Effect of Cys, GSH, and pH on Mercury Release from Tibetan Medicine Zuotai, β-HgS, and α-HgS in Artificial Gastrointestinal Juices


Zuotai, also named as “gTso thal”, a known Tibetan medicinal mixture containing insoluble cubic crystal mercuric sulfide (β-HgS), has been used to treat diseases with long history. The mercury release ratio from Zuotai in gastrointestinal environment is one determinant factor for its bioavailability and biological effect. However, the information is still scarce now. Therefore, the study was designed to investigate the effect of sulfhydryl biomolecules [l-cysteine (Cys) and glutathione (GSH)] and pH on mercury dissociation from Zuotai, β-HgS, and hexagonal crystal mercuric sulfide (α-HgS) in artificial gastrointestinal juices or pure water with a 1:100 solid-liquid ratio. And, the digestion and peristalsis of gastrointestinal tract were simulated in vitro. The results showed the following trend for the mercury release ratio of Zuotai, artificial gastric juice > artificial intestinal juice > pure water, whereas the trend for β-HgS and α-HgS was as follows, artificial intestinal fluid > artificial gastric fluid > pure water. The mercury release ratios of Zuotai, β-HgS, and α-HgS significantly increased in artificial intestinal juice containing l-Cys or GSH compared to those without sulfhydryl biomolecules in the juice. However, in contrast to the results observed for β-HgS and α-HgS, the mercury release ratio of Zuotai was reduced remarkably in pure water and artificial gastric juice with Cys or GSH. And, we found that strong acidic or strong alkaline environments promoted the dissociation of mercury from Zuotai, β-HgS, and α-HgS. Taken together, current findings may contribute to other studies regarding clinical safety and bioavailability of the traditional drug Zuotai containing β-HgS.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5



Mercuric sulfide





LD0 or MTD:

Lethal dose 0% or maximal tolerance dose

LD50 :

Median lethal dose

K sp :

Solubility product constant


  1. 1.

    Chen C, Wu S, Wang Y, Sun X (2012) Recent researches of synthetic mercury sulfide in traditional medicine system. China J Chin Mater Med 37:2968–2970

  2. 2.

    Gamaqupei, Tudenggesang, Geqiong (1988) The processing method of mercury medicinal powder (Zuotai). 88107006.8,

  3. 3.

    Li C, Yang H, Du Y, Xiao Y, Zhandui, Sanglao et al (2016) Chemical species, micromorphology, and XRD fingerprint analysis of Tibetan medicine Zuotai containing mercury. Bioinorg Chem Appl 2016:1–11.

  4. 4.

    Wang Z (2010) The reinterpreting of Tibetan medicine essence Zuota. Health World (Academic Edition) 4:84–85

  5. 5.

    Lanke (1999) Brief review of Tibetan medicine Zuotai. Chin J Ethnomed Ethnopharm 5:86.

  6. 6.

    Goldman LR, Shannon MW (2001) Technical report: mercury in the environment: implications for pediatricians. Pediatrics 108:197–205.

  7. 7.

    Luosang DJ, Gongga LB (2008) The quality control method of a processing product in Tibetan medicine and its new application. 200810093949.5

  8. 8.

    Suolang (2007) The processing technology of Zuotai. Chin J Ethnomed Ethnopharm 5:40.

  9. 9.

    Zeng Y, He S, Liu Y, Wang Z, Zhang Y (2005) Study on the pharmacological effects in central nervous system of Tibetan medicine Zuota. J Sichuan Tradit Chin Med 23:33–34.

  10. 10.

    Jiang EN, Zhang CG, Wang JH, Li ZG, Cheng F, Xue X et al (2009) Study on the pharmacodynamics of Tibetan medicine Zuotai. Lishizhen Med Mater Medic Res 20:3–4

  11. 11.

    Chen Z, Xianglan P, Li W, Wu K, Lan G, Cui J (2011) The influence on Drosophila life of Tibetan medicine Zuota. Lishizhen Med Mater Medic Res 22:422–423

  12. 12.

    Li H, Li W-K, Lu Y-F, Wei L-X, Liu J (2016) The Tibetan medicine Zuotai influences clock gene expression in the liver of mice. PeerJ 4:e1632.

  13. 13.

