No abstract

Traditional herbal medicine has long been practiced as a method of health care in many countries worldwide. The usage of herbal products has been increasing and is expected to continue to do so in the future. However, admixture and adulteration are concerns regarding the quality of herbal medicine, including its safety and efficacy. We aimed to develop a reference DNA barcode library of plants listed in the Thai Herbal Pharmacopoeia (THP) and Monographs of Selected Thai Materia Medica (TMM) (n = 101 plant species) using four core barcode regions, namely, the ITS2, matK, rbcL and trnH-psbA intergenic spacer regions, for authentication of the plant origin of raw materials and herbal products. Checking sequences from samples obtained from local markets and the Thai Food and Drug Administration (Thai FDA) against our digital reference DNA barcode system revealed the authenticity of eighteen out of twenty tested samples as claimed on their labels. Two samples, no. 3 and 13, were not Cyanthillium cinereum (L.) H.Rob. and Pueraria candollei Wall. ex Benth. as claimed, respectively. They were recognized as Emilia sonchifolia (L.) DC. and Butea superba (Roxb.), respectively. Hence, it is important for the Thai FDA or regulatory agencies to immediately initiate strict enforcement for the development of pharmacopoeial standards as well as revisions or modifications of available regulatory guidelines and to implement close monitoring for the quality control of herbal products in terms of authentication before they enter the herbal market. The centralized digital reference DNA barcode database developed here could play a very important role in monitoring or checking the authenticity of medicinal plants.

Objective This study evaluated the heavy metal identity and content of registered Thai Traditional medicine (TTM) preparations in Thailand to ensure consumer safety. Methods Both qualitative and quantitative information about the elemental composition of the heavy metal content in each TTM crude drug and the heavy metal content in some registered TTM preparations in Thailand was performed. Seven kinds of mineral-based TTM crude drugs, namely realgar, orpiment, Chinese powder, Sen, vermilion, natural vermilion, and cinnabar, were analyzed with X-ray diffraction and scanning electron microscopy and energy-dispersive spectroscopy techniques to determine the type of metal and elemental composition to confirm their chemical formulas. Furthermore, the number of heavy metals, such as arsenic (As), lead (Pb), and mercury (Hg), was in three samples of realgar-containing preparations; one sample of Sen-containing preparation, and eight samples of cinnabar-containing preparations. Heavy metals were determined with inductively coupled plasma-optical emission spectrometry. Results It was observed that realgar and orpiment consisted of arsenic sulfide (AsS) and arsenic trisulfide (As2S3), respectively. Both crude drugs contained approximately 50% of As. Vermilion, natural vermilion, and cinnabar consisted of mercuric sulfide (HgS), with Hg accounting for approximately 66%. Sen consisted of Pb (II, IV) oxide (Pb3O4) with an approximate Pb percentage of 80%. However, Pb was absent in Chinese powder and consisted mainly of calcium carbonate (CaCO3). A traditional detoxification procedure can reduce the amount of As and Hg in processed crude drugs by at least 20%. Conclusions Pb was higher in some TTM preparations, and no CaCO3 was detected in Chinese powder. Our results raise concerns on both safety and efficacy to consumers and alert public health policymakers that they should implement regulations so that the quality (authenticity) and quantity of elemental medicine used in traditional medicine are correctly labeled and within permissible limits to prevent threats to consumers.