-hydroxyphenyl)chlorin as the internal standard and separation on a C18 reversed phase column with acetonitrile:0.1% trifluoroacetic acid (77:23 v/v) as the mobile phase. The drug was detected specifically and sensitively at its absorption maximum of 423 nm with a detection limit of 15 ng/mL (signal-to-noise ratio of 5). The intra- and inter-assay coefficients of variation (CV) on analysis of a plasma spiked with m-THPC (1 micrograms/mL) were 2.3 and 3.4% (n = 6), respectively.

Absence of rhodamine 123-photochemotoxicity in human tumor xenografts

Rhodamine 123 (R123)-photochemotoxicity was assessed in BALB/c nude mice bearing a xenografted human squamous cell carcinoma at various power densities and wavelengths and a given incident fluence of 150 Joules/cm2. One hour before light delivery, 1 mg R123/kg was injected i.p. in 20 animals. Surface irradiance was performed on the tumor and an equal size hind leg area of 40 animals. Three groups of 10 animals were treated at 514.5 nm and 0.1 W/cm2, 1 W/cm2, and 30 W/cm2, and one at 488 nm and 30 W/cm2. In each group, five animals received R123. The R123 concentration was measured in the tumor (0.023 +/- 0.007 micrograms/g) and tumor-free tissue (0.023 +/- 0.008 micrograms/g) in three additional animals by high performance liquid chromatography 1 hour after R123-administration. Histologic assessment 72 hours after light delivery revealed no tissue damage at nonthermal power densities, either in the tumor or in the tumor-free tissue, irrespective of R123-administration. At 30 W/cm2, neither in the tumor nor in tumor-free tissues was there any significant difference in the depth of necrosis, irrespective of R123-administration and the wavelength applied. Our results question the validity of R123 as a photosensitizer, at least in this rodent tumor model.

Molecular typing of Neisseria gonorrhoeae by restriction fragment length polymorphisms

OBJECTIVE

To characterise Neisseria gonorrhoeae isolates by restriction fragment length polymorphisms (RFLPs) in ribosomal RNA genes.

DESIGN

Generation of RFLP patterns by HincII restriction of rRNA genes followed by hybridisation with a non-radioactive labelled broad spectrum 16 + 23S rRNA gene probe. This typing method was developed and compared with MAb based serotyping.

SPECIMENS

Forty three randomly collected isolates from Bangkok (27 isolates) and Singapore (16 isolates) were studied.

RESULTS

The RFLP patterns generated were reproducible and highly discriminatory between strains. Analysis of RFLPs produced by HincII restriction of rRNA genes established 9 patterns amongst the 43 isolates examined. Strains present within a common serovar could be further subdivided by RFLP typing. Identical RFLP patterns were found in some strains that belonged to various serovars.

CONCLUSION

RFLP typing based on heterogeneities of rRNA gene restriction patterns could be advantageously used to complement monoclonal antibody based serotyping for further subdivision of serovars. Higher sensitivity of this combined approach would enable better differentiation of strains in epidemiological studies.

Photodynamic therapy with chlorins for diffuse malignant mesothelioma: initial clinical results

Four patients underwent intraoperative photodynamic therapy after surgery with meso-tetra-(hydroxyphenyl)-chlorin (mTHPC-PDT) for diffuse malignant mesothelioma. Preliminary procedures were performed in two patients in order to establish the efficacy of mTHPC-PDT and to optimise its tumoricidal effect. The tumoricidal effect was related to the mTHPC dose, light dose and the time interval between sensitation and activation. 0.3 mg kg-1 mTHPC activated after 48 h with 10 Joules cm-2 of non-thermal laser light at 650 nm resulted in a 10 mm deep tumour infarction, due to tumour vessel necrosis and thrombosis. The mTHPC tissue concentration was up to 14 times higher in the tumour than in normal tissues. Skin photosensitivity was mild, dose dependent and occurred 3 to 10 days after administration of mTHPC. According to the results obtained, intraoperative mTHPC-PDT was performed following pleuropneumonectomy in two, pleurectomy and lobectomy in one and pleurectomy in one patient. Ten Joules cm-2 were delivered to the diaphragm and the costophrenic sulcus and 5 Joules cm-2 to the remaining thoracic cavity. The postoperative course was marked by loss of appetite, fluid retention, hypoproteinemia and severe chest pain. One patient succumbed from aspiration pneumonia. The remaining patients developed no neural or vascular alterations and no bronchial stump insufficiency during follow-up. mTHPC-PDT following surgical tumour resection deserves further evaluation in good risk patients with diffuse malignant mesothelioma.