    Zhu T, Shen B, Wang W, Chiren B, Yao G (2013) The proliferation of 239 cell promoted by Tibetan medicine Zuotai through caspase-3. J Med Pharm Chin Minorities 5:47–49

  14. 14.

    Wang D, Wei L, Du Y, Yang H, Xia Z, Lv P et al (2010) Study on the method of determination of mercury sulfide in Tibetan medicine GTso Thal. Lishizhen Med Mater Medic Res 21:1359–1361

  15. 15.

    Xia ZJ, Wei LX, Wang DP, Du YZ, Chen XM, Yang HX (2010) Quality control of traditional Tibetan medicine Zsuotai. J Chin Med Mater 33:688–690

  16. 16.

    Zhang B-B, Li W-K, Hou W-Y, Luo Y, Shi J-Z, Li C et al (2017) Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats. Toxicol Appl Pharmacol.

  17. 17.

    Wu Q, Li WK, Zhou ZP, Li YY, Xiong TW, Du YZ et al (2016) The Tibetan medicine Zuotai differs from HgCl2 and MeHg in producing liver injury in mice. Regul Toxicol Pharmacol 78:1–7.

  18. 18.

    Liu J, Lu Y-F, Li W-K, Zhou Z-P, Li Y-Y, Yang X et al (2016) Mercury sulfides are much less nephrotoxic than mercury chloride and methylmercury in mice. Toxicol Lett 262:153–160.

  19. 19.

    Xu SF, Wu Q, Zhang BB, Li H, Xu YS, Du YZ et al (2016) Comparison of mercury sulfides with mercury chloride and methylmercury on hepatic P450, phase-2 and transporter gene expression in mice. J Trace Elem Med Biol 37:37–43.

  20. 20.

    Dean JA (1999) Lange’s handbook of chemistry, 8 Section: 8.13. 15th ed. McGraw-Hill, New York

  21. 21.

    Li C, Wang D, Duo J, Duojie L, Chen X, Du Y et al (2014) Study on safety of Tibetan medicine zuotai and preliminary study on clinical safety of its compound dangzuo. China J Chin Mater Medic 39:2573–2582

  22. 22.

    Zheng Z-Y, Li C, Zhang M, Yang H-X, Geng L-J, Li L-S et al (2015) Dissolution, absorption and bioaccumulation in gastrointestinal tract of mercury in HgS-containing traditional medicines Cinnabar and Zuotai. Zhongguo Zhongyao Zazhi 40:2455–2460.

  23. 23.

    Bridges CC, Zalups RK (2010) Transport of inorganic mercury and methylmercury in target tissues and organs. J Toxicol Environ Health Part B, Crit Rev 13:385–410.

  24. 24.

    Zhou X, Zeng K, Wang Q, Yang X, Wang K (2010) In vitro studies on dissolved substance of cinnabar: chemical species and biological properties. J Ethnopharmacol 131:196–202.

  25. 25.

    Zhou X, Wang L, Sun X, Yang X, Chen C, Wang Q et al (2011) Cinnabar is not converted into methylmercury by human intestinal bacteria. J Ethnopharmacol 135:110–115.

  26. 26.

    Mrázek J, Štrosová L, Fliegerová K, Kott T, Kopečný J (2008) Diversity of insect intestinal microflora. Folia Microbiol 53:229–233.

  27. 27.

    Chinese Pharmacopeia Commission (2010) Chinese pharmacopoeia (2010 version). Appendix V C. China Medical Science Press, Beijing

  28. 28.

    United Nations (2015) Globally harmonized system of classification and labelling of chemicals (GHS) (Rev.6). Chapter 3.1:113–123. 2015.

  29. 29.

    Chen X. (2009) The substance composition analysis and the preliminary security research of Tibetan medicine Zuotai. Xi’ning (Master's Thesis)

  30. 30.

    Jay JA, Morel FMM, Hemond HF (2000) Mercury speciation in the presence of polysulfides. Environ Sci Technol 34:2196–2200.

  31. 31.

    Sharma VK, Moulin A, Millero FJ, De Stefano C (2006) Dissociation constants of protonated cysteine species in seawater media. Mar Chem 99:52–61.

  32. 32.

