以正常大鼠为实验对象，观察单纯外用花椒毒内酯，结香甲素，连续给药7d，致骨髓细胞染色体畸变率相应各达2％及0．2％。两者比较具显著性差异（P＜0．01）。结合UV－N辐照，给药1周，花椒毒内酯组致染色体畸变率为6．0％，结香甲素组为1．0％（P＜0．001）；治疗2周则分别为4．0％、2．0％（P＜0．05）均呈显著性差异。实验表明在光化学疗法中，花椒毒内酯外搽有明显的致诱变毒性，而结香甲素具有明显的抗诱变作用。

External use of either xanthotoxin or umbelliferone alone in normal rats showed that the chromosomes of the myelocyte were mutated at an aberrant rate of 2.0% and 0.2%, respectively (P0.01 ). When used in combination with UV-N irradiation for one week, the aberrant rate was 6.0%, and 1.0% respectively (P0.001). At two week's treatment they were 4.0%, and 2.0%, respectively (P0.05 ). It is thus suggested that in photochemotherapy xauthotoxin for external use have obvious mutational effect and umbelliferone have a protective action against irra diation.