**7. Other applications**

Plant bioactive compounds (primarily flavonoids) have been used in dermatology and cos‐ metic preparations for a long time due to several associated properties such as antioxidant, antimicrobial, anti‐inflammatory and therapeutic properties [8, 75]. Flavonoids are gaining popularity as cosmetic ingredients because they can protect skin from UV light and cure the skin from oxidative stress, so they can improve skin appearance [76]. The activity of flavo‐ noids on the skin is associated with their antiradical properties due to the presence of phe‐ nolic groups, but these activities on the skin are poorly investigated. Many studies have been demonstrated that the scavenging of flavonoids depends mainly to a high degree on their structures and physicochemical properties [47].

In order to protect the skin against UV radiation, the use of herbal and biodegradable prod‐ ucts has been increased; cosmetic products are being recognized for their benefits in the pre‐ vention of various pathologies and in the improvement of several dermatologic conditions, which represent a viable alternative for industrial application of natural extracts [70, 76]. Recent dermatological studies have been demonstrated that herbal extracts were added to cosmetic preparations due to antioxidant properties of flavonoids in addition to impart UV protection and inhibit metal chelating properties to protect skin [75].

The protective action of flavonoids on the skin is manifested through their anti‐inflammatory activity. This activity is given by the action of bioactive compounds on the enzymes and other factors that promote inflammation stages. The other mechanism of action is the inhibition of enzymes linked to cellular activation that promotes skin deterioration and the secretion of regulatory substances for their propagation. The affinity for protein structures and with estro‐ gen receptors is another property of flavonoids, as well as anti‐irradiating activities; because of these features, they are used in the cosmetic industry to reduce congestion problems, with the aim of reducing inflammatory symptoms that damage humans [47].
