Introduction

Microalgae are fast-growing species formed by one or multiple simple cells that are able to live in extreme environmental conditions (e.g., temperature variations, oxygen absence, increased salt concentration, photo-oxidation, osmotic pressure, and high ultraviolet (UV) radiation). Their productivity exceeds that of high vascular plants, since they have shown less seasonal variation and easier extraction processes of useful compounds, producing abundant raw materials. They can be artificially cultivated in batch, fed-batch, or continuous systems. In such processes, the culture conditions could be modulated to obtain autotrophic, heterotrophic, or mixotrophic growth according to biomass applications (Safafar et al. 2015; Chen et al. 2017; Hu et al. 2018). Thus, different closed systems for microalgae production have been developed to be applied at industrial scale. Such closed systems, known as photobioreactors, have been designed to ensure high microalgae quality with high productivities for different industrial applications (Bresaola et al. 2019; Avila-León et al. 2020). One of the fastest growing applications in biorefineries is pigment production (Ruiz et al. 2016; Khanra et al. 2018; Cezare-Gomes et al. 2019). Therefore, microalgae species are sources of biofuels, feed additives, food, and other compounds; they could be used in wastewater treatment as well as nutraceuticals and potential pharmaceuticals (Caporgno et al. 2015; Wang et al. 2015; Hamed 2016; Zhang et al. 2020).

Different microalgae compounds have been studied for their biological activities, such as anti-mutagenic, anti-allergic, antiviral, immune-enhancing, anticancer, lipid-lowering, as well as hepato-protective (De Jesus Raposo et al. 2013a; De Jesus Raposo et al. 2013b; Koller et al. 2014; Sathasivam and Ki 2018). Moreover, the presence of a high amount of pigments is conducive to enhance their antioxidant activities (De Jesus Raposo et al. 2013a; Safafar et al. 2015; Wang et al. 2015).

Free radicals, such as superoxide anions (O2·−) or hydroxyl radicals (·HO), have high oxidizing potency that can cause irreversible injury to human tissues, cell membranes, and genetic material. Thus, deleterious effects such as wrinkles, spots, and other aging signs are evident in skin (Lorencini et al. 2014). As it is well known, personal care products containing microalgae extracts have developed to claim antioxidant and anti-aging properties. Hence, this mini-review briefly reports cosmetic and cosmeceutical potential applications of biopigments obtained from microalgae and cyanobacteria biomasses.

Microalgae in cosmetics and cosmeceuticals

One of the most accepted definitions of cosmetics is “articles intended to be rubbed, poured, sprinkled or sprayed on, introduced into, or otherwise applied to the human body or any part for cleansing, beautifying, promoting attractiveness, or altering the appearance” (Brandt 2011). Therefore, cosmetics are not designed to disturb human structure and function, controversially to drugs/medicines. On the other hand, cosmeceuticals are a mid-step between cosmetics and drugs, not globally harmonized, and sometimes called as over-the-counter products (OTC) in the USA or quasi-drugs in Japan. The nomenclature is controversial and lies mainly on the concentration of active ingredients, stratum corneum penetration, mechanism of action elucidation, and clinical trials to validate claims (Wanjari and Waghmare 2015). Herein, the terms “cosmetics” and “cosmeceuticals” will be addressed as one single class in this publication.

Microalgae use in cosmetics/cosmeceuticals is an interesting strategy to fill the increment in searching of new natural ingredients from environmentally sustainable biomass, since they have high productivity and easy extraction under controlled conditions (Wang et al. 2015). Thus, new extraction and purification methods have been tested to explore its potential in cosmetics, since the whole microalgae biomass is difficult to incorporate in cosmetic formulations.

