Polysaccharide (laminaran and fucoidan), fucoxanthin and lipids as functional components from brown algae (Padina tetrastromatica) modulates adipogenesis and thermogenesis in diet-induced obesity in C57BL6 mice.

Currently, mounting demand for safe natural bioactives has strengthened marine algae as an important source of
nutraceuticals to tackle lifestyle diseases. Indian brown algae (Padina tetrastromatica) comprises several nutraceutical
constituents with proposed anti-obese properties. In the present study, we have isolated, characterized
fucoxanthin, polysaccharides (laminaran and fucoidan) and total lipid from brown algae and investigated
comparative potential on obesity in high fat-fed obese C57BL6 mice through adipogenesis and thermogenesis
regulated by serine/threonine-protein kinase (Akt), phosphorylated protein kinase (p-Akt), mitogen-activated
protein kinase (p38), peroxisome proliferator-activated receptor-γ (PPAR-γ) and uncoupling protein-1 (UCP-1)
markers. Biochemical and oxidative stress markers (lipid peroxidase, nitric oxide and protein carbonyl) were
investigated. Fucoxanthin, polysaccharide and total lipid exhibited anti-obese effect by reducing body weight
and triglycerides and cholesterol levels towards control. Further, antioxidant enzymes catalase, superoxide
dismutase, glutathione peroxidase and glutathione transferase showed decreased levels in liver and plasma of
high fat diet-fed group compared to control, which were significantly (p < 0.05) increased on fucoxanthin,
polysaccharide and total lipid treatment. The molecular docking showed the superior binding potential of
fucoxanthin and its metabolites fucoxanthinol and amarouciaxanthin A with adipogenic markers insulin like
growth factor-1 (IGF-1R), protein kinase B (PKB), serine/threonine-protein kinase (Akt-1), peroxisome
proliferator-activated receptor-γ (PPAR-γ) and mitogen-activated protein kinase (p38). In addition, the protein
expression pattern in the visceral adipose tissue showed higher up-regulation of Akt, UCP-1 in fucoxanthin,
polysaccharide and total lipid groups. Down-regulation of p-Akt, p38 and PPAR-γ in visceral adipose tissue
further broadened our understanding of the signalling pathway involved and its mechanism. Our findings
demonstrate that Padina tetrastromatica nutraceuticals could be a potential candidate for managing obesity and
related metabolic disorders.