Bioavailability study of arsenic and mercury in traditional Chinese medicines (TCM) using an animal model after a single dose exposure

Mercuric sulfide nanoparticles suppress the neurobehavioral functions of Caenorhabditis elegans through a Skp1-dependent mechanism

Cinnabar is the naturally occurring mercuric sulfide (HgS) and concerns about its safety have been grown. However, the molecular mechanism of HgS-related neurotoxicity remains unclear. S-phase kinase-associated protein 1 (Skp1), identified as the target protein of HgS, plays a crucial role in the development of neurological diseases. This study aims to investigate the neurotoxic effects and molecular mechanism of HgS based on Skp1 using the Caenorhabditis elegans (C. elegans) model. We prepared the HgS nanoparticles and conducted a comparative analysis of neurobehavioral differences in both wild-type C. elegans (N2) and a transgenic strain of C. elegans (VC1241) with a knockout of the SKP1 homologous gene after exposure to HgS nanoparticles. Our results showed that HgS nanoparticles could suppress locomotion, defecation, egg-laying, and associative learning behaviors in N2 C. elegans, while no significant alterations were observed in the VC1241 C. elegans. Furthermore, we conducted a 4D label-free proteomics analysis and screened 504 key proteins significantly affected by HgS nanoparticles through Skp1. These proteins play pivotal roles in various pathways, including SNARE interactions in vesicular transport, TGF-beta signaling pathway, calcium signaling pathway, FoxO signaling pathway, etc. In summary, HgS nanoparticles at high doses suppress the neurobehavioral functions of C. elegans through a Skp1-dependent mechanism.

Neurobehavioral effects of cinnabar and the cinnabar-containing pediatric prescription, Yi-Nian-Jin, in juvenile rats

BACKGROUND

Cinnabar, a mercury-containing mineral medicine, has long been widely used in pediatric prescriptions. The safety of cinnabar-containing prescriptions, particularly for children, is drawing increasing attention worldwide. However, whether cinnabar and these pediatric prescriptions have adverse effects on neurobehavior is unknown. Yi-Nian-Jin (YNJ), a classic pediatric prescription, contains 5.66% (w/w) cinnabar, along with other four herbs. YNJ is widely prescribed to promote digestion, eliminate phlegm, and prevent constipation in children (aged 0-6 years). In this study, we used YNJ as an example of cinnabar-containing pediatric prescriptions to determine mercury absorption, distribution, and accumulation and further investigate its potential neurotoxicity in juvenile rats.

MATERIAL AND METHODS

Low (67.9 mg/kg), middle (169.8 mg/kg), and high dose (339.6 mg/kg) of cinnabar, and low (1.2 g/kg), middle (3.0 g/kg), and high dose (6.0 g/kg) of YNJ were used in this study, corresponding to 3, 7.5, and 15 times the clinically equivalent dose, respectively. Juvenile rats were orally administered different doses of cinnabar or YNJ for 14 consecutive days. The mercury content in rat blood and tissues (brain, liver, and kidney) and serum biochemical changes on day 14 of consecutive administration and on day 14 after cessation were measured. Moreover, a series of behavioral assays (open field, elevated plus-maze, and Morris water maze assays) were performed after 14 consecutive days of administration.

RESULTS

The mercury absorption, distribution, and accumulation of cinnabar and YNJ in juvenile rats were substantially different. Mercury in cinnabar was absorbed to a greater extent than that in YNJ, and the mercury content in cinnabar high-dose group (cinnabar-H) was approximately seven times higher than that in YNJ high-dose group (YNJ-H) on day 14 of administration. In contrast, compared with that of cinnabar, the mercury content in YNJ accumulated more in the tissues, especially in the brain and kidney. Repeated administration of cinnabar or YNJ did not affect liver function, renal function, learning, and memory in juvenile rats. However, repeated administration of YNJ at a high dose (6.0 g/kg) affected locomotor activity in juvenile rats. Repeated administration of cinnabar (339.6 mg/kg) or YNJ (>1.2 g/kg) induced anxiety-related behavior in juvenile rats.

