macbecin macbecin macbecin belongs to the ansamycin family of antibiotics and was first isolated from actinomycete bacteria. macbecin possesses potent antitumor properties. in-vitro studies have shown that macbecin is effective in the eradication of gram-positive bacteria, fungi, and protozoa including tetrahymena pyriformis. macbecin i names iupac name (4e,6z,8s,10e,12r,13s,14r,16s,17r)-13,14,17-trimethoxy-4,8,10,12,16-pentamethyl-3,20,22-trioxo-2-azabicyclodocosa-1(21),4,6,10,18-pentaen-9-yl carbamate other names macbecin i identifiers cas number 73341-72-7 y 3d model (jsmol) interactive image pubchem cid 5458728 smiles cc1cc(c(c(c=c(c(c(c=cc=c(c(=o)nc2=cc(=o)c=c(c1oc)c2=o)c)c)oc(=o)n)c)c)oc)oc properties chemical formula c30h42n2o8 molar mass 558.66308 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). y verify (what is yn ?) infobox references macbecin ii names iupac name (4e,6z,8s,10e,12r,13s,14r,16s,17r)-20,22-dihydroxy-13,14,17-trimethoxy-4,8,10,12,16-pentamethyl-3-oxo-2-azabicyclodocosa-1(22),4,6,10,18,20-hexaen-9-yl carbamate other names macbecin ii identifiers cas number 73341-73-8 3d model (jsmol) interactive image pubchem cid 5458729 smiles cc1cc(c(c(c=c(c(c(c=cc=c(c(=o)nc2=c(c(=cc(=c2)o)c1oc)o)c)c)oc(=o)n)c)c)oc)oc properties chemical formula c30h44n2o8 molar mass 560.67896 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references structure macbecin has an unusual macrocyclic lactam structure. there are two variants macbecin i and ii which correspond to the oxidized 1,4-benzoquinone and reduced hydroquinone respectively. mechanism of action macbecins mechanism of action is in part due to heat shock protein hsp90 protein inhibition.