ALIZARIN RED S excellent quality manufacturer, exporter and supplier. Alizarin is one of ten dihydroxyanthraquinone isomers. Its molecular structure can be viewed as being derived from anthraquinone by replacement of two neighboring hydrogen atoms (H) by hydroxyl groups (-OH). Alizarin Red is used in a biochemical assay to determine, quantitatively by colorimetry, the presence of calcific deposition by cells of an osteogenic lineage. In clinical practice, it is used to stain synovial fluid to assess for basic calcium phosphate crystals.