title: Generation of new derivatives of the antitumor antibiotic mithramycin by altering the glycosylation pattern through combinatorial biosynthesis.
abstract: Mithramycin is an antitumor drug produced by Streptomyces argillaceus. It consists of a tricyclic aglycone and five deoxyhexoses that form a disaccharide and a trisaccharide chain, which are important for target interaction and therefore for the antitumor activity. Using a combinatorial biosynthesis approach, we have generated nine mithramycin derivatives, seven of which are new compounds, with alterations in the glycosylation pattern. The wild-type S. argillaceus strain and the mutant S. argillaceus M7U1, which has altered D-oliose biosynthesis, were used as hosts to express various "sugar plasmids", each one directing the biosynthesis of a different deoxyhexose. The newly formed compounds were purified and characterized by MS and NMR. Compared to mithramycin, they contained different sugar substitutions in the second (D-olivose, D-mycarose, or D-boivinose instead of D-oliose) and third (D-digitoxose instead of D-mycarose) sugar units of the trisaccharide as well as in the first (D-amicetose instead of D-olivose) sugar unit of the disaccharide. All compounds showed antitumor activity against different tumor cell lines. Structure-activity relationships are discussed on the basis of the number and type of deoxyhexoses present in these mithramycin derivatives.
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Pérez
authors.forename: Irfan
authors.initials: I
authors.lastname: Baig
authors.forename: Alfredo F
authors.initials: AF
authors.lastname: Braña
authors.forename: José A
authors.initials: JA
authors.lastname: Salas
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rohr
authors.forename: Carmen
authors.initials: C
authors.lastname: Méndez