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Zuotai, a famous Tibetan medicinal mixture containing β-HgS, has been used to combine with herbal remedies for treating diseases for more than 1 300 years. The target organ for inorganic mercury toxicity is generally considered to be the kidney. Therefore, it is crucial to reveal the chemical speciation, spatial distribution and potential nephrotoxicity of mercury from Zuotai in kidney. To date, this remains poorly understood. We used X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (μ-XRF) imaging based on synchrotron radiation to study mercury chemical forms and mercury special distribution in kidney after mice were treated orally with Zuotai, β-HgS or HgCl2. Meanwhile, the histopathology of kidney was observed. Mice exposed with Zuotai showed kidney with significant proportion of mercury ions bound to sulfydryl biomolecules (e.g. Cys-S-Hg-S-Cys) plus some of unknown species, but without methylmercury cysteine, which is the same as β-HgS and HgCl2. The mercury is mainly deposited in renal cortex in mouse treated with Zuotai, β-HgS or HgCl2, but with a low level of mercury in medulla. The total mercury in kidney of mice treated with HgCl2 was much higher than that of β-HgS, and the later was higher than that of Zuotai. And, HgCl2 cause severe impairments in mouse kidney, but that was not observed in the Zuotai and β-HgS groups. Meanwhile, the bio-metals (Ca, Zn, Fe and Cu) micro-distributions in kidney were also revealed. These findings elucidated the chemical nature, spatial distribution and toxicity difference of mercury from Zuotai, β-HgS and HgCl2 in mouse kidney, and provide new insights into the appropriate methods for biological monitoring.

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.

Four common traditional tibetan medicine prescription preparations "Anzhijinghuasan, Dangzuo, Renqingchangjue and Rannasangpei" in tibetan areas were selected as study objects in the present study. The purpose was to try to establish a kind of wet digestion and flow injection-hydride generation-atomic absorption spectrometry (FI-HAAS) associated analysis method for the content determinations of lead and arsenic in traditional tibetan medicine under optimized digestion and measurement conditions and determine their contents accurately. Under these optimum operating conditions, experimental results were as follows. The detection limits for lead and arsenic were 0.067 and 0.012 µg · mL(-1) respectively. The quantification limits for lead and arsenic were 0.22 and 0.041 µg · mL(-1) respectively. The linear ranges for lead and arsenic were 25-1,600 ng · mL(-1) (r = 0.9995) and 12.5-800 ng · mL(-1) (r = 0.9994) respectively. The degrees of precision(RSD) for lead and arsenic were 2.0% and 3.2% respectively. The recovery rates for lead and arsenic were 98.00%-99.98% and 96.67%-99.87% respectively. The content determination results of lead and arsenic in four traditional tibetan medicine prescription preparations were as fol- lows. The contents of lead and arsenic in Anzhijinghuasan are 0.63-0.67 µg · g(-1) and 0.32-0.33 µg · g(-1) in Anzhijinghua- san, 42.92-43.36 µg · g(-1) and 24.67-25.87 µg · g(-1) in Dangzuo, 1,611. 39-1,631.36 µg · g(-1) and 926.76-956.52 µg- g(-1) in Renqing Changjue, and 1,102.28-1,119.127 µg-g(-1) and 509.96-516.87 µg · g(-1) in Rannasangpei, respectively. This study established a method for content determination of lead and arsenic in traditional tibetan medicine, and determined the content levels of lead and arsenic in four tibetan medicine-prescription preparations accurately. In addition, these results also provide the basis for the safe and effective use of those medicines in clinic.

Zuotai (gTso thal) is a typical representative of Tibetan medicines containing heavy metals, but there is still lack of modem safety evaluation data so far. In this study, acute toxicity test, sub-acute toxicity test, one-time administration mercury distribution experiment, long-term mercury accumulative toxicity experiment and preliminary study on clinical safety of Compound Dangzuo were conducted in the hope of obtain the medicinal safety data of Zuotai. In the acute toxicity test, half of KM mice given the lethal dose of Zuotai were not died or poisoned, and LD50 was not found. The maximum tolerated dose of Zuotai was 80 g x kg(-1). In the subacute toxicity test, Zuotai could reduce ALT, AST, Crea levels in serums under low dose (13.34 mg x kg(-1) x d(-1)) and medium dose (53.36 mg x kg(-1) x d(-1)), with significant difference under low dose, and increase the levels of ALT, AST, MDA, Crea in serums under high dose (2 000 mg x kg(-1) x d(-1)); besides, the levels of BUN and GSH in serums reduced with the increase in dose of Zuotai, indicating a significant dose-effect relationship. In the one-time administration distribution experiment, the content of mercury in rat kidney, liver and lung increased after the one-time administration with Zuotai, with a significant dose-dependent relationship in kidney. In the long-term mercury accumulative toxicity experiment, KM mice were administered with equivalent doses of Zuotai for 4.5 months and then stopped drug administration for 1.5 months. Since the 2.5th month, they showed significant mercury accumulation in kidney, which gradually reduced after drug withdrawal, without significant change in mercury content in liver, spleen and brain and ALT, AST, TBIL, BUN and Crea in serum. At the 4.5th month after drug administration, KM mice showed slight structural changes in kidney, liver and spleen tissues, and gradually recovered to normal after drug withdrawal. Besides, no significant difference in weight gain was found between the Zuotai group and the control group. According to the findings of the clinical safety study of Dangzuo, after subjects administered Dangzuo under clinical dose for one month, their serum biochemical indicators, blood routine indicators and urine routine indicators showed no significant adverse change. This study proved that traditional Tibetan medicine Zuotai was slightly toxic, with a better safety in clinical combined administration and no adverse effects on bodies under the clinical dose and clinical medication cycle. However, long-term high-dose administration of Zuotai may have a certain effect on kidney.;