| Summary: | Physiological processes in skin are associated with exposure to UV light and are essential for skin maintenance and regeneration. Here, we investigated whether the leaf and callus extracts of <i>Perilla frutescens (Perilla)</i>, a well-known Asian herb, affect DNA damage response and repair in skin and keratinocytes exposed to Untraviolet B (UVB) light. First, we examined the protective effects of <i>Perilla</i> leaf extracts in UVB damaged mouse skin in vivo. Second, we cultured calluses using plant tissue culture technology, from <i>Perilla</i> leaf explant and then examined the effects of the leaf and callus extracts of <i>Perilla</i> on UVB exposed keratinocytes. HaCaT cells treated with leaf and callus <i>Perilla</i> extracts exhibited antioxidant activities, smaller DNA fragment tails, and enhanced colony formation after UVB exposure. Interestingly, keratinocytes treated with the leaf and callus extracts of <i>Perilla</i> showed G1/S cell cycle arrest, reduced protein levels of cyclin D1, Cyclin Dependent Kinase 6 (CDK6), and γH<sub>2</sub>AX, and enhanced levels of phosphorylated checkpoint kinase 1 (pCHK1) following UVB exposure. These observations suggest that the leaf and callus extracts of <i>Perilla</i> are candidate nutraceuticals for the prevention of keratinocyte aging.
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