CONCLUSIONS

Mercury in YNJ exhibited lower absorption but higher accumulation in tissues than those of the mercury in cinnabar. Consecutive oral administration of cinnabar or YNJ had no impact on liver function, renal function, learning, and memory, but could cause motor dysfunction and anxiety in juvenile rats.

MRTCM: A comprehensive dataset for probabilistic risk assessment of metals and metalloids in traditional Chinese medicine

Traditional Chinese medicine (TCM) is still considered a global complementary or alternative medical system, but exogenous hazardous contaminants remain in TCM even after decocting. Besides, it is time-consuming to conduct a risk assessment of trace elements in TCMs with a non-automatic approach due to the wide variety of TCMs. Here, we present MRTCM, a cloud-computing infrastructure for automating the probabilistic risk assessment of metals and metalloids in TCM. MRTCM includes a consumption database and a pollutant database involving forty million rows of consumption data and fourteen types of TCM potentially toxic elements concentrations. The algorithm of probabilistic risk assessment was also packaged in MRTCM to assess the risks of eight elements with Monte Carlo simulation. The results demonstrated that 96.64% and 99.46% had no non-carcinogenic risk (hazard indices (HI) were < 1.0) for animal and herbal medicines consumers, respectively. After twenty years of exposure, less than 1% of the total carcinogenic risk (CR_t) was > 10^-4 for TCM consumers, indicating that they are at potential risk for carcinogenicity. Sensitivity analysis revealed that annual consumption and concentration were the main variables affecting the assessment results. Ultimately, a priority management list of TCMs was also generated, indicating that more attention should be paid to the non-carcinogenic risks of As, Mn, and Hg and the carcinogenic risks of As and Cr in Pheretima and Cr in Arcae Conch. In general, MRTCM could significantly enhance the efficiency of risk assessment in TCM and provide reasonable guidance for policymakers to optimize risk management.

Target RNA expression omics approach to reveal the liver detoxification effect induced by Chinese medicine prescription Niu Huang Jie Du against realgar overexposure to mice

ETHNOPHARMACOLOGICAL RELEVANCE

Niu Huang Jie Du prescription (NHJD) is a traditional Chinese medicine (TCM) widely used in patients suffering from excessive inner fire toxin (Huo Du Nei Sheng) syndrome, such as sore throat, gingival swelling, and pain, mouth and tongue sores, etc. This formula contains realgar (As₄S₄) which is one of the 28 toxic medicinal materials promulgated by the Chinese Ministry of Health. Many studies reported its toxicity on the liver and kidney, and the detoxification effect of NHJD. However, its detoxification mechanism is still unclear.

AIM OF THE STUDY

To clarify the detoxification mechanism of NHJD to realgar, this study evaluated the detoxification effect of NHJD on realgar exposure in mice, and analyzed differences in mRNA expression profiles in liver tissues and associated functional predictions.

MATERIAL AND METHODS

ICR mice were administered with NHJD, realgar, and CMC-Na as blank control for 12 weeks, respectively. Liver injury was evaluated by histopathologic examination and liver mRNA gene were sequenced by Illumina. Differentially expressed gene, functionally enrichment and protein association network analysis were conducted.

RESULTS

43 genes were screened out, among which 15 genes in the realgar group were decreased, but the extent of the decline has been restored in the NHJD group. The remaining 28 genes have exactly the opposite trends. Functional module analysis revealed that those detoxification function-related genes were primarily for positive regulation of glutathione metabolism, P450 on the metabolism of exogenous compounds, oxidative stress and immune-related, etc. CONCLUSIONS: The results indicated that realgar mainly causes liver damage by changing the common enzymes of drug metabolism, especially the expression of genes related to CYPs, GSTs family, oxidative stress, and complement immunity, while the TCM prescription NHJD has a regulatory effect on the abnormal expression of corresponding genes. Our results will provide some clues for the detoxification mechanism of arsenic-containing TCM prescriptions.

