BC6 bc6 (4E,8S,9R,10E,12S,13R,14S,16R)-13,20-dihydroxy-14-methoxy-4,8,10,12,16-pentamethyl-3-oxo-2-azabicyclo[16.3.1]docosa-1(22),4,10,18,20-pentaen-9-yl carbamate BC6