Introduction

Cosmetics are products applied to the human body for the purpose of alteration or enhancement of appearance. Cosmeceuticals contain active nutrients or ingredients such as vitamins, minerals, essential amino acids, fatty acids and antioxidants that are designed to cleanse, beautify, and promote attractiveness. The active ingredient can be incorporated in products in the form of creams, ointments, powders, gels, or lotions (Hatziantoniou et al. 2024). The value of the global cosmeceutical industry was estimated at nearly US$50 billion in the year 2021 and is likely to increase to ~ US$114 billion by 2030. The Asia Pacific region currently dominates this with ~ 40% of the market (Cosmeceuticals Market Size, Share & Growth Analysis [2030] 2023). The increasing recognition of the cosmetic industry’s value has been accompanied by a reliance on synthetic chemicals. This has also led to a growing interest in natural product alternatives that offer a wealth of benefits for skin care. The global surge in environmental awareness and improving health trends through the adoption of ‘green’ consumption patterns are leading to increased demand for, and use of, environmentally friendly products, such as cosmetics with natural ingredients that avoid the use of chemical additives. The development of allergic reactions and skin damage issues arising from the use of synthetic beauty products inevitably draw the attention of consumers to the environmental impacts of cosmetic items (Pudaruth et al. 2015). This trending desire in healthy, safe, and clean cosmetics is promoting the active transition towards natural products as a safer alternative due to the potential adverse effects that traditional products may have (Suphasomboon and Vassanadumrongdee 2022).

Marine resources represent a plentiful and prospective source of distinctive as well as active compounds with the potential to produce green and eco-friendly products (Ariede et al. 2017; Guillerme et al. 2017). Among these resources, seaweeds have successfully gained attention as sources of cosmeceuticals recently due to their effectiveness in skincare, as demonstrated in numerous scientific studies (López-Hortas et al. 2021; Noviendri et al. 2022). For instance, brown algae are a well-known source for fucoxanthin, a xanthophyll that has demonstrated bioactivities such as photoprotection (Matsui et al. 2016; Tavares et al. 2020) and anti-aging (Cao et al. 2020). In the current literature landscape, there has been increased focus on the exploration of microalgae due to their fast growth rate, high biomass, and minimal need for cultivation space. These advantages promote their potential as valuable bioactive sources (Yap et al. 2021).

Microalgae are photoautotrophic microorganisms that produce distinct functional secondary metabolites in response to stress (Zhuang et al. 2022; Kolackova et al. 2023). Some of these compounds have diverse biochemical properties relevant to human nutrition and health. These compounds derived from microalgae, such as pigments, lipids, phenolics, and polysaccharides, have gained traction in the cosmeceutical industry due to their valuable functions such as whitening, photoprotective, anti-aging, antioxidant, and anti-inflammatory activities (Thiyagarasaiyar et al. 2020; Yarkent et al. 2020; Saide et al. 2021; Martínez-Ruiz et al. 2022). Hence, exploration of microalgal products opens possibilities for the development of novel cosmetics and cosmeceutical formulations.

Microalgae have the potential to provide alternative sustainable resources of high value bioproducts due to their natural availability, diversity, and versatility (Nethravathy et al. 2019). The sustainable and unique characteristics of microalgae underpin their potential for use in the development and manufacture of cosmetic products. Studies have demonstrated this through the incorporation of extracted microalgal compounds as a primary active ingredient in diverse products such as sunscreens, face lotions, creams, shampoos, body soaps, and colorants for cosmetic formulations (Yarkent et al. 2020). Aside from these products, microalgae also have potential benefits in wellness treatments such as thalassotherapy due to their abundance of bioactive compounds. Therefore, it is of interest to spa and thalassotherapy centres to incorporate microalgal products in their treatments for the improvements in skin moisture, elasticity, and fatigue (Mourelle et al. 2017).

Growing environmental awareness globally and resulting increases in green consumption patterns are highlighting the crucial need for consumer research in this burgeoning sector. Hence, this review provides an overview of the changing balance in the use of long-established topical agents used in whitening cosmetics and other products obtained from microalgae as a favourable alternative for the future beauty industry.