Determination of hydroxy and peroxy acid derivatives of uroporphyrin in the plasma of patients with congenital erythropoietic porphyria by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method is described for the determination of hydroxy and peroxy acid derivatives of uroporphyrin in the plasma of patients with congenital erythropoietic porphyria. The porphyrins were extracted from the plasma with 20% trichloroacetic acid-dimethyl sulphoxide (1:1, v/v). The supernatant after centrifugation was chromatographed on a Hypersil-ODS column by gradient elution with 9% (v/v) acetonitrile in 1 M ammonium acetate buffer (pH 5.16) (solvent A) and 10% (v/v) acetonitrile in methanol (solvent B) as the gradient mixture. The method was also suitable for the preparative isolation of the porphyrins.

High-performance liquid chromatographic assays for protoporphyrinogen oxidase and ferrochelatase in human leucocytes

Rapid, sensitive and specific high-performance liquid chromatographic assays are described for protoporphyrinogen oxidase and ferrochelatase in human leucocytes. The enzyme reaction products were separated and quantitated by reversed-phase high-performance liquid chromatography with fluorescence detection. The optimal pH for the protoporphyrinogen oxidase assay was 8.6 and the Michaelis constant for protoporphyrinogen IX was 9.78 +/- 0.96 microM (mean +/- S.D.). The mean (+/- S.D.) activity of protoporphyrinogen oxidase in fourteen apparently healthy subjects was 0.146 +/- 0.023 nmol protoporphyrin IX per min per mg protein. In one patient with variegate porphyria, the activity was 0.028 nmol protoporphyrin IX per min per mg protein. The optimal pH for ferrochelatase was 7.4 and with protoporphyrin and Zn2+ as substrates, the Michaelis constants were 1.49 and 8.33 microM, respectively. The mean activity of ferrochelatase in ten control subjects was 0.24 nM Zn-protoporphyrin or 2.05 nM Zn-mesoporphyrin formed per h per mg protein.

Random decarboxylation of uroporphyrinogen III by human hepatic uroporphyrinogen decarboxylase

The type III heptacarboxylic porphyrinogens derived from enzymic decarboxylation of an acetic acid substituent on uroporphyrinogen III to a methyl group by human hepatic uroporphyrinogen decarboxylase has been analysed by reversed-phase high-performance liquid chromatography with electrochemical detection. The results showed that all four possible heptacarboxylic acid porphyrinogen isomers, with the methyl group attached to rings A, B, C and D of the tetrapyrrole macrocycle, respectively, were formed in almost equal proportions. It was concluded that the normal pathway of uroporphyrinogen III decarboxylation in human liver follows a random mechanism.

Identification of peroxyacetic acid uroporphyrin I in the urine of patients with congenital erythropoietic porphyria by liquid chromatography and mass spectrometry

A new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid.

Coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase activities in iron-overloaded and ethanol-treated rats

The activities of coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase in liver homogenates of iron-overloaded and acutely or chronically ethanol-treated rats were assayed by high performance liquid chromatographic methods. Decreased coproporphyrinogen oxidase activity was found in chronically carbonyliron-fed rats while the activities of protoporphyrinogen oxidase and ferrochelatase remained unchanged. Coproporphyrinogen oxidase and protoporphyrinogen oxidase activities in both chronically and acutely ethanol-treated animals were not significantly different from controls. In chronically ethanol-fed rats normal ferrochelatase activity was found.

High performance liquid chromatographic studies of erythrocytes haem biosynthetic enzyme activities in alcoholic macrocytosis

The activities of 5-aminolaevulinate dehydrase (ALA-D), hydroxymethylbilane synthase (HMB-S), uroporphyrinogen III synthase (URO-S) and uroporphyrinogen decarboxylase (URO-D) in the erythrocytes of alcoholics were assayed and compared with those in controls and abstaining alcoholics. The HMB-S and URO-S activities in alcoholics were significantly higher than the controls and there were significant correlations between enzyme activities and mean corpuscular volume (MCV). Alcoholics abstaining from alcohol over a nine-month period showed a return to normal enzyme activities in parallel with the normalization of their MCV. Abstaining alcoholics thus all had normal HMB-S and URO-S activities. The ALA-D and URO-D activities of alcoholics were not significantly different from controls or from abstaining alcoholics. Alcohol appears to have a selective effect on the haem biosynthetic enzymes in the erythron.

