Chemometrics as a Tool for Quality Control of Commercial Samples of Equisetum Teas in Brazil

• Published in: Revista brasileira de farmacognosia Vol. 34; no. 4; pp. 758 - 766
• Main Authors: de Matos, Rafael Christian, de Souza, Tiago J. T., Scopel, Marina
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 2024
• Subjects: Medicine; Original Article; Pharmacy; Flavonoids; Green chemistry; Herbal drug; Aglycones; Chromatography; Horsetail
• ISSN: 1981-528X; 1981-528X
• DOI: 10.1007/s43450-024-00516-9

The genus
Equisetum
, Equisetaceae, is widely used as a diuretic and is one of the most widely consumed teas in Brazil. However, analytical approaches for the physicochemical control of the raw material are needed, requiring the supervision and studies to investigate the quality of commercial teas. The present study aimed to carry out quality control of samples of
Equisetum
sp. commercialized at the Central Market of Belo Horizonte and other localities, using chemometric tools to group similar species. A total of 17 samples of
Equisetum
sp. herb were evaluated by thin-layer chromatography and high-performance liquid chromatography using hydrolysis of the samples as an auxiliary for the identification of the main aglycones. All chromatographic results were processed using chemometric tools, such as hierarchical cluster analysis, principal component analysis, and partial least squares discrimination analysis. Additionally, quality control parameters in pharmacopeial assays, including physical–chemical characteristics and total flavonoid dosage, were taken into consideration. These parameters were partially validated by reducing reagent volume, aligning with principles of green chemistry. Based on the chromatographic findings, it was possible to identify phenolic compounds in the samples by comparison with literature data. Differentiation of the three
Equisetum
species was possible. Hydrolysis of the samples and evaluation of PLS-DA provided the more robust results for the distinction of the analyzed species. After the quality control analysis, some samples showed noncompliance with international references, indicating the need for national references. The partially validated method of reducing the solvent volume was accurate, precise, and non-selective for glycosylated and aglycone flavonoids, making its application appropriate with the possibility for expanding to other plant species rich in this class of active secondary metabolites.
Graphical Abstract