Table 2.

Durvillaea antarctica as a key player in gut microbiota modulation.

Author (REF)	Phytochemical Compound Tested	Rationale	Results–Key Findings
He et al. [23]	Combination of deep-sea water (DSW) and/or fucoidan (CDF)	The combined effect of DSW and fucoidan was investigated on a T2DM rat model induced by a high-fat diet and streptozocin injection. Fecal metabolomics and 16S rDNA analysis were used to explore the relationship between these interventions and identify potential metabolic pathways.	CDF was more effective than DSW or fucoidan alone in improving blood glucose, lipid levels, and histopathological changes in T2DM rats. CDF also enhanced the phosphorylation of Akt and GSK3β, which are important steps in insulin signaling. Fecal metabolomics and 16S rDNA analysis showed that CDF altered the composition of gut microbiota and metabolic pathways.
Bai et al. [25]	Alginate	Alginate overproducing mutant of P. aeruginosa was obtained through transposon mutagenesis libraries. The in vitro functions of human gut microbiota in degrading seaweed and mutant Pseudomonas alginates were comparatively studied.	Both bacterial and seaweed alginates were found to be completely degraded by fecal bacteria isolated from study volunteers. Moreover, their regulatory function on gut microbiota was similar, as they promoted the proliferation of beneficial bifidobacteria while reducing the abundance of pathogenic bacterial strains.
Siddiqui et al. [29]	Crude polysaccharide from seaweed, Dictyopteris divaricata (CDDP)	The impact of streptozotocin-induced T1DM on gut barrier permeability and gut microbiota dysbiosis.	CDDP treatment increased beneficial bacteria (Firmicutes, Bacteroidetes, Lactobacillus) via 16S rRNA sequencing. Immunohistological analysis confirmed CDDP’s anti-inflammatory effects, restoring colon morphology and maintaining gut structure and barrier permeability.
du Preez et al. [39]	Sargassum siliquosum extract	Evaluated the impact of S. siliquosum on metabolic syndrome parameters, including heart/liver function, plasma biochemistry, glucose/insulin responses, body composition, and gut microbiota composition.	S. siliquosum decreased body weight, fat mass, abdominal fat deposition, liver fat vacuole size, and improved glucose tolerance and insulin sensitivity. S. siliquosum also increased the population of beneficial bacteria in the gut and reduced inflammation.

Abbreviations: Glycogen synthase kinase-3 beta (GSK-3 beta); serine/threonine-protein kinase (akt).