Scientific research about the biological activities of microalgae extracts or their compounds enhance the development of several cosmetic products containing microalgae, such as rheology modifiers, like some described polysaccharides (Delattre et al. 2016; Mourelle et al. 2017). Other molecules may induce biochemical mechanisms on the skin: biopeptides to collagen stimulation (Apone et al. 2019), as well as astaxanthin and its esters with high antioxidant properties to inhibit hyperpigmentation from tyrosinase (Rao et al. 2013). Therefore, those molecules may be available in some commercial cosmetic formulations, including anti-aging and regenerating creams, emollients, sunscreens, and hair care products (Ariede et al. 2017, 2020; Couteau and Coiffard 2018; Zhang et al. 2020). However, only a few products are commercialized worldwide. Thus, biopigments extracted from microalgae biomass are good alternatives with potential for new market due to the fast-growing ability and the high pigment content with a vast variability of colors without or minimum risk of skin allergenic effects (Begum et al. 2016; Saini et al. 2020; Zhang et al. 2020).

Microalgae as a source of pigments for cosmetic applications

Table 1 summarizes microalgae pigment application in cosmetics available on the market. Natural pigments derived from the microalgae photosynthetic system are responsible for biomass color. Photosynthetic pigments are chemical substances divided into three groups: carotenoids, chlorophylls, and phycobiliproteins. Thus, autotrophic organisms, such as plants, algae, and cyanobacteria, use them to capture solar energy to be transformed into chemical energy by photosynthesis (Varela et al. 2015). Considering microalgae production, as it is largely reported in specialized literature, controlled environmental conditions during cultivation could enhance the production of lipids, proteins, and pigments (Koller et al. 2014; Hamed 2016; Bresaola et al. 2019; Avila-León et al. 2020). Extraction and application of microalgae compounds for cosmetics are related to the most traditional species in literature, such as Dunaliella, Chlorella, Haematococcus, and Arthrospira (Ariede et al. 2017; Mourelle et al. 2017; Zhang et al. 2020). Among the different pharmacological activities demonstrated for some microalgae compounds, pigments from microalgae could be applied in cosmetics, as recently reported (Mourelle et al. 2017; Couteau and Coiffard 2018).

Table 1 Cosmetic products on the market with pigments from microalgae.
Full size table

Table 2 shows the novel discoveries in pigment production. It is remarkable that not only environmental conditions for microalgae cultivation but also extraction methods induce a strong influence on the final pigment concentration on biomass. Consequently, these aspects are the most important keys in choosing species to obtain compounds for new innovative cosmeceuticals.

Table 2 Pigment composition examples in recent studies of photosynthetic microorganisms
Full size table

Carotenoids

Isoprenoid molecules, named carotenoids, are the main pigments (yellow to red) in vegetables, flowers, fruits, and even insects, birds, and marine species. They are classified into xanthophylls and carotenes. Microalgal eukaryotes contain such pigments as crucial constituents to absorb light energy in photosynthetic reactions as well as photoprotective defenses against high light stress. Carotenoids are currently used as natural color enhancers or to add healthy claims into food, cosmetics, and even pharmaceutical products (Ryu et al. 2015). Thus, carotenoids have been largely explored due to their health benefits (Sathasivam et al. 2017).

Among microalgae, Dunaliella sp. and Haematococcus sp. are largely studied for carotene production. Many studies focused on changes of light and nitrogen regimes to enhance carotenes and xhantophylls biosynthesis. For instance, high light intensities could induce high β-carotene and astaxanthin production in Dunaliella salina and Haematococcus pluvialis, respectively (Koller et al. 2014; Safafar et al. 2015; Hamed 2016). Carotenoids, one of the most important microalgae pigments from Dunaliella sp., are considered safe natural dyes and have been used for different applications in food and cosmetics industries due to their coloring (Novoveská et al. 2019).

The biological activities of carotenoids in the skin are associated to their provitamin A function, as well as the property of photoprotection against UV radiation, as physical quenching. Hence, the direct absorption of UV light is the mechanism of action to prevent sun damage to the skin. Some clinical studies demonstrated that premature skin aging could be controlled by using carotenoids as nutricosmetic ingredients (Yeager and Lim 2019).

