Optimization of biaryloxazolidinone as promising antibacterial agents against antibiotic-susceptible and antibiotic-resistant gram-positive bacteria.

We previously discovered a series of novel biaryloxazolidinone analogues bearing a hydrazone moiety with potent antibacterial activity. However, the most potent compound OB-104 exhibited undesirable chemical and metabolic instability. Herein, novel biaryloxazolidinone analogues were designed and synthesized to improve the chemical and metabolic stability. Compounds 6a-1, 6a-3, 14a-1, 14a-3 and 14a-7 showed significant antibacterial activity against the tested Gram-positive bacteria as compared to radezolid and linezolid. Further studies indicated that most of them exhibited improved water solubility and chemical stability. Compound 14a-7 had MIC values of 0.125-0.25 µg/mL against all tested Gram-positive bacteria, and showed excellent antibacterial activity against clinical isolates of antibiotic-susceptible and antibiotic-resistant bacteria. Moreover, it was stable in human liver microsome. From a safety viewpoint, it showed non-cytotoxic activity against hepatic cell and exhibited lower inhibitory activity against human MAO-A compared to linezolid. The potent antibacterial activity and all these improved drug-likeness properties and safety profile suggested that compound 14a-7 might be a promising drug candidate for further investigation.

Design and synthesis of biaryloxazolidinone derivatives containing a rhodanine or thiohydantoin moiety as novel antibacterial agents against Gram-positive bacteria.

Novel biaryloxazolidinone derivatives containing a rhodanine or thiohydantoin moiety were designed, synthesized and evaluated for their antibacterial activity. The key compounds 7 and 9 were synthesized by the knoevenagel condensation of intermediate aldehyde 5 with rhodanine derivatives 6a-6b. The preliminary study showed that compounds 7, 9 and 10e exhibited potent antibacterial activity with MIC values of 0.125 µg/mL against S. aureus, MRSA, MSSA, LREF and VRE pathogens, using linezolid and radezolid as the positive controls. The most promising compound 10e exhibited potent antibacterial activity against tested clinical isolates of MRSA, MSSA, VRE and LREF with MIC values in the range of 0.125-0.5 µg/mL, and the potency of 10e against clinical isolates of LREF was 64-fold higher than that of linezolid. Moreover, compound 10e was non-cytotoxic with an IC50 value of 91.04 µM against HepG2 cell. Together, compound 10e might serve as a novel antibacterial agent for further investigation.

Synthesis and antibacterial activity evaluation of novel biaryloxazolidinone analogues containing a hydrazone moiety as promising antibacterial agents.

A series of linezolid analogues containing a hydrazone moiety were designed, synthesized and evaluated for their antibacterial activity. Most compounds exhibited more potent antibacterial activity against S.aureus, MRSA, MSSA, LREF and VRE pathogens as compared with linezolid and radezolid. Compounds 9a, 9c, 9f, 9g, 10m and 10t were more potent against tested clinical isolates of MRSA, MSSA, VRE and LREF as compared to linezolid. Compound 9a exhibited comparable activity with linezolid against human MAO-A for safety evaluation and showed moderate metabolism in human liver microsome. The most promising compound 9a showed remarkable antibacterial activity against S.aureus, MRSA, MSSA, LREF and VRE pathogens with MIC value of 0.0675 mg/mL, respectively, which was 15- to 30-fold more potent than linezolid.