2.4.1. Carotenoids

Carotenoids are terpenoid pigments widely distributed that are divided into two main groups: carotenes (unsaturated hydrocarbons) and xanthophylls (carotenes' oxygenated derivatives—of which in algae the most representatives are fucoxanthin, astaxanthin, lutein, and zeaxanthin) [50,51]. β-carotene is the major unsaturated hydrocarbon in brown and green seaweeds [37,52].

Carotenoids are a well-known as antioxidant agents [53]. Fucoxanthin exerts strong 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging activity, most of it under anoxic conditions, being also recognized to exhibit anti-inflammatory properties. Its inhibitory activity against proinflammatory agents, such as nitric oxide (NO), tumor necrosis factor alpha (TNFα), interleukin-1β, prostaglandin E2 (PGE2), and interleukin-6 (IL-6) was reported in [54]. A number of studies sugges<sup>t</sup> that fucoxanthin is a promising and upcoming anticancer and antitumor agen<sup>t</sup> and can suppress metastatic potential [55,56]. It also exhibited favorable levels of chemopreventive and/or chemotherapeutic activities against di fferent human colon cancer cell lines, in combination with troglitazone being able to induce cell apoptosis via DNA fragmentation [57]. *U. pinnatifida* ethanolic extract, rich in fucoxanthin, was found to improve the plasma and lipid profile in high-fat diet mice. Aki et al. [58] investigated the e ffects of the seaweed carotenoids on unsaturated fatty acid metabolism in a hepatocyte culture (BRL-3A). The molecular mechanism revealed that fucoxanthin and its physiological metabolite, fucoxanthinol, caused alterations in fatty acid composition, leading to a decrease in EPA and the accumulation of docosahexaenoic acid.