Separation of anionic and cationic compounds of biomedical interest by high-performance liquid chromatography on porous graphitic carbon

The separation of small, ionizable compounds of biomedical interest on porous graphitic carbon is described. The retention of anionic compounds is dominated by electronic interaction between the solute and the delocalized electron clouds on the graphitized carbon, while cationic compounds are mainly retained by reversed-phase interaction with the hydrophobic carbon surface. Anionic and cationic compounds can be separated simultaneously with a mobile phase containing an electronic modifier (e.g., trifluoroacetic acid) and an organic modifier (e.g., acetonitrile) for elution. Examples of applications include the measurement of oxalic acid in urine, the determination of creatine and creatinine in urine and in serum, the separation of basic drugs (remoxipride and FLA 981) and the simultaneous analysis of pertechnetate anion and the cationic technetium-amine complexes.

Isolation and characterization of beta-hydroxypropionic acid- and hydroxyacetic acid-uroporphyrin I in the urine of a patient with congenital erythropoietic porphyria by high performance liquid chromatography and liquid secondary ion mass spectrometry

beta-Hydroxypropionic acid- and hydroxyacetic acid-uroporphyrin I have been isolated from the urine of a patient with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The compounds were characterized by their chemical behaviour and confirmed by liquid secondary ion mass spectrometry.

Decarboxylation of uroporphyrinogen III by erythrocyte uroporphyrinogen decarboxylase. Evidence for a random decarboxylation mechanism

The isomeric composition of type-III heptacarboxylic porphyrinogens derived from decarbosylation of uroporphyrinogen III by erythrocyte uroporphyringogen decarboxylase was analysed by h.p.l.c. with electrochemical detection. All four possible isomers were identified, and there were little differences in the proportion of isomers formed by erythrocytes from normal subjects and from patients with sporadic porphyria cutanea tarda. The results provide conclusive evidence that the normal decarboxylation pathway is random in nature, and the fourth isomer only increases when enzyme abnormality is found.

Streptomyces griseus streptomycin phosphotransferase: expression of its gene in Escherichia coli and sequence homology with other antibiotic phosphotransferases and with eukaryotic protein kinases

The aphD gene of Streptomyces griseus, encoding a streptomycin 6-phosphotransferase (SPH), was sub-cloned in the pBR322-based expression vector pRK9 (which contains the Serratia marcescens trp promoter) with selection for expression of streptomycin resistance in Escherichia coli. Two hybrid plasmids, pCKL631 and pCKL711, were isolated which conferred resistance. Both contained a approximately 2 kbp fragment already suspected to include aphD. The properties of in vitro deletion derivatives of these plasmids were consistent with the presumed location of aphD. In vitro deletion of a sequence including most of the trp promoter largely, but not quite completely, abolished the ability of the plasmid to confer streptomycin resistance, confirming that expression was indeed principally from the trp promoter. A polypeptide of approximately 34.5 kDa was present in minicells containing plasmids that conferred streptomycin resistance, but was absent when the plasmids contained in vitro deletions removing streptomycin resistance. Part of the fragment was sequenced and an open reading frame corresponding to aphD identified. A computer-assisted comparison of the deduced SPH sequence with those of other antibiotic phosphotransferases suggested a common structure A-B-C-D-E, where B and D were conserved between all sequences compared while A, C and E divided between the streptomycin and hygromycin B phosphotransferases on one hand and kanamycin/neomycin ones on the other. A composite sequence data base was searched for homologues to consensus matrices constructed from five approximately 12-residue subsequences within blocks B and D. For one subsequence, corresponding to the N-terminal portion of block D, those sequences from the database that yielded the highest homology scores comprised almost entirely either antibiotic phosphotransferases or eukaryotic protein kinases. Possible evolutionary implications of this homology, previously described by other groups, are discussed.

Identification of meso-hydroxyuroporphyrin I in the urine of a patient with congenital erythropoietic porphyria

A new porphyrin, meso-hydroxyuroporphyrin I, was isolated from the urine of a patient with congenital erythropoietic porphyria. The structure was characterized as the methyl ester, ethyl ester and acetoxy derivatives by fast-atom-bombardment m.s., by conversion into uroporphyrin I and by chemical synthesis.