Existing whitening cosmetics and their drawbacks

Various traditional agents such as hydroquinone, kojic acid, and azelaic acid, are commonly used in the cosmetic industry with a wide range of functions. These synthetic ingredients are known to be incorporated in formulations of many cosmetic products. They are often used to treat skin pigmentary disorders and acne-related skin issues. These agents also provide anti-aging, anti-bacterial, and anti-inflammatory activities (Owolabi et al. 2020; Liu 2022; King et al. 2023). While it is clear that marketed products incorporate these agents in their formulation, accurate and up-to-date information regarding their efficacy and safety remains inadequate. These widely used topical agents have proven effectiveness in treating aesthetic-related skin disorders in past studies; however, potentially adverse effects have received insufficient attention in clinical trials and safety profile studies (Table 1) (Sinha et al. 2016; Meena et al. 2017; Shakeel et al. 2021).

Table 1 Uses of topical agents and their reported adverse effects
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Hyperpigmentation disorders, acne and aging skin are amongst the common aesthetic conditions affecting all skin types. A range of topical medications, chemical peels, injectable products, and energy-based devices are among the current therapeutic options commercially available for these disorders. Topical treatments, including creams, gels, lotion, foams, solutions, and ointments, are generally the first line of treatment, and they are widely and easily available ‘over the counter’ (OTC) and are affordable (Alghamdi et al. 2021; Moolla and Miller-Monthrope 2022). This ease of availability also underlies cases of misuse increasing in prevalence in recent years, with the highest rates of such abuse being recorded in Africa, Asia, the Caribbean and the Middle East, as well as in immigrant populations in North American and Europe regions (Ah et al. 2019; Khamanarong et al. 2021). Most individuals using these products do so due to reasons related to social preference (peer group pressure) and of the perceived importance of better skin appearance (Ah et al. 2019; Alghamdi et al. 2021).

As an example, the use of topical hydroquinone for depigmenting purposes has become widespread in recent decades and its use is common in managing various pigmentation-related conditions such as melasma, age spots, freckles, and post-inflammatory hyperpigmentation (PIH) resulting from acne or trauma (Juliano 2022). Although hydroquinone is often regarded as the dermatological gold standard among traditional topical treatments for the treatment of such conditions, many reports have associated its use with various adverse side effects, particularly when used long-term, including skin irritation and contact dermatitis, while ochronosis, nail discolouration, corneal degeneration, and conjunctival melanosis have also been discovered when hydroquinone is used persistently (Bandyopadhyay 2009; Gandhi et al. 2012; Glazer et al. 2016). Trimethylaminuria, commonly known as “fish odour syndrome”, is a rare consequence of prolonged hydroquinone use and results from trimethylamine excretion in urine, vaginal secretions, sweat and saliva (Ladizinski et al. 2011).

Other established topical agents, including tretinoin, kojic acid, and azelaic acid, have been considered as alternatives to hydroquinone. Known adverse effects of some of these agents, such as kojic acid and azelaic acid are mild and transient when applied at the recommended concentration (Liu et al. 2006; Liu 2022). Common side effects include local cutaneous irritation symptoms (Fitton and Goa 1991; Liu et al. 2006; Grobel and Murphy 2018; Liu 2022). Aside from the clinical consequences noted on the skin, non-cutaneous adverse effects involving respiratory and neurological events have been reported in past studies of topical tretinoin usage (Shapiro et al. 2011). Selcen et al. (2000) revealed the association of otocerebral anomalies associated with topical tretinoin use. During the early development of the structures during embryogenesis, severe malformations of auricles were evident from tretinoin toxicity.

While various local adverse effects caused by topical agents have been documented, information relating to systemic impacts is scarce. In order to improve the efficacy and reduce the occurrence of side effects, the combination of other agents such as hydroquinone and tretinoin has been used to develop combinations of topical cream product (Ah et al. 2019). However, contact dermatitis characterised by acute onset redness, itching, burning, and cauterised appearance of facial skin, was still prominent in patients after usage (Nordlund et al. 2006; Mathe et al. 2021). Such outcomes have led to increasing concerns about the long-term effects caused using these established topical agents.

Role of microalgae in skin whitening, photoprotection and anti-aging products

Increasing awareness of the negative effects that synthetic materials can have on both health and the environment have fuelled a notable alteration in customer preferences towards natural skin care products. As a result, research interest in cosmeceuticals is shifting towards natural bioactive compounds generated from a variety of natural resources (Amberg and Fogarassy 2019).