Comparative pharmacokinetics and urinary excretion of arsenic and mercury after oral administration of realgar, cinnabar and AnGongNiuHuang Pill to rats

Realgar- and cinnabar-containing AnGongNiuHuang Pill (AGNHP) is widely used for treating encephalopathy syndrome. However, it raises great safety concerns due to the adverse effects reported by arsenic or mercury poisoning. Although AGNHP has been generally recognized, little is known about the metabolism of arsenic and mercury and their resulting potential health risk in vivo. Thus, comparative pharmacokinetics and urinary excretion of arsenic and mercury were conducted in rats after oral administration of realgar, cinnabar and AGNHP, respectively. The contents of arsenic and mercury in rat blood and urine were determined by hydride-generation atomic fluorescence spectrometry (HG-AFS) after wet digestion. AGNHP significantly reduced the absorption of arsenic in blood and promoted urinary arsenic excretion. Whereas, it increased the blood mercury absorption and reduced urinary mercury excretion. No significant toxicity was observed in the clinical dose range of AGNHP. However, excessive exposure to arsenic and mercury may still pose risks especially by long-term or excessive medication. The results are helpful for the rational clinical applications of realgar- and cinnabar-containing TCMs.

Compatibility of Niuhuang Jiedu Tablets Results in Attenuated Arsenic Bioaccumulation and Consequent Protection against Realgar-Induced Toxicity in Mice

Niuhuang Jiedu Tablets (NJT) is a popular over-the-counter traditional Chinese medicine (TCM) preparation. It is composed of realgar (As₂S₂) and seven other TCMs. The safety of NJT is of growing concern because arsenic (As) is carcinogenic to humans. The toxicity of realgar in vivo can mainly be attributed to the absorbed and accumulated As. This study investigated the correlation between the detoxification effects of the other TCMs in NJT on realgar and their influences on arsenic accumulation of realgar in mice. Histopathological examination, clinical biochemical test, and metabolic profiling analysis were used to evaluate the toxicity of realgar. The concentration of arsenic in mice whole blood as the hazard indicator was determined by inductively coupled plasma mass spectrometry (ICP-MS). The compatibility of NJT could decrease arsenic bioaccumulation of realgar in mice whole blood and consequently reduce the toxicity of realgar, which could be considered as one detoxification mechanism to realgar in NJT. The combination of Rhei Radix et Rhizoma, Scutellariae Radix, Platycodonis Radix, and Glycyrrhizae Radix et Rhizoma exhibited almost the same effects as NJT in regulating the serum biochemical parameters and metabolic profiles disturbed by realgar and in reducing arsenic accumulation of realgar in mice whole blood.

Comparative evaluation of in vivo relative bioavailability and in vitro bioaccessibility of arsenic in leafy vegetables and its implication in human exposure assessment

Arsenic (As) contamination in vegetables is a severe threat to human health. However, the evaluation of As relative bioavailability (As-RBA) or bioaccessibility in vegetables is still unexplored. The study sought to evaluate the As-RBA in commonly consumed ten leaf vegetables collected from As-polluted farmlands. Additionally, the As-RBA was determined using rat bioassay and compared with As bioaccessibility through five commonly used in vitro methods, including UBM (Unified BARGE Method), SBRC (Solubility Bioavailability Research Consortium), DIN (Deutsches Institut für Normung e.V.), IVG (In Vitro Gastrointestinal), and PBET (Physiologically Based Extraction Test). Results showed that the As-RBA values were 14.3-54.0% among different vegetables. Notably, significant in vivo-in vitro correlations (IVIVC) were observed between the As-RBA and the As bioaccessibility determined by the PBET assay (r² = 0.763-0.847). However, the other assays (r² = 0.417-0.788) showed a comparatively weaker relationship. The estimation of As-RBA using derived IVIVC to assess As exposure risk via vegetable consumption confirmed that As exposure risk based on As-RBA was lower than that the total As concentrations. Therefore, it was concluded that PBET could better predict the As-RBA in vegetables than other in vitro assays. Furthermore, As-RBA values should be considered for accurate health risk assessment of As in vegetables.

