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hubie [soylentnews.org] writes:

Erythromycin belongs to a class of antibiotics known as macrolides [wikipedia.org], which are important alternatives to penicillins for treating infection. However, eventually some bacteria build a resistance to the antibiotic and it becomes necessary to make new ones. New antibiotics are made through a process called semisynthesis [wikipedia.org] where an existing macrolide is chemically modified into a new molecule. This is how derivatives of erythromycin, such as azithromycin and clarithromycin, were developed. The drawback of semisynthesis is that it is very hard to target a specific change, or the complexity of the macrolide molecules limit the kinds of changes available via chemical processes. Unfortunately, thus far the only process by which new macrolide antibiotics have been successfully made was by chemically modifying erythromycin.

Now, a group of researchers have found a way to completely synthetically construct macrolides by assembling them from simple molecular building blocks. Instead of going through the semisynthesis approach to come up with a single new candidate, they have made over 300 new antibiotic candidates using their new approach [rsc.org], most of which are not even possible to make otherwise, including one that is currently in clinical trials (solithromycin). What's more, the majority of the new candidates have shown some antibiotic activity, including some against bacteria strains that are currently resistant to the macrolides currently in use.

'Our goal was not to make a single molecule [as with semi-synthesis] but to develop a design strategy that by its nature would enable the preparation of thousands or even tens of thousands of clinical candidates,' explains Andrew Myers at Harvard University, US, whose group led the study. 'With a fully synthetic route we have access to orders of magnitude greater numbers of structures for study, and can effectively modify just about any position of the scaffold. That can’t be said of semi-synthetic approaches.'

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