A sensitive internal standard method for the determination of melatonin in mammals using precolumn oxidation reversed-phase high-performance liquid chromatography

Hamase, Kenji; Hirano, Junzo; Kosai, Yuki; Tomita, Tatsunosuke; Zaitsu, Kiyoshi

doi:10.1016/j.jchromb.2004.08.027

Cited by 11 publications

(10 citation statements)

References 25 publications

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“…Melatonin was measured in parallel by a method based on derivatization of melatonin to N ‐[(6‐methoxy‐4‐oxo‐1,4‐dihydroquinoline‐3‐yl)methyl]acetamid (6‐MOQMA) under alkaline conditions in the presence of hydrogen peroxide [44–46]. The product was quantified fluorometrically ( λ ex / λ em = 245/380 nm) by the same HPLC system that was used for purification of the extracts.…”

Section: Methodsmentioning

confidence: 99%

Quantification of melatonin in phototrophic organisms

Pape

Lüning

2006

Journal of Pineal Research

127

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Melatonin, the chief secretory product of the vertebrate pineal gland is also known to occur in numerous photoautotrophic organisms. The indoleamine is suspected to act as a transducer of photoperiodic information and/or to participate in antioxidative protection. In higher plants and other photoautotrophic organisms, contradictory results for melatonin content for samples from the same species show that further improvement of methods for reliable quantification is required. In the present study, melatonin was quantified in tomatoes, ginger and the marine green macroalga, Ulva lactuca, after extraction with three different extraction methods based on ether, acetone or perchloric acid. Melatonin was determined by enzyme-linked immunosorbent assay (ELISA) in high-performance liquid chromatography (HPLC)-purified extracts. The same HPLC system used for purification of extracts was used for parallel quantifications after derivatization of melatonin under alkaline conditions in the presence of hydrogen peroxide (HPLC-PD). Both quantification methods gave similar results with a high correlation [f(x) = 0.99x + 3.01; R(2) = 0.99]. In ginger, the melatonin concentration was below 5 pg/g (fresh weight, f.w.), whereas in tomatoes about 1200 pg/g (f.w.) were found, and in the green alga, U. lactuca, approximately 12 pg/g (f.w.). Taking into account the recovery rates for synthetic melatonin added prior to extraction, no substantial differences were observed in melatonin quantification between different extraction methods. The demonstrated methods based on HPLC purification and subsequent quantification by ELISA and HPLC-PD allow highly sensitive melatonin determinations in diverse photoautotrophic organisms with a low risk of overestimations by false-positive results.

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Section: Methodsmentioning

confidence: 99%

Quantification of melatonin in phototrophic organisms

Pape

Lüning

2006

Journal of Pineal Research

127

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“…Melatonin or GWC22 aqueous solution was added to a freshly made 10 −2 m linoleic acid emulsion and the pH of the mixed solution was adjusted to 10.5 with sodium hydroxide (10 −1 m ) in order to quantitatively deprotonate the carboxylic groups and to form sodium linoleate micelles [11, 18]. Quantification of melatonin in micelles was achieved by fluorescence measurement on a Kontron spectrofluorimeter (Montigny Lebretonneux, France) ( λ excitation = 285 nm, λ emission = 352 nm) [19, 20]. Fluorescence of 10 −2 m solutions of linoleic acid was measured in the absence and the presence of melatonin at final concentrations of 3 × 10 −5 , 5 × 10 −5 , 7 × 10 −5 and 10 −4 m , with a 1‐cm pathlength quartz cell.…”

Section: Methodsmentioning

confidence: 99%

Quantification of the water/lipid affinity of melatonin and a pinoline derivative in lipid models