Xanthophylls are oxygenated molecules, e.g., astaxanthin, lutein, canthaxanthin, zeaxanthin, and fucoxanthin (Fig. 1). Among xanthophyll industrial production, astaxanthin showed the most promising market (Panis and Carreon 2016; Zhang et al. 2020). However, fucoxanthin production of some microalgae species was recently evaluated by means of salinity effects on pigment production (Ishika et al. 2017). Recently, three groups of volunteers/subjects were treated with lutein and zeaxanthin: the first group received both molecules in oral and topical applications; the second one received the association topically; and the third one only received oral supplementation. The results revealed that all treatments showed significant enhancement of skin elasticity with cutaneous hydration more pronounced in the combined treatment than in the isolated ones. The synergistic effect of oral and topical treatments also provided the highest degree of antioxidant protection (Palombo et al. 2007).

Fig. 1
figure 1

Main carotenoids and summarized carotenogenesis

Full size image

Regarding the most of carotenoids, their maximum wavelength absorption ranges are in the visible region. Phytoene and phytofluene are the exceptions, which absorb wavelengths covering the UVB and UVA regions as a response of their 3 and 5 conjugated double bonds, respectively. Accordingly to their versatility, many cosmetic effects of carotenoids have been studied (Stahl and Sies 2012). However, the real application for optimum skin health is under discussion, with recent application in patents (Table 3).

Table 3 Recent patents using microalgae pigments for cosmeceuticals
Full size table

Chlorophylls

Chlorophyll is easily extracted from microalgae biomass. Thus, it can be used in food, pharmaceutic, and cosmetic industries thanks to its high green pigmentation. Particularly, chlorophyll from Chlorophyta species is also used as dyeing, as well as in products with anti-inflammatory properties. Moreover, some detailed studies are recently compiled in some reviews (Ariede et al. 2017; Levasseur et al. 2020; Yarkent et al. 2020). For instance, it exhibits the ability to mask odors in deodorants, toothpastes, and other hygienic products (Mourelle et al. 2017).

Phycobiliproteins

Phycobiliproteins are formed by phycobilins bounded to water-soluble proteins. For instance, phycocyanin is a blue pigment from cyanobacteria while phycoerythrin is from red algae (D’Alessandro and Antoniosi Filho 2016). As it is known, phycocyanin has been studied due to its antioxidant and anti-inflammatory activities, as well as immune enhancer. Moreover, another important point is its stability that turns phycocyanin into a valuable ingredient in cosmetic formulations, like lipsticks, eyeliners, eye shadow powders, and perfumes (Sekar and Chandramohan 2008), and it has already been approved as food colorant (Table 2).

Toxicological aspects (safety) of microalgae pigments

In the last decades, many studies have been published about the chemical composition and functional ingredients of several species of microalgae. Nevertheless, the potential toxicity of some species should also be considered. Recently, there has been an emphasis on the adverse effects of algae on fisheries, aquaculture, and freshwater resources (Rhodes and Wood 2014). Algal cells have developed different strategies to defend and adapt to their environment, which in some cases include the production of metabolites, including some with biological activities and also toxins, known as phycotoxins (Rhodes and Wood 2014; Caruana and Amzil 2018).

Nonetheless, of the thousands of microalgae species that exist, only around 200 are considered to have harmful effects, and just about 100 species have the capacity to produce toxins (Hallegraeff 2014; Caruana and Amzil 2018). The main toxic microalgae include dinoflagellates (e.g., planktonic and benthic genus) and diatoms (e.g., planktonic genus). In humans, phycotoxins can lead to different harmful effects, including gastrointestinal, skin, and neurological problems, and they are even lethal in some cases (Hallegraeff 2014; Caruana and Amzil 2018). Furthermore, microalgae and its extracts can also contain heavy metals, inorganic arsenic, or cyanotoxins (Rzymski et al. 2015; Scoglio 2018). In addition, standard guidelines provided by international regulatory organizations (e.g., Food and Drug Administration (FDA)) could be a valuable tool to guarantee the quality and safety of microalgae-derived compounds (Buono et al. 2014). Moreover, the use of proper extraction techniques may be a valuable strategy to obtain pigments or other components from microalgae avoiding the presence of harmful residues of phycotoxins or other toxics. Thus, microalgae from aquaculture, which has a more controlled environment, can avoid some toxicological risks of contamination and bioaccumulation when compared with those from natural sources. Nevertheless, industry should implement monitoring systems to detect the presence of harmful algal species, phycotoxins, and other toxic compounds throughout the manufacturing process. In the last years, important advances have been achieved towards the development of more specific, sensitive, and rapid methodologies that allow the identification of the different microalgae species and toxins (Penna and Galluzzi 2014).

