Natural Antioxidants in Cosmetic Formulation

Natural Antioxidants in Cosmetic Formulation: History

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Subjects: Plant Sciences

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A natural antioxidant can be a single pure compound/isolate, a combination of compounds, or plant extracts; these antioxidants are widely used in cosmetic products.

natural antioxidants
vitamins
flavonoids
polyphenols

1. Introduction

The skin is the body’ s largest living organ, and it protects the body from the outside environment by maintaining homeostasis, keeping harmful microbes and chemicals out, and blocking sunlight [1]. The stratum corneum, the outermost layer of the skin, is a selectively permeable, heterogeneous epidermal layer that provides protection against dryness and environmental damage while retaining sufficient moisture to function. [2]. Impairment in skin barrier function frequently manifests as altered stratum corneum integrity, which leads to an increase in transepidermal water loss and a decrease in skin hydration [3]. The term “cosmeceutical” refers to cosmetics that contain active chemicals having drug-like properties. Cosmeceuticals with medicinal properties have beneficial local effects and prevent degenerative skin diseases. [4]. They enhance appearance by supplying nutrients required for healthy skin. They can improve skin tone, texture, and radiance while reducing wrinkles. Cosmeceuticals are a rapidly expanding subset of the natural personal care industry. Although natural ingredients have been used for centuries in skincare, they are becoming increasingly prevalent in modern formulations [5]. The phrase “natural” refers to a substance that is derived directly from plants or animal products and is generated or found in nature [6]. Herbs, fruits, flowers, leaves, minerals, water, and land can be sources of natural ingredients.

Natural ingredients’ efficacy in skincare products is determined by their in vitro and in vivo efficacy as well as the type of dermatological base into which they are incorporated. Plants have long been used for medicinal purposes, and it is likely that new products containing natural oils and herbs will continue to emerge on the market in the coming years. Before the use of synthetic substances with similar properties, plants were the primary sources of all cosmetics [7]. Natural plant molecules continue to pique the interest of researchers. However, using extracts necessitates paying close attention to extraction methods, plant-to-solvent ratios, and active-ingredient content. The use of plant extracts in skincare products is demanded by consumers, who are becoming increasingly concerned with purchasing ecofriendly products [8]. However, consumers, are frequently unaware that natural products are complex mixtures of many chemical compounds that can cause adverse reactions. To avoid this issue, researchers should chemically characterize their extracts with regard to composition [9]. Furthermore, the in vitro cytotoxic potential of extracts should be tested in several human cell lines prior to human use, and the irritant potential of cosmetic formulations can be screened. These procedures can help to ensure the safety of natural products and thus their acceptability on the market [10,11]. Bioactive extracts and phytochemicals from various botanicals are used for two purposes: (1) body care and (2) as ingredients to influence the biological functions of the skin, providing nutrients for healthy skin [12]. Vitamins, antioxidants, essential oils and oils, hydrocolloids, proteins, terpenoids, and other bioactive substances are all abundant in botanical products [13]. These extracts can have a variety of properties depending on their compositions. Modern skincare cosmetics are distinguished by their multiactivity, which enables multidirectional complex effects even in relatively simple formulations. The biologic impacts of the most widely used cosmetic surgery, which involves coating the epidermis with a hydrolipid occlusion layer or various forms of antiradical protection, are a good example. The meaning of cosmetic multi-activity is encoded in a legal definition of cosmetic product use: “keeping (the skin) in good condition” [14,15,16].

2. Natural Antioxidants in Cosmetics

Natural antioxidants used in the cosmetic industry include various substances and extracts derived from a wide range of plants, grains, and fruits, and are capable of reducing oxidative stress on the skin or protecting products from oxidative degradation [22]. One of the major causes of oxidative stress that accelerates skin aging is reactive oxygen species (ROS) [23]. Intrinsic aging is associated with the natural process of aging, whereas extrinsic aging is associated with external factors that affect the aging process (e.g., air pollution, UV radiation, and pathogenic microorganisms). Photoaging is most likely the primary cause of ROS production [24,25,26,27,28]. Factors that drive the process of skin aging are presented in Figure 1. Several potential skin targets have been discovered to interact with ROS (e.g., lipids, DNA, and proteins) [29]. Antioxidant molecules can be enzymes or low-molecular-weight antioxidants that donate an electron to reactive species, preventing the radical chain reaction, which prevents the formation of reactive oxidants, or behave as metal chelators, oxidative enzyme inhibitors, or enzyme cofactors [30]. Antioxidants can also be used as stabilizers, preventing lipid rancidity. Lipid oxidation occurs not only in cosmetics but also in the human body [31]. Thus, when antioxidants are present in a product, they may serve multiple functions. The number of radicals increases during the initiation phase of lipid oxidation. Molecular oxygen and fatty acid radicals react during the propagation phase, resulting in the formation of hydroperoxide products. Hydroperoxides are unstable and can degrade to produce radicals, which can accelerate the propagation reaction. The termination phase is dominated by radical reactions. Antioxidants can inhibit lipid oxidation by reacting with lipid and peroxy radicals and converting them to more stable, non-radical products [32,33,34,35]. Additionally, antioxidants can deplete molecular oxygen, inactivate singlet oxygen, eliminate peroxidative metal ions, covert hydrogen into other antioxidants, and dissipate UV light [36]. Antioxidants can be used in cancer treatments, because the production of ROS is altered during tumorigenesis, with anti-inflammatory and antimicrobial effects. Plants are well known for producing natural antioxidant compounds that can reduce the amount of oxidative stress caused by sunlight and oxygen [37]. Plant extracts are used in a variety of patents and commercial cosmetic products. Green tea, rosemary, grape seed, basil grape, blueberry, tomato, acerola seed, pine bark, and milk thistle are some of the plant extracts commonly found in cosmetic formulations. Polyphenols, flavonoids, flavanols, stilbenes, and terpenes are natural antioxidants found in plant extracts (including carotenoids and essential oils) [38].

