Chemical characterization of seaweed ( <i>Sargassum pallidum</i> (turn.) C.Ag.) and kelp ( <i>Laminaria japonica</i> Aresch.) from different origins by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Seaweed (Sargassum pallidum (turn.) C.Ag.) and kelp (Laminaria japonica Aresch.) are two common marine plants, typical Chinese herbs with the same use as medicine and food. They are widely distributed in China and exhibit biological properties such as antioxidant, hypolipidemic, antitumor and hypoglycemic effects. This study developed an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) method coupled with chemometric techniques to identify the chemical components in seaweed and kelp from different origins and examine the similarities and differences between the two herbs. A total of 48 constituents were identified, including fatty acids, alkaloids, terpenoids, amino acids, sterols, etc. For two compounds, Aurantiamide and Linoleic acid, the identification and fragmentation patterns were analyzed. Seaweed and kelp demonstrated a clear distinction. Principal component analysis, orthogonal partial least squares discriminant analysis, and cluster heatmap analysis were performed on seaweed and kelp. The seaweed samples were found to have high similarity and aggregation among different origins, while the kelp samples showed greater dispersion. Heatmap analysis further revealed the similarities and differences between seaweeds and kelp from different origins. This study provides a reliable foundation for the clinical application of the two herbs.