Electronic interaction chromatography on porous graphitic carbon. Separation of [99mTc]pertechnetate and perrhenate anions

The oxo anions of technetium-99m and rhenium, pertechnetate (TcO4-) and perrhenate (ReO4-), have been separated by high performance liquid chromatography on porous graphitic carbon with aqueous trifluoroacetic acid or salt solutions as eluent. Chromatographic retention was a result of electronic interaction between the lone pair electrons of the anions and the delocalised pi-electron clouds of the porous graphitic carbon. Retention and resolution can be controlled by the concentration and/or species of eluents which can compete with the solutes for electronic interaction being used for elution.

Preparation, high-performance liquid chromatographic separation and characterization of hexacarboxylic porphyrinogens

A simple method for the preparation and reversed-phase high-performance liquid chromatographic separation of hexacarboxylic porphyrinogen isomers is described. Uroporphyrin I or III was partially decarboxylated in 0.5 M hydrochloric acid at 150 degrees C. Unreacted uroporphyrin and the hepta-, hexa- and pentacarboxylic porphyrins formed were esterified and then group-separated by thin-layer chromatography. After hydrolysis, the porphyrins were reduced to the corresponding porphyrinogens with 3% (w/w) sodium amalgam. The hexacarboxylic porphyrinogens were separated on an ODS-Hypersil column by elution with acetonitrile-methanol-1 M ammonium acetate, pH 5.16 (8:12:80, v/v/v) as mobile phase. Isomers were identified by high-performance liquid chromatography of the characteristic mixture of two pentacarboxylic porphyrins formed after partial decarboxylation of individual isomers. Except for the two type I isomers, resolution of the hexacarboxylic porphyrinogens was superior to that of the corresponding porphyrins.

Isocratic reversed-phase high-performance liquid chromatography of ribonucleotides, deoxynucleotides, cyclic nucleotides and deoxycyclic nucleotides

An isocratic reversed-phase high-performance liquid chromatographic system is described for the separation of a relatively large number (greater than 20) of ribonucleotides, deoxynucleotides, cyclic nucleotides and deoxycyclic nucleotides. A 25 cm x 5 mm ODS-Hypersil (5 microns particle size) column was used with methanol-triethylammonium phosphate buffer as eluent. The effects of methanol content, pH, and ionic strength of the buffer on retention and resolution of the nucleotides have been studied. The applicability of the system was demonstrated by the analysis of nucleotides in cells and tissue extracts.

Coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase activities in human liver biopsies with special reference to alcoholic liver disease

The activities of coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase have been assayed in human liver biopsies using recently developed highly sensitive specific enzyme assays. The specific activities (nmol/min/mg protein) in controls were 0.010 +/- 0.003 (mean +/- S.D., n = 11), 0.18 +/- 0.07 (n = 9) and 0.062 +/- 0.022 (n = 8), respectively. The total activities (mumol/min/liver) were determined, using ultrasound to determine liver volumes, and were 2.6 +/- 0.6 (n = 5), 36.6 +/- 13.9 (n = 6) and 14.2 +/- 5.4 (n = 3), respectively. Both specific and total enzyme activities in alcoholics with fatty liver were not significantly different from normal controls. Decreased protoporphyrinogen oxidase activity (0.08 nmol/min/mg protein or 20.2 mumol/min/liver) was found in two patients with variegate porphyria. In a patient with erythrohepatic protoporphyria a reduction of the ferrochelatase activity (0.01 nmol/min/mg protein) was demonstrated.

Accurate and specific HPLC assay of coproporphyrinogen III oxidase activity in human peripheral leucocytes

An HPLC method is described for the assay of coproporphyrinogen III oxidase in human leucocytes. The optimal pH for the assay was 6.5-7.0 and the Km for coproporphyrinogen III was 0.12 +/- 0.021 mumol/l. The mean activity in 28 apparently health subjects was 0.249 (2 SD range 0.130-0.368) nmol/h per mg protein. In two patients with hereditary coproporphyria, the activities were 0.029 and 0.078 nmol/h per mg protein.

