Processing of Reynoutria multiflora: transformation of catechin and gallic acid derivatives and their identification

Junqi Bai; Qiyu Zou; He Su; Baosheng Liao; Ping Wang; Juan Huang; Danchun Zhang; Lu Gong; Wen Xu; Jing Zhang; Zhihai Huang; Xiaohui Qiu

doi:10.3389/fphar.2024.1356876

Processing of Reynoutria multiflora: transformation of catechin and gallic acid derivatives and their identification

Front Pharmacol. 2024 Feb 26:15:1356876. doi: 10.3389/fphar.2024.1356876. eCollection 2024.

Authors

Junqi Bai¹, Qiyu Zou¹, He Su¹, Baosheng Liao¹, Ping Wang², Juan Huang¹, Danchun Zhang¹, Lu Gong¹, Wen Xu¹, Jing Zhang¹, Zhihai Huang¹, Xiaohui Qiu¹

Affiliations

¹ Guangdong Provincial Hospital of Traditional Chinese Medicine, The Second Clinical Medical College of Guangzhou University of Chinese Medicine, Guangzhou, China.
² Shanghai Dehua Traditional Chinese Medicine Co., Ltd., Shanghai, China.

Abstract

Introduction: The root of Reynoutria multiflora (Thunb.) Moldenke (RM) has been used widely in formulations of herbal medicines in China for centuries. Raw R. multiflora (RRM) should be processed before use to reduce toxicity and increase efficacy. However, detailed regulation of the processing endpoint is lacking, and the duration of processing can vary considerably. We conducted in-depth research on stilbene glycosides in RM at different processing times. Previously, we discovered that 219 stilbene glycosides changed markedly in quantity and content. Therefore, we proposed that processing causes changes in various chemical groups. Methods: To better explain the mechanism of RM processing for toxicity reduction and efficacy enhancement, we used a method of tandem mass spectrometry described previously to research gallic acid based and catechin based metabolites. Results: A total of 259 metabolites based on gallic acid and 112 metabolites based on catechins were identified. Among these, the peak areas of 157 gallic acid and 81 catechins gradually decreased, those of another 71 gallic acid and 30 catechins first increased and then decreased, those of 14 gallic acid and 1 catechin gradually increased. However, 17 of the gallic acids showed no significant changes. We speculate that many gallic acid metabolites hydrolyze to produce gallic acid; moreover, the dimers/trimers of catechins, after being cleaved into catechins, epicatechin, gallic acid catechins, and epicatechin monomers, are cleaved into gallic acid and protocatechualdehyde under high temperature and high humidity, subsequently participating in the Maillard reaction and browning reactions. Discussion: We showed that processing led to changes in chemical groups, clarification of the groups of secondary metabolites could provide a basis for research on the pharmacological and toxic mechanisms of RM, as well as the screening of related markers.

Keywords: Reynoutria multiflora (Thunb.) Moldenke; catechin; gallic acid; processing; tandem mass spectrometry.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by National Natural Science Foundation of China (81373967, 82204622), Quality standard system construction for the whole industry chain of Chinese medicinal detection pieces from Guangdong Provincial Drug Administration of China (2019KT1261/2020ZDB25).