In the theories of empirical identification of "arguments on quality" and "five elephants and seven originals", color is regarded as one of the important indicators in the quality evaluation of Chinese medicine. The color of medicinal material including the surface color, the internal color, and the color after processing is caused by the pigment in the cells, which is a characteristic of the "optimal shape". Most pigments have a wide range of pharmacological activities such as anti-oxidation, anti-tumor, anti-atherosclerosis, prevention of coronary heart disease, protection of cardiovascular function, enhancement of immunity, etc. Therefore, the "optimal color" of medicinal materials is unified with the "high quality". This article systematically reviews the research status of "quality discrimination by color", the correlation between L~*, a~*, b~* color space and active ingredients such as alkaloids, flavonoids, terpenes, etc. to explain the "quality discrimination by color" in quantitative characterization. We also summary the research progress on the biosynthesis and regulation of the main pigment components of traditional Chinese medicine, and analyze the biological causes that affect the accumulation of the main pigments. We aim to provide a reference for the theory "quality discrimination by color" in biological knowledge to establish a modern quality control system for Chinese herbal medicines.
Keywords: Chinese medicine quality; biosynthesis; color; high quality; optimal character.