Phytomelatonin contents in macroalgae

Abstract Phytomelatonin is an indoleamine with clearly established antioxidant, regulatory, and signalling actions in vascular plants and also several studies have highlighted its presence in macroalgae. Despite this, its quantitative distribution in macroalgae remains insufficiently investigated and documented. In this study, phytomelatonin was quantified in six seaweeds ( Cystoseira compressa , Carpodesmia tamariscifolia , Halopteris scoparia , Sargassum vulgare , Ulva intestinalis and Ulva linza ) using high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). The phytomelatonin content in the six seaweeds ranged from 27.96 ± 4.28 to 639.33 ± 36.61 ng g -1 fresh weight (FW). These results emphasize the potential of these macroalgae as a natural source of phytomelatonin for sustainable agricultural and biotechnological applications, and give rise to the hypothesis that the phytomelatonin content of these algae may contribute independently and/or synergistically to their biostimulant and bioprotectant effects on plants, but further studies are required to confirm this hypothesis and investigate phytomelatonin fluctuations in these seaweeds.