Discovery, synthesis of novel fusidic acid derivatives possessed amino-terminal groups at the 3-hydroxyl position with anticancer activity

A series of novel fusidic acid (FA) derivatives were synthesized and screened for their in vitro cytotoxicity against the Hela, U87, KBV and MKN45 cancer cell lines. Selected FA derivatives with anti-tumor activity were firstly identified including compound 4, which exhibited good anti-proliferative activity with IC₅₀ values in the range of 1.26–3.57 μM. Further research revealed that compound 4 induced Hela cells to undergo apoptosis by increasing the ratio of the cells in the Sub-G₀/G₁ phase via decreasing the neo-synthesized proteins in a dose-dependent manner from 1 to 10 μM. Compound 4 also showed good in vivo anti-tumor activity against the xenograft tumor of Hela cells and had no apparent toxicity. This study highlights the advantage of introducing the medium-length amino-terminal groups at the 3-OH position of FA to enhance its anti-tumor activity and suggests that compound 4 provides a starting point for designing more potent derivatives in the future.