Quality control of dietary supplements based on melatonin manufactured and marketed in Tunisia

This study aimed to establish the stability conditions for melatonin in solution and to estimate its content in food supplements manufactured and marketed in Tunisia by optimizing and validating an analytical method based on high performance. We began by studying the effect of light on the melatonin content of the solution during storage. The significance of both factors, temperature and storage time of melatonin, was assessed using a complete factorial plan. The dosing method was optimized by considering three factors: the mobile phase, the stationary phase, and the wavelength. The performance of the dosage method has been validated according to the guidelines of the French company of pharmaceutical sciences and techniques (SFSTP). We were able to demonstrate the molecule's photosensitivity and thermolability based on its shelf life. Our dosing technique is both easy to use and reliable in terms of specificity, linearity, accuracy, and fidelity. Significant deviations from the declared strength on the label were found in 66% of supplements. Regarding the health claims, as well as the mention of the vulnerable population, the manufacturers were in the majority not respected. The urgency of structuring the regulatory framework for this type of product is evident.