title: Synthesis and structure-activity relationship studies of novel tubulysin U analogues--effect on cytotoxicity of structural variations in the tubuvaline fragment.
abstract: Tubulysins are cytotoxic natural products with promising anti-cancer properties, originally isolated from myxobacterial cultures. Structurally, tubulysins are tetrapeptides, incorporating three unusual (Mep, Tuv and Tup) and one proteinogenic amino acid (Ile). Here we describe the synthesis and structure-activity relationship studies of novel tubulysin U and V analogues, with variations in the central Tuv fragment, which is known to be of paramount importance for tubulysins' potency and hence cytotoxicity, but has seldom been modified in previous studies. Specifically, we replaced the natural iso-propyl and acetoxy functionalities with other structurally related groups. In general, the new analogues showed much lower potency relative to native tubulysin U. However, one of the synthetic analogues (1f) having a MOM function replacing the acetyl group exhibited a 22 nM IC50 on the HT-29 cell line which is comparable to the IC(50) displayed by tubulysin U (3.8 nM). Furthermore, the synthetic methodology reported herein was found to be flexible enough to deliver different core-modified tubulysin analogues and hence may be regarded as a scalable and convenient strategy for the chemical generation of novel tubulysin analogues.
authors: Dipartimento di Chimica, Materiali e Ingegneria Chimica Giulio Natta, Politecnico di Milano, Via Mancinelli 7, 20131 Milan, Italy.
authors: Sreejith P
authors: SP
authors: Shankar
authors: Monika
authors: M
authors: Jagodzinska
authors: Luciana
authors: L
authors: Malpezzi
authors: Paolo
authors: P
authors: Lazzari
authors: Ilaria
authors: I
authors: Manca
authors: Iain R
authors: IR
authors: Greig
authors: Monica
authors: M
authors: Sani
authors: Matteo
authors: M
authors: Zanda
mesh_terms: D045744:Cell Line, Tumor; D018360:Crystallography, X-Ray; D014644:Genetic Variation; D019073:HT29 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D015394:Molecular Structure; D009369:Neoplasms / Q000188:drug therapy; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D010875:Pipecolic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D009842:Oligopeptides; D010446:Peptide Fragments; D010875:Pipecolic Acids; C516471:tubulysin U; C516472:tubulysin V