Abstract

Marine macrophytes are promising coastal bioresources, yet their biochemical composition and metabolite profiles along Vietnam’s Mekong Delta coast remain poorly characterized. This study compared the proximate composition, phenolic-related compounds, photosynthetic pigments, and ultraperformance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry operated in MS? acquisition mode (UPLC–ESI– QTOF–MS?)-based metabolite profiles of Sargassum sp., Padina sp., Turbinaria ornata, and Enhalus acoroides. Taxonomic assignments were supported by partial chloroplast 23S rRNA gene sequencing, and the samples were analyzed for moisture, crude protein, n-hexane-extractable lipid, total ash, total polyphenol, total flavonoid, total chlorophyll, and total carotenoid contents. Ethanolic extracts were further examined by exploratory UPLC–ESI– QTOF–MS? screening. Sargassum sp. showed the highest crude protein content (23.22% DW), although it was not significantly different from Padina sp. (22.19% DW). Padina sp. exhibited the highest total polyphenol (18.48 mg GAE/g DW), total flavonoid (11.21 mg CE/g DW), and total chlorophyll contents (3.31 mg/g DW). Under the applied screening conditions, the pooled Padina sp. extract yielded the highest number of tentatively assigned molecular features, mainly related to fatty acids, terpenoids, organic acids, sugar alcohols, and phenolics. These findings provide preliminary biochemical baseline data for local marine macrophytes and support further replicated, targeted analyses to confirm the molecular features and evaluate their potential applications.

Key words: Brown seaweed, marine macrophytes, Mekong Delta, pigments, polyphenols, UPLC–ESI–QTOF–MSᴱ profiling