The effect of liver transplantation in a 13-year-old boy with erythropoietic protoporphyria

A 13-year-old boy who had had recurrent photosensitive skin reactions due to erythropoietic protoporphyria from 18 months of age, suddenly developed rapidly progressive hepatic failure with increasing cholestatic jaundice and variceal bleeding. Liver biopsy confirmed extensive protoporphyrin deposition with cirrhosis, and so orthotopic liver transplantation was performed. Postoperatively his skin rash settled within 72 hr, and in spite of subsequent exposure to the sun he has had no further skin reaction or blistering, although he does still have some itching. He made a good recovery and was able to return to school within six months of operation. Prior to liver transplantation, the hepatic ferrochelatase activity was reduced to only 0.81 nmol zinc-protoporphyrin formed/mg protein/hr (controls 3.30 +/- 1.00 nmol zinc-protoporphyrin formed/mg protein/hr, while the red cell protoporphyrin level was markedly elevated at 188 mumol/L red cells (normal less than 1.6 mumol/L red cells). The free plasma porphyrin level of 0.95 mumol/L (normal less than 0.02 mumol/L), and the urinary and fecal porphyrin levels were also raised. Following liver grafting these elevated porphyrin levels fell rapidly, with the red cell protoporphyrin level dropping to 10% of its preoperative value, and the rest returning to virtually normal within three months of operation.

High-performance liquid chromatography of porphyrins

Techniques for the analysis of porphyrins in the biomedical fields are reviewed. The emphasis is on high-performance liquid chromatography and its aspplications in: (1) the quantitative analysis of porphyrins in blood, urine and faeces; (2) qualitative porphyrin profiles in normal subjects and in the porphyrias; (3) assay of haem biosynthetic enzyme activities and (4) resolution of type isomers of porphyrins and porphyrinogens. Detection systems, quantitation methods, peak identification and sample preparation procedures are discussed.

Adenine nucleotide concentrations in peripheral blood lymphocytes from patients with common variable hypogammaglobulinaemia and B-cell chronic lymphatic leukaemia

The adenine nucleotide profiles (AMP, ATP, NAD and NADH2) of peripheral blood lymphocytes isolated from patients with common variable hypogammaglobulinaemia (CVH) were similar to those in control cells. AMP and ATP levels were also similar in the lymphocytes of patients with chronic lymphatic leukaemia (CLL). Since CVH and CLL patients have reduced activity of plasma membrane ecto-5'-nucleotidase, our data suggests that this enzyme does not regulate the levels of intracellular adenine nucleotides, at least in "resting" cells.

Manifestation of familial porphyria cutanea tarda after childbirth

We report the case of a woman with hereditary porphyria cutanea tarda which manifested 3 weeks after she gave birth to her second child. The mother of the patient had also been diagnosed and treated for porphyria cutanea tarda. Reduced red cell uroporphyrinogen decarboxylase activity was found in the patient, the new-born child and the patient's mother. Normal enzyme activity was found in the patient's first child.

High-performance liquid chromatography of type-III heptocarboxylic porphyrinogen isomers

A reversed-phase h.p.l.c. system is described for the separation of the four type-III heptacarboxylic porphyrinogen isomers. The effects of buffer concentration, pH and type and proportion of organic modifier in the mobile phase on retention and resolution of isomers were studied. Optimum separation on an ODS-Hypersil column was by elution with a ternary mobile phase of acetonitrile, methanol and 1 M-ammonium acetate, pH 5.16 (7:3:90, by vol.). Isomer identification was based on a comparison of their retention times with those of authentic standards, and was further confirmed by h.p.l.c. analysis of the characteristic mixture of three pentacarboxylic porphyrins formed after partial decarboxylation of individual isomers in 0.3 M-HCl at 160 degrees C.

Uptake and localisation of haematoporphyrin derivative in normal rat liver

Fluorescence microscopy and analytical subcellular fractionation were used to investigate the hepatic localisation of haematoporphyrin derivative (HPD) after intraperitoneal administration. HPD was found to rapidly accumulate in the liver and then to slowly decline over 48 hr. Fluorescence microscopy showed that although at early times porphyrins could not be localised to a particular cell type, at 24 hr porphyrins were preferentially localised to the Kupffer cells of the liver. Subcellular fractionation studies indicated that the initial rapid uptake of HPD was to the cytosol. However, at 24 hr, porphyrins appeared to be localised to lysosomes. Lysosomal localisation was confirmed using the selective organelle perturbant, Triton WR 1339. No evidence was found either at the light microscope level or by subcellular fractionation to suggest association of HPD with other organelles. HPLC analysis showed that the porphyrins present in the plasma and in the cytosol and lysosome fractions were mainly the (RS, SR) and (RR, SS) diastereoisomers of haematoporphyrin and the two position isomers 8-(1-hydroxyethyl)-3-vinyldeuteroporphyrin and 3-(1-hydroxyethyl)-8-vinyldeuteroporphyrin. There was no evidence for the involvement of dimers such as dihaematoporphyrin ether.

