(E)-4-Hydroxytamoxifen

(E)-4-Hydroxytamoxifen is the less active isomer of 4-hydroxytamoxifen. 4-Hydroxytamoxifen is the active metabolite of tamoxifen, a selective estrogen receptor modulator (SERM) that acts as an agonist or antagonist in various tissues. 4-Hydroxytamoxifen exhibits anticancer chemotherapeutic activity, inducing autophagy and vacuole formation as well as KRAS degradation in various cancer cell lines. In cardiac myocytes, 4-hydroxytamoxifen decreases Ca2+ amplitude, slowing relaxation and decreasing contractility.