Used in photochemotherapy (PUVA therapy) to treat skin conditions like psoriasis, vitiligo, and eczema. When activated by ultraviolet A (UVA) light, psoralen binds to DNA and inhibits rapid cell division, making it effective for managing overactive skin cell growth. Also used in research for its ability to cross-link nucleic acids upon UV exposure, aiding in molecular biology studies. Found in some plant extracts used in traditional medicine and occasionally in tanning activators, though the latter use carries increased risk of skin damage.