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Bulbus Fritillariae is the most commonly used antitussive herb in China. Eleven species of Fritillaria are recorded as Bulbus Fritillariae in the Chinese Pharmacopoeia. Bulbus Fritillariae Cirrhosae is a group of six Fritillaria species with higher efficiency and lower toxicity derived mainly from wild sources. Because of their higher market price, five other Fritillaria species are often sold deceptively as Bulbus Fritillariae Cirrhosae in the herbal market. To ensure the efficacy and safety of medicinal herbs, the authentication of botanical resources is the first step in quality control. Here, a DNA based identification method was developed to authenticate the commercial sources of Bulbus Fritillariae Cirrhosae. A putative DNA marker (0.65 kb) specific for Bulbus Fritillariae Cirrhosae was identified using the Random Amplified Polymorphic DNA (RAPD) technique. A DNA marker representing a Sequence Characterized Amplified Region (SCAR) was developed from a RAPD amplicon. The SCAR marker was successfully applied to differentiate Bulbus Fritillariae Cirrhosae from different species of Fritillaria. Additionally, the SCAR marker was also useful in identifying the commercial samples of Bulbus Fritillariae Cirrhosae. Our results indicated that the RAPD-SCAR method was rapid, accurate and applicable in identifying Bulbus Fritillariae Cirrhosae at the DNA level.

Edible bird’s nest (EBN; 燕窩, Yan Wo) is a glue-like substance secreted bythe specific glands of the swiftlets (e.g. Aerodramus fuciphagus), which is valuable Chinese delicacy for several hundreds of years. Despite of the long history of human consumption, the detailed chemical compositions and biological functions of EBN are largely unknown. In this report, a comprehensive research on EBN including food safety, quality control and potential biological functions was performed. A high content of nitrite (NO2-), a toxic food additive, was found in EBN, which aroused the public concern on the safety of EBN consumption. Here, the nitrite content of EBN selling in the market of Hong Kong was investigated. The traditional processing method in EBN cooking was evaluated for the efficiency of the nitrite removal. The highest content of nitrite found in EBN was 6,400 ppm, and Red EBN contained the highest nitrite content, followed by Yellow EBN and White EBN. Up to 98% of nitrite was removed in the first step of soaking. Further removal of nitrite from EBN after stewing was found. The origin of nitrite found in EBN was investigated by the EBN samples collected directly from their production sites. The nitrite content of EBN collected from the production sites were similar to that of EBN purchased from Hong Kong market. The high content of nitrate (NO3-) found in the environment of production sites suggested that nitrate might be involved in the cause of high content of nitrite found in EBN. By proteomic analysis, a protein was isolated from Red EBN, which was identified as nitrate reductase deriving from microbes, and this enzyme converted nitrate to nitrite within EBN. The addition of specific inhibitor of nitrate reductase successfully abolished the formation of nitrite in EBN. In addition, the changed in colour of EBN (i.e. from white to red) was shown to be related to the nitrite content in EBN. Taken together, the nitrite found in EBN was derived fro

The discovery of nitrite contamination aroused public concern on the safety of cubilose consumption. Here, forty-eight batches of cubilose were randomly purchased from Hong Kong market. The median nitrite content of different types of cubilose was as follows: Red cubilose (600ppm)Yellow cubilose (510ppm);White cubilose (100ppm). Under a developed standardized processing method, up to 98% of nitrite was removed from cubilose; nitrite was not detected in the stewed cubilose. To search for the source of nitrite, droppings from swiftlets and water samples were collected from production sites of cubilose in Malaysia and Indonesia, and which contained a high amount of nitrate. On the other hand, the protein extract of cubilose was subjected to proteomics analysis. A microbial nitrate reductase was identified by mass spectroscopy, which converted nitrate to nitrite in cubilose. A specific inhibitor of nitrate reductase successfully abolished the nitrate reduction activity found in cubilose, which subsequently reduced the nitrite in cubilose. This phenomenon was successfully proven by the field study. Thus, the nitrite on cubilose could be a result of the contaminating nitrate reductase. © 2013 Elsevier Ltd.