on the skin against aging and photo‐damaged effects [93, 94, 115]. Fucoidans are known to enhance multiplication skin fibroblast and augment the retention of native collagen [95, 126]. Fucoidans are known to protect the elastic fiber network in human dermal cells, and hence they are used as a natural whitening agent in lotion and skin creams to reduce age spot and increased radiance, increase smooth texture skin [96, 127]. In human skin, melanocytes cells are known to impart the skin complexion. The pigment melanin is produced and stored inside the melanocytes and is primarily obtained from amino acid L‐tyrosine, which is converted to dopaquinone by the action of the enzyme tyrosinase. Hence, suppression of tyrosinase‐related proteins plays an important role in anti‐melanogenesis and skin whitening [128]. In this regard, several studies have demonstrated the inhibition of enzyme tyrosinase, antioxidant activity, and anti‐melanogenesis of fucoidan fraction from various macroalgae [96, 128, 129]. Furthermore, the property of fucoidans to readily solubilize in water makes it attractive to combine into several ranges of cosmetic formulations such as lotions, creams, ointments, and other beauty products.
4.4.4.3 Laminaran
Laminaran is also widely known as laminarin or leucosin. Laminarin is a glucan polysaccharide made up of β(1→3)‐glucan with β(1→6)‐branches with a β(1→3):β(1→6) in the ratio of 3:1. They are obtained from brown seaweeds Laminaria japonica, E. kurome, Eiseniabicyclis, Saccharina, Ascophyllum, Fucus, Sargassum, and Undaria species. Several reports have confirmed to have anticancerous, anti‐inflammatory, anticoagulant, and antioxidant properties in laminarin extracts of seaweeds [87]. Laminarin is widely used as filler composition in cosmetic products for the treatment of wrinkles, folds, and as anti‐cellulite agents [98, 99].
4.4.4.4 Ulvans
Ulvans are cell wall polysaccharide derived from the genus Ulva (Ulvaarmoricana, Ulvalactuca, Ulvarotundata, and Ulvarigida) of green macroalgae belonging to the Chlorophyta group. Ulvan roughly contributes from 9 to 36% dry weight of the biomass of Ulva and primarily consist of sulfated rhamnose, uronic acids (glucuronic acid and iduronic acid), and xylose units [88, 104, 105]. The ulvans are widely known for the antioxidative, chelating, gelling, moisturizing, and protective properties. The antioxidant capacity of ulvan is modulated by ROS scavenging and inhibition of lipid peroxidation. Besides, ulvans are also known to suppress antiaging by enhancing the endogenous enzymatic antioxidant systems such as superoxide dismutase, catalase, and glutathione peroxidase activities owing to the abundant sulfated polysaccharides [88, 90, 104]. Moreover, the gelling property of ulvan is not significantly affected in the presence of various cations (Ca2+, Cu2+, and Zn2+), in the pH range of 7.5–8.0 and temperature up to 180 °C makes it a rheological suitable in cosmetic formulations [88, 91].
4.4.4.5 Porphyran
Porphyrans are exclusively derived from Porphyra species belonging to genus Rhodophyta. Porphyran is a sulfated polysaccharide consisting of D‐galactose, 3,6‐anhydro‐L‐galactose, 6‐O‐methyl‐D‐galactose, and L‐galactose 6‐sulfate units [151]. Porphyran demonstrates high solubility in an aqueous solvent and safe for the skin when it is formulated in cosmetic products as a solvent in liquid or emulsion form. The bio‐functional activity of porphyrans includes skin whitening, anti‐inflammatory, and moisturizing properties and hence used in topical or systemic skin cleansers, cosmetic wipes, cosmetic cotton, sanitary cotton, wet tissue, skin lotion, skin cream, ointments, gel, face pack, shaving agents, facial cleansing agents, etc. [78, 88, 93, 100].