An h.p.l.c. assay for protoporphyrinogen oxidase activity in rat liver

An h.p.l.c. method is described for the assay of protoporphyrinogen oxidase activity in rat liver. A relatively pure protoporphyrinogen IX substrate was obtained by selectively removing any protoporphyrin IX unreduced by sodium amalgam on a small disposable cartridge packed with a strong anion-exchanger. The protoporphyrin IX formed was extracted with dimethyl sulphoxide/methanol (3:7, v/v) containing mesoporphyrin as the internal standard for separation and quantification by reversed-phase chromatography. The Km for protoporphyrinogen was 9.5 +/- 1.6 microM, and the enzyme activities were 0.59 +/- 0.11 nmol of protoporphyrin IX produced/min per mg of mitochondrial protein and 33.5 +/- 2.7 nmol protoporphyrin IX produced/min per g of liver tissue homogenate. The method is applicable to the determination of enzyme activity in small amounts of human liver biopsy.

Separation and characterization of pentacarboxylic porphyrinogen isomers by high-performance liquid chromatography with electrochemical detection

A reversed-phase h.p.l.c. system is described for the separation of all five naturally occurring pentacarboxylic porphyrinogen isomers. The compounds are detected electrochemically with high sensitivity. The peaks are positively identified by h.p.l.c. analysis of the pentacarboxylic porphyrinogens from reduction of pentacarboxylic porphyrins prepared by partial decarboxylation of hexa- and hepta-carboxylic porphyrin III of known structures. The resolution of pentacarboxylic porphyrinogens is superior to that of the porphyrins and the method is applicable to the small-scale preparative isolation of pure isomers.

High-performance liquid chromatographic analysis of phytoestrogens in soy protein preparations with ultraviolet, electrochemical and thermospray mass spectrometric detection

The phytoestrogens daidzein, genistein, coumestrol, formononetin, and Biochanin A are separated on a C18 reversed-phase column (Hypersil ODS) with methanol-0.1 M ammonium acetate buffer, pH 4.6 (60:40, v/v) as eluent. The retention and resolution are affected by buffer concentrations, pH type, and proportion of organic solvent in the mobile phase. Detection in the (low pg range) is achieved with an electrochemical detector, and the compounds are positively identified by high-performance liquid chromatography-thermospray mass spectrometry. Daidzein and genistein were found in high concentrations in all soy protein preparations analyzed.

Rapid high-performance liquid chromatography assay for salivary and serum caffeine following an oral load. An indicator of liver function

A rapid isocratic reversed-phase high-performance liquid chromatography (HPLC) system for the quantitative measurement of serum and salivary caffeine is described. The best separation of caffeine from other methylxanthines was achieved by chromatography on an ODS-Hypersil column using a solvent system of 0.1 M ammonium acetate pH 4.6-acetonitrile (85:15, v/v). The effluent was monitored at 280 nm. Caffeine was extracted from diluted serum and saliva samples (10-500 microliter) by adsorption on a small Bond-Elut C18 cartridge and recovered by elution with methanol. Thermospray HPLC-mass spectrometry conditions were optimized to afford a means of directly identifying caffeine in samples. The positive-ion mass spectrum was characterized by an intense protonated molecular ion, MH+, at m/z 195 and negligible fragmentation. When the mass spectrometer was operated in selected ion monitoring mode, caffeine could be detected in less than 1 microliter of serum and saliva at a concentration of 1 microgram/ml. Caffeine (3.5 mg/kg body wt.) was administered orally to healthy adults, children, and newborn infants, and to patients with liver disease. The clearance rate and half-life were determined as a test of liver function. A prolongation in the elimination of caffeine was observed in patients with liver disease and, although there was some overlap in the values obtained for patients with noncirrhotic liver disease and healthy persons, the oral caffeine load test may usefully serve as a dynamic assessment of liver function in the serial follow-up of patients with liver disease.

