Assessment of the Authenticity of Herbal Dietary Supplements: Comparison of Chemical and DNA Barcoding Methods.

About 7 % of the U. S. population reports using botanical dietary supplements. Increased use of such supplements has led to discussions related to their authenticity and quality. Reports of adulteration with substandard materials or pharmaceuticals are of concern because such substitutions, whether inadvertent or deliberate, may reduce the efficacy of specific botanicals or lead to adverse events. Methods for verifying the identity of botanicals include macroscopic and microscopic examinations, chemical analysis, and DNA-based methods including DNA barcoding. Macroscopic and microscopic examinations may fail when a supplement consists of botanicals that have been processed beyond the ability to provide morphological characterizations. Chemical analysis of specific marker compounds encounters problems when these compounds are not distinct to a given species or when purified reference standards are not available. Recent investigations describing DNA barcoding analysis of botanical dietary supplements have raised concerns about the authenticity of the supplements themselves as well as the appropriateness of using DNA barcoding techniques with finished botanical products. We collected 112 market samples of frequently consumed botanical dietary supplements of ginkgo, soy, valerian, yohimbe, and St. John's wort and analyzed each for specific chemical markers (i.e., flavonol glycosides, total isoflavones, total valerenic acids, yohimbine, and hypericins, respectively). We used traditional DNA barcoding techniques targeting the nuclear ITS2 gene and the chloroplast gene psbA-trnH on the same samples to determine the presence of DNA of the labelled ingredient. We compared the results obtained by both methods to assess the contribution of each in determining the identity of the samples.

Method development and survey of Sudan I-IV in palm oil and chilli spices in the Washington, DC, area.

Sudan I, II, III and IV dyes are banned for use as food colorants in the United States and European Union because they are toxic and carcinogenic. These dyes have been illegally used as food additives in products such as chilli spices and palm oil to enhance their red colour. From 2003 to 2005, the European Union made a series of decisions requiring chilli spices and palm oil imported to the European Union to contain analytical reports declaring them free of Sudan I-IV. In order for the USFDA to investigate the adulteration of palm oil and chilli spices with unapproved colour additives in the United States, a method was developed for the extraction and analysis of Sudan dyes in palm oil, and previous methods were validated for Sudan dyes in chilli spices. Both LC-DAD and LC-MS/MS methods were examined for their limitations and effectiveness in identifying adulterated samples. Method validation was performed for both chilli spices and palm oil by spiking samples known to be free of Sudan dyes at concentrations close to the limit of detection. Reproducibility, matrix effects, and selectivity of the method were also investigated. Additionally, for the first time a survey of palm oil and chilli spices was performed in the United States, specifically in the Washington, DC, area. Illegal dyes, primarily Sudan IV, were detected in palm oil at concentrations from 150 to 24 000 ng ml(-1). Low concentrations (< 21 µg kg(-1)) of Sudan dyes were found in 11 out of 57 spices and are most likely a result of cross-contamination during preparation and storage and not intentional adulteration.