Structure-activity relationship study of novel evodiamine amino acid conjugates with potent anti-colorectal cancer efficacy

Evodiamine has been a promising lead structure with broad-spectrum antitumor activity. Druggability optimization is the most challenging part of evodiamine-based lead-to-candidate campaign. Amino acids as building blocks for conjugates are widely incorporated into approved drug and drug candidates, demonstrating highly attractive druggability. Herein, a series of evodiamine amino acid conjugates were designed and synthesized based on the evodiamine lead compound (±)-8b discovered in our previous work. The structure−activity relationship (SAR) studies culminated in the identification of a promising conjugate (−)-15h featuring a N-Boc-l-glutamine group and a chiral carbon atom (sinister), which exhibited nanomolar antiproliferative activity against LoVo and RKO colorectal cancer cells. Moreover, (−)-15h could inhibit topoisomerases I, arrest the cell cycle in the G2/M phase, and induce apoptosis. Importantly, (−)-15h (tumor growth inhibition rate was 82.53 % in 40 mpk) showed better efficacy and tolerability to that of parent compound (−)-8b (tumor growth inhibition rate was 51.22 % in 40 mpk) in LoVo xenograft model. Further, (−)-15h (tumor growth inhibition rate was 70.09 % in 40 mpk) showed comparable efficacy and better tolerability to that of topotecan (tumor growth inhibition rate was 70.67 % in 0.5 mpk) in HT-29 xenograft model. Collectively, this study further provided a strong scientific basis for amino acid-based structural modifications and a drug lead for anti-colorectal cancer applications.