## 1 Introduction  
According to ancient Egyptian writings, the study upon vitamin A's significance dates back to around 1500 BC. The year 1913 has specifically marked the beginning of the contemporary study on vitamin A, while in the year span of 1913 to the 1950s, many important findings led the scientific community to delve more into this compound's unique profile. Because of the colored plant lipids' and colorless liver extracts' biological activity, [PERSON] [1, 2] proposed the interconversion of two vitamin types (1919), and it was only ten years later when [PERSON] [3] exhibited how liver tissue changed the plant pigment \(\beta\)-carotene into vitamin A's colorless form [1, 3]. Those research findings were enough for scientists to shortly after discover that a vitamin A shortage also existed in children and that the retinene present in the eye's visual pigments was the same compound as the chemical substance retinaldehyde [1; 3]. Moreover, in the 1940s, [PERSON] and his colleagues [1; 4] synthesized the all-trans vitamin A from the less expensive precursor \(\beta\)-ionone, which led to a decrease in its price in the global market, while in the 1950s, the discovery of the radioactive vitamin A isotopes further clarified its metabolic pathways and behavior. Once the specifics of the rhodopsin-related visual cycle in the eye were introduced, scientific research shifted to vitamin A's potential biological role in cellular differentiation and growth, promoting skin's well-being [1; 4]. As apparent, the pursuit of youthful and healthy skin has long been a driving force in cosmetic science. As consumers increasingly seek formulations that are both effective and natural, bioactive compounds such as carotenoids, vitamin A, and its vitaminoids have gained substantial attention in the cosmetic industry. These compounds, derived from natural or synthetic sources, have several biological effects and have offered multifaceted benefits, such as antioxidant protection, skin repair, and anti-aging properties. Their integration into cosmeceuticals reflects a growing alignment between dermatological science and consumer expectations for more effective skincare solutions [5; 6; 7]. A glimpse of these bioactives' skin health-related activity is depicted in Figure 1.  
Carotenoids, mainly found in plants and algae, including \(\beta\)-carotene, lutein, and lycopene, have the ability to neutralize reactive oxygen species (ROS), hence to protect skin cells from oxidative damage induced by environmental factors like ultraviolet radiation (UV) and pollution. Furthermore, carotenoids may enhance skin tone and radiance in plant-based, eco-conscious formulations [1; 5; 6; 7; 8; 9]. Following, vitamin A and its derivatives, such as retinol and retinoic acid, are responsible for regulating cell turnover, stimulating collagen production, and addressing several skin concerns, like fine lines, wrinkles, and hyperpigmentation [3; 4; 10; 11]. However, challenges such as irritation and photosensitivity have recently been managed by advancements in vitamin A encapsulation and slow-release delivery systems [1; 11]. Lastly, vitaminoids, mainly in the form of retinoids, are integral factors to skin hydration, barrier function, and repair mechanisms, being compatible with many skin-related formulations [12; 13; 14]. Figure 1: The beneficial use of carotenoids, vitamin A, and vitaminoids in cosmetic products. Recent innovations in cosmetic science have focused on improving the stability, bioavailability, and delivery of these active ingredients by investigating their structure, molecular activity, biochemical behavior, and skin-health benefits [1; 6]. By examining bioactives like vitamin A, vitaminoids, and carotenoids of animal, marine, plant, and microorganism origin, their skin regeneration, wound healing, hyperpigmentation, and acne treatment activity, as well as their ability to promote hydration, skin elasticity, and barrier repair, have been quite supported [6].