Antioxidants are classified as primary or natural antioxidants and as secondary or synthetic antioxidants according to their function. Mineral antioxidants (such as selenium, copper, iron, zinc, and manganese), vitamins (C and E), and phyto-antioxidants are examples of primary antioxidants. Generally, a mineral antioxidant is a cofactor of enzymatic antioxidants [39,40,41,42,43]. Secondary or synthetic antioxidants capture free radicals and stop the chain reaction. BHA, BHT, propyl gallate, metal chelating agents, tertiary butylhydroquinone, and nordihydroguaiaretic acid are examples of secondary antioxidants [44,45]. The use of plant antioxidants is increasing and may eventually replace the use of synthetic antioxidants. A natural antioxidant can be a single pure compound/isolate, a combination of compounds, or plant extracts; these antioxidants are widely used in cosmetic products. Table 1 presents a summary of natural antioxidants commonly used in cosmetic preparations. Innate antioxidants act as oxygen free radical scavengers (singlet and triplet), ROS, peroxide decomposers, and enzyme inhibitors [46,47,48]. Polyphenols and terpenes are the most common phyto-antioxidants; this distinction is based on their molecular weight, polarity, and solubility. Polyphenols have benzene rings with -OH groups attached. The number and position of—OH groups on the benzene ring determine their antioxidant activity. Phenolic groups influence protein phosphorylation by inhibiting lipid peroxidation. The most abundant polyphenols are flavonoids and stilbenes, and the most abundant terpenes are carotenoids, which act as singlet oxygen quenchers [49].

Figure 1. Driving factors of skin aging.

Table 1. Natural antioxidants.