Microalgae are known renewable and sustainable sources due to their economical cultivation and versatile capabilities in producing a broad spectrum of metabolites (Mourelle et al. 2017; Puchkova et al. 2020). They are an eco-friendly choice for cosmetics, aligning with the growing demand for ‘green’ cosmeceuticals. Microalgae are now a popular choice in cosmeceutical research on account of the high diversity of bioactive compounds that impart a plethora of remarkable skin benefits (Puchkova et al. 2021; Martínez-Ruiz et al. 2022).

Various microalgal-derived compounds including pigments, proteins, peptides, polyunsaturated fatty acids (PUFAs), phytosterols, polyphenols, amino acids, carbohydrates, and vitamins have been revealed to exhibit biological activities such as protection from stress (antioxidant, anti-aging and anti-inflammatory properties) and promotion of skin quality (skin brightening, moisturising activity and collagen synthesis) (Choo et al. 2020; Martínez-Ruiz et al. 2022). This diverse range of beneficial compounds combined with their strong safety profiles has led to enthusiasm for research exploring their application in the cosmetic industry (Aslam et al. 2021; Udayan et al. 2023).

Skin whitening and pigmentation control

Light skin tones have long been associated in Asian cultures with youth and beauty. Considerable growth in investment in the manufacture of skin-whitening products and their use has been evident in Asian markets, largely in China, Korea, Japan, and India (Pillaiyar et al. 2017; Masum et al. 2019; Khamanarong et al. 2021). The pigmentation of human skin, hair, and eyes is determined by the amount of melanin produced through melanogenesis. The functional role of this pigmentation is to act as a protective barrier against damaging UV injury to the skin. However, an uncontrolled generation or accumulation of melanin also gives rise to potentially significant aesthetic problems, such as melasma, post-inflammatory hyperpigmentation, lentigo, and even cancer (Pillaiyar et al. 2017; Favas et al. 2021). To overcome such conditions, research effort has focused on the key regulatory enzyme in melanogenesis, tyrosinase.

Tyrosinase is a crucial determinant in melanin synthesis, and tyrosinase inhibitors have therefore been the centre of attention in research studies into reducing or inhibiting skin pigmentation (Pillaiyar et al. 2017). Commercially available topical agents for hyperpigmentation treatment, including hydroquinone, kojic acid, azelaic acid, and arbutin, are well-known tyrosinase inhibitors. However, despite their widespread use in the market as whitening agents in the market, these compounds have disadvantages (Pillaiyar et al. 2017; Favas et al. 2021). In additions to reported adverse effects such as contact dermatitis, irritation, high toxicity, and skin sensitivity, many of these compounds also showed poor skin penetration and low formulation stability (Masum et al. 2019). As a result, there is a crucial need to discover and develop novel tyrosinase inhibitors from various sources that are effective with minimal side effects and microalgae can be a promising alternative.

Initial studies have reported a range of microalgal extracts demonstrating tyrosinase inhibition similar to traditional whitening agents. Some carotenoids and phenolic compounds derived from microalgae exhibit effective anti-melanogenic effects accompanied by other biological functions, including antioxidant, anti-cancer, and anti-aging activities. These have been demonstrated in compounds derived from microalgal species including Arthrospira platensis (Sahin 2018), Nostoc verrucosum (Sato et al. 2023), Schizochytrium limacinum (Kose 2023), Dunaliella tertiolecta (Ji et al. 2021), Haematococcus pluvalis (Rao et al. 2013), Oscillatoria agardhii (Sano and Kaya 1996), Nannochloropsis sp. (Kim et al. 2021), and Chlamydomonas reinhardtii (Sedjati et al. 2020) (Table 2).

Table 2 Microalgae species, extracted compounds, extraction methods and their potential use in cosmetics
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UV protection

High doses of ultraviolet (UV) radiation cause cell damage and produce reactive oxygen species (ROS). Photoaging is the superposition of the addition of solar radiation damage to the intrinsic aging process of the skin. Underlying mechanisms include reduction of skin collagen content due to upregulation of matrix metalloproteinases (MMPs), hyperpigmentation, and solar elastosis (Araújo et al. 2022). These consequences can be associated with increased inflammation as well as oxidative stress (Campiche et al. 2018). The UV part of the electromagnetic spectrum is primarily responsible for the detrimental effects of solar radiation. UV radiation is classified into three categories, namely UV-A (320–400 nm), UV-B (290–320 nm), and UV-C (200–290 nm).

