Abstract: The present invention concerns a new antibiotic substance arbitrarily denominated antibiotic A 40926 complex and its factors antibiotic A 40926 factor A, antibiotic A 40926 factor B, antibiotic A 40926 factor B.sub.0, antibiotic A 40926 factor PA and antibiotic A 40926 factor PB, a process for producing them by culturing the new strain Actinomadura sp. ATCC 39727 or an A 40926 producing variant or mutant thereof and the use of these new antibiotic substances in the treatment of infectious diseases involving microorganisms susceptible to them. The antibiotic substances of the invention are glycopeptidic substances belonging to the vancomycin class of antibiotics which have binding capacity to Acyl-D-Alanyl-D-Alanine.

Abstract: The present invention concerns a new antibiotic substance arbitrarily designated as antibiotic SB 22484, to a process for its production by culturing Streptomyces sp. NRRL 15496 or a producing variant or mutant thereof, and to the use of the new antibiotic substance in the treatment of infectious diseases involving microorganisms susceptible to this antibiotic substance.

Abstract: Novel rifamycins characterized by the following structural formula ##STR1## WHEREIN Me represents a methyl group, n represents 3, 4, 5 or 6; g represents 0, 1 or 2; and each R represents a lower alkyl group selected from methyl or ethyl substituting for a hydrogen atom of a --CH.sub.2 -- group; and wherein, when g is 2, the two lower alkyl groups may replace hydrogen atoms of two different methylene groups as well as hydrogen atoms of the same methylene group. The compounds of this invention possess a broad spectrum antibacterial utility accompanied by a low toxicity.

Abstract: Substituted piperazinyliminorifamycins having the following structural formula: ##STR1## wherein Me represents a methyl group and Z represents alkenyl of 3 to 5 carbon atoms, alkynyl of 3 to 5 carbon atoms, 5- or 7-membered cycloalkenyl, cycloalkyl-(C.sub.1 -C.sub.2) alkyl wherein the cycloalkyl moiety is a 3- or 7-membered ring or cycloalkenyl-(C.sub.1 -C.sub.2)alkyl wherein the cycloalkenyl moiety is a 5- or 7-membered ring. The compounds have a broad spectrum antibacterial utility accompanied by a low toxicity.