Significant breakthroughs in search for anti-infectious agents derived from erythromycin A.

As a well-established class, macrolide antibiotics continue to enjoy a remarkable interest within pharmaceutical industry. Several stunning breakthroughs in semi-synthetic study of erythromycin A (EMA) contribute to the important role played by the macrolide class in search for new anti-infectious agents. Earlier structural modifications of EMA to address the issue of acid instability resulted in the first breakthrough in search for anti-infectious agents derived from EMA. Clarithromycin (CAM) and azithromycin (AZM) are two representative antibacterials commercialized during this period. Afterwards, continued research on the modifications of EMA to combat bacterial resistance culminated in the second breakthrough in this field. Telithromycin and cethromycin are two innovative antibacterials discovered in this period for treating community-acquired pneumonia (CAP). Recently, further structural modifications of EMA generate promising antibacterials endlessly, which will hopefully arouse another breakthrough in the near future. In this review, we will give an account of these breakthroughs and discuss the future directions of semi-synthetic research on EMA. In particular, the design and synthesis of some distinguished or promising antibacterials derived from EMA will be highlighted.