Rapid analysis of porphyrins at low ng/l and μg/l levels in human urine by a gradient liquid chromatography method using octadecylsilica monolithic columns

Rapid gradient RP-HPLC method with fluorimetric detection for trace analysis of diagnostically significant porphyrins in human urine was developed for clinical and diagnostic purposes. Results show that optimized high-pressure gradient elution and monolithic column Chromolith SpeedRod RP18e enabled separation of seven urine porphyrins including baseline separation of I and III positional isomers of uro- and coproporphyrins within 3.2 min. Problems associated with high metal cation complexing ability of the analytes and common stainless steel based instrumentation were substantially reduced by use of 0.1 mol/l ammonium citrate buffer (pH 5.47) and methanol as a mobile phase components. Good reproducibilities of retention times (within +/- 0.36% RSD) and peak areas (from +/- 0.6 to +/- 2.5% RSD) at 5-20 microg/l level of the analytes were achieved. Determined LOQ (10 x S/N) values of diagnostically important porphyrins using fluorimetric detection (ex.405 nm/em.620 nm) were 82 pmol/l (65 ng/l, 1.30 pg/injection) for uroporphyrin I, 44 pmol/l (33 ng/l, 0.66 pg/injection) for uroporphyrin III, 50 pmol/l (40 ng/l, 0.80 pg/injection) for coproporphyrin I and 47 pmol/l (39 ng/l, 0.78 pg/injection) for coproporphyrin III. Attained LOQ concentration level is approximately 20-120 times lower than concentration of porphyrins in a urine of healthy person. Calculated LOD's (3 x S/N) were at a low ng/l levels, what enabled quantification of carry-over effect to be from 2.0% to 0.2% in each of three consecutive blank runs and from 2.5% to 7% in total after injection of mixed standard of porphyrins with 5-20 microg/l concentrations. Recovery of porphyrins at low microg/l concentration levels was from 93% to 97.5%. Devised method increases productivity of clinical laboratory from 2 to 10 times in dependence of duration of currently used method.

Stacking and separation of coproporphyrin isomers by acetonitrile-salt mixtures in micellar electrokinetic chromatography

The effectiveness of the addition of salt and acetonitrile in the sample matrix to induce narrowing of the analyte zones is demonstrated for the first time in micellar electrokinetic chromatography (MEKC). Using coproporphyrin (CP) I and III isomers as test compounds, the use of sodium cholate (SC) as the micelle in the separation buffer and a high concentration of sodium chloride in the aqueous sample solution (without the presence of an organic solvent) were found to provide enhancement in peak heights for both CP I and III, but yielded very poor resolution of these two positional isomers at sample size of 10% capillary volume or larger. With the addition of acetonitrile as the organic solvent in the aqueous sample solution (acetonitrile-salt mixtures), baseline/partial resolution of CP I and III was obtained even at large injection volumes, along with significant increase in peak heights for both isomers. Possible mechanisms responsible for the narrowing of analyte zones are briefly discussed. The effects of experimental parameters, such as concentrations of salt and acetonitrile, on peak heights and resolution of the test compounds were studied. Importantly, the usefulness of the present method was demonstrated for the MEKC determination of endogenous CP I and III present in normal urine samples with good separation and detection performances.

Singlet oxygen (1 delta g) generation from coproporphyrin in Propionibacterium acnes on irradiation

Although singlet oxygen has been postulated to be a highly reactive and toxic intermediate, there has been no evidence of considerable generation of singlet oxygen in vivo level except for special cases. In this work, we firstly measured the near-infrared emission spectra corresponding to the O2(1 delta g) --> O2(3 epsilon g-) transition of singlet oxygen of cutaneous Propionibacterium acnes (P. acnes) porphyrin under laser excitation. A comparison of the singlet oxygen production of coproporphyrin, which is produced predominantly from P. acnes, with that of other photosensitizers revealed coproporphyrin to be a highly efficient singlet oxygen generator under ultraviolet light A irradiation on the skin. These results suggest that singlet oxygen can be generated on the skin surface from P. acnes porphyrin under ultraviolet irradiation and induce serious damage to the skin.

