3-Methoxy-10H-phenothiazine is used in the synthesis of 10-Dechlorovancomycin (D226740), which is an impurity of Vancomycin (V096500, HCl salt) which is an amphoteric glycopeptide antibiotic produced by Streptomyces orientalis discovered in soil. Vancomycin inhibits bacterial cell wall synthesis by binding to peptidoglycan.