4.4.4.6 Carrageenan
Carrageenan is naturally derived from the Rhodophyta genus (carrageenophytes). Carrageenan is a sulfated polysaccharide with galactose units with alternating α (1–3) and β (1–4) bonds. There are three main classes of carrageenan, kappa (κ), iota (Ι), and lambda (λ) owing to differences in the degree of sulfation. Κ‐carrageenan has one sulfate moiety per disaccharide, Ι‐carrageenan has two sulfate moieties, while λ ‐carrageenan has three. Furthermore, Ι‐carrageenan and Κ‐carrageenan are used as gelling agents, and λ ‐carrageenan are used as thickening and viscosifier agent in cosmetic application due to its unique rheological properties [130, 131]. Carrageenan is known to decrease the effect of photoaging, sunburn, wrinkles, and skin cancer induced by harmful ultraviolet‐B rays (UVB) (290–320 nm) [132]. Several studies have demonstrated significant photo‐protection properties of carrageenan against detrimental effects of UVB‐induced cell damage and ROS, suggesting its crucial role as a photo‐protective cosmetic excipient in skin lightening products [101–103].
4.4.4.7 Agar
Agar is commonly known as agar or agarose, and is fundamentally a combination of two polysaccharides, agaropectin, and agarose obtained from several different genus of Rhodophyta. Agarose, the chief component of agar, consists of straight‐chain polymeric units of agarobiose. Agarobiose is made up of disaccharide units of D‐galactose and 3,6‐anhydro‐L‐galactopyranose. While the agaropectin consists of β‐1,3‐linked D‐galactose units altered with sulfate and pyruvate moieties [78, 88]. As mentioned earlier, the gelling property of these polysaccharides exclusively depends on the degree of sulfation and the number of 3, 6‐anhydrogalactose molecules present.
The distinctive property of agar to easily melt at 85 °C and solidify at 32–40 °C makes it a prominent candidate in various industrial, laboratory, cosmetic, and culinary applications. Furthermore, agar is a biocompatible and inert substance and hence can be readily formulated with various other biochemical compounds used in cosmetic products such as hand lotions, deodorants, antiaging treatment creams, facial and acne treatment, and so on [78, 82, 88, 92, 122].
Other agarose‐derived polysaccharides (agar oligosaccharides) also have antiaging, anti‐melanogenesis, skin brightening, and ROS scavenging properties [92, 133, 134]. There are two forms of agar oligosaccharides, namely, neo‐form and agaro‐form. Neo‐form AOSs are called neoagarooligosaccharides (NAOSs) and have repeating neoagarobiose units composed of d‐galactose at the nonreducing end and 3,6‐anhydro‐L‐galactose [92].
4.4.4.8 Alginic Acids
Alginic acids are obtained from brown seaweed, i.e. Pheaeophyta genus. Alginic acid is made up of linear polymers of α‐l‐guluronic acid and β‐d‐mannuronic acid units connected by 1 → 4 glycosidic bonds. Alginates can rapidly form hydrogels in the existence of divalent cations (Mg2+, Ca2+etc) at room temperature. Moreover, Na+‐alginate and Ca2+_alginate are used in microencapsulation and immobilization of various compounds, enzymes, cells, etc. owing due to its gelling, biocompatibility, and biodegradability properties [135]. The chelating and gelling properties of alginates have widely attracted its use in cosmetic products as thickeners, emulsion stabilizers, hand jellies, ointment bases, skin lightening face packs, wound dressing for skin recovery, etc. The alginate masks are known to restore type I and type III collagen synthesis in the skin, and also helps in moisturizing by enhancing the water holding capacity of the skin. Furthermore, alginate is known to provide vital minerals and microelements to deeper dermal layers in the skin [136]. Several commercially available formulation is exploiting the benefit of alginate in the treatment of ulcers, wounds, and skin burns anti‐cellulite programs, face sculpturing, and skin regeneration therapy [136–138] (Figure 4.3).
4.4.5 Pigments from Algae