Generally, UV-A and UV-B exposure are of concern related to UV radiation as they comprise a high proportion of the solar radiation energy that reaches the Earth’s surface (Santiesteban-Romero et al. 2022). UVC is of higher energy but is completely absorbed by oxygen and ozone in the atmosphere (Araújo et al. 2022). Chronic exposure to UV without protection induces alterations related to skin aging and greater risk of skin cancers (Santiesteban-Romero et al. 2022). Growing concerns regarding the ecologically and dermatologically negative impacts of most currently available sun protectants have, again, accelerated the need for development of safer alternatives.

Microalgae are a polyphyletic and biochemically varied assemblage of chlorophyll a-containing microorganisms capable of oxygenic photosynthesis that are primarily found in aquatic environments, often experiencing high UV radiation levels (Dionisio-Sese 2010; Araújo et al. 2022). To protect themselves from UV radiation damage while allowing exposure to visible radiation, needed to drive photosynthesis, some microalgae synthesise organic metabolites that can be incorporated into cosmetics to combat the harmful effects of UV radiation (Núñez-Pons et al. 2018; Saide et al. 2021). The presence and role of UV-absorbing compounds such as mycosporine-like amino acids (MAAs), sporopollenin, and scytonemin to mention a few, have been extensively studied and have shown promising results in effectively absorbing and filtering UV radiation (Núñez-Pons et al. 2018; Santiesteban-Romero et al. 2022; Ručová et al 2023). Such compounds function in UV protection by absorbing and scattering UV radiation, effectively preventing it from penetrating the skin and causing damage. Examples of other defence and/or tolerance mechanisms functioning within microalgae include DNA repair, synthesis of antioxidants, suppression of MMPs production, and promotion of fibroblast proliferation (Araújo et al. 2022; Rincón-Valencia et al. 2022).

The susceptibility of different microalgal species to UV radiation varies greatly though research has shown that Antarctic microalgal species are strong photoprotectors due to their evolutionary adaptations to the extremely harsh environment of polar regions (Teoh et al. 2004, 2020; Santiesteban-Romero et al. 2022; Montuori et al. 2023). They are characterised by high xanthophyll to chlorophyll ratios, implying a high content of UV-absorbing compounds (Santiesteban-Romero et al. 2022). Comparably, tropical microalgae have also exhibited a high potential to contain natural antioxidants such as carotenoids and phenols due to constant exposure to their surroundings that are characterised by high temperature, light, and UV radiation (Wong et al. 2011; Rahman et al. 2020; Wang et al. 2023). The harsh habitat that they exist in requires photoprotective compounds and defence mechanisms to shield themselves from potential damage triggered by excessive exposure to solar radiation and subsequently oxidative stress (Rahman et al. 2020; Sheibani Madrahi & Naeimpoor 2023).

Research on microalgae and their UV-protective properties has shed light on the potential of these organisms as sources of sustainable and effective alternative sources of compounds for UV protection (Dianursanti et al. 2020). For instance, most of commercial cosmetics used to date invoke a large range of Spirulina (Arthrospira) properties. Ragusa and colleagues (2021) reviewed the current emergence of Spirulina in effective and safe cosmetics applications including as a sunscreen (Ragusa et al. 2021). Moreover, a study by Ariede et al. (2020) that investigated the potential of Botryococcus braunii dry biomass in enhancing UV-B protection in topical formulations revealed an improved sun protection factor (SPF) when the biomass was combined with a self-emulsifying base. This study presents the on-going safety and efficacy improvements incorporating microalgae in cosmetics applications.

This opens new opportunities for the development of eco-friendly sun protectants. Through leveraging the inherent UV-protective attributes of microalgae and advancing understanding of underlying molecular mechanisms, innovative opportunities are likely to emerge to enable development of sun-care products that are both environmentally responsible and beneficial for human health.

