Differential effects of baicalein and its sulfated derivatives in inhibiting proliferation of human breast cancer MCF-7 cells

• BoS and BcS are synthesized by baicalein (Bai).
• The growth-inhibitory activities against MCF-7 cells were ranked BcS > Bai > BoS.
• ROS as H2O2 generation is involved in the growth inhibition and apoptosis.
• Water-soluble BcS has potential to be explored as novel anti-proliferative flavonoid.

This study was to investigate the anticancer effects of baicalein (Bai) and its two sulfated derivatives, namely baicalein-7-O-sulfate (BoS) and baicalein-8-sodium sulfonate (BcS). BcS was shown to exhibit stronger growth inhibition against human breast cancer MCF-7 cells, compared with structurally related Bai and BoS, where IC50 values of BoS, Bai and BcS were 97.7, 68.3 and 30.4 μM, respectively. BoS, Bai and BcS were further shown to mediate the cell-cycle arrest principally in G0/G1-phase within 12 h of treatment with MCF-7 cells, and after 12 h, they arrested principally in S-phase. It was also found that 17.7%, 44.9% and 70.5% of MCF-7 cells entered the early phase of apoptosis when treated with 200 μM BoS, Bai and BcS for 24 h, followed by an intracellular ROS generation. BcS displays strong antitumor effect through ROS-dependent apoptosis pathway in MCF-7 cells, and has promising potential to be developed as an antitumor compound.