Nail Melatonin Content: A Suitable Non-Invasive Marker of Melatonin Production

Abstract

Melatonin plays multiple physiological roles in the human body. Evaluation of melatonin production by the determination of urinary 6-sulfatoxymelatonin in 24-h samples has important drawbacks which hinder the successful evaluation of melatonin production in large cohorts. Here, we evaluated the potential of nail analysis for estimating melatonin production. Firstly, mass spectrometry methodology for the determination of melatonin in nails was optimized and successfully validated. The method was found to be linear in the range 6.5–830 fg/mg with intraday and interday accuracy in the range 100–104 %, precision below 15 % and a LOD of 3.5 fg/mg. Secondly, nail melatonin concentrations from 84 volunteers (age 5–96) were determined. The expected correlation between melatonin and age was obtained (correlation coefficient −0.615; p < 0.001). Additionally, we showed that fingernails are preferable to toenails to determine nail melatonin content. Finally, fingernails collected for 180 days after melatonin administration (two volunteers, 1.9 mg/night during 5 days) were analyzed. Nail melatonin concentrations immediately rose after administration and went back to pre-administration values after ≈100 days in both volunteers. Our results suggest that melatonin determination in nails is a suitable non-invasive tool for the estimation of global melatonin production. Due to the easy collection and storage of nails, the long-term information obtained and the multiple functions of melatonin, nail melatonin content might complement dim light melatonin onset, which is commonly measured from plasma/saliva samples, paving the way for melatonin research.

Mineral, Nutritional, and Phytochemical Composition and Baking Properties of Teff and Watermelon Seed Flours

“…The MS analyses were performed in positive ion mode, and the following instrumental parameters were used: capillary and cone voltages—3.0 kV and 30 V; source and desolvation temperatures—150 and 450 °C, desolvation and cone gas flow—900 and 100 L/h. The detection of MEL and MEL-d4 was performed in selected reaction monitoring (SRM) mode using the following transitions: 233→159 (CE 30 V), 233→174 (CE 10 V), and 237→163 (CE 30 V), 237→178 (CE 10 V), respectively [ 60 ]. Waters MassLynx v.4.1 software was used for data acquisition and processing.…”

ABCG2 transporter plays a key role in the biodistribution of melatonin and its main metabolites

“…Chromatographic separation was achieved on an Acquity BEH C18 column (Waters Associates) at a flow rate of 0.3 ml/min and water and methanol as mobile phases (both with ammonium formate [1 mM] and formic acid [0.01% v/v]). Based on previous work carried out by our group, 21 a gradient program was used for analyte separation. Analytes were determined in the selected reaction monitoring mode including two ion transitions for each analyte: melatonin (233 → 159, 233 → 174), 6‐OH‐Mel (249 → 158, 249 → 190), and 6‐SO‐Mel (329 → 190, 329 → 249).…”

“…Chromatographic separation was achieved on an Acquity BEH C18 column (Waters Associates) at a flow rate of 0.3 ml/min and water and methanol as mobile phases (both with ammonium formate [1 mM] and formic acid [0.01% v/v]). Based on previous work carried out by our group, 21…”

Unveiling the Collaborative Effect at the Cucurbit[8]uril‐MoS2 Hybrid Interface for Electrochemical Melatonin Determination

“…MLT is of paramount significance in organisms since it regulates circadian rhythms and blood pressure, acts as antioxidant and anti‐inflammatory agent, and is a free radical scavenger playing therefore, an important role in cell protection [12–14] . Such a wide scope has made that recent applications are focused on MLT analysis in food, [15–17] pharmaceutical [16–18] or biological samples as urine, saliva and nails [19–22] . Therefore, various analytical methods have been developed for MLT quantification.…”

“…[ 12 , 13 , 14 ] Such a wide scope has made that recent applications are focused on MLT analysis in food,[ 15 , 16 , 17 ] pharmaceutical[ 16 , 17 , 18 ] or biological samples as urine, saliva and nails. [ 19 , 20 , 21 , 22 ] Therefore, various analytical methods have been developed for MLT quantification. Although different chromatographic techniques with UV‐vis, [18] fluorescence [15] or mass spectrometry detection [21] have been proposed, electrochemical methods result an interesting alternative to these expensive and sophisticated techniques.…”