Heavy Metals and Probabilistic Risk Assessment via Pheretima (a Traditional Chinese Medicine) Consumption in China

Earthworms are known to accumulate inorganic contaminants from the soil; they are also used as a traditional Chinese medicine (TCM) called Pheretima, which might cause safety problems with long-term exposure. Here, this study was conducted to determine and analyze the level of heavy metal contamination such as arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), and lead (Pb) in Pheretima and then explore the probabilistic health risks caused by 8 heavy metals in 98 batches of Pheretima using Monte Carlo simulation. A risk assessment strategy was conducted to assess heavy metal-associated health risk of Pheretima based on consumption data. For random consumption sampling, the results found that the non-carcinogenic risk of As is higher than the acceptable level, and the carcinogenic risk levels of As and Cr exceeded the acceptable risk recommended by the USEPA. Cr and As were regarded as the priority metals for risk control in the present study. Finally, it was recommended that the dosing frequency should be less than 24 d/y. In general, this study conducted a probabilistic risk assessment of heavy metals in Pheretima, which would be of significance for policy makers to take effective strategies to improve the quality and safety of Pheretima.

Arsenic-Related Health Risk Assessment of Realgar-Containing NiuHuangJieDu Tablets in Healthy Volunteers Po Administration

Realgar, an arsenic-containing traditional Chinese medicine of As₂S₂, has significant therapeutic effects for hundreds of years. NiuHuangJieDu tablets (NHJDT) is one of the most commonly prescribed realgar-containing preparations for the treatment of sore throat, swelling, and aching of gums. However, realgar-containing TCMs raise great safety concerns due to the adverse effects reported by arsenic poisoning. In this study, the arsenic-related health risk assessment of NHJDT was conducted in healthy volunteers after single and multiple doses oral administration. Blood, plasma, and urine samples were collected after dosing at predetermined time points or periods. Simple, rapid, and sensitive methods were established for the quantification of total arsenic and arsenic speciation in biological samples. The total arsenic and arsenic speciation were determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and high-performance liquid chromatography–hydride generation–atomic fluorescence spectrometry (HPLC-HG-AFS), respectively. No significant fluctuation of total arsenic was observed in human blood, and no traces of arsenic speciation were found in human plasma. Dimethylarsenic acid was detected as the predominated arsenic species in human urine after dosing. Therapeutic dose administration of NHJDT was relatively safe in single dose for the limited blood arsenic exposure, but long-term medication may still pose health risks due to the accumulation of arsenics in blood and its extremely slow excretion rate. Therefore, arsenic exposure should be carefully monitored during realgar-containing TCM medication, especially for long-term regimen. The results obtained in this study will provide scientific references for the clinical application of realgar and its-containing TCMs.

Minerals in biology and medicine

Natural minerals ('stone drugs') have been used in traditional Chinese medicines for over 2000 years, but there is potential for modern-day use of inorganic minerals to combat viral infections, antimicrobial resistance, and for other areas in need of new therapies and diagnostic aids. Metal and mineral surfaces on scales from milli-to nanometres, either natural or synthetic, are patterned or can be modified with hydrophilic/hydrophobic and ionic/covalent target-recognition sites. They introduce new strategies for medical applications. Such surfaces have novel properties compared to single metal centres. Moreover, 3D mineral particles (including hybrid organo-minerals) can have reactive cavities, and some minerals have dynamic movement of metal ions, anions, and other molecules within their structures. Minerals have a unique ability to interact with viruses, microbes and macro-biomolecules through multipoint ionic and/or non-covalent contacts, with potential for novel applications in therapy and biotechnology. Investigations of mineral deposits in biology, with their often inherent heterogeneity and tendency to become chemically-modified on isolation, are highly challenging, but new methods for their study, including in intact tissues, hold promise for future advances.

