A preparation containing a mixture of glycosidic antibiotics isolated from Streptomyces olivoreticuli with fluorescent microscopy applications and potential antineoplastic activities. Olivomycin preferentially binds to DNA and can be utilized as a fluorescent marker during the characterization of heterochromatin. Additionally, binding to DNA inhibits both RNA transcription and RNA elongation by RNA polymerase; therefore protein synthesis is inhibited. In addition, olivomycin antibiotics are able to induce apoptosis in tumor cells through a mechanism that has not yet been fully elucidated.