Natural ingredients have been used in skincare products for thousands of years. The current focus is on novel natural bioactivities that shield the skin from UV rays and free radicals, among other damaging elements, while enhancing skin health. Free radicals significantly contribute to skin damage and hasten ageing by interfering with defence and restorative processes. Plants contain natural chemicals that can scavenge free radicals and have antioxidant capabilities. Plant materials are becoming increasingly popular as natural antioxidants related to the expanding interest in plant chemistry. This review focuses on the significance of medicinal plants in skin health and ageing and their potential as a source of antioxidant substances such as vitamins, polyphenols, stilbenes, flavonoids, and methylxanthines.
For many years, skincare products have been made with natural components, whether they come from mineral, animal, or plant origins. In this century, the use of naturally occurring chemicals continues to increase, probably due to the social media influence. Between 2015 and 2019, the global market for naturally made cosmetics was growing by 10–11% per year. This market also offers a substantial opportunity for the cosmetics industry because many consumers are willing to pay more for these products. Plant-based products may be used topically to treat a variety of skin conditions and for skin care. In addition to being more ecologically friendly than traditional cosmetics, cosmetics enhanced with bioactive ingredients are well adapted to the demands of the skin. Plant extracts, which are a rich source of physiologically active chemicals that have a substantial impact on human skin, are a class of natural compounds that are often utilized in cosmetics. We have to emphasize that there are a limited number of studies concerning substances added to food that had an effect on the skin. In some cases, scientific evidence is lacking and the effect is only an assumption.
Many factors, including environmental exposure, gut microbes, stability, activity, and variability in endogenous chemical levels that modulate biotransformation pathways, can influence an organism’s metabolism. Antioxidant phytochemicals including vitamins, such as vitamin E, vitamin A, and vitamin C, and polyphenols, tocopherols, and carotenoids have been shown to enhance our aesthetic well-being. These phytochemicals have anti-inflammatory, antioxidant, photoprotective, anti-ageing, antiviral, and antibacterial characteristics. Synergistic stabilizing effects have been demonstrated when combining synthetic and natural antioxidants. Antioxidants include both enzymatic and non-enzymatic compounds. Their distribution is frequently influenced by the various skin cell types. For example, melanocytes lack antioxidant enzymes. Antioxidants are classified as biopharmaceuticals according to their permeability and solubility.
According to estimates, there are three different types of antioxidants: low solubility—low permeability, low solubility—high permeability, and high solubility—low permeability (vitamin C is present in cellular fluids and vitamin E is found in cell membranes). When used in topical treatments, water solubility, restricted permeability, and instability are the primary concerns. The instability caused by external stresses (such as air, light, moisture, heat, oxygen, etc.) affects the product’s shelf life. Due to their restricted permeability and water solubility, they have limited possibilities of entering deeper epidermal layers and reaching the target location. Antioxidant delivery systems must be capable of being absorbed into the food or beverage matrix without affecting the end product’s appearance, texture, flavour, or shelf life. Throughout manufacturing, storage, transit, and usage, it must tolerate environmental stresses like thermal processing, exposure to light, dynamic agitation, cooling, freezing, and dehydration. This study aims to underline the physicochemical importance of antioxidant compounds used in cosmetics, considering their delivery and mechanism of action, summarizing the novelty of the results studied in vitro and in vivo.
Since most connected papers and themes were published recently, our research included all studies published in PubMed, Scopus, and a manual Google Scholar search. The keywords “antioxidants” AND (“dermatology” OR “inflammation” OR “cosmetics” OR “proliferation”) formed the basis of the scientific literature search approach. Significant publications were chosen based on different plants’ biological, chemical, and functional characteristics.
Following criteria, like experimental and review studies, full articles for each selected abstract were retrieved for review. All English-language research articles were included. Investigations were based on in vivo and in vitro research publications. Research publications dealing with specific plant extracts were included. Still, those that considered a combination of plant extracts or a formulation of some other chemical ingredients were excluded. The CAS numbers of the compounds were mentioned in the article, providing valuable information and facilitating the future search for the classification and labelling in the database.
