ESR1 and breast cancer: Amongst them, single chloro-substituted derivative 3h was the strongest tubulin inhibitor, disrupting the microtubule structure by inhibiting the colchicine site, while potently inhibiting aromatase (IC50 = 1.8 μM) with strong activity against the estrogen receptor-positive T47D breast cancer cell line (IC50 = 2.4 μM).