Impact of Sulfur Fumigation on Ginger: Chemical and Biological Evidence

Metals/bisulfite system involved generation of 24-sulfonic-25-ene ginsenoside Rg1, a potential quality control marker for sulfur-fumigated ginseng

Ginseng is a most popular health-promoting food with ginsenosides as its main bioactive ingredients. Illegal sulfur-fumigation causes ginsenosides convert to toxic sulfur-containing derivatives, and reduced the efficacy/safety of ginseng. 24-sulfo-25-ene ginsenoside Rg1 (25-ene SRg1), one of the sulfur-containing derivatives, is a potential quality control marker of fumigated ginseng, but with low accessibility owing to its unknown generation mechanism. In this study, metals/bisulfite system involved generation mechanism was investigated and verified. The generation of 25-ene SRg1 in sulfur-fumigated ginseng is that SO2, formed during sulfur-fumigation, reacted with water and ionized into HSO3-. On the one hand, under the metals/bisulfite system, HSO3- generates HSO5- and free radicals which converted ginsenoside Rg1 to 24,25-epoxide Rg1; on the other hand, as a nucleophilic group, HSO3- reacted with 24,25-epoxide Rg1 and further dehydrated to 25-ene SRg1. This study provided a technical support for the promotion of 25-ene SRg1 as the characteristic quality control marker of sulfur-fumigated ginseng.

Selection and application of aptamers for p-hydroxybenzyl hydrogen sulfite after Gastrodia elata Bl. fumigated with sulfur

Gastrodia elata Bl. is a widely used traditional Chinese medicine known for its medicinal properties. However, during the drying process, G. elata is often fumigated with sulfur to prevent corrosion and improve its appearance. Sulfur-fumigation can result in a reduction in the effective components of the herb and can also be hazardous to human health due to the remaining sulfur dioxide. Sulfur-fumigation of G. elata poses a significant challenge to both end-users and researchers. The detection of p-hydroxybenzyl hydrogen sulfite (p-HS) is a useful tool in determining whether G. elata has been fumigated with sulfur. Unfortunately, the current method for detecting p-HS is costly and requires sophisticated instruments. Therefore, there is a need to develop a more cost-effective and user-friendly method for the detection of p-HS. This study utilized the Capture-SELEX technique to screen high-affinity aptamers for p-HS, which were subsequently characterized by isothermal titration calorimetry (ITC). An aptamer sequence (seq 6) with a high affinity of Kd = 26.5 μM was obtained following 8 rounds of selection against p-HS. With the aptamer serving as the recognition element and gold nanoparticles as the colorimetric indicator, a simple and efficient colorimetric sensor was developed for the specific detection of p-HS. This detection method exhibited a limit of detection of 1 μg/ml, while the p-HS recoveries demonstrated a range of between 88.5 % and 105 % for samples of G. elata obtained in the market. In summary, the aptamer exhibited a high affinity for p-HS, and the sensor developed through the use of a colloidal gold detector based on nucleic acid aptamer can be utilized for rapid detection of sulfur-fumigated G. elata. With these findings, this research paper provides valuable scientific insights and highlights significant potential for future studies in this area.

Tryptophan sulfonate: A new chemical marker for accurate and efficient inspection of sulfur-treated food products

Sulfur treatment for the pesticidal and antibacterial processing of food products has been criticized since it impairs the quality of treated products. The inspection of sulfur-treated products is thus required to achieve the regulation of sulfur treatment. Sulfite assay is currently available for the inspection, but it bears the disadvantages of inaccurate results and complex experimental procedures. Here we report a new chemical marker, namely tryptophan sulfonate, that can be used for the accurate and efficient inspection of sulfur-treated foods. First, the marker was discovered in sulfur-fumigated ginger, yam, and ginseng by untargeted metabolomics. The marker identity was then elucidated using chromatographic separation, nuclear magnetic resonance analysis and chemical synthesis. Finally, to demonstrate its applicability in the inspection, a tryptophan sulfonate assay was developed to test 50 commercial food samples, and the results indicated that it performed better than the sulfite assay in terms of both accuracy and efficiency.

Unveiling the Chemical Composition of Sulfur-Fumigated Herbs: A Triple Synthesis Approach Using UHPLC-LTQ-Orbitrap MS-A Case Study on Steroidal Saponins in Ophiopogonis Radix

Ophiopogonis Radix (OR) is a traditional Chinese medicine. In recent years, in order to achieve the purpose of drying, bleaching, sterilizing and being antiseptic, improving appearance, and easy storage, people often use sulfur fumigation for its processing. However, changes in the chemical composition of medicinal herbs caused by sulfur fumigation can lead to the transformation and loss of potent substances. Therefore, the development of methods to rapidly reveal the chemical transformation of medicinal herbs induced by sulfur fumigation can guarantee the safe clinical use of medicines. In this study, a combined full scan-parent ions list-dynamic exclusion acquisition-diagnostic product ions analysis strategy based on UHPLC-LTQ-Orbitrap MS was proposed for the analysis of steroidal saponins and their transformed components in sulfur-fumigated Ophiopogonis Radix (SF-OR). Based on precise mass measurements, chromatographic behavior, neutral loss ions, and diagnostic product ions, 286 constituents were screened and identified from SF-OR, including 191 steroidal saponins and 95 sulfur-containing derivatives (sulfates or sulfites). The results indicated that the established strategy was a valuable and effective analytical tool for comprehensively characterizing the material basis of SF-OR, and also provided a basis for potential chemical changes in other sulfur-fumigated herbs.

A FRET-based ratiometric fluorescent probe for SO32- detection in Chinese medicine and living cells

Chinese herbal medicine is receiving more and more attention at home and abroad as a traditional Chinese clinical medicine. To make herbal medicines can be preserved for a long time, they are usually fumigated with sulfur. However, after the medicinal materials have been fumigated with sulfur, SO₂ residues will remain, which, when exposed to water, will create sulfites and bisulfites. Excessive sulfites can cause a variety of severe ailments and diminish the quality and effectiveness of therapeutic plants. Therefore, developing an effective SO₃^2-/HSO₃^- detection method is important. This study chose coumarin derivatives as fluorescent acceptors and pyridinium acrylonitrile structures as fluorescent donors to create a ratiometric fluorescent probe CPA using the fluorescence resonance energy transfer (FRET) effect. The probe CPA exhibited a fluorescence transition from red to green under excitation at 405 nm with an interval of 149 nm, a reaction time of less than 1 min, a low detection limit of 86 nM, and the probe CPA has good specific recognition of SO₃^2- and is resistant to interference. In addition, CPA has low in vitro cytotoxicity and can successfully detect endogenous sulfites in living cells.