UPLC-TOF-MS/MS characterization of sulfated phytochemicals in Conocarpus lancifolius

Abstract

Sulfated metabolites, particularly sulfated flavonoids, represent a unique subclass of plant secondary metabolites that have gained increasing attention due to their diverse biological activities and ecological roles. Little is known about the existence and characteristics of sulfated flavonoids in Conocarpus species, particularly those cultivated in Saudi Arabia under harsh environmental stress conditions. In this study, the sulfated metabolome of C. lancifolius leaves was investigated for the first time using LC-MS/MS in the negative ion mode, enabling the tentative identification of ten sulfated metabolites, including five flavonoid sulfates, two sulfated fatty alcohols, two phenolic acid sulfates, and the phytohormone derivative 12-sulfoxyjasmonic acid. The mass fragmentation profiles of syringetin-3-sulfate and 1,2-tetradecanediol 1-(hydrogen sulfate), two tentatively identified metabolites, were presented here for the first time. The MS/MS fragmentation patterns were dominated by the neutral loss of SO₃, producing characteristic aglycone or backbone-related ions that supported structural assignments. The diversity of sulfated metabolites detected in C. lancifolius indicated that sulfate conjugation plays a substantial role in the secondary metabolism of the plant, potentially contributing to adaptive responses to environmental stress. These findings provided a groundwork for understanding the sulfur-associated metabolome of this species and underscore the need for further phytochemical, physiological, and pharmacological investigations.