Abstract
Boswellia serrata ole-gum-resin extracts (BSEs) are commonly used as food supplements, especially in osteoarthritis management. The quality standard is established by determining 11-keto-β-boswellic acid (KBA) and acetyl-11-keto-boswellic acid (AKBA) content using high-performance liquid chromatography (HPLC) or assessing the total boswellic acid (TBA) content by titrimetry. The limited geographical distribution of Boswellia species and increasing industrial demand could increase the risk of adulteration in Boswellia-containing products. In this study, 14 BSEs from commercial sources, used in food supplements, were analyzed in comparison with a USP Reference Standard extract. The KBA and AKBA content was determined by HPLC, whereas the TBA content was determined by titration. Targeted UHPLC-high-resolution mass spectrometry (HRMS) was applied to identify the carboxylic acid content in the samples. The 1H NMR spectra of extracts were also analyzed. Only two products met the criteria for KBA and AKBA content. Although, the TBA content complied with the expected amount, 10 extracts contained citric acid levels of 6–11% even though citric acid is not a characteristic component of BSEs. Our results suggest undeclared addition of citric acid to comply with declared contents of TBA when using titration methods. Incorporation of citric acid to industrial samples – in order to alter the outcomes of the titration analysis – was demonstrated for the first time.
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The authors declare no conflicts of interest. The authors alone are responsible for the content and writing of the article.
Data availability statement
Data are available for research purpose upon reasonable request to the corresponding author.
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Notes on contributors
Péter Püski
Péter Püski holds PharmD and is a PhD student at Institute of Pharmacognosy (University of Szeged, Faculty of Pharmacy). His research interests are phytochemistry and analytics of dietary supplements.
Tímea Körmöczi
Tímea Körmöczi is a researcher at Institute of Pharmaceutical Analysis (University of Szeged, Faculty of Pharmacy). Her research fields are liquid chromatography, mass spectroscopy, and metabolomics.
Róbert Berkecz
Róbert Berkecz holds PhD and he is an associate professor at Institute of Pharmaceutical Analysis (University of Szeged, Faculty of Pharmacy). He is the author of 70+ papers in field of analytics.
Anita Barta
Anita Barta obtained her PharmD and is in the final stage of her PhD at University of Szeged. Her research field is preparative phytochemistry and NMR spectroscopy of plant secondary metabolites.
Ákos Bajtel
Ákos Bajtel PharmD is a clinical pharmacist and researcher at University of Szeged. He is working on completion of his PhD thesis.
Tivadar Kiss
Tivadar Kiss holds PhD in pharmacognosy. He is an assistant professor at Institute of Pharmacognosy (University of Szeged, Faculty of Pharmacy). His research interests include phytochemistry, analytics of dietary supplements and science education.