MELATONIN AND ITS PRECURSORS IN PLANTS BY CYCLODEXTRIN-MODIFIED MICELLAR ELECTROKINETIC CHROMATOGRAPHY

FEDERICO J. V. GOMEZ; ISMAEL GATICA HERNANDEZ; SOLEDAD CERUTTI; MARIA FERNANDA SILVA

Tenerife

Simposio; ITP 2013, 20th International Symposium on Electro - and Liquid Phase separation Techniques; 2013

Melatonin is a ubiquitous, highly conserved molecule which may function as a hormone, protective antioxidant, and a mediator of light/dark signaling. It was discovered in higher plants by Dubbels et al. [1] and Hattori et al. [2] in two separate studies aimed at determining the natural sources of melatonin in human nutritional diets. In 1997, melatonin was found at higher than expected levels in medicinal plants traditionally used in treatments of human neurological diseases [3]. The physiological role of melatonin in plants is still unclear. Because of its structural similarity with the plant growth hormones of the auxin family, a hormone-like role has been attributed to melatonin in some plant species. Further studies using radioisotope tracer techniques indicated that, in higher plants, tryptophan (Trp) is the common precursor for melatonin (MT), serotonin (5-HT) and indole-3-acetic acid (IAA) [4]. In this work, an original analytical method has been developed for the simultaneous determination of melatonin and its precursors in vegetal tissues. The optimized cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method consisted of employing -CD, 20 mM SDS in a 10 mM borate buffer (pH 9.2) with a 10% (v/v) of acetonitrile, employing a voltage of 20 kV and a temperature of 25 °C. The sample pretreatment was carried out by a fast and reliable solid face microextraction (SPE). For this propose C18, C8 and STRATA X cartridges were tested. After validation, the method was applied to the analysis of MT, 5-HT, Trp and IAA in different tissues of edible plants, with very good results being obtained. All analites were found at ppb levels.