Excretion pattern of faecal coproporphyrin isomers I-IV in human porphyrias

The relative proportions of the four coproporphyrin isomers I-IV were analysed in faeces of 20 healthy subjects and 60 patients suffering from one of the seven common types of hepatic or erythropoietic hereditary porphyrias. A newly developed, reliable method for sample preparation was applied, using reversed-phase thin layer chromatography for the isolation of naturally occurring coproporphyrin free carboxylic acids. Accurate separation and quantitation of the individual isomers I-IV were achieved with the help of ion-pair high-performance liquid chromatography. The four coproporphyrin isomers I-IV were positively identified by on-line scanning of their fluorescence spectra in the emission and excitation modes. Recovery rates with this new analytical procedure were between 90 and 100%, and coefficients of variation varied between 0.8 and 5.7% (N = 7). Diagnostically important findings were greatly increased proportions of isomer I and decreased proportions of isomers III, II and IV in erythropoietic porphyrias, such as congenital erythropoietic porphyria and protoporphyria. Significantly increased proportions of isomers III, II and IV, on the other hand, were observed in acute hepatic porphyrias, e.g. acute intermittent porphyria and porphobilinogen synthase deficiency porphyria, as compared with porphyria cutanea tarda (p < 0.005 and p < 0.03, respectively). Inversion of the faecal coproporphyrin III to I ratios and markedly elevated percentages of the atypical isomers II and IV were important diagnostic markers for variegate porphyria and hereditary coproporphyria. The highest proportions of isomer III were found in hereditary coproporphyria, where the amount of the isomers II and IV exceeded that of isomer I. Asymptomatic carriers of the relevant gene defect in families with hereditary coproporphyria could be detected by an increased faecal coproporphyrin III to I ratio. Our results clearly demonstrate the potential of faecal coproporphyrin I-IV isomer ratios for the diagnosis and differential diagnosis of hereditary porphyrias.

Isolation and characterization of zinc coproporphyrin I: a major fluorescent component in meconium

We isolated a substance from an organic extract of meconium (in neutral pH) that exhibited a porphyrin-like fluorescence peak at 580 nm on excitation at 405 nm and deduced its structure. Spectrometric data suggest that the substance is not free coproporphyrin I or free coproporphyrin III, but is a chelate of coproporphyrin I with Zn2+. We also detected a chelate of coproporphyrin III with Zn2+ by HPLC. These substances may be useful as new indicators of the presence of meconium.

Characterization of a coproporphyrin-protein complex from Rhodobacter capsulatus

Rhodobacter capsulatus strain AJB530 excretes large amounts of coproporphyrin into the culture supernatant. The coproporphyrin was precipitable with ammonium sulfate, suggesting that it was part of a macromolecular complex. Analysis of an ammonium sulfate fraction indicated that the coproporphyrin was bound to a 66-kDa protein with a pI' of 4.0. The same protein was found in the culture supernatant of the bch+ strain PAS100.

The isomer ratios of urinary coproporphyrins I--IV are pH-dependent

The percentage of porphyrinogens as related to total porphyrin excretion was determined in the urine of healthy subjects. Acidic urines (pH 5.0 to 5.9) contained 62.9 +/- 10.7% (means +/- s, N = 11) porphyrinogens, whereas in neutral urines (pH 6.0 to 7.2) a somewhat lower percentage (51.2 +/- 15.3%, N = 11) was detected. However, there was no significant difference between the mean porphyrinogen contents of acidic and neutral urines. Evidence was found for a previously unreported pH-dependent influence on the isomer ratios of urinary coproporphyrins I and III. Acidic urines (N = 18) from healthy subjects showed significantly higher percentages of isomer I (27.1 +/- 6.4%), isomer II (2.7 +/- 1.1%), and isomer IV (5.0 +/- 1.3%) as compared to respective values from neutral urines (22.2 +/- 5.1% isomer I, 0.6 +/- 0.6% isomer II, and 1.5 +/- 1.3% isomer IV; N = 16, p less than 0.001). Conversely, the percentage of isomer III was markedly lower in acidic urines than in neutral urines (65.1 +/- 7.9% vs. 75.9 +/- 5.4%; p less than 0.001). The same relationship was confirmed in an individual subject by analysis of a series of urines (N = 13) with pH values ranging from 5.4 to 7.3. These results point to the possibility that the atypical coproporphyrin isomers II and IV are predominantly formed by an increased isomerization rate of coproporphyrinogens under acidic intravesical conditions.

