Introduction: Skin ageing is a natural process caused by both intrinsic and extrinsic factors, such as exposure to solar radiation, smoking, environmental pollution, improper skin care, improper lifestyle, stress and lack of sleep. These factors accelerate the ageing process of the skin by impairing and limiting many of its functions. In order to protect the skin against the harmful effects of ultraviolet radiation, photoprotective preparations and antioxidants are used, which neutralize the action of free radicals affecting the abnormal homeostasis of the body. Antioxidants are the main group of ingredients used in anti-ageing prophylaxis. Many raw materials of natural origin are rich in these ingredients. The aim of the study was to assess the antioxidant activity of the aloe vera extracts and to evaluate extraction conditions including the effect of solvent used as an extractant on the observed antioxidant potential and the ability to absorb solar radiation by aloe vera (Aloe vera).
Materials and methods: The material for the study consisted of alcoholic extracts prepared from the peel and flesh of aloe vera. Extracts in 40%, 70% or concentrated ethanol, methanol, n-propanol and isopropanol were used. Extracts were obtained after 15, 30 or 60 min of ultrasound-assisted extraction. Antioxidant activity was determined spectrophotometrically using the DPPH and ABTS methods, while the Folin–Ciocalteu method was used to determine total polyphenol content. Absorption spectra of the prepared extracts were taken to evaluate the absorption capacity.
Results: The highest average antioxidant activity was shown by aloe leaf peel extract in 40% methanol, subjected to a 60 min extraction and determined by the DPPH method. For aloe vera leaf peel extracts tested by the DPPH and ABTS methods, the best solvent seems to be 40% methanol, while in the Folin–Ciocalteu method it was 96% ethanol. For aloe vera flesh extracts evaluated by the DPPH method, the best solvents were undiluted alcohols, while for those evaluated by the ABTS method, it was 40% methanol, and for the determination of total polyphenol content, it was 96% ethanol. If compared to the evaluated parts of the plant studied, aloe leaf peel showed the most favourable antioxidant properties of the raw materials used. The UV-VIS spectra of the majority of extracts show an absorption maximum at a wavelength of about 300 nm, which corresponds to the UVB range.
Conclusion: Aloe vera is a valuable source of antioxidant components. Ultrasound-assisted extraction is a useful method to isolate antioxidant substances from plant material. The antioxidant potential is influenced by the extraction time of the raw material and the solvent used. Aloe vera leaf peel extracts showed higher antioxidant activity than extracts prepared from its flesh. It can be successfully used as a raw material in anti-ageing prevention and as a potential photoprotective ingredient.
| 08 oct. 2023