title: Preparation and DNA-binding properties of substituted triostin antibiotics.
abstract: Novel derivatives of the triostin group of antibiotics were prepared by supplementing cultures of the producing organism Streptomyces triostinicus with a variety of aromatic carboxylic acids. Five new antibiotics, each having both the natural quinoxaline chromophores replaced by a substituted ring system, were purified to homogeneity and characterized by high-pressure liquid chromatography and nuclear magnetic resonance. Their antibacterial activities and DNA-binding properties were investigated. Addition of a halogen atom at position 6 of the quinoxaline ring or an amino group at position 3 had little effect on either the biological activity or the DNA-binding characteristics. The bis-3-amino derivative is fluorescent, and its fluorescence is strongly quenched by calf thymus DNA and polydeoxyguanylate-polydeoxycytidylate but not by polydeoxyadenylate-polydeoxythymidylate, suggesting that it binds preferentially to guanosine-cytosine-rich sequences in natural DNA. Binding constants for the bis-6-chloro and bis-3-amino derivatives do not differ greatly from those of unsubstituted triostin A. The analogs having two quinoline chromophores or a chlorine atom in position 7 of the quinoxaline ring display little or no detectable antibacterial activity, in marked contrast to the other congeners. Bis-7-chloro-triostin A binds conspicuously more tightly to polydeoxyadenylate-polydeoxythymidylate than to any other polynucleotide tested.
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D004247:DNA; D005453:Fluorescence; D011810:Quinoxalines / Q000096:biosynthesis* / Q000494:pharmacology; D012995:Solubility; D013302:Streptomyces / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D011810:Quinoxalines; C031945:triostin A; D004247:DNA