Arsenic Accumulation of Realgar Altered by Disruption of Gut Microbiota in Mice

Objective

To investigate the influence of gut microbiota on arsenic accumulation of realgar in mice.

Methods

Mice were treated with antibiotics to form a mouse model of gut microbial disruption. Antibiotic-treated and normally raised mice were given 15 mg/kg, 150 mg/kg, and 750 mg/kg realgar by gavage and 0.2 mg/kg and 1 mg/kg arsenic solution by subcutaneous injection for 7 days. The concentration of arsenic in mice whole blood was determined by inductively coupled plasma mass spectrometry (ICP-MS). Arsenic accumulation in antibiotic-treated mice and normally raised mice was compared.

Results

After exposure to low dose (15 mg/kg) and middle dose (150 mg/kg) of realgar, significantly, more arsenic was accumulated in the whole blood of antibiotic-treated mice compared to normally raised counterparts, which indicated that the disruption of gut microbiota could lead to higher arsenic load of realgar in mice. The homeostasis of gut microbiota was supposed to be disrupted by high dose (750 mg/kg) of realgar because after exposure to high dose of realgar, there was no significant difference in arsenic accumulation between antibiotic-treated and normally raised mice. Furthermore, arsenic solution was administered by subcutaneous injection to mice to investigate the influence of gut microbial differences on arsenic accumulation in addition to the absorption process, and there was no significant difference in arsenic accumulation between mice with these two different statuses of gut microbiota.

Conclusions

Gut microbiota disruption could increase arsenic accumulation of realgar in mice.

Pharmacokinetics study of 16 active ingredients from Tabson-2 decoction in normal and d-galactose induced osteoporosis rats by liquid chromatography-tandem mass spectrometry

Tabson-2 decoction is the traditional Mongolian formula for anti-osteoporosis, and the ambiguous of active ingredient is an important factor in restricting its modernization and globalization. Although pharmacokinetic profiles research is a viable approach to find the components being responsible for formula efficacy, the pharmacokinetics study of Tabson-2 decoction has not been elucidated yet. Owing to the existence of isomers, low bioavailability of some small molecule and interference of endogenous, the pharmacokinetics study of Tabson-2 decoction are more difficult than that of chemical drugs. In our experiment, a specific and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for simultaneous determination of 16 active ingredients in Tabson-2 decoction, which could fulfill the requirements of multi-compounds pharmacokinetic study of Tabson-2 decoction. Additionally, the ingredients with significant distributions in rats were gentianic acid, chlorogenic acid, and aucubin, which could be the main potential active components in Tabson-2 decoction. The components with a significant bioavailability difference between normal and d-galactose induced osteoporosis rats were achieved as well. These data offer useful information for screening the active ingredients in Tabson-2 decoction, and assessing the bioavailability of these active ingredients in different physiological status, which might provide a possible mechanism of anti-osteoporosis efficacy of Tabson-2 decoction.

Toxicity and risk assessment of mercury exposures from cinnabar and Baizi Yangxin Pills based on pharmacokinetic and tissue distribution studies

ETHNOPHARMACOLOGICAL RELEVANCE

Baizi Yangxin Pills (BZYXP), a popular cinnabar (α-HgS) contained Traditional Chinese Medicines (TCMs) is widely used in clinical trials. However, mercury is one of the most toxic elements. The adverse effects of cinnabar-containing TCMs have been occasionally reported in recent years, leading to the growing concerns about their toxicity and safety.

AIM OF THE STUDY

The health risks of BZYXP and cinnabar related to the mercury exposures were evaluated through blood pharmacokinetic and tissue distribution studies in rats.

