Design and synthesis of small molecule RhoA inhibitors: A new promising therapy for cardiovascular diseases?

RhoA is a member of Rho GTPases, a subgroup of the Ras superfamily of small GTP-binding proteins. RhoA, as an important regulator of diverse cellular signaling pathways, plays significant roles in cytoskeletal organization, transcription, and cell-cycle progression. The RhoA/ROCK inhibitors have emerged as a new promising treatment for cardiovascular diseases. However, to date, RhoA inhibitors are macromolecules, and to our knowledge, small molecular-based inhibitors have not been reported. In this study, a series of first-in-class small molecular RhoA inhibitors have been discovered by using structure-based virtual screening in conjunction with chemical synthesis and bioassay. Virtual screening of ∼200,000 compounds, followed by SPR-based binding affinity assays resulted in three compounds with binding affinities to RhoA at the micromolar level (compounds 1-3). Compound 1 was selected for further structure modifications in considering binding activity and synthesis ease. Fourty-one new compounds (1, 12a-v, 13a-h, and 14a-j) were designed and synthesized accordingly. It was found that eight (12a, 12j, 14a, 14b, 14d, 14e, 14 g, and 14h) showed high RhoA inhibition activities with IC₅₀ values of 1.24 to 3.00 μM. A pharmacological assay indicated that two compounds (14g and 14 h) demonstrated noticeable vasorelaxation effects against PE-induced contraction in thoracic aorta artery rings and served as good leads for developing more potent cardiovascular agents.