Studies on Lankacidin-Group (T-2636) Antibiotics

The lankacidin-group (T-2636) antibiotics, neutral seventeen-membered macrocyclic antibiotics, are mainly active against Gram-positive bacteria.Chemical modifications of certain functions of lankacidin C has provided a group of lankacidin C analogs and derivatives.These new antibiotics were examined for their in vitro antimicrobial activities, their therapeutic effects against experimental infections in mice, and for their acute toxicities in mice and subacute toxicities in rats.Some of the lankacidin C mono-esters were found to be superior in their biological properties to the parent antibiotic.The antibiotics, lankacidin A, lankacidin C, lankacidinol A, lankacyclinol A, lankacidinol* and lankacyclinol** have been isolated from Streptomyces rochei var.volubilis and their chemical structures have been determined (see Chart I.1"61).Chart 1.Chemical structures of lankacidin-group antibiotics isolated from the culture filtrate of Streptomyces rochei var.volubilis.Amongthese antibiotics, lankacidin C shows the strongest antimicrobial activities in vitro against Gram-positive bacteria, mycoplasma, Neisseria gonorrhoeae, Vibrio cholerae, Xanthomonas oryzae and clinically isolated staphylococci.Lankacidin A and lankacidinol are less active than lankacidin C.2'4>7) The remaining members have very poor activity.Lankacidins A and C administered orally * The names of these antibiotics have been tentatively designated as T-2636 A, C, D, E and F, respectively.** The metabolite described in the following paper.