Study on the synthesis and anti-tumor activities of rhein-amino acid conjugates

Abstract

20 novel rhein-amino acid conjugates were designed and synthesized from the rhein via esterification, etherification, hydrolysis, condensation and salification. Their structures were confirmed by 1H NMR, 13C NMR and HRMS. All the target compounds were tested for cytotoxic activity against five cancer cell lines including Hela, MCF-7, HepG2, KB and HEK293T by methyl thiazolyl tetrazolium (MTT) method in vitro. The results showed that sodium (4,5-bis(benzyloxy)-9,10-dioxo-9,10-dihydroanthracene-2-carbonyl)leucinate (6eb) demonstrated moderate cytotoxic activities (IC50<50 μmol•L-1). The fluorescence of compounds sodium (4,5-dibutoxy-9,10-dioxo-9,10-dihydroanthracene-2-carbonyl)leucinate (6db) and 6eb could be both quenched by DNA. It was speculated that compound 6db interacted with DNA by the static attraction or was partially embedded into DNA.