of photosynthetic pigments categorized as chlorophylls, carotenoids (carotenes and xanthophylls), and phycobilins [139]. The chlorophylls and carotenes are fat‐soluble molecules and can be readily extracted by using organic solvents (acetone, methanol, or DMSO). However, the phycobilins being water‐soluble can be extracted by using polar and nonpolar solvent mixtures. Most of these pigments can counteract against the UV light exposure during growth and development of algae and are known to involve in protecting the cell against harmful oxidative ROS species [140, 141]. Hence, these pigments are used in cosmetic formulations not only to reduce the oxidation of oils, occurring due to rancidity, but also to reduce skin aging, owing due to antioxidant nature. Moreover, these pigments are a natural source of dyes and colorants, making it useful in the various cosmetic industry as the replacement against synthetic dyes (Table 4.2). The various pigments and their cosmeceutical application with respect to antiaging and skin lightening are discussed as follows.
4.4.5.1 Phycobiliproteins
Phycobiliproteins obtained from algae and cyanobacteria are categorized into three main classes depending on absorption properties: phycoerythrins (PE, λ = 540–570 nm), phycocyanins (PC, λ = 610–620 nm), and allophycocyanins (APC, λ = 650–655 nm) [118]. PEs are of utmost interest owing to their fluorescent and antioxidant properties. These pigments are red and are known to absorb light in the green wavelength (λ = 498 and λ = 565 nm) and emit in the yellow wavelength (λ = 573 nm). In vitro, the antioxidant activity of PE is a well‐studied phenomenon in Caenorhabditis elegans, which resembles the human aging pathways, wherein PE is known to upregulate enzymes such as superoxide dismutase, catalase activities, and reduce oxidative stress damage [142]. The PC and APC are also known to express antioxidant activities and radical‐scavenging properties in several studies [97, 119, 120]. PC is involved in inducing expression of heme‐oxygenase‐1 (HO‐1), thereby reducing the UV‐B‐induced cell death in skin cells, demonstrating the photo‐protective role [121].
Figure 4.3 Important carbohydrates from algae used in cosmetic applications.
Source: Aderibigbe et al. [136], Dantas et al. [137] and Huang anf Fu [138].
4.4.5.2 Chlorophylls
Chlorophylls are green pigments and are fat‐soluble. They are predominantly found in algae, cyanobacteria, and higher plants. Both chlorophyll‐a and chlorophyll‐b are known for their exceptional antioxidant properties. Moreover, chlorophyll pigments are known to absorb light in red and blue regions; hence, they are used as an excellent coloring agent in cosmeceutical formulations and food industry (identified as E140 and E141 in the European Union) [112]. Chlorophyll‐a and its breakdown product (pheophorbide‐a) are used as a photosensitizer, which can carry out photodegradation of harmful UV rays. Both chlorophyll and pheophorbide‐a are effective in diminishing skin‐related inflammation and reducing wrinkles arising from UV rays [113]. Moreover, pheophorbide‐a has a profound role in inhibiting the production of MMPs, which are induced by UV rays, suggesting a potential role in the cosmetic formulation [113, 114].
4.4.5.3 Carotenoids
Carotenoids are lipophilic compounds, belonging to the class of tetraterpenoids, containing 8 isoprene units with at least 40 carbon atoms [106, 143]. The peculiar feature of carotenoids is to absorb wavelengths in the range of 400–550 nm (violet to green light), resulting in deeply colored yellow, orange, red, or colorless compounds subjected to presence or absence of conjugated double bonds [107]. Carotenoids can be classified into two groups based upon the availability of oxygen. Xanthophyll group shows the presence of oxygen (e.g. astaxanthin, fucoxanthin, zeaxanthin, violaxanthin, loroxanthin, and lutein), while carotenes groups are devoid of oxygen and contain pure hydrocarbons (α, β, γ‐carotene, and lycopene) [106]. Carotenoids are present in the stratum corneum of human skin, which imparts the normal skin color and UV protection [108]. The worldwide carotenoids production is expected to reach $1.53 billion by 2021, primarily dominated by β‐carotene, lycopene, astaxanthin, zeaxanthin, and lutein owing to their well‐established applications in cosmetics, food, confectionary, and aquaculture (Figure 4.4).
4.4.5.4 β‐carotene
β‐carotene are known to be precursors of vitamin‐A and are known to impart orange color. β‐carotene are widely explored for providing good vision, healthy skin texture, and functioning of the mucous membrane [79]. The antioxidant potential of β‐carotene is widely demonstrated by numerous studies, and hence they are used as radical scavenging as an antioxidant in cosmetic creams, formulations, sunscreen lotions to enhance the appearance of dry or damaged skin, reducing skin flake, restoring moisture, and suppleness of the skin. β‐carotene is very popularly used in sunscreen lotions as a photo‐protective ingredient because of its ability to protect the skin against early aging damaged by UV rays [109]. Furthermore, β‐carotene is a pro‐oxidant involved in the peroxidation of lipids [110]. Numerous microalgae such as Chlorella, Spirulina, and Dunaliella salina are cultivated for the production of β‐carotene.
Figure 4.4 Important carotenoids pigments from algae used in cosmetic applications.
4.4.5.5 Canthaxanthins
Canthaxanthins are keto‐carotenoid pigments and are orange‐red in color, predominantly found in bacteria, fungi, algae, land plants, and animals. Being a carotenoid, they have a potential role in free radical scavenging and have antioxidant properties (initiated by catalase and superoxide dismutase) [144]. They are known to produce an orange‐brown color in the skin are used as sun tanning pills (Orobronze) [108, 145].
4.4.5.6 Astaxanthin
Astaxanthin belongs to a xanthophyll and is another recognized pigment used in the aquaculture industry for providing red and pink color to aquatic fish and shrimps [106]. Haematococcus pluvialis is a well‐known species that produces astaxanthin up to 3–7% of dry cell mass. In human dermal fibroblasts (HDF), astaxanthin are proven to be potent against UVA‐induced oxidative impairment [146]. Astaxanthin neutralizes free radicals or other oxidants by involving in redox reaction and slowing down the age‐related skin process. In another study, a 6‐mg per day oral dose and 2 ml per day topical application of astaxanthin‐derived Haematococcus pluvialis showed improvements in skin wrinkle, age spot size, elasticity, skin texture, and increase in the moisture content of corneocyte layer suggesting its effective role in antiaging and skin protection [147].
4.4.5.7 Fucoxanthin
Fucoxanthin belongs to a xanthophyll found in brown algae (Fucus, Dictyota, and Laminaria) and diatoms. Fucoxanthin is known for its high commercial value in the global market for its various biological properties such as anti‐obesity, antioxidant, anti‐inflammatory, anticancer, and skin photo‐protection [115]. Fucoxanthin suppress ROS formation, reduce cell DNA