An HPLC assay for rat liver ferrochelatase activity

A rapid, reliable, sensitive and reproducible HPLC method was developed for the assay of ferrochelatase activity in rat liver. The assay was carried out aerobically with Zn2+ and mesoporphyrin or protoporphyrin IX as substrates. Zn-porphyrins formed were extracted with dimethyl sulphoxide/methanol (30:70, v/v) containing Zn-deuteroporphyrin as the internal standard for separation and quantification by reversed-phase chromatography. The Km for mesoporphyrin was 5.9 microM, for protoporphyrin IX 8.8 microM and for zinc 6.0 microM. The specific activities were 33.1 +/- 5.0 nmol Zn-mesoporphyrin or 13.4 +/- 2.0 nmol Zn-protoporphyrin formed per hour per mg of protein for mitochondria and 12.3 +/- 2.2 nmol Zn-mesoporphyrin or 4.6 +/- 0.9 nmol Zn-protoporphyrin per hour per mg of protein for liver homogenate.

Assaying erythrocyte haem biosynthetic enzyme activities by high-performance liquid chromatography with the advanced automated sample processor

The four cytosolic haem biosynthetic enzymes in erythrocytes were assayed with the Varian advanced automated sample processor (AASP) for rapid sample concentration and clean-up with fast and effective high-performance liquid chromatography systems for separation and quantitation. In the assay for 5-aminolaevulinic acid dehydrase, the porphobilinogen (PBG) formed was extracted on a C18 AASP cartridge and separated by reversed-phase ion-pair chromatography with 32% methanol in 0.05 M sodium acetate buffer (pH 3.5), containing 5.4 mM of 1-heptane-sulphonic acid as eluent. PBG was the substrate for the simultaneous assay of hydroxymethylbilane synthase and uroporphyrinogen III synthase. The uroporphyrinogen I and III isomers formed were oxidised to porphyrins, concentrated on a C2 or C8 cartridge, and separated by reversed-phase chromatography with 13% acetonitrile in 1 M ammonium acetate buffer (pH 5.16) as eluent. Uroporphyrinogen decarboxylase was estimated with pentacarboxylic porphyrinogen III as substrate. The coproporphyrinogen formed was extracted on a C2 or C8 cartridge, oxidised to coproporphyrin and separated by reversed-phase chromatography with 30% acetonitrile in 1 M ammonium acetate buffer (pH 5.16) as mobile phase.

Assay of blood acetaldehyde by HPLC with fluorescence detection of its 2-diphenylacetyl-1,3-indandione-1-azine derivative

A simple sensitive method for the assay of blood acetaldehyde is described. Samples are collected into an organic solution of 2-diphenylacetyl-1,3-indandione-1-hydrazone. Proteins are precipitated immediately and carbonyl compounds react to form fluorescent azine derivatives. Methanol in the reagent mixture prevents the oxidation of any ethanol present, precipitates protein and releases any absorbed acetaldehyde. After protein removal, the reaction is completed by the addition of an acid catalyst and a portion of the reaction mixture is subjected to quantitative analysis by high performance liquid chromatography.

A high-performance-liquid-chromatographic method for the assay of coproporphyrinogen oxidase activity in rat liver

An h.p.l.c. method was developed for the assay of coproporphyrinogen oxidase activity in rat liver. The protoporphyrinogen IX formed is completely oxidized to protoporphyrin IX for separation and quantification by reversed-phase chromatography with mesoporphyrin as the internal standard. The Km of coproporphrinogen oxidase is 1.01 +/- 0.23 microM. The activities are 4.07 +/- 0.40 nmol of protoporphyrin IX/h per mg of mitochondrial protein and 224 +/- 19 nmol of protoporphyrin IX/h per g of liver tissue homogenate. The method is sensitive enough for measuring enzyme activity in small amounts of human tissue from needle biopsy.

High-performance liquid chromatography of uroporphyrinogen and coproporphyrinogen isomers with amperometric detection

A reversed-phase h.p.l.c. system, with an ODS-Hypersil column with acetonitrile or methanol in ammonium acetate buffer as mobile phase, is described for the separation of uro-and copro-porphyrinogen isomers. The porphyrinogens are detected amperometrically with sensitivity comparable with that of the fluorescent detection of porphyrins. The effects of pH, buffer concentration and organic modifiers on retention and resolution were studied. The method is suitable for both analytical and preparative separation of porphyrinogens.

