Sulfated flavonoids, a class of polyphenols integral to plant secondary metabolism and chemical defense, exhibit notable pharmacological potential. Seagrasses, marine angiosperms with critical ecological and socioeconomic roles, often accumulate these compounds in high concentrations. However, their complex chemical profiles-including closely related sulfated flavonoids-are challenging to characterize due to potential degradation during extraction. This study provides the first comprehensive analysis of sulfated flavonoids in