Mekhloufi¹,

Vitrac²,

Yous³

et al. 2007

Journal of Pineal Research

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This study assessed the location of melatonin (N-acetyl-5-methoxytryptamine) and of a pinoline derivative (GWC22) [6-ethyl-1-(3-methoxyphenyl)-2-propyl-1,2,3,4-tetrahydro-beta-carboline], when present in lipid assemblies such as linoleate micelles, phosphatidylcholine liposomes or low density lipoproteins (LDL). The efficiency of radical scavenging by these compounds is highly dependent on their partitioning between the lipidic and aqueous phases. We determined the proportion of melatonin or GWC22 in the aqueous and lipid phases of each system (concentrations of the antioxidants ranging between 3 x 10(-5) and 10(-4) m) by assaying melatonin or GWC22 by HPLC/UV detection, or by fluorescence for melatonin in micelles. Our results show that melatonin and GWC22 were preferentially located in the aqueous phase of micelles (68.4% and 59.0%, respectively), whereas only 30.5% of melatonin and 39.0% of GWC22 were found in the lipid phase. By contrast, in phosphatidylcholine liposomes, both compounds were essentially present in the lipid phase (73.5% for melatonin and 79.1% for GWC22, versus 25.9% and 19.5% in the aqueous phase, respectively). In the case of LDL, 99.9% of the melatonin added was found in the methanol/water extracting phase containing phospholipids, unesterified cholesterol and apolipoprotein B100. The partitioning of melatonin and GWC22 in linoleate micelles gave new insights on the marked protective effect of GWC22 towards radiation-induced lipid peroxidation and allowed us to determine more accurately the lower limit values of the reaction rate constants of the two molecules studied with lipid peroxyl radicals, i.e. k(LOO.+melatonin)) >or= 9.0 x 10(4)m(-1)s(-1) and k(LOO.+GWC22) >or= 3.5 x 10(5)m(-1)s(-1).

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“…In contrast to MLT, the contents of other indolic compounds were seldom investigated, primarily due to the limitations related to analytical methods. Currently, the most effective techniques for measuring 5-hydroxyindoles and 5-methoxyindoles are HPLC methods [21] with electrochemical [22,23,24,25,26] or fluorescence detection [27,28,29,30,31]. Fluorescence detection has been less frequently used in pineal studies than electrochemical detection [21], usually for assays of melatonin only [29] or after derivatization procedures [30,31].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, the most effective techniques for measuring 5-hydroxyindoles and 5-methoxyindoles are HPLC methods [21] with electrochemical [22,23,24,25,26] or fluorescence detection [27,28,29,30,31]. Fluorescence detection has been less frequently used in pineal studies than electrochemical detection [21], usually for assays of melatonin only [29] or after derivatization procedures [30,31]. The considerable problems with using HPLC methods in pineal research include the following: (1) large differences in the pineal contents of various indoles, complicating fluorometric detection; (2) insufficient sensitivity to measure all essential compounds in the pineal organ over a 24-h-cycle; and (3) large differences in the polarity and retention times between 5-hydroxyindoles and 5-methoxyindoles, causing difficulties in the simultaneous detection of both groups of indoles within a single run.…”

Section: Introductionmentioning

confidence: 99%

Diurnal Profiles of Melatonin Synthesis-Related Indoles, Catecholamines and Their Metabolites in the Duck Pineal Organ

Lewczuk

Ziółkowska

Prusik

et al. 2014

IJMS

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This study characterizes the diurnal profiles of ten melatonin synthesis-related indoles, the quantitative relations between these compounds, and daily variations in the contents of catecholamines and their metabolites in the domestic duck pineal organ. Fourteen-week-old birds, which were reared under a 12L:12D cycle, were killed at two-hour intervals. The indole contents were measured using HPLC with fluorescence detection, whereas the levels of catecholamines and their metabolites were measured using HPLC with electrochemical detection. All indole contents, except for tryptophan, showed significant diurnal variations. The 5-hydroxytryptophan level was approximately two-fold higher during the scotophase than during the photophase. The serotonin content increased during the first half of the photophase, remained elevated for approximately 10 h and then rapidly decreased in the middle of the scotophase. N-acetylserotonin showed the most prominent changes, with a more than 15-fold increase at night. The melatonin cycle demonstrated only an approximately 5-fold difference between the peak and nadir. The 5-methoxytryptamine content was markedly elevated during the scotophase. The 5-hydroxyindole acetic acid, 5-hydroxytryptophol, 5-methoxyindole acetic acid and 5-methoxytryptophol profiles were analogous to the serotonin rhythm. The norepinephrine and dopamine contents showed no significant changes. The DOPA, DOPAC and homovanillic acid levels were higher during the scotophase than during the photophase. Vanillylmandelic acid showed the opposite rhythm, with an elevated level during the daytime.

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A sensitive internal standard method for the determination of melatonin in mammals using precolumn oxidation reversed-phase high-performance liquid chromatography

Cited by 11 publications

References 25 publications

Quantification of melatonin in phototrophic organisms

Quantification of melatonin in phototrophic organisms

Quantification of the water/lipid affinity of melatonin and a pinoline derivative in lipid models

Diurnal Profiles of Melatonin Synthesis-Related Indoles, Catecholamines and Their Metabolites in the Duck Pineal Organ

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