## 4 Natural Antioxidants and Their Role in Cosmetics
### Selected Plant Species with Antioxidant Activity
#### 4.11.7. Aloe vera ([PERSON] is a drought-resistant tropical succulent belonging to the family Asphodelaceae. It is indigenous to the Mediterranean region, the Arabian Peninsula, India, China, and Eastern Africa. Wild populations of Aloe are frequently found in regions such as Cyprus, Malta, Sicily, the Canary Islands, and India. This plant is a rich source of bioactive compounds, including flavonoids, terpenoids, lectins, fatty acids, anthraquinones, mono- and polysaccharides (e.g., pectins, hemicelluloses, and glucomannan), tannins, sterols (notably campesterol and \(\beta\)-sitosterol), enzymes, and salicylic acid. Additionally, it contains an array of essential minerals (such as calcium, chromium, copper, iron, magnesium, manganese, potassium, phosphorus, sodium, and zinc) and vitamins (A, C, E, \(\beta\)-carotene, B-complex vitamins including B1, B2, B3, B6, B12, choline, and folic acid) [225; 226].  
The health-promoting potential of _Aloe vera_--encompassing its whole leaf extract, gel, and latex--has been extensively documented globally. It exhibits a wide range of biological activities, including antioxidant, anti-inflammatory, antibacterial, antifungal, antiparasitic, antiviral, immunomodulatory, anticancer, hepatotoxicity, and cardioprotective effects. Scientific evidence indicates that _Aloe vera_ gel enhances skin flexibility while reducing its fragility. Moreover, the mucopolysaccharides, amino acids, and zinc present in _Aloe vera_ contribute to improved skin integrity by promoting moisture retention and mitigating erythema, thereby aiding in the prevention of ulcers. Its therapeutic applications extend to conditions such as erythema, genital herpes, seborrheic dermatitis, psoriasis, oral lichen planus, and UV-induced erythema [226].  
_Aloe vera_ contains aloesin, which causes a skin-lightening effect and inhibits melanogenesis. Mucopolysaccharides and the amino acids of _A. vera_ improve water retention in the stratum corneum. Aloe gel, with its antioxidant activity, enhances the metallothioneein, superoxide dismutases, and glutathione peroxidase activities in skin cells. Aloe improves elastin and collagen production by fibroblasts making the skin more elastic and reducing wrinkles [220].  
Aloe polysaccharide not only has external moisturizing effects but also can promote the expression of aquaporin in epidermal keratinocytes. Aloe polysaccharide is the main active ingredient of Aloe extract and is a widely used moisturizing raw material in cosmetics. Acetylated mannan is the main component of Aloe polysaccharide, which has a good effect on healing skin wounds and locking skin moisture [227].  
Plant materials derived from the Aloe used as cosmetic ingredients include Aloe Barbadensis flower extract, Aloe Barbadensis leaf, Aloe Barbadensis leaf extract, Aloe Barbadensis leaf juice, Aloe Barbadensis leaf polysaccharides, and Aloe Barbadensis leaf water. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005% [32].  
_Aloe vera_ plants are typically harvested 7 to 8 months after planting, with leaves carefully cut to minimize juice loss, and optimal yields obtained in the second year of cultivation. Mechanical extraction methods, such as hand-filleting and cold-pressing, are commonly used to obtain the gel, while solvent extraction with ethanol or acetone ensures higher compound yields. Enzymatic extraction is an eco-friendly alternative that breaks down cell walls, facilitating the release of active compounds while preserving bioactivity [228].