*5.3. Cosmetic Industry*

Cosmetics and cosmeceuticals are commonplace therapies for improving the skin's appearance and treating several dermatological problems. Seaweeds are a valuable component in product development because of their wide range of functional, sensory, and biological properties. Consumer demand for green or eco-friendly products has risen in recent years. This pattern can be seen in the globally competitive cosmetics industry, in need of natural, secure, or effective ingredients to make innovative skin care products [367]. The usage of seaweed-isolated compounds in cosmetic products rose steadily as a result of various scientific studies revealing prospective skincare properties of seaweed bio-actives. Biologically active substances include carotenoids, polysaccharides, phlorotannins, fatty acids, sterols, tocopherol, vitamins, phycocyanins, or phycobilins [368–372]. In this context, a *Sargassum plagyophyllum* extract was shown to have antioxidant and anti-collagenase that can considered to be potent pharmaceutical ingredient for anti-wrinkle cosmetics action [373–376]. As a form of polyphenol, phlorotannins contain a group of heterogeneous polymeric molecules with substantial chemical modifications and various chemical structures [377]. These molecules can play a key role in the interaction between the skin and UVR, such as preventing radiation from penetrating the skin and lowering inflammation, oxidative stress, DNA damage, and maintaining signaling pathways intact. They also attracted a lot of interest because of their participation in several phototoxic pathways and mechanisms [378]. Brown algae *Sargassum fusiforme* [379], *Halidrys siliquosa* [380], *Padina*

*australis* [381], *Sargassum coreanum* [382], and *Polycladia myrica* [383] have been explored for using in cosmetic products.