Anti-Aging/Anti-wrinkle

Aging is a physiological process of atrophy that occurs over time. Intrinsic (genetic) and extrinsic (external) factors trigger and accelerate skin aging through the gradual structural disorganisation in the skin, causing wrinkles, blemishes, flaccidity, fragility, and dryness. Intrinsic elements include hormone responses, metabolic processes, stress, and lifestyle choices, while UV radiation, pollution, and toxicity reactions are examples of extrinsic influences (Falcao et al. 2020). Collagenase, elastase, and hyaluronidase are enzymes pivotal in the aging process, affecting the skin’s filling, elasticity, and moisture, respectively. Activity of these enzymes has been reported to be elevated in the presence of high levels of ROS (Hadi and Dianursanti 2021).

Microalgae extracts have shown to be effective inhibitors of these enzymes. Metabolites including carotenoids, PUFAs, peptides, phenols and phytosterols are known to be strong antioxidants, free radical scavengers and photoprotectors contributing inhibitory effects on such enzymes (Choo et al. 2020). As a result, induced cellular damage, ROS production, extracellular matrix (ECM) degradation and cellular senescence are suppressed. For instance, amino acids and carotenoids isolated from Aphanothece halophytica (Tarasuntisuk et al. 2018) and Dunaliella salina (Havas et al. 2022), respectively displayed protection from glycation-induced aging.

The explant model conducted by Havas et al. (2022) confirmed that compounds extracted from D. salina exhibited anti-glycation along with anti-inflammatory activity through reductions in key interleukins. Zhang et al. (2019) showed similar indications of anti-inflammatory and anti-aging properties expressed by a pigment-protein complex (PPC) derived from Chlorella pyrenoidosa. Further studies have confirmed that Nannochlorpsis sp. (Letsiou et al. 2017; Zainoddin et al. 2020; Kim et al. 2021), Chlamydomonas reinhardtii (Falcao et al. 2020), Trachydiscus minutus (Georgakis et al. 2023), Nostochopsis lobatus (Yamaguchi and Koketsu 2016), Pophyridium cruentum (Agustina et al. 2020), and Spirulina sp. (Hadi and Dianursanti 2021) all exhibit commercial potentiality in cosmetics due to their potent anti-aging and antioxidant effects (Table 2).

Patents are important indicators of the potential applications of research outputs and can be granted for any device, substance, process, or method that is novel, inventive and functional. The aptitude mention of microalgal in patents for cosmetic products and formulations is notable (Pazik and Gagala 2023). For instance, an invention that incorporated Nannochloropsis gaditana extract in cosmetic formulations indicated protection against oxidative stress and provided enhancement of skin elasticity. The protective role was achieved through stimulating increased expression of transcripts of fibrillin in skin cells, strengthening skin elasticity since this protein provides the scaffold for the proper conformation of elastin (Koutsianas et al. 2017).

Microalgae are increasingly accepted to be a sustainable choice for skin care products due to their capacity for self-renewal, basic nutritional requirements, minimal cultivation space, and low environmental impact characteristics. They can provide a wide range of applications capable of inhibiting skin aging features such as wrinkles development, pigmentation, collagen degradation and loss of elasticity (Favas et al. 2021).

Clinical efficacy of microalgae in cosmetic formulations and products

To realise the potential for microalgae-based cosmetic products in the industry, clinical trials, and tests of the efficacy of cosmetic formulations using microalgae are vital (Bagatin and Miot 2013). While there is ample research demonstrating the benefits of microalgae in skincare, there is a need for more comprehensive clinical trials to validate these claims and establish the effectiveness of microalgae-based cosmetic products (Puchkova et al. 2020; Martínez-Ruiz et al. 2022; Santiesteban-Romero et al. 2022). In addition to the existing research on microalgae, further in-depth studies are required to understand the specific mechanisms of action of different microalgal species and their bioactive compounds on the skin. This deeper understanding can provide insights into how these compounds interact with skin cells and the potential long-term effects of using microalgae-based skincare products (Thiyagarasaiyar et al. 2020).

Table 3 presents a list of clinical effects recognised from testing of cosmetic products formulated with different microalgal species such as Arthrospira (Spirulina) platensis (Delsin et al. 2015; Silva et al. 2019; Jungclaus et al. 2023), and Neochloris oleoabundans (Morocho-Jácome et al. 2022). These studies displayed effective outcomes with no side effects reported. However, the studies had small sample sizes and were of short duration. Thus, there is an urgent need for increased and larger sample sizes to authenticate the safety and effectiveness of microalgae use in cosmetics. On the other hand, in vitro skin models have been progressively advanced and employed. The availability of the models introduced that can reproduce the key components of healthy and sick human skin will significantly aid in the design of novel cosmetic products (Cruz et al. 2023). Such models provide advantages of being affordable, accurate, fast, and simple to assess a product’s efficacy, making a strong case for further research in developing this technology.

