Botanical derivatives and their bioactive phytochemicals have the potential to manage skin photoaging and photodamage-related skin problems including abnormal pigmentation and inflammation and thus can be used as practical prophylactic and therapeutic methods for different conditions. However, developing such products demands undertaking Ethnopharmacological studies.

Understanding the roles of phytochemicals in diminishing ultraviolet radiation (UVR)-induced skin damage is important to establish their medicinal and ethnopharmacological potential for developing novel and effective photoprotective agents. 

UVR activates apoptosis, oxidative stress, DNA damage and inflammation in skin cells leading to skins early aging (or photoaging) and impairing its integrity and function. 

Further, melanin shows a protective role against UVR-induced skin damage. However, alteration in melanin synthesis may cause skin damage, especially in fair-skinned individuals. UVR-induced oxidative stress boosts the process of skin aging and inflammation by activating associated signalling pathways, in epidermal keratinocytes and dermal fibroblasts, like mitogen-activated protein kinase (MAPK), activator protein-1 (AP-1), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription (STAT).

Reactive oxygen species (ROS) formed by UVR also regulates melanogenesis in melanocytes by modulating MAPK, PI3K/Akt and the melanocortin 1 receptor (MC1R)-microphthalmia-associated transcription factor (MITF) signalling cascades. Additionally, antioxidant defenses regulated by nuclear factor erythroid 2-related factor 2 (Nrf2) have an impact on the major signalling pathways responsible for photoaging, inflammation associated with skin barrier dysfunction and melanogenesis. 

Thus phytochemicals act as Nrf2 inducers and improve photoaging, inflammation and hyperpigmentation by regulating cellular homeostasis involved in skin integrity and function. 

In summarizing, apprehending the role of phytochemicals targeting Nrf2 regarding photoprotection could help in the potential development of natural products as a promising strategy to slow skin photoaging and enhance skin conditions.

Source: Chaiprasongsuk A, Panich U. Role of phytochemicals in skin photoprotection via regulation of Nrf2. Front Pharmacol. 2022;13:823881.