State Key Laboratories of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, PR China.
J Ethnopharmacol. 2011 Apr 26;135(1):110-5. doi: 10.1016/j.jep.2011.02.032. Epub 2011 Mar 4.
Cinnabar (Cin), a naturally occurring mercuric sulfide (HgS), is a mineral widely used in traditional Chinese medicine throughout history. As for the toxicity of cinnabar, one important assumption is that cinnabar may be transformed into highly toxic methylmercury by gastrointestinal flora. There is no evidence in humans to support this assumption.
To investigate the biotransformation of cinnabar (HgS) in the human intestinal bacteria with modern analytical techniques.
A gas chromatograph, equipped with electron capture detection (GC-ECD) and mass spectrometry (GC-MS), were used to detect the formation of methylmercury after incubation of cinnabar with human intestinal bacteria. The content of soluble mercury in the bacteria media was determined by cold vapor-atomic absorption spectrometry (CV-AAS). In addition, X-ray absorption near-edge structure spectroscopy (XANES) was used to confirm the possible transformation of cinnabar in the bacteria media, and under mimetic intestinal condition by measuring the species of sulfur and mercury in the reaction extraction of cinnabar and Na(2)S mixture.
No methylmercury was detected by both GC-ECD and GC-MS, which suggest that cinnabar (HgS) is not methylated in the human intestine. A small amount of soluble mercury was found to be released in the flora medium of HgS or cinnabar by CV-AAS. The XANES analyses revealed that polysulfides exist in the flora medium, and the simulated results showed that the products by incubating cinnabar with Na(2)S were mercuric polysulfides.
These results showed that under gut flora conditions cinnabar would be transformed into mercuric polysulfides rather than methylmercury. Our work provides evidences of nontoxic transformation of cinnabar in the human intestinal bacteria.
辰砂（Cin），一种天然存在的硫化汞（HgS），是一种在历史上广泛应用于中药的矿物质。至于辰砂的毒性，有一个重要的假设是，辰砂可能会被胃肠道菌群转化为剧毒的甲基汞。目前尚无人类证据支持这一假设。
用现代分析技术研究辰砂（HgS）在人类肠道菌群中的生物转化。
采用配备电子捕获检测（GC-ECD）和质谱（GC-MS）的气相色谱仪，检测辰砂与人肠道菌群孵育后甲基汞的形成情况。采用冷蒸气原子吸收光谱法（CV-AAS）测定细菌培养基中可溶性汞的含量。此外，采用 X 射线吸收近边结构光谱（XANES）技术，通过测量辰砂与 Na 2 S 混合物反应萃取中硫和汞的形态，确认细菌培养基中辰砂可能发生的转化，并模拟肠道内环境。
GC-ECD 和 GC-MS 均未检测到甲基汞，这表明辰砂（HgS）在人肠道中不发生甲基化。CV-AAS 发现少量可溶性汞在 HS 或辰砂的菌群培养基中释放。XANES 分析表明菌群培养基中存在多硫化物，模拟结果表明，用辰砂与 Na 2 S 孵育的产物是硫化汞多硫化物。
这些结果表明，在肠道菌群条件下，辰砂会转化为硫化汞多硫化物，而不是甲基汞。我们的工作为辰砂在人类肠道细菌中的非毒性转化提供了证据。
