Integrative approaches for unmasking hidden species in herbal dietary supplement products: What is in the capsule?

Abstract

Herbal dietary supplement products are often marketed as herbal mixtures, which makes quality control processes difficult. Herein, paired-end next-generation sequencing (NGS), microscopic examination and high-performance thin layer chromatography (HPTLC) were integrated to unveil herbal ingredient compositions in a selected herbal dietary supplement product. The product was labeled as containing capsicum, cactus, wheat, white bean, Garcinia cambogia, psyllium husk and black pepper in each capsule. A laboratory-made sample was prepared as a reference sample according to the product label. NGS indicated that six out of the seven herbal species were detected in the laboratory-made sample, while 97.02 ± 0.15% of sequencing reads from the commercial product belonged to Senna alexandrina. Microscopic examination also confirmed the presence of Senna. Similar chemical constituents of the product and Senna powder were observed by HPTLC patterns. Surprisingly, there was a distinct band difference between samples. After extraction and LC-MS/MS analysis, oleamide was found as an adulterant in the product. None of the plants listed on the commercial product label were detected by any of the methods. Therefore, the integrative approaches successfully unmasked nonlisted herbal species in a selected herbal dietary supplement product. These approaches should be applied to other dietary supplement products for registration and regulation processes.