Table 3 Past clinical efficacy studies on cosmetic products with microalgae formulation
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Exploring the synergistic effects of combining microalgae with other natural skincare ingredients can open new possibilities for formulating innovative and effective cosmetic products. By delving into the interactions between microalgae and other natural compounds, cosmetic researchers can create tailored formulations that address a wide range of skin concerns while minimising the use of synthetic chemicals. As the cosmetic industry continues to pivot towards sustainability and natural alternatives, investing in extensive clinical trials and research on microalgae holds the key to unlocking their full potential. Collaborations between cosmetic companies, research institutions, and regulatory bodies can shape the future of microalgae in cosmetics, paving the way for safe, efficacious, and sustainable skincare solutions.

Unlocking the potential: recent development of microalgal production and the market demand

Owing to their rapid growth, efficient space utilisation, low costs and wide range of possible applications, microalgae are consistently gaining traction in contemporary research agendas (Zhuang et al. 2022). Extraction of products from microalgal biomass is under constant development. As with all biotechnological processes, the optimisation of multiple parameters across solvent type, extraction period, solvent-to-biomass ratio and cell disruption method is carried out in order to maximize yield with minimized costs.

Solvent extraction, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) are some common examples of extraction methods currently available (Salinas-Salazar et al. 2019). The recent use of compressed fluids-based extraction techniques such as supercritical fluid extraction (SFE), pressurised liquid extraction (PLE), and gas-expanded liquids (GXL) have also been proposed to have exceptional potential in the recovery of natural bioactive compounds (Herrero 2023). By bridging the gap between the research laboratories and the market, such approaches can be used to generate accessible compounds based on natural bioactive substances that may be employed in cosmetic applications (Ariede et al. 2017; Guillerme et al. 2017; Amador-Luna et al. 2023).

Central to ongoing research is the refinement of cosmetic formulations with effective active ingredients. Familiar microalgal taxa including Spirulina, Tetraselmis sp., Dunaliella sp., and Chlorella vulgaris, are known to be excellent potential sources of anti-aging cosmetic substances with high levels of antioxidant activity. The stabilities and sensory characteristics of creams supplemented with the aforementioned microalgae were recently investigated (Dammak et al. 2022). To date, marketed aesthetic and personal care products with the incorporation of microalgae are largely focussed on haircare (shampoo and conditioner) and skin care (sunscreen, anti-aging creams, and emollients) sectors (Joshi et al. 2018; Silva et al. 2019; Gupta et al. 2023). Such extraction and utilisation of microalgae-derived compounds reflect a paradigm shift in the cosmetic industry toward embracing sustainable and eco-friendly ingredients.

Driven by growing demand, many companies directly manufacture and advertise cosmetic products with ‘green’ claims. However, a lack of regulation and false marketing information are barriers that could undermine consumer confidence in this developing industry. Consumers are known to be confused by the diverse standards and exaggerated marketing of green cosmetics (Lin et al. 2018). Media reports suggest that some cosmetic brands make only the claim of green credentials in the absence of adopting them in practice. A robust perception of green cosmetics depends on clear confirmation of key factors including the incorporated ingredients and the manufacturing process as well as packaging utilisation (Lin et al. 2018; Ma et al. 2018; Suphasomboon and Vassanadumrongdee 2022).

According to market research, brand trust is a highly significant element influencing buying (Suphasomboon and Vassanadumrongdee 2022). Thus, a product must be authenticated with established research competence and aligned sustainability (Pitaloka and Widiatami 2022). The commercialisation of microalgae for cosmetic use entails a complex process, from harvesting and biological identification to meeting regulatory standards, while the latter may also need creation and documentation. It is essential to adhere to strict guidelines to secure the safety and value of algal products for cosmetic implementations (Segal and Yang 2015; Vieira et al. 2020). As the industry continues to explore the potential of microalgae, the development of mild extraction procedures and the enhancement of market application processes are critical for harnessing the full potential of these valuable bioresources.

