Ansamycins

Geldanamycin is a 1,4-benzoquinone ansamycin antitumor antibiotic that inhibits the function of Hsp90 (Heat Shock Protein 90) by binding to the unusual ADP/ATP-binding pocket of the protein. HSP90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, angiogenesis and oncogenesis.

Maitansine (INN), or maytansine (USAN), is a cytotoxic agent. It inhibits the assembly of microtubules by binding to tubulin at the rhizoxin binding site. The maytansine binding site and binding mode has been characterized.

thumb|Structure of geldanamycin, one of the benzoquinone ansamycins. Ansamycins is a family of bacterial secondary metabolites that show antimicrobial activity against many Gram-positive and some Gram-negative bacteria, and includes various compounds, including streptovaricins and rifamycins. In addition, these compounds demonstrate antiviral activity towards bacteriophages and poxviruses.

Herbimycin is a benzoquinone ansamycin antibiotic that binds to Hsp90 (Heat Shock Protein 90) and alters its function. Hsp90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, angiogenesis and oncogenesis.

Tanespimycin ('17-N-allylamino-17-demethoxygeldanamycin, 17-AAG') is a derivative of the antibiotic geldanamycin that is being studied in the treatment of cancer, specifically in younger patients with certain types of leukemia or solid tumors, especially kidney tumors.

Macbecins are a pair of chemical compounds in the ansamycin family of antibiotics. They are designated macbecin I and macbecin II and they were first isolated from actinomycete bacteria. Macbecin possesses antitumor properties. In vitro studies have shown that macbecins are effective in the eradication of Gram-positive bacteria, fungi, and protozoa including Tetrahymena pyriformis. ==Structure== Macbecins have an unusual macrocyclic lactam structure. The two variants, macbecin I and II, correspond to the oxidized 1,4-benzoquinone and reduced hydroquinone, respectively.