Separation of porphyrin isomers by high-performance liquid chromatography

A high-speed reversed-phase high-performance liquid chromatographic method using an octadecylsilyl 3 cm long (3 microns particle size) column to separate the free acids of uroporphyrins I and III and coproporphyrins I and III from each other, and from the type I isomers of several other porphyrin carboxylic acids, is described. Separation of the porphyrins was achieved in less than 8 min, and injections were possible every 12 min. The detection limits of uroporphyrin, coproporphyrin, and mesoporphyrin were 75, 45, and 35 fmol (at a signal-to-noise ratio of 2), respectively. Application of the method to the determination of urinary and liver porphyrin patterns is shown.

[Fluorescent immunoanalysis. Synthesis, spectro-fluorescent and immunologic properties of conjugates of coproporphyrin I with antibodies]

The synthesis of protein conjugates with the new high-efficient fluorescent labile coproporphyrin-I was optimized. A number of conjugates of monoclonal antibodies with different coproporphyrin-I content were synthesized, and their spectral properties were studied in water and micellar solutions, i.e. adsorption, excitation and emission spectra, fluorescence quantum yields, fluorescence pH-dependences. The binding constants of coproporphyrin-I and its protein conjugates with serum albumin were determined. The antibodies labelled with coproporphyrin-I retain the functional activity and photochemically stable in water solutions. The sensitivity of fluorometric detection of coproporphyrin-I and its conjugates with proteins is more than 10 times greater than in case of FITC.

Extraction and isolation by high performance liquid chromatography of uroporphyrin and coproporphyrin isomers from biological tissues

A simple, rapid procedure has been developed for extraction of uroporphyrin and coproporphyrin isomers from biological tissues. The recoveries of known standards of uroporphyrin I and III and coproporphyrin I and III were performed from liver, kidney, testis, and bone marrow of the rat. The extracted samples were analyzed by high performance liquid chromatography. This method is suitable for the study of drug- and toxicant-induced porphyrias characterized by alterations of the ratios of the I and III isomers of uroporphyrin and coproporphyrin.

High-performance liquid chromatography of coproporphyrin isomers

A reversed-phase system is described for the simultaneous isocratic separation of coproporphyrin I, II, III and IV isomers. The retention behaviour of coproporphyrin I and III is studied in detail. The method is suitable for both analytical and semi-preparative separation.

Liquid-chromatographic separation and determination of coproporphyrins I and III in urine

We describe a method of determining coproporphyrin I, III, and I plus III in urine by "high-performance" liquid chromatography. Urine is simply injected after dilution with an equal volume of glacial acetic acid. Some urinary coproporphyrin apparently binds zinc without acetic acid treatment. The working linear range of coproporphyrin concentrations is 10 to 2000 micrograms/L of urine. The sensitivity of the method is sufficient to detect as little as 10 micrograms of coproporphyrins per liter of urine. Analytical recoveries for both coproporphyrins were 96.7-106%. Results by the present method and those by an extraction method (Br J Ind Med 31:72-74, 1974) correlate well (r = 0.975). Mean (and range) coproporphyrin I, III, and I plus III concentrations in urine from normal subjects are 33.7 (7-75), 28.6 (0-130), and 62.2 (7-174) micrograms/L, respectively.

Production of copper coproporphyrin III by Bacillus cereus. I. Purification and identification of copper coproporphyrin III

Bacillus cereus strains 2 and T did not form spores and accumulated a large amount of purple pigment inside the cells, when cultured in a yeast extract-ammonium salt medium with excess glucose. The pigment was extracted and crystallized as the ethyl ester. It was identified as copper coproporphyrin III.

The use of thin layer chromatography in the separation of free porphyrins and porphyrin methyl esters

Thin layer chromatographic techniques for the separation and subsequent quantification of free porphyrins, coproporphyrin isomers and the methyl esters of porphyrins are described including a 2-dimensional system. The relevant RFs for a wide range of porphyrins are given. These methods have been in use in Cardiff and Barcelona for a number of years and were used in the survey of cases described by Pinol et al. (1975) which resulted in the discovery of the new porphyria, hepato-erythrocytic porphyria.