stain

Hematoxylin (Natural Black 1) is a dye obtained from the heartwood of logwood (Haematoxylon campechianum Linn., Leguminosae) used as a stain in microscopy and in the manufacture of ink.

Chromomycin A3 is an antibiotic produced by Streptomyces sp that binds to gc-rich DNA sequences in the presence of divalent cations and inhibits DNA replication and transcription; it is also used as a fluorescent DNA stain and assay; and it has anticancer activity against diseases such as Hodgkin's, lung adenocarcinomas, melanomas, and breast cancer.