Synthesis and bioassay of a boron-dipyrromethene derivative of estradiol for fluorescence imaging in vivo

► A fluorescent derivative of estradiol (E2) with a boron-dipyrromethene (BODIPY) moiety attached to C7α. ► Syntheses by olefin metathesis reaction of 7α-allylestradiol and 9-decenyl-BODIPY. ► E2-BODIPY promoted growth of uterine tissue similar to estradiol in vivo. ► Twenty-four hours after subcutaneous injection, we observed fluorescence of E2-BODIPY in nuclei of uterine epithelial cells. C7α-substituted estradiols bind to estrogen receptors in cell nuclei, yet these derivatives remain little used in bioimaging. Here, we describe a fluorescent derivative of estradiol (E2) with a boron-dipyrromethene (BODIPY) moiety attached to C7α, synthesized by olefin metathesis reaction of 7α-allylestradiol and 9-decenyl-BODIPY. In ovariectomized rats and non-ovariectomized mice, E2-BODIPY promoted the growth of uterine tissue similar to the effect of estradiol. Twenty-four hours after subcutaneous injection of E2-BODIPY in non-ovariectomized mice, we observed fluorescence of E2-BODIPY in the nuclei of uterine epithelial cells. Our findings suggest that fluorescence microscopy can localize this derivative in E2-responsive cells during normal development and tumorigenesis in vivo.