ABSTRACT
Ilotycin (CAS number: 114-07-8), thereafter renamed erythromycin A, was first isolated at Eli Lilly from a strain of Streptomyces erythreus (McGuire et al., 1952). It is the first representative of the class of macrolide antibiotics introduced for clinical use. Macrolides are characterized by a macrocyclic lactone ring substituted by two sugars, among which a desosamine confers a character of weak base responsible for their ability to accumulate inside the cells. Erythromycin is made of a 14-membered ring, substituted by a desosamine in position 5 and a cladinose in position 3. The empirical formula is C37H67NO13 and the molecular weight is 733.93; the chemical structure is shown in Figure 59.1. Chemical structure of erythromycin A. Chemical instability in acid medium is due to the reaction between the ketone in position 9 and the hydroxyl in position 6 to form a hemicetal, followed by the reaction of this hemicetal with the hydroxyl in position 1 to form a cetal. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315152110/08d8042d-9481-4a8d-8c27-9bd589f6de6b/content/fig59_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
