Synthesis and biological evaluation of platensic alcohol as an adamantane surrogate in antitumor drug lead adaphostin

Adamantane has been widely used as a lipophilic bullet in drug discovery and development, due to its unique diamond-like architecture with benign pharmacological/ pharmaceutical properties. Platensimycin is a natural product isolated from a soil streptomycete, which contains an adamantane-like moiety extensively modified from a diterpenoid precursor. In the current study, platensic alcohol was semisynthesized from platensimycin and used as an adamantane surrogate in anticancer drug lead adaphostin. The resulting hybrid platensic alcohol/adaphostin compounds, eg. 4a and 4b, exhibited similar cytotoxic activity with adaphostin against the tested cancer cell lines. In particular, 4b generates significantly more reactive oxygen species (ROS) and shows stronger synergy with the clinically used histone deacetylase inhibitor vorinostat than adaphostin, probably due to the presence of two hydroquinone groups. Density functional theory calculation supports that there could be certain 7C-7C stacking interaction in 4b in aqueous solution, which might explain that 4b has similar serum stability with adaphostin. Our study not only leads to the identification of 4b as a potent ROS generating agent, but showcases a simple scaffold hopping strategy to harvest lipophilic scaffolds from natural products.

Automated summary

Platensic alcohol was semisynthesized from platensimycin and used as an adamantane surrogate in anticancer drug lead adaphostin, demonstrating similar cytotoxic activity with adaphostin but stronger ROS generation and synergy with vorinostat. Density functional theory calculation suggests certain stacking interaction in 4b, which explains its similar serum stability with adaphostin. This study showcases a simple scaffold hopping strategy to harvest lipophilic scaffolds from natural products and identifies 4b as a potent ROS generating agent.