In recent years, interest in the health effects of natural antioxidants has increased due to their safety and applicability in cosmetic formulation. Nevertheless, efficacy of natural antioxidants in vivo is less documented than their prooxidant properties in vivo. Plant extracts rich in vitamins, flavonoids, and phenolic compounds can induce oxidative damage by reacting with various biomolecules while also providing antioxidant properties. Because the biological activities of natural antioxidants differ, their effectiveness for slowing the aging process remains unclear. This review article focuses on the use of natural antioxidants in skincare and the possible mechanisms underlying their desired effect, along with recent applications in skincare formulation and their limitations.

Ultraviolet (UV) radiation has been demonstrated to cause skin disorders, including sunburn and relative symptoms of prolonged exposure. It has been reported that sunscreens have beneficial effects in reducing the incidence of skin disorders (sunburn, skin aging, and immunosuppression) through their ability to absorb, reflect, and scatter UV. Many commercial products have recently been manufactured from not only usual organic and inorganic UV filters, but also hybrid and botanical ingredients using typical formulations (emulsion, gel, aerosol, and stick). Particularly, these products have been supplemented with several preeminent properties to protect against the negative effects of not only UVB, but also UVA. However, the use of sunscreen has faced many challenges, including inducing photoallergic dermatitis, environment pollution, and deficiency of vitamin D production. Therefore, consumers should efficiently apply suitable products to improve sun protection. as well as to avoid the side effects of sunscreen.

Bioactive peptides have gained significant attention in the cosmetic industry due to their potential in enhancing skin health and beauty. These small protein fragments exhibit various biological activities, such as antioxidant, anti-aging, anti-inflammatory, and antimicrobial activities, making them ideal ingredients for cosmetic formulations. These bioactive peptides are classified into four categories: signal, carrier, neurotransmitter-inhibitory, and enzyme-inhibitory peptides. This review provides insight into applying bioactive peptides in cosmetics and their mechanisms of action (e.g., downregulating pro-inflammatory cytokines, radical scavenging, inhibiting collagen, tyrosinase, and elastase synthesis). The abundant natural origins (e.g., animals, plants, and marine sources) have been identified as primary sources for extractions of cosmetic peptides through various techniques (e.g., enzymatic hydrolysis, ultrafiltration, fermentation, and high-performance liquid chromatography). Furthermore, the safety and regulatory aspects of using peptides in cosmetics are examined, including potential allergic reactions and regulatory guidelines. Finally, the challenges of peptides in cosmetics are discussed, emphasizing the need for further research to fully harness their potential in enhancing skin health. Overall, this review provides a comprehensive understanding of the application of peptides in cosmetics, shedding light on their transformative role in developing innovative and effective skincare products.

The measurement of deposited aerosol particles in the respiratory tract via in vivo and in vitro approaches is difficult due to those approaches’ many limitations. In order to overcome these obstacles, different computational models have been developed to predict the deposition of aerosol particles inside the lung. Recently, some remarkable models have been developed based on conventional semi-empirical models, one-dimensional whole-lung models, three-dimensional computational fluid dynamics models, and artificial neural networks for the prediction of aerosol-particle deposition with a high accuracy relative to experimental data. However, these models still have some disadvantages that should be overcome shortly. In this paper, we take a closer look at the current research trends as well as the future directions of this research area.