Synthesis and biological evaluation of thiophosphate tricyclic coumarin derivatives as steroid sulfatase inhibitors

Abstract

Steroid sulfatase (STS) enzyme inhibition is an important approach to the management of hormone-dependent breast cancer. In this paper, we report convenient methods for the synthesis and biological evaluation of thiophosphate tricyclic coumarin analogs exhibiting STS activity. The described methods are based on the straightforward preparation of 7-hydroxy-2,3-dihydro-1H-cyclopenta[c]chromen-2-one, 3-hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one, and 3-hydroxy-8,9,10,11-tetrahydro-7H-cyclohepta[c]chromen-6-one and their further modification by the introduction of various thiophosphate moieties. The inhibition properties of the synthesized compounds were tested toward STS isolated from human placenta. Most of the new STS inhibitors possessed good to moderate activity toward STS. During the course of our investigation, the largest inhibitory effects in the STS enzyme assays were observed for the two compounds 3f and 4r, with IC₅₀ values of 13.3 and 30.3 μM, respectively (the IC₅₀ value of 1 μM for the 665-COUMATE was used as a reference). The structure–activity relationships of the synthesized coumarin derivatives toward STS enzymes are discussed.

Keywords::

• breast cancer
• coumarin
• thiophosphate
• steroid sulfatase inhibitors

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Science Centre (Poland) [grant number 2011/03/D/NZ7/03985].