In addition to this, legislations and regulatory aspects about the commercialization of carotenoids from microalgae biomass are recently described for food and cosmetic products in the USA, Japan, China, and Europe (Novoveská et al. 2019). Thus, astaxanthin, β-carotene, and chloprophyll derived from some microalgae species are regulated and approved by the FDA due to their nontoxic and noncarcinogenic properties (Begum et al. 2016). Moreover, astaxanthin from Haematococcus pluvialis has been approved as a color additive in Europe, the USA, and Japan. Thus, it is approved for direct human consumption and has been recognized as safe by the FDA using “generally recognized as safe (GRAS)” status (Davinelli et al. 2018).

Potential use of microalgae pigments in cosmetics

The increased use of algae in the cosmetic industry is due to the fact that some algae have promising properties, like antioxidant and collagen production stimulant (anti-aging) (Ariede et al. 2017). Also, the incorporation of safe microalgae compounds in cosmeceuticals adds organic value to these products.

Considering that the incorporation of microalgae extracts and compounds into cosmeceuticals is kept as an industrial secret, this section presents some tendencies about pigments from microalgae in cosmetics (Table 3). Cosmetic Ingredient Database (CosIng) offers more than 120 examples of ingredients derived from microalgae (European Commission 2020). Most of them are related to extracts or polysaccharide compositions; however, there is no evidence of pigments isolated from microalgae biomass in such important reference. Finally, regarding safety aspects, it is essential to select nontoxic microalgal species and analyze each toxicological profile before industrial applications. Hence, nontoxic microalgae and cyanobacteria could be a valuable source of biopigments and other bioactive compounds with potential health-promoting properties, as well as cosmeceutical properties for novel products with high quality assurance.

Conclusions and perspectives

We briefly summarize the cosmeceutical applications of pigments derived from microalgae biomass. Currently, there are researches conducted for the enhancement of knowledge on the application of active ingredients in cosmeceuticals claiming antioxidant, anti-inflammatory, and antipollution activities (Velasco et al. 2018), with further skin collagen production stimulant, among others. Thus, the biopigments described among this study were safe, highly efficient, and with low environmental impact. Several compounds found in microalgae species have these potential characteristics, with emphasis on the pigments that are already part of the formulation of some cosmetics and personal products, claiming organic value. Otherwise, production of these biopigments may be considered relatively expensive, with a consequent increment in costs of final raw materials. In addition to this, microalgae cultivation is linked to high demand of water, although water recycling in “red stage” production could decrease water footprint (Panis and Carreon 2016). However, it is important to recognize that the rapid growth with simple medium composition of most microalgae strains could be cited as the best advantage to produce their pigments in large scale. Furthermore, the increase in pigment production by microalgae and cyanobacterial species with a significant reduction in costs is a very attractive field for industries to use these biopigments in personal care products. Thus, one of the most promising ways to make this challenge possible is to obtain detailed information on DNA sequencing, for instance, to provide valuable information on metabolic pathways for metabolic and genetic engineering for the enhancement of biopigment production (Saini et al. 2020). Therefore, these aspects reflect the importance of the growing interest for the discovery of new applications for microalgae pigments. Despite the complications of stablishing extraction methods environmentally safer, there is still a need for further investigations to evaluate safety, efficacy, and real potential alternatives of using microalgae pigments in the cosmetic industry.