Seaweeds Compounds | Encyclopedia MDPI

Seaweeds Compounds: History

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Subjects: Ecology | Chemistry, Applied

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Seaweeds’ compounds present important qualities for cosmetic application, such as low cytotoxicity and low allergens content. Several seaweeds’ molecules already demonstrated a high potential as a cosmetic active ingredient (such as, mycosporine-like amino acids, fucoidan, pigments, phenolic compounds) or as a key element for the products consistency (agar, alginate, carrageenan). Moreover, it
focuses on the ecological and sustainable scope of seaweed exploitation to guarantee a safe source of ingredients for the cosmetic industry and consumers.

seaweeds
cosmeceutical
seaweed ecology
sustainability
seaweed compounds

1. Introduction

Seaweeds (macroalgae) are photoautotrophic aquatic organisms (they use photosynthesis to metabolize the necessary energy to carry out their physiological processes), which inhabit almost every corner of the planet earth, especially coastal areas. Due to their trophic level they are considered as primary producers, similar to terrestrial plants. Although seaweeds and terrestrial plants have some common traits, such as the presence of chlorophyll, algae are non-vascular organisms and do not share some physiological characteristics with terrestrial plants, such as a root, stem and leaf division or conductive vessels [1].

From a taxonomic perspective, the easiest way of addressing the different seaweeds is to group them into supergroups defined by the coloration presented by the seaweed thallus (green, red and browns seaweeds) [1,2].

Seaweeds biotechnological potential is diversified, and they can be directly or indirectly employed in different industries, such as pharmaceutical, food and feed, agricultural, bioenergy and cosmetics [1,3,4,5,6]. Within the worldwide economy, cosmetics business is among the foremost growing and profitable industries. In agreement with some reports, each woman spends around $15,000 in cosmetic products in her lifetime [7,8]. According to Eurostat, the cosmetics market has foreseen an annual total income of US $170 billion [8,9]. In 2016, the European cosmetics market was esteemed at €77 billion (wholesale rate), followed by the North and South American countries, namely USA and Brazil [7,8]. In several developing countries, the increase of the middle-class population will allow the continuously growing of beauty products market [10]. This econometric analysis suggests that the cosmetic industry is a market in expansion, where the innovation is also prioritized, leading to the research and quest for novel products. Nowadays, most of the cosmetic products available in the market are composed by synthetic chemicals, which can result in an expensive product and lead to noxious side effects for the consumer [8]. Within the increase of consumer awareness regarding these disadvantages, natural based products are preferred among the clients [1,8].

2. The Seaweeds Compounds: Cosmetic Potential?

Cosmetic products are conceived as cleaning and beautifying agents, with the aim of improving the aesthetics of the user, without harmful side effects. Several products, such as creams, lotions, and ointments are also composed by bioactive molecules (i.e., vitamins, minerals, antioxidants) that can promote skin, nails and hair health [14,34,35]. These products can assume a variety of formats, such as simple cream or lotion, or even edible products, such as pills or functional foods with cosmeceutical activity [34,35]. However, since they cannot claim a real therapeutic function, it is important to distinguish these products from cosmetic preparations, which aims skin diseases prevention, for example, a sunscreen is considered a drug that prevents skin diseases due to the solar exposure [34,35]. In order to accommodate cosmetic products that can claim to have biological action, the term “cosmeceutical” was created, being a nomenclature currently used in countless products [1,36].

Cosmetics played a central role, since immemorial times, in human society, mainly for religious and ornamental purposes. In ancient times, such products were extracted from natural compounds (i.e., milk, flowers, fruits, seeds, vegetables) and minerals (i.e., clay, ash) [39]. In certain parts of the world, there is a practice of using seaweed as an alternative remedy for skin-related diseases, making it into an incredible natural raw material for cosmetics [1,8]. The bioactive compounds found on seaweed have multiple activities, which allows them to be used as an active ingredient when formulating cosmetics [8,14,40]. Various reviews and research articles demonstrate the wide range bioactivities that seaweeds can offer, such as the prevention of tumors or allergies development, microbial growth inhibition, as well as antioxidant and anti-lipidemic properties [8,39,41,42,43,44].

Trending alongside the search for raw materials to cosmetic and cosmeceutical in macroalgae, there is also a recent growing interest in bioactive compounds from microalgae. This subject will not be a part of this review, but it is worth mentioning that the scientific community show us that microalgae have much of the bioactive potential of seaweed and are able to include most of the same applications, including the cosmetic and cosmeceutical products [45].