To make microalgae industrial utilisation economically sustainable various approaches have been made to overcome challenges associated with cost, operation, maintenance, and social barriers. Recent efforts have introduced the utilisation of continuous cultures, phycoprospecting, genetic modifications, and increased automation and computer control of cultures (Novoveská et al. 2023). Photobioreactors (PBR) are commonly used in cultivation, but recent review studies have proposed cultivation through high rate microalgal ponds (HRAPs), also known as open raceway ponds (ORPs) (Rafa et al. 2021; De Morais et al. 2023). Such cultivation systems were reviewed in the context of microalgal-based biodiesel production and wastewater treatment and have been shown to be cost-effective and require low energy to enhance biomass production (Show et al. 2017). Nevertheless, both cultivation methods have their limitations in different aspects (Novoveská et al. 2023).

To counter the limitations faced by both PBRs and ORPs, hybrid systems integrating both cultivation methods can maximize both algal biomass and lipid productivity (Rafa et al. 2021). Microalgae species including H. pluvialis (Huntley and Redalje 2007), A. platensis (Chernova and Kiseleva 2017), and Tetraselmis sp. (Narala et al. 2016) have been subjected to hybrid cultivation and displayed enhanced biomass production, high lipid productivity and lower risk of contamination. Alternatively, a techno-economic evaluation by Vázquez-Romero et al. (2022) has revealed that the production of biomass in a vertically stacked tubular PBR, combined with ultrafiltration (UF) and spray drying, was the most promising strategy to increase photosynthetic efficiency and reduce the production cost.

Incorporating microalgae in cosmetics formulations can be cost-effective in the long run, despite initial challenges in harvest, extraction, and production. While the initial cost of extracting bioactive compounds from microalgae may be higher than synthetic alternatives, the long-term sustainability and environmental benefits make it a compelling choice. Microalgae are highly renewable and can be cultivated in controlled environments, reducing the reliance on finite synthetic chemical feedstock. Additionally, the diverse range of bioactive compounds found in microalgae can offer multiple functionalities within the same raw material, potentially replacing the need for multiple synthetic ingredients. These multifaceted benefits of microalgae can contribute to streamlining the formulation process and reducing overall production costs.

It is important to note that the cost-effectiveness of incorporating microalgae in cosmetics formulations depends on various factors such as the scale of production, technological advancements in extraction methods, and market demand. As research and development in microalgae cultivation and extraction technologies continue to progress, the cost-effectiveness of utilising microalgae in cosmetics formulations is likely to improve, making it a more viable and sustainable option compared to synthetic products.

Figure 1 depicts the current challenges facing the industrial application of microalgae and their potential solutions. Solving these challenges requires a collaborative effort from researchers, industry stakeholders and policymakers. Ongoing research, technological innovation, and a commitment to sustainable practices are essential for unlocking the full potential of microalgae in cosmetics. As the industry continues to develop, overcoming these challenges will contribute to the widespread adoption of microalgae-derived ingredients, offering sustainable and effective solutions in the beauty and skincare market.

Fig. 1
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Current challenges of microalgae in cosmeceuticals and the potential solutions

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Conclusion and future direction

The use of microalgae in sustainable beauty and cosmetics products represents a promising and evolving field. As the industry, as well as wider society, embraces a more sustainable and eco-conscious approach, microalgae offer a renewable resource with diverse applications in skincare. The unique properties of microalgae products, including their antioxidant, moisturizing, and anti-aging benefits, align well with the growing demand for natural and effective cosmetic products. However, despite their great potential, at present the development and use of extensive clinical trials, efficacy validation, and effective extraction techniques are inadequate. Compounding this, the availability of robust reports on the safety and efficacy of currently widely used traditional topical drugs are generally limited and out of date. Therefore, future studies should address such aspects concerning the continuous pavement for integrating microalgae into cosmetic formulations.

The contemporary emphasis on the use of microalgal products in the cosmetic industry embodies a progressive shift towards natural and sustainable solutions. This creates exciting opportunities for developing eco-friendly products that prioritise environmental conservation and human well-being. As research continues to unravel the largely untapped potential of microalgae, the cosmetic industry is poised for revealing new opportunities towards embracing these bioresources.