A simple, fast and precise reverse phase high performance liquid chromatographic method has been developed for the simultaneous determination of Melatonin and Octyl Methoxycinnamate. Melatonin has become an attractive substrate in sunscreen formulations because of its high antioxidant and photo-protection properties. Octyl methoxycinnamate is one of the chemical UV filter that can be found most of the sunscreen formulations up to 7.5 % according Food and Drug Administration. The aim of the present study was to develop and validate a High-Performance Liquid Chromatography method for the determination of Melatonin and Octyl Methoxycinnamate in combined pharmaceutical or cosmetic applications. As a model of combined pharmaceutical applications, a microemulsion consisting of Melatonin and Octyl Methoxycinnamate was also prepared and characterized in terms of droplet size, pH and viscosity. The separation was performed with a Waters XTerra RP C18 (5 μm, 4.6 x 150 mm). All HPLC assays were performed with 10 µl injection volume, mobile phase consisting of acetonitrile and water, using gradient elution starting at 20% and ending at 90% of acetonitrile with a flow rate of 1.5 ml min-1.The eluent was monitored with UV detection at 222 nm for Melatonin and 306 nm for Octyl Methoxycinnamate. The method was validated according to ICH guidelines. Validation parameters were specificity, accuracy, precision (repeatability and reproducibility), linearity, limit of detection (LOD) and limit of quantification (LOQ). Analytical method development results indicated that the LOD values were 0.132 and 0.049 μg/ml; LOQ values were 0.4 and 0.15 μg/ml and assay exhibited a linear range of 0.5- 60 μg/ml for Melatonin and Octyl Methoxycinnamate, respectively.
___
FDA, Reviewer Guidance—Validation of chromatographic methods. Rockville, United States of America. 1994.
Songkro S, Lo NL, Tanmanee N, Maneenuan D, Boonme P. In vitro release, skin permeation and retention of benzophenone-3 from microemulsions (o/w and w/o). J Drug Deliv Sci Technol 2014; 24: 703-11.
ICH (Q2 (R1); Validation of Analytical Procedures: Text and methodology. International Conference on Harmonization, Geneva. 2005.
Andrisano V, Bertucci C, Battaglia A, Cavrini V. Photostability of drugs: Photodegradation of melatonin and its determination in commercial formulations. J Pharm Biomed Anal 2000; 23: 15-23.
Kedor-Hackmann ERM., De Lourdes Pérez González ML, Singh AK, Santoro MIRM. Validation of a HPLC method for simultaneous determination of five sunscreens in lotion preparation. Int J Cosmet Sci 2006; 28: 219–24.
Lin J, Zhang C, Gao Y, Zhao X, Li X. A validated HPLC method for determining melatonin in capsule dosage form. Spatula DD 2012; 2: 147-51.
Carlotti ME, Gallarate M, Rossatto V. O/W microemulsion as a vehicle for sunscreens. J Cosmet Sci 2003; 54: 451–62.
Lopes LB. Overcoming the cutaneous barrier with microemulsions. Pharmaceutics 2014; 6: 52-77.
Heuschkel S, Goebel A, Neubert R.H.H. Microemulsions— modern colloidal carrier for dermal and transdermal drug delivery. J Pharm Sci 2008; 97: 603–31.
Wang SQ, Lim HW. Current status of the sunscreen regulation in the United States: 2011 Food and Drug Administration’s final rule on labeling and effectiveness testing. J Am Acad Dermatol 2011; 65: 863-9.
Marto J, Ascenso A, Gonçalves LM, Gouveia LF, Manteigas P, Pinto P, Oliveira E, Almeida AJ, Ribeiro HM. Melatoninbased pickering emulsion for skin’s photoprotection. Drug Deliv 2016; 23: 1594-607.
Sierra AF, Ramírez MLG, Campmany ACC, Martínez AR, Naveros BC. In vivo and in vitro evaluation of the use of a newly developed melatonin loaded emulsion combined with UV filters as a protective agent against skin irradiation. J Dermatol Sci 2013; 69: 202-14.
Slominski AT, Kleszczyński K, Semak I, Semak I, Janjetovic Z, Zmijewski MA, Kim TK, Slominski RM, Reiter RJ, Fischer TW. local melatoninergic system as the protector of skin integrity. Int J Mol Sci 2014; 15: 17705-32.
Slominski A, Fischer TW, Zmijewski MA, Wortsman J, Semak I, Zbytek B, Slominski RM, Tobin DJ. On the role of melatonin in skin physiology and pathology. Endocr 2005; 27: 137-48.