title: Semisynthetic macrolide antibacterials derived from tylosin. Synthesis and structure-activity relationships of novel desmycosin analogues.
abstract: A series of 20-O-substituted and 3,20-di-O-substituted derivatives of desmycosin were synthesized and their biological properties were evaluated. In particular, we have synthesized numerous side chain modified analogues of desmycosin as well as some analogues possessing a combination of modified side chain and alternative C-3 substituents. Thus, alpha,beta-unsaturated analogues of desmycosin (2), tylosin (1), 10,11,12,13-tetrahydrotylosin (11), and 2,3-didehydrodesmycosin (13) were prepared from the corresponding aldehydes by a Wittig reaction with the stabilized ylides (a-d), generating a trans-double bond, followed by modified Pfitzner-Moffat oxidation of the C-3 hydroxyl group. To evaluate the importance of the C-3 position of desmycosin for biological activity, the C-3 substituted derivatives were synthesized by a standard sequence of protective group chemistry followed by Wittig reaction and esterification as the key steps. For the attachment of the C-3 ester functionality, a mixed anhydride protocol was adopted. Reaction proceeded smoothly to give corresponding esters in yields ranging from 70 to 80%. Base- and acid-catalyzed rearrangement products including desmycosin 8,20-aldols (24a and 24b) and desmycosin 3,19-aldol (25) are also described. Parallel array synthesis and purification techniques allowed for the rapid exploration of structure-activity relationships within this class and for the improvement in potency. In vitro evaluation of these derivatives demonstrated good antimicrobial activity against Gram-positive bacteria for most of the compounds. The present derivatives of 16-membered macrolides were active against MLS(B)-resistant strains that were inducibly resistant, but not those constitutively resistant to erythromycin.
authors.affiliation: PLIVA Pharmaceutical Industry Inc., Research Division, Prilaz baruna Filipovića 25, HR-10000 Zagreb, Croatia.
authors.forename: Stjepan
authors.initials: S
authors.lastname: Mutak
authors.forename: Natasa
authors.initials: N
authors.lastname: Marsić
authors.forename: Miroslava Dominis
authors.initials: MD
authors.lastname: Kramarić
authors.forename: Drazen
authors.initials: D
authors.lastname: Pavlović
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001682:Biological Availability; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D051379:Mice; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014018:Tissue Distribution; D015645:Tylosin / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; C052318:tylosin B; D004917:Erythromycin; D015645:Tylosin