Comparative study of the free amino acid compositions and contents in three different botanical origins of Coptis herb

Free amino acids are important bioactive ingredients in herbs and herbal products. Coptis herbs contain a variety of free amino acids; however, studies have not yet analyzed the relationship between free amino acids and species of Coptis herbs. In the current study, the contents of 20 free amino acids in Coptis chinensis Franch., Coptis teeta Wall., and Coptis deltoidea C.Y. Cheng et Hsiao were determined using an automatic amino acid analyzer to evaluate the differences between the three species. We found that the major amino acids (Asn, Arg, and gamma-aminobutyric acid (GABA)) were significantly more in C. chinensis than in the other two species. In addition, Asp content was significantly more in C. deltoidea. The study concluded that Asn can be used to identify C. deltoidea, C. chinensis, and C. teeta, and Gln and Arg can be used to distinguish C. teeta from C. chinensis and C. deltoidea. These findings suggested that free amino acids as active ingredients can be used to identify Coptis herb species.