MATERIALS AND METHODS

The distribution of absorbed mercury in rats' blood and tissues were measured by the developed cold-vapor atomic fluorescence spectrometric method. And the tissue damages were determined through the histopathological examinations. For single dose study, the low and high oral doses were equivalent to 1 and 10-fold therapeutic dose, respectively. The multiple doses study was conducted at low and high dose levels every 12 h for 30 consecutive days.

RESULTS

Significant differences of mercury blood pharmacokinetic and tissue distribution characteristics were observed between the corresponding BZYXP and cinnabar groups. The herbal ingredients in BZYXP promoted the absorption of bio-accessible mercury of cinnabar and prolonged the elimination process, posing potential health risks. Although mercury was found easily accumulated in kidney, liver and brain tissues, kidney and liver didn't show obvious damages even after 30 days consecutive administration of BZYXP or cinnabar at 10-fold clinically equivalent doses. But brain did show some histopathological changes, and autonomic activities of rats decreased, pointing the potential neurotoxicity.

CONCLUSIONS

Mercury tend to be accumulated especially when over-dose or prolonged medication with cinnabar-containing TCMs are given. The mercury exposures even at therapeutic doses of BZYXP or cinnabar do pose health risks from the neurotoxicity point of view.

Effects of β-HgS on cell viability and intracellular oxidative stress in PC-12 cells

Traditional Tibetan medicines containing β-HgS have been used to treat chronic ailments for thousands of years. The effects were studied of β-HgS on cell viability and intracellular oxidative stress in PC-12 cells.

Arsenic Bioaccessibility of Realgar Influenced by the Other Traditional Chinese Medicines in Niuhuang Jiedu Tablet and the Roles of Gut Microbiota

Niuhuang Jiedu tablet (NJT), a realgar (As2S2) containing Traditional Chinese Medicine (TCM), is a well-known formula. The safety of NJT is of growing concern since arsenic (As) is considered as one of the most toxic elements. NJT was demonstrated to be safer than realgar by our previous experiments and some other studies. The toxicity of realgar has been shown to be related to the amount of soluble or bioaccessible arsenic. In this study, the influences of the other TCMs in NJT on the bioaccessibility of arsenic from realgar, and the roles of gut microbiota during this process were investigated in vitro. Results showed that Dahuang (Rhei Radix et Rhizoma), Huangqin (Scutellariae Radix), Jiegeng (Platycodonis Radix), and Gancao (Glycyrrhizae Radix et Rhizoma) could significantly reduce the bioaccessibility of arsenic from realgar in artificial gastrointestinal fluids. Gut microbiota played an important role in decreasing the bioaccessibility of realgar because it was demonstrated to be able to absorb the soluble arsenic from realgar in the incubation medium. Dahuang, Huangqin, and Jiegeng could modulate the gut microbiota to enhance its arsenic absorption activity.

Realgar and cinnabar are essential components contributing to neuroprotection of Angong Niuhuang Wan with no hepatorenal toxicity in transient ischemic brain injury

Realgar and cinnabar are commonly used mineral medicine containing arsenic and mercury in Traditional Chinese Medicine (TCM). Angong Niuhuang Wan (AGNHW) is a representative realgar- and cinnabar-containing TCM formula for treating acute ischemic stroke, but its toxicology and neuropharmacological effects are not well addressed. In this study, we compared the neuropharmacological effects of AGNHW and modified AGNHW in an experimental ischemic stroke rat model. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 22 h of reperfusion. Although oral administration of AGNHW for 7 days in the rats increased arsenic level in the blood and liver tissue, there were no significant changes in the arsenic level in kidney, mercury level in the blood, liver and kidney as well as hepatic and renal functions in MCAO rats. AGNHW revealed neuroprotective properties by reducing infarction volume, preserving blood-brain barrier integrity and improving neurological functions against cerebral ischemia-reperfusion injury. Interestingly, removing realgar and/or cinnabar from AGNHW abolished the neuroprotective effects. Meanwhile, AGNHW could scavenge peroxynitrite, down-regulate the expression of p47_phox, 3-NT and MMP-9 and up-regulate the expression of ZO-1 and claudin-5 in the ischemic brains, which were abolished by removing realgar and/or cinnabar from AGNHW. Notably, realgar or cinnabar had no neuroprotection when used alone. Taken together, oral administration of AGNHW for one week should be safe for treating ischemic stroke with neuroprotective effects. Realgar and cinnabar are necessary elements with synergetic actions with other herbal materials for the neuroprotective effects of AGNHW against cerebral ischemia-reperfusion injury.