S. No	Source	Antioxidant	Potential Activity	Reference
1.	Apple	Phenolic compounds	Inhibitors of sulfotransferases, influence epigenetic processes and heritable changes not encoded in the DNA sequence, DNA protection against UV radiation	[50,51]
2.	Baccharis species	Phenolic compounds	Inhibit reactive oxygen and nitrogen species (RONS), inhibit carrageenan induced edema	[52]
3.	Basil leaves	Phenolic compounds	Antiacne, antiaging, remove dead skin cells	[53,54]
4.	Blueberry pomace	Phenolic compounds	Enhance polyphenol oxidase activity, potent antioxidant	[55,56]
5.	Cape gooseberry	Phenolic compounds and carotenoids	Anticoagulant, antispasmodic	[57,58]
6.	Carrot	Carotenoids, anthocyanins	Protection from UV-induced lipid peroxidation, in treatment of erythropoietic protoporphyria	[59,60]
7.	Chest nut	Polyphenols	Moisturizer, in treatment of oxidative stress-mediated diseases and photoaging	[61,62]
8.	Coffee leaves	Chlorophylls and carotenoids	Antioxidant, antimicrobial, antiaging	[63,64]
9.	Feijoa	Phenolic compounds	Antioxidant, antimicrobial	[65,66]
10.	Ginkgo biloba leaves	Flavonoids	Prevent UVB-induced photoaging, anti-inflammatory, antioxidant, blood microcirculation	[67,68]
11.	Goji berry	Phenolic compounds	Antioxidant, prevent skin aging, immunomodulatory	[69,70]
12.	Goldenberry	Polyphenols	Anti-inflammatory, antiallergic	[71]
13.	Grape	Anthocyanins and phenolic compounds	Protection from UV radiation, antioxidant and antiaging, depigmenting, anti-inflammatory, wound healing	[72,73]
14.	Green algae	Carotenoids and phenolic compounds	Prevention of skin aging, protection from UVR, inhibition of melanogenesis, anti-inflammatory, antioxidant	[74,75]
15.	Green propolis	Phenolic compounds	Anti-inflammatory, antimicrobial, wound healing	[76,77]
16.	Jussara fruit	Phenolic compounds	Antioxidant, natural coolant	[78,79]
17.	Kumquat peel	Phenols and flavonoids	Antioxidant, anti-inflammatory, skin lightening, suppression of lipid accumulation	[80,81]
18.	Mango	Carotenoids	Wound healing, prevent skin aging, antioxidant	[82,83]
19.	Myrtle	Phenolic compounds, flavonoids, and anthocyanins	Treatment of burn injury, anti-inflammatory, antifungal	[84,85]
20.	Olive	Phenolic compounds	Antioxidant, anticancer, antiallergic, antiatherogenic, antimutagenic effects	[86,87]
21.	Papaya seeds	Phenolic compounds	Antioxidant, insecticidal and repellent, antibacterial, wound healing, anti-inflammatory and immunomodulatory	[88,89]
22.	Peach fruit	Flavonoids and phenolic compounds	Anticancer, antioxidant	[90,91]
23.	Peel of egg plant	Phenolic compounds, flavonoids, tannins, and anthocyanins	Antioxidant, anti-inflammatory, antiviral and antimicrobial	[92]
24.	Peppermint	Phenolic compound and essential oils	Antioxidant, antiaging	[93]
25.	Pineapple	Polyphenols	Antimalarial, antinociceptive, and anti-inflammatory activities, improve skin barrier function	[94,95]
26.	Pomegranate	Phenolic compounds	Anti-inflammatory, antioxidant, antimicrobial, promote hair follicles	[96,97]
27.	Propolis	Phenolic compounds	Wound healing, immunomodulatory, anti-inflammatory	[98,99]
28.	Red Macroalgae	Proteins, polyphenols and polysaccharides	Prevent skin-aging processes, promote transepidermal water loss, simulate sebum content, and increase erythema and melanin production	[100,101]
29.	Bananas	Phenolic compounds and flavonoids	Provide UV protection, antimicrobial, wound healing	[102,103]
30.	Spent grain	Phenolic compounds	Antioxidant, skin lightening, anti-inflammatory	[104,105]
31.	Turmeric	Phenolic compounds	Anti-inflammatory, antioxidant, treatment of psoriasis	[106,107]
32.	Strawberry	Anthocyanins and phenolic compounds	Antimicrobial, antioxidant, antiaging	[108,109]
33.	Sweet potato	Polyphenols and anthocyanins	Antioxidant, wound healing, serve as natural, safe and effective colorants, antimicrobial, antifungal	[110,111]
34.	Tomato	Flavonoids and lycopene	Antioxidant, protection from cell damage, provide protection against UV rays, wound repair	[112,113]
35.	Horse radish	Phenolic compounds and flavonoids	Antimicrobial, antioxidants	[114]
36.	Withania somnifera	Phenolic compounds	Antioxidant, skin whitening	[115,116]

3. Conclusions

Consumers are increasingly turning away from synthetic chemicals in beauty and cosmetic products in favor of natural alternatives. Plant extracts can be used in cosmetic science to beautify and maintain the physiological balance of human skin due to the inherent economic potential in the exploitation of natural resources in ecosystems. Additionally, they are biodegradable and have lower toxicity than synthetic cosmetic ingredients. However, several by-products of plant-processing industries (for example, the food industry) pose a significant disposal problem. Some of these by-products, however, are promising sources of compounds with biological properties suitable for cutaneous application. Thus, natural plant extracts derived from both naturally occurring plants and industrially processed plants can be used to create natural topical antioxidants, lighteners, and preservatives, maximizing the utility of products that are currently underutilized or discarded. As primary ingredients in cosmetics, vitamins and antioxidants are extremely popular. There is substantial scientific evidence, as well as anecdotal experience, of the benefits of these more bioactive cosmetics for consumers. To be beneficial, an ingredient must be stable in production, storage, and use; nontoxic to the consumer; and active at the target site once applied. More research is needed to improve the penetration of these bioactive cosmetics into the skin. Perhaps instrumentation, e.g., iontophoresis, is needed to improve delivery into the skin. Market-driven economics clearly suggest that antioxidant and vitamin formulations are popular and well liked. However, the instability and hydrophilic nature of vitamins limit their use. In recent years, drug delivery systems have been developed, and they appear to overcome these limitations through improved encapsulation and targeted delivery. Furthermore, research has led to a better understanding of these molecules, which has resulted in the development of more stable derivatives with different chemical properties. Topically, vitamins are effective for treating hyperpigmentation, differentiating keratinocytes, preventing skin photodamage, and improving dermal–epidermal junction cohesion. Flavonoids, multi-active ingredients found in many cosmetics, are primarily used for their antioxidant and soothing properties. Despite their multifunctional properties, flavonoids are underutilized. The objective of this study was to discuss the potential applications of flavonoids as the main active ingredients in cosmeceuticals. We discussed major potential antioxidants from plant sources that can be used in cosmetics. Although the use of antioxidants is promising, there are limited clinical trials in humans examining the role of antioxidants in preventing skin aging. Thus, further experimental data can be explored in the future, and synergistic effects are recommended for better efficacy in combination.

This entry is adapted from the peer-reviewed paper 10.3390/cosmetics8040106

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