Reversed-phase high-performance liquid chromatography of conjugated and unconjugated bilirubins in body fluids

A novel high-performance liquid chromatography (HPLC) system is described for the separation of bilirubin and its conjugates in body fluids. Biliary bilirubin mono- and diglucuronide can be analysed directly on a C18 reversed-phase column with acetonitrile-dimethyl sulphoxide-0.1 M ammonium acetate (pH 5.16) (50:50:85, v/v/v) as mobile phase. However, the simultaneous determination of conjugated and unconjugated bilirubins in plasma required conversion of the conjugates into their methyl esters by alkaline methanolysis before HPLC separation of the C18 column eluted with acetonitrile-dimethyl sulphoxide-0.50 M ammonium acetate (pH 4.6) (50:50:40, v/v/v). The method is superior to, and more flexible than, previously described reversed-phase systems by allowing precise control of retention times by adjustment of pH, buffer concentration and the relative proportion of organic modifier in the mobile phase.

Analysis of tumour-localizing haematoporphyrin derivative by high-performance liquid chromatography and fast-atom bombardment mass spectrometry

Reversed-phase chromatography using a MOS-Hypersil (C8) column with methanol-1 M ammonium acetate buffer (pH 4.6) (60:40) as mobile phase has been developed for the isolation of tumour-localizing haematoporphyrin derivative (HPD). The system effectively resolved the diastereoisomers of haematoporphyrin and its acetyl derivatives. The chromatography peaks were identified by fast-atom bombardment mass spectrometry and were confirmed by chemical synthesis. The main components of HPD before alkaline hydrolysis were diacetylhaematoporphyrin, 8-(1-acetoxyethyl)haematoporphyrin and 3-(1-acetoxyethyl)haematoporphyrin with small amounts of haematoporphyrin, 8-(1-hydroxyethyl)-3-vinyldeuteroporphyrin, 3-(1-hydroxyethyl)-8-vinyldeuteroporphyrin, 8-(1-acetoxyethyl)-3-vinyldeuteroporphyrin, 3-(1-acetoxyethyl)-8-vinyldeuteroporphyrin and protoporphyrin. After hydrolysis with 0.1 M sodium hydroxide, the main components were haematoporphyrin, hydroxyethylvinyldeuteroporphyrins, and protoporphyrin.

The effects of ethanol and anticonvulsants on erythroid delta-aminolaevulinic acid synthase

The activity of delta-aminolaevulinic acid (ALA) synthase was measured in bone marrow from 13 control subjects, 12 chronic alcoholic patients and 9 patients on long term anticonvulsant therapy. The majority of patients in both groups had macrocytic red cells in the absence of megaloblastic changes in the marrow. There was a significant increase in ALA synthase activity in the alcoholic patients but no significant increase in enzyme activity in the patients on anticonvulsants and overall there was no correlation of activity with MCV. The macrocytosis associated with these drugs does not therefore appear to result from accelerated erythroid haem synthesis.

High-performance liquid chromatography of dicarboxylic porphyrins and metalloporphyrins: retention behaviour and biomedical applications

The retention behaviour of the main dicarboxylic porphyrins, haemato-, deutero-, meso- and protoporphyrins, together with the Fe, Co, Cu and Zn complexes of meso- and protoporphyrins have been systematically studied. Hydrophobic chromatography with methanol-ammonium acetate buffer systems on reversed-phase columns provided the best selectivity, efficiency and resolution. The retention of the porphyrins is controlled by the relative hydrophobicity of the porphyrin side-chain substituents. The insertion of a metal ion into the porphyrin macrocycle, however, completely alters the electronic environment around the central nitrogen atoms of the porphyrins. The retention is then greatly influenced by the species of inserted metal ion, to accept axial ligands from the mobile phase, although hydrophobic interaction of the side-chain substituents with the stationary phase surface is still an important factor. The retention behaviour can be precisely controlled by adjusting the pH, buffer concentrations and types and proportions of organic solvents in the mobile phase. The analysis of porphyrins and metalloporphyrins in blood, and the determination of ferrochelatase in bone marrow are examples of biomedical applications.

Ammonium acetate: a general purpose buffer for clinical applications of high-performance liquid chromatography

The chromatographic properties of ammonium acetate have been studied, and its use as a general purpose buffer for reversed-phase chromatography has been investigated. Simple ammonium acetate systems can often replace complicated and expensive buffers, with or without ion-pairing agents, with improved column selectivity and efficiency. A wide range of clinically important compounds have been successfully separated by ammonium acetate buffer systems. These include creatinine, bilirubin, verapamil and its metabolites, etoposide and teniposide, vitamin A, biogenic amines and porphyrins.