UVB is a high energy source that causes the major risk factor for sunburn and skin tumor. However, photochemical interactions lead to beneficial effects such as synthesis of vitamin D and corticosteroids. Therefore, a reasonable therapeutic regime is advocated to reduce UVB injuries but makes use of synthesizing sunlight metabolite. Many natural compounds improving plant cells resistant to oxidative stress by the harnessing of solar energy may be also used to protect human cells. Although many nature plants have shown photoprotective effects on skin, the mechanisms underlying of the effects are still ambiguous.

This study evaluates the protective effects of cultivated Cordyceps against UVB-induced damage in human keratinocytes and identifies the photoprotective mechanisms using a transcriptomic network approach.

Cordyceps extract compositions were investigated by HPLC analysis. Cell survival, reactive oxygen species (ROS) generation, H₂O₂ content, aquaporin 3 (AQP3) level and DNA damage were determined upon UVB irradiation in the presence of Cordyceps extract. In addition, next-generation sequencing was used to profile transcriptomic alteration of 20 mJ/cm² UVB and non-UV. Finally, a network pharmacology method was applied to study Cordyceps extract-related natural compounds and their UVB-induced differentially change targets using the Cytoscape 3.7.1 software.

Adenosine and mannitol were the major contents in Cordyceps extract. Cordyceps caused a significant diminished in intracellular UVB-induced oxidative stress, including ROS production and intracellular H₂O₂ content. Besides, AQP3 which mediated intracellular signal transmission and transported H₂O₂ into cells was significantly increased in the presence of Cordyceps extract against UVB irradiation. In addition, DNA repair effect of Cordyceps extract after UV irradiation was proven to be effective by comet assay. Moreover, KEGG analysis showed steroid hormone biosynthesis, ovarian steroidogenesis, fat digestion and absorption were enriched in top 3 between 20 mJ/cm² UVB and non-UV. Gene ontology (Go) analysis showed that steroid metabolic process, sterol metabolic process, and cholesterol metabolic process were enriched in top3 biology process. By using network analysis, 125 potential bioactive ingredients in Cordyceps and 201 targets were identified. Finally, signal pathway analyses suggested that the protective effects of Cordyceps compounds against low dose UVB‑induced changes might target PPAR signaling pathway, cholesterol metabolism, and ovarian steroidogenesis.

Cordyceps extract may be an ideal product for external use of skin which could not only avoid UVB-induced adverse effects, but also could application of metabolite products by UVB such us steroid hormone and vitamin D3.