The application of seaweed to the cosmetic industry is based on their valuable bioactive compounds, such as carbohydrates, phenolic molecules, natural pigments, sterols, proteins, lipids (polyunsaturated fatty acids) peptides, amino acids, vitamins and minerals, and their use as active ingredients due to their potent bioactivity [8,41,46]. We go on to describe the bioactive potential and the biochemical characterization of such compounds.

3.1. Phenolic Compounds

Phenols are seaweeds’ secondary metabolic products that constitute an interesting group of compounds for cosmetic application, due to their numerous biological activities [8]. It is a diverse group of water-soluble chemical compounds that share a hydroxyl group linked to an aromatic hydrocarbon group. According to the number of substituents, phenols can be categorized into simple phenolic compounds or polyphenols, comprising terpenoids, flavonoids, phlorotannins, bromophenols and several mycosporine-like amino acids [6]. This is one of the major differences between terrestrial origin polyphenols, which are composed of flavonoids and gallic acid [1,8]. Phlorotannins are in higher concentration in brown seaweeds. However, in green and red seaweeds bromophenols, flavonoids, phenolics acids, terpenoids, and mycosporine-like amino acids are usually predominant [6,47,48]. Thus, phenolic compounds can be metabolized with different molecular weights (126 to 65,000 Da) through the metabolic acetate-malonate pathway [1,35].

Phlorotannins acts as an inhibitory agent of hyaluronidase (Haase) activation, conferring to cosmetic products antiallergic, anti-wrinkle, skin antiaging and whitening properties, and since seaweeds are the only producers of these molecules on the whole planet, these turned to be valuable ingredients for the cosmetic industries [1,49].

The bioactivity potential of seaweed phenolics is the consequence of their enzyme inhibitory effect and antimicrobial, antiviral, anticancer, antidiabetic, antioxidant, or anti-inflammatory activities, which can be very attractive to be applied in cosmetic and cosmeceutical products [50].

Although deficiencies in polyphenol intake, this does not result in specific diseases, however the consumption of an adequate level of polyphenols could have health benefits, mainly the prevention of diseases such as obesity, metabolic syndrome, Alzheimer’s or cancer [50]. We now discuss the main groups of phenolic compounds.

3.2. Phycocolloids and Other Polysaccharides

Polysaccharides represent around 60% of all active metabolites occurring in seaweed. They are composed by several building blocks (monosaccharides) linked by glycosidic bonds, forming long chained carbohydrates. These compounds are characterized by being hydrophilic, water-soluble and to possess a regular structure [1].

Polysaccharides have a structural role on seaweeds cell wall and as an energetic reservoir. Thus, seaweeds’ contains several polysaccharides with proved biological activities, and can be applied in cosmeceutical products as moisturizers and antioxidant [1,35].

Macroalgal hydrocolloids-known as phycocolloids-are, of all the polysaccharides, the most relevant in terms of their industrial commercialization. Phycocolloids are structural polysaccharides, found in seaweed, that usually form colloidal solutions-an intermediate phase between a solution and a suspension. Hence, polysaccharides can be used in several industries, particularly in cosmetic, as thickeners, gelling and stabilizers agents for suspensions and emulsions [1,35,73].

3.3. Pigments

The coloring of food and cosmetics can be accomplished by the presence of substances derived from natural sources, which also have beneficial effects on human health by serving to protect the body and prevent diseases. Seaweed has several photosynthetic pigments with that capacity divided into three main classes: chlorophylls, carotenoids (carotenes and xanthophylls), and phycobilins [1]

3.4. Lipids

One of the three main nutrient groups is lipids. They represent the “building blocks” of all living cells alongside proteins and carbohydrates. They are a diversified group of lipophilic organic compounds found in animals, microorganisms, and plants. As a general characteristic, lipids reflect a group of chemical compounds that have a lipophilic character. Seaweeds presents as lipids fatty acids, sterols, glycolipids, phospholipids, and others [117,130,131]. However, algae fatty acids have been studied for its anti-allergic, antioxidant and anti-inflammatory activities. Lipids may also serve as emollient-softening compounds that safeguard the skin from water loss [116].

This entry is adapted from the peer-reviewed paper 10.3390/cosmetics8010008

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