Lawsone (aka hennatannic acid) is a red-orange dye present in the leaves of the henna plant as well as the flower of water hyacinth. Henna extracts have been used by humans as hair and skin dyes for more than 5000 years. Henna extracts have been clinically investigated as a method of reducing dose-limiting Chemotherapy-Induced Palmoplantar Erythrodysesthesia.

Rose bengal sodium (RB) is a small molecule, halogenated xanthene being developed by Provectus Biopharmaceuticals (formerly Provectus Pharmaceuticals). It is commonly used in eye drops to stain damaged conjunctival and corneal cells and thereby identify damage to the eye. The stain is also used in the preparation of Foraminifera for microscopic analysis, allowing the distinction between forms that were alive or dead at the time of collection. A form of rose bengal is also being studied as a treatment for certain cancers and skin conditions. The cancer formulation of the drug, known as PV-10, is currently undergoing clinical trials for melanoma and breast cancer. Recently, interest in RB as a therapeutic cancer treatment has increased due to significant anti-tumor responses with direct tumor injection in human clinical trials for metastatic melanoma. In these patients, there has been the implication that RB may mount a T-cell mediated anti-tumor response and impart antigen-specific responses in distant bystander lesions.

Indigo, or indigotin, is a dyestuff originally extracted from the varieties of the indigo and woad plants. Indigo was known throughout the ancient world for its ability to color fabrics a deep blue. Egyptian artifacts suggest that indigo was employed as early as 1600 B.C. and it has been found in Africa, India, Indonesia, and China. Indigo is unique in its ability to impart surface color while only partially penetrating fibers. When yarn died with indigo is untwisted, it can be seen that the inner layers remain uncolored. The dye also fades to give a characteristic wom look and for this reason it is commonly used to color denim.

D&C RED NO. 36 1-[(2-chloro-4-nitrophenyl)azo]-2-naphthalenol (CAS Reg. No. 2814-77-9) is a color additive. According to FDA the color additive D&C Red No. 36 may be safely used for coloring ingested drugs, other than mouthwashes and dentifrices, in amounts not to exceed 1.7 milligrams per daily dose of the drug for drugs that are taken continuously only for less than 1 year. For drugs taken continuously for longer than 1 year, the color additive shall not be used in amounts to exceed 1.0 milligram per daily dose of the drug. D&C Red No. 36 may be safely used for coloring externally applied drugs in amounts consistent with current good manufacturing practice. In cosmetics and personal care products, D&C Red No. 36 is a colorant used in the formulation of blushers, lipsticks, face powders, and other makeup products, as well as nail polish and enamels.

Carminic acid is a natural compound extracted from cochineal insects, such as the cochineal, Armenian cochineal, and Polish cochineal. . The chromophore in this molecule is the conjugated pi system extending across the central anthraquinone ring system. Carminic acid can combine with various metals to form the pigment carmine.2 In industry, it is commonly complexed with aluminum to produce a purple/pink precipitate (with calcium as a counterion). Carmine’s color differs depending on the metal it is complexed to. For centuries, carminic acid and carmine have been used as dyes. The source material is cochineal, a blood-like fluid found within the cochineal insect. Currently, carminic acid and carmine have a multitude of applications in the modern world. They are used as nontoxic food additives and biological stains and are finding new uses as electrochemical modifiers and photosensitizers.