The luteolin from Flos Chrysanthemi was found to directly bind to the Bcl-2 protein and inhibit the tumor cell growth in our previous study. However, it has been shown to possess wide and week biological activities. In this study, a series of derivatives of luteolin were designed and synthesized, and their tumor cell growth inhibitory activities were evaluated against human leukemia cell line HL-60. The results showed that compounds 1B-2, 2A-3, and 2B-5, with hydrophobic substituted benzyl groups introduced to B ring and hydrogen or methyl introduced to 7-OH group of luteolin, exhibited the strongest inhibitory activity with the IC50 lower than 10 μM, which were significantly more potent than luteolin. The studies presented here offer a good example for modifications of flavones to improve their tumor cell growth inhibitory activities.

A series of new combretastatin-A4 analogs were synthesized, in which a six-membered ring connects the linking bridge and A ring, and their tumor cell growth and tubulin-polymerization inhibitory activity were evaluated. These compounds appear to be potential tubulin-polymerization inhibitors. Compounds 1b with amino substituted on position 3 of B ring conferred optimal bioactivity, higher than that of the lead compound 22b and equivalent to that of CA-4. The binding modes of these compounds to tubulin were obtained by molecular docking, which can explain the structure–activity relationship. The studies presented here provide a new structural type for the development of novel antitumor agents.A series of new combretastatin-A4 analogs in which a six-membered ring connects the linking bridge and A ring were synthesized, and their tumor cell growth and tubulin-polymerization inhibitory activity were evaluated.

The benzyl-substituted flavone compounds are rare in nature, while some of which have interesting biological activities. The total synthesis of benzyl-substituted flavone derivatives via the acidic rearrangement of benzyl groups in flavone benzyl ethers, and the complicated regioselectivity of the rearrangement were reported. The regioselectivity was proposed to be determined by the steric hindrance as well as the ease of electrophilic substitution reaction for benzyl cations at different positions of corresponding debenzylated flavone compounds.Complicated regioselectivity was observed in the acidic rearrangement of benzyl groups in flavone benzyl ethers. It probably determined by the steric hindrance, as well as the ease of electrophilic substitution reaction for benzyl cations.