Bioprospecting of Microorganism-Based Industrial Molecules. Группа авторов

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 damage and are known to delay the apoptosis induced by hydrogen peroxide [116]. Fucoxanthin has been reported to reduce the enzyme tyrosinase in UVB‐irradiated dermal cells of guinea pig and inhibit melanogenesis in UVB‐irradiated mice. Oral treatment of fucoxanthin has been found to downregulate the skin m‐RNA expression associated with melanin production [117].

      4.4.5.8 Zeaxanthin

      The xanthophyll cycle is involved in the removal and addition of epoxy group from xanthophyll. The zeaxanthin is the product of a de‐epoxidized xanthophylls and has known to be involved in a photoprotective role and as an antioxidant. Although zeaxanthin was primarily known to be isolated from Zea maize, they are also found to be present in algae as well. Zeaxanthin is known to inhibit tyrosinase enzyme averting hyperskin pigmentation, thereby acting as a skin whitening agent. The pure extract of Nannochloropsis oculata, which contains zeaxanthin, as an antityrosinase substance [148]. Lutein‐ and zeaxanthin‐containing creams (Lutemax® 2020) are known to promote skin lightening and improve skin health conditions [149].

      4.4.5.9 Violaxanthin

Violaxanthin is an orange‐colored, natural xanthophyll pigment occurring in a variety of algae and land plants. Violaxanthin pigments are biosynthesized from its precursor zeaxanthin by undergoing epoxidation carried out by de‐epoxidase enzyme. It is approved as a food additive coloring agent and only in countries like Australia and New Zealand (INS number 161e). Violaxanthin extract from microalgae Nannochloropsis oceanica has shown to reduce skin photoaging, induced by ultraviolet B (UVB) radiation in HDF [150].

Figure 4.5 Important secondary metabolites and mycosporine‐like amino acids from algae used in cosmetic applications.

      4.4.6 Secondary Metabolites

Various secondary metabolites are known to obtain from algae and are formulated in cosmetic products. Phlorotanins derived from algae Eisenia bicyclis, Ecklonia cava are proved to benefit the skin by reducing the elastase activity significantly. Mycosporine‐like amino acids (MAAs) such as scytonemin, asterina‐330, shinorine, and palythine are well‐known UV‐protective compounds, found in most of the algal and cyanobacterial species and widely used as photoaging protectant [79,122–124, 141] (