Plants produce compounds (phytochemicals) through their secondary metabolism that can protect them from pests, bacteria, and atmospheric pollutants. In both people and animals, some of these compounds (such as polyphenols, cysteine sulphoxides, and carotenoids) can be combined with free radicals to create stable chemical species. Numerous biological effects of phytochemicals which are beneficial to human health include photoprotective, anti-ageing, anti-inflammatory, antibacterial, antiviral, and anticancer activities. Vitamins E, C, and A, for example, have the potential to be antioxidants and have skincare benefits. Collagen synthesis is controlled by vitamin C. Free radicals are actively neutralized by vitamin E, which also helps to soften the skin. Stretch marks, burn scars, and new skin cell growth are reduced by vitamin A, which also boosts collagen formation.
Beta-carotene (pro-vitamin A), vitamin A and its derivatives, and other ingredients have been used as cosmetic additives. Beta-carotene can be found in foods like tomatoes, carrots, and yellow vegetables, whereas the main animal sources of vitamin A are liver and egg yolk. Beta-carotene and vitamin A were also found to be photoprotective by decreasing the quantity of peroxyl lipid radicals in the skin of mice exposed to UV radiation. However, because beta-carotene is so fragile, other types of vitamin A are frequently included in cosmetic compositions. The capacity of vitamin A (CAS number: 68-26-8) and its derivatives to correct keratinization is the main advantage of these ingredients in the cosmetics industry. Tretinoin (CAS number: 302-79-4), vitamin A alcohol (retinol), vitamin A esters (retinyl palmitate (CAS number: 79-81-2), retinyl acetate (CAS number: 127-47-9)), and vitamin A aldehyde (retinal) (CAS number: 116-31-4) are some of the common vitamin A compounds that can be found in cosmetics. These are present in cosmetic compositions in various concentrations due to their involvement in controlling epithelial cell proliferation and differentiation.
Vitamin C (CAS number: 50-81-7), or ascorbate, is a hydrosoluble vitamin found in vegetables and citrus fruits. Its antioxidant properties and role as a cofactor in collagen hydroxylation events make it an essential nutrient. Since humans cannot produce ascorbate, nutritional intake is crucial. The capacity of vitamin C to immediately quench UV-induced free radicals and replenish vitamin E, another effective antioxidant, contributes to its popularity as a cosmetic element. To maximize UV protection, combining sunscreen with a topical antioxidant is essential. Vitamin C does not absorb UV radiations but protects them by radical scavenging, in contrast to sunscreens, which do not. Under laboratory circumstances, 10% topical vitamin C treatment reduced UVB-induced erythema by 52% and sunburn cell development by 40 to 60%. Due to its capacity to promote collagen formation, vitamin C is also used as a component of anti-ageing products. Ascorbyl palmitate (CAS number: 137-66-6), magnesium ascorbyl phosphate (CAS number: 114040-31-2), and L-ascorbic acid (CAS number: 50-81-7) are the three primary forms of ascorbic acid that are frequently found in cosmetics.
Vitamin E (CAS number: 59-02-9) is a liposoluble vitamin found in various foods, especially soybeans, nuts, wholemeal flour, and oils. It is claimed that systemically reducing lipid peroxidation has several health advantages for the eyes and cardiovascular system. Numerous dermatological benefits of topically administered substances have been demonstrated. The powerful antioxidant properties of vitamin E serve as the main mechanism of action to support its significance. The “protective” term has been employed to characterise the protective effects of vitamin E and its derivatives due to its ability to scavenge free radicals, specifically lipid peroxyl radicals. Numerous studies have demonstrated their capacity to lessen erythema and edema, sunburn cell development, and lipid peroxidation caused by UV radiation. Reduced skin wrinkling and skin tumour growth have been linked to clinical improvement in the obvious indications of skin ageing.
Coenzyme Q10 (CAS number: 303-98-0) is a botanical food ingredient, and its derivatives are used in functional foods and nutritional supplements. The antioxidant properties of coenzyme Q10 have been correlated with the speed-up in recovery of ATP levels following radiation in human fibroblasts and maintaining the stability of cellular energy levels in human keratinocytes. It prevents the harmful effects of photoaging, minimizes wrinkles, and improves skin smoothness on human skin. It is an internal lipophilic molecule that is essential or useful for mitochondrial strength biotransformation and effective for antioxidants and human health.
