Hybrid molecules of dihydroartemisinin with fluoroquinolones linked by L-homoserine have anti-tuberculosis and lipid-lowering effects

Eighteen dihydroartemisinin-fluoroquinolone molecules conjugated with L-homoserine were designed and synthesized using fragmented drug splicing approaches. The in vitro activities of the synthesized conjugates against Mycobacterium tuberculosis (MTB) and the lipid-lowering target PCSK9 were evaluated. The bioassay test results showed that most of the synthesized molecules had anti-tuberculosis (anti-TB) activity. Five compounds showed greater than 80% inhibitory activity against MTB in the replication state and three compounds exhibited more than 50% inhibitory activity against H₃₇Rv in the non-replication state. A structure-activity relationship analysis demonstrated that TM2 series compounds (Boc protection) have better anti-TB activity than TM1 series compounds (Cbz protection). There were 13 compounds with strong inhibitory activity toward PCSK9 (>73%) and TM1-3 compounds reached 92%. The determination of physical parameters showed that all the molecules are largely nontoxic. The structure-toxicity relationship analysis showed that the safety of TM2 is higher than that of TM1 in all parameters, perhaps related to the protecting group of the amino acid in the target molecule, and provides new ideas for the design and structural modification of subsequent molecules. This study sets a precedent for L-homoserine as a linking structural unit in multi-target drug molecules.