    Jalilehvand F, Leung BO, Izadifard M, Damian E (2006) Mercury(II) cysteine complexes in alkaline aqueous solution. Inorg Chem 45:66–73.

  33. 33.

    Mah V, Jalilehvand F (2008) Mercury(II) complex formation with glutathione in alkaline aqueous solution. J Biol Inorg Chem 13:541–553.

  34. 34.

    Li C, Duoji, Zhandui, Xia Z, Du Y, Wei L (2012) Chemical and structural analysis of Nengchi Bajin ashes in refining of Tibetan medicine gTSo thal. China J Chin Mater Medic 37:1952–1957

  35. 35.

    Li C, Suolang, Zege, Wang Z, Du Y, Wei L (2011) Chemical and structural analysis of Nengchi Bakuang ashes in refining of Tibetan medicine Zuotai. Chin J Pharm Anal 31:2220–2224

  36. 36.

    Dreybrodt W, Lauckner J, Zaihua L, Svensson U, Buhmann D (1996) The kinetics of the reaction CO2 + H2O → H+ + HCO3− as one of the rate limiting steps for the dissolution of calcite in the system H2O-CO2-CaCO3. Geochim Cosmochim Acta 60:3375–3381.

  37. 37.

    Li C (2014) Converted chemical special and transmembrane aborption of mercuric sulfide of traditional Tibetan medicine Zuotai in gastrointestine. Fourth chapter: 49–63. Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xi’ning

  38. 38.

    Liu J, Shi J-Z, Yu L-M, Goyer RA, Waalkes MP (2008) Mercury in traditional medicines: is cinnabar toxicologically similar to common mercurials? Exp Biol Med (Maywood) 233:810–817.

  39. 39.

    Pubic Health England (PHE) (2016) Compendium of chemical hazards: inorganic mercury/elemental mercury toxicological overview. Page: 4. Accessed 4 May 2017

  40. 40.

    Win KY, Feng S-S (2005) Effects of particle size and surface coating on cellular uptake of polymeric nanoparticles for oral delivery of anticancer drugs. Biomaterials 26:2713–2722.

  41. 41.

    Jung T, Kamm W, Breitenbach A, Kaiserling E, Xiao JX, Kissel T (2000) Biodegradable nanoparticles for oral delivery of peptides: is there a role for polymers to affect mucosal uptake? Eur J Pharm Biopharm 50:147–160.

Download references


Yuzhi Du (Professor), Hongxia Yang (PhD), Lujing Geng (PhD), and Hongtao Bi (PhD) of Northwest Institute of Plateau Biology, Chinese Academy of Sciences, are acknowledged for their assistance in measurements and data analysis.


This work was supported by “The Dawn of West China” 2014 Talent Training Program of Chinese Academy of Sciences (Y529021211), the Science Foundation for Young Scholars of Qinghai Province (2016-ZJ-919Q), the National Natural Science Foundation of China (81374063), and the Development Program of Key Laboratory in Qinghai Province (2017-ZJ-Y08).

Author information

Zhiyuan Zheng ( and Ming Zhang ( performed the main experiments with equal contribution to this work, and are joint first authors. Yuancan Xiao ( performed auxiliary implementation of experiments. Lixin Wei ( and Cen Li ( contributed equally to the experiment design and the composition of this manuscript.

Correspondence to Lixin Wei or Cen Li.

Ethics declarations

Conflict of Interest

The authors declare that they have no conflicts of interest.

Raw data 1: Mercury leaching ratio (μg/g) from Tibetan medicine Zuotai, β-HgS, and α-HgS in pure water and artificial gastrointestinal juices containing Cys (or GSH) or not.

Raw data 2: Leaching ratio (μg/g) of mercury from Tibetan medicine Zuotai, β-HgS, and α-HgS in different pH solutions.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Zheng, Z., Zhang, M., Xiao, Y. et al. Effect of Cys, GSH, and pH on Mercury Release from Tibetan Medicine Zuotai, β-HgS, and α-HgS in Artificial Gastrointestinal Juices. Biol Trace Elem Res 184, 536–545 (2018).

Download citation


  • Tibetan medicine
  • Zuotai
  • Mercury release
  • Mercuric sulfide
  • l-Cysteine
  • Glutathione
  • pH