## 1 Introduction  
Aging is a complex and multifactorial process caused by intrinsic (chronological aging) and extrinsic factors such as stress, obesity, air pollution, smoking, and, especially, sunlight exposure (photoaging), which result in spotted and wrinkled, aged skin. While chronological aging depends on intrinsic individual factors, photoaging is the result of the unprotected exposure to solar ultraviolet (UV) radiation. The latter was also demonstrated to be implicated in various types of skin carcinomas. Although the leading causes are different, the cellular and molecular mechanisms that determine both chronological aging and photoaging share fundamental molecular pathways implicating the production of free radicals [1, 2]. Anti-aging products act through different mechanisms aimed at minimizing the visible signs of aging or preventing the photoaging process. The employed active ingredients are moistrizers, emollients, sun filters, exfoliants, depigments, and antioxidants [3]. The latter are also inserted as supplements in sunscreen products together with micronutrients and DNA repair enzymes as secondary protective agents (the primary ones are the physical and chemical sun filters) to limit skin damage and provide additional anticarcinogenic protection. Vitamins C and E, zinc, and selenium and phenols are the most representative substances [4; 5; 6]. In particular, natural phenols contribute to reducing oxidative stress, inflammation, and cellular damage both in the aged dermis and in wounded skin, also improving effectiveness when appropriately administered [7; 8]  
Antioxidants work on three levels to combat free radicals: (i) they inhibit the radicals' formation both before and (ii) after the sunlight-determined insult, (iii) they may also correct some sunlight-determined damages [9]. In the last few years, there has been a growing demand for \"naturally derived\" or \"organic\" products as cosmeceutical ingredients useful in the personal care and beauty. Moreover, from the perspective of a circular economy, the recycling of agri-food waste to recover functional biomolecules represents an environmental-friendly strategy to obtain sustainable cosmetic/pharmaceutical ingredients [10; 11]. As a result, remarkable effort has been made to assess the efficacy of plant-derived compounds and oils as bioactive ingredients in the cosmetic industry [12]. Particularly, vegetable oils are natural-based ingredients that have gained interest as active ingredients to develop cosmeceuticals due to their UV absorbing and antioxidant properties [13]. Vegetable oils have considerable antioxidant properties through different mechanisms such as radical scavenging, due both to their unsaturated fatty acid composition and high levels of natural antioxidants, such as phenols (polyphenols and tocopherols) and carotenoids [14; 15; 16; 17]. EPR spectroscopy is an effective technique to evaluate the antioxidant properties and compare different materials. It was used to monitor the level of radicals resulting from irradiation of pharmaceuticals and dried fruit [18] and could be effective in evaluating the amount of free radicals produced during UV exposure of vegetable oils. It is unlikely that vegetable oils form very reactive radicals that never reach a concentration high enough to be directly detected. To this aim, the use of selected compounds, called spin-trapping agents, is of crucial importance. The spin-trapping agents react with the mentioned transient reactive species to yield stabilized radicals to be detected and measured via EPR spectroscopy. Most of the spin-trapping agents have a niritone-type group, which forms a nitroxide (spin adduct) during the trapping of the free radical. Among several nitrones used as spin traps, N-t-butyl-\(\alpha\)-phenylnitrone (PBN) was preferred due to its lipophilic character and stability of the resulting spin adducts [19]. Furthermore, PBN was successfully used as a spin-trapping agent to evaluate lipid free radicals in food lipids [20], edible vegetable oils, and their mixtures [21].