Determination of organic acids for quality evaluation in Coptis herbs by ion chromatography

Abstract

Coptis herbs are important herbal medicinal materials. The bioactive composition, the quality and medicinal efficacy of these herbs, are determined significantly by their geo-authentic features. Among the effective components of these herbs are seven organic acids (quinic, acetic, formic, tartaric, malic, succinic, and oxalic acids). However, no quantitative data of these seven acids in these herbs are available. Therefore, we developed a method for simultaneous separation and determination of the seven organic acids in Coptis herbs using gradient ion chromatography (mobile phase and gradient were shown in Table 1). The seven acids were separated and determined in no more than 35 min. We found that the organic acid levels in C. teeta was obviously higher than in C. chinensis and C. deltoidea, in particular, the content of quinic acid in C. teeta was about eight times than that in C. chinensis and C. deltoidea. Furthermore, we analyzed the relationships between the contents of organic acids and clinical effects, and found that organic acids (content of total acids or content of quinic acid) could act as an reference ingredient for quality evaluation in Coptis herbs. Our studies would lay the foundation for effective quality evaluation of these herbs.

Keywords: Coptis herbs; Herbal quality; Ion chromatography; Organic acids.

Fig. 1

Representative ion chromatograms of: a standards organic acids; b C. deltoidea ; c C. teeta; d C. chinensis. 1 quinic acid, 2 acetic acid, 3 succinic acid + tartaric acid, 4 tartaric acid, 5 oxalic acid, 6 citric acid. The unassigned peaks were inorganic anions

Fig. 2

The percentage of seven organic acids in three Coptis herbs samples