Gas-liquid chromatography of carotenoids and other terpenoids

Use of high-precision gas isotope ratio mass spectrometry to determine natural abundance 13C in lutein isolated from C3 and C4 plant sources

A method was developed for high-precision stable carbon isotope ratio analysis of lutein isolated from a C3 (marigold flower) and a C4 (corn gluten meal) plant source using gas chromatography-combustion interfaced isotope ratio mass spectrometry. The natural abundance of 13C (expressed as delta 13C versus the international standard, Pee Dee Belemnite, in per mil units, denoted /1000) in lutein isolated from marigold flower and corn gluten meal was determined to be -29.90 +/- 0.20/1000 and -19.77 +/- 0.27/1000 (mean +/- S.D.), respectively. The high precision of gas isotope ratio mass spectrometry is potentially applicable to detect differences of isotopic composition of lutein in the blood, tissues, or excreta of animal models or humans that result from differences in the natural abundance of 13C in C3 and C4 plant foods.

Pigments of Staphylococcus aureus, a series of triterpenoid carotenoids

The pigments of Staphylococcus aureus were isolated and purified, and their chemical structures were determined. All of the 17 compounds identified were triterpenoid carotenoids possessing a C30 chain instead of the C40 carotenoid structure found in most other organisms. The main pigment, staphyloxanthin, was shown to be alpha-D-glucopyranosyl 1-O-(4,4'-diaponeurosporen-4-oate) 6-O-(12-methyltetradecanoate), in which glucose is esterified with both a triterpenoid carotenoid carboxylic acid and a C15 fatty acid. It is accompanied by isomers containing other hexoses and homologs containing C17 fatty acids. The carotenes 4,4'-diapophytoene, 4,4'-diapophytofluene, 4-4'-diapophytofluene, 4-4'-diapo-zeta-carotene, 4,4'-diapo-7,8,11,12-tetrahydrolycopene, and 4,4'-diaponeurosporene and the xanthophylls 4,4'-diaponeurosporenal, 4,4'-diaponeurosporenoic acid, and glucosyl diaponeurosporenoate were also identified, together with some of their isomers or breakdown products. The symmetrical 4,4'-diapo- structure was adopted for these triterpenoid carotenoids, but an alternative unsymmetrical 8'-apo-structure could not be excluded.

Determination of plasma levels of two aromatic retinoic acid analogues with antipsoriatic activity by high-performance liquid chromatography

A method is described for the quantitative analysis in plasma of Ro 10-9359, an aromatic retinoic acid analogue, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate and its major metabolite Ro 10-1670, all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,3,6,8-nonatetraenoic acid. The compounds are extracted from patient plasma with diethyl ether, separated on a reversed-phase column and detected and quantified by their UV absorption. The experimental error is below 9% in the concentration range 42-445 ng/ml. The detection limit is about 10 ng/ml. The method was applied to the analysis of plasma levels in healthy volunteers, receiving 75 mg orally.

Determination of retinoic acid (13-cis- and all-trans-) and aromatic retinoic acid analogs possessing anti-tumor activity, in biological fluids by high-performance liquid chromatography

A sensitive and specific high-performance liquid chromatographic assay was developed for the determination of 13-cis- and all-trans-retinoic acid in blood or urine with an overall recovery of 90 +/- 5.0% and a limit of detection of 10-20 ng/ml of sample. The method provides for rapid and simple quantitation of the compounds using 1 ml of blood. The assay was applied in the determination of blood levels of 13-cis-retinoic acid in the dog following intravenous and oral administration of 9.5 mg/kg and 2.0 mg/kg doses, and in man following a single 100-mg oral dose and following divided daily doses totalling 2 mg per kg of body weight. The assay is also applicable with minor modifications to the determination of a series of aromatic retinoic acid analogs of clinical interest as anti-tumor agents.

Determination of the carotenoid phytoene in blood by high-pressure liquid chromatography

A sensitive and specific high-pressure liquid chromatographic assay was developed for the determination of phytoene in blood with an overall recovery of 86 +/- 6.0% and a limit of detection of 50-100 ng per ml of blood. This method provides for rapid and simple quantitation of phytoene using 1 ml or less of blood. The assay was used in the determination of phytoene blood levels in the dog following intravenous and oral administration of 10-mg/kg doses.