Neuroprotective Effects and Hepatorenal Toxicity of Angong Niuhuang Wan Against Ischemia-Reperfusion Brain Injury in Rats

Angong Niuhuang Wan (AGNHW) is a classic prescription in traditional Chinese medicine (TCM) used for stroke treatment, but its efficacies remain to be confirmed. With its arsenic- and mercury-containing materials, the application of AGNHW raises great safety concerns. Herein, we aim to explore the neuropharmacological effects against cerebral ischemia-reperfusion injury and evaluate the toxicological effects of AGNHW for better use. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) and following 22 h of reperfusion. AGNHW (257 mg/kg, 1× AGNHW) were orally administered for pharmacological effects and 257, 514, and 1,028 mg/kg (equivalent to 1×, 2×, 4× AGNHW) were used for the toxicological study. The results revealed that AGNHW treatment reduced the infarct size and protected the blood-brain barrier (BBB) integrity in the MCAO rat ischemic stroke model. AGNHW treatment up-regulated bcl-2 expression and down-regulated the expressions of Bax, p47_phox, inducible nitric oxide synthase (iNOS), and 3-nitrotyrosine (3-NT), and inhibited the expressions and activities of matrix metalloproteinase-2 (MMP-2), MMP-9, and reserved tight junction protein zonula occludens-1 (ZO-1) and claudin-5 in the ischemic brains. These results indicated that the neuroprotective mechanisms of AGNHW could be associated with its antioxidant properties by inhibiting oxidative/nitrative stress-mediated MMP activation and protecting tight junction proteins in the ischemic brains. Administration of 1× AGNHW for 7 days would not induce the accumulation of mercury in blood, liver, and kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days increased the level of mercury in the kidney. For arsenic level, administration of 1× AGNHW for 7 days would increase the level of arsenic in the liver and blood without increase of arsenic in the kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days would further increase the level of arsenic in the liver and blood. There is no influence on body weight, organ index, histological structures, and renal and liver functions. These results suggest that short-term treatment of AGNHW within 1 week should be safe and has neuroprotective effects against cerebral ischemia-reperfusion injury.

Chemical Compositions of Metals in Bhasmas and Tibetan Zuotai Are a Major Determinant of Their Therapeutic Effects and Toxicity

Minerals are alchemically processed as Bhasmas in Ayurvedic medicines or as Zuotai in Tibetan medicines. Ayurveda is a knowledge system of longevity and considers the mineral elixir made from “nature” capable of giving humans perpetual life. Herbo-metallic preparations have a long history in the treatment of various diseases in India, China, and around the world. Their disposition, pharmacology, efficacy, and safety require scientific evaluation. This review discusses the Bhasmas in Ayurvedic medicines and Zuotai in Tibetan medicines for their occurrence, bioaccessibility, therapeutic use, pharmacology, toxicity, and research perspectives. A literature search on Mineral, Bhasma, Ayurvedic medicine, Zuotai, Tibetan medicine, and Metals/metalloids from PubMed, Google and other sources was carried out, and the relevant papers on their traditional use, pharmacology, and toxicity were selected and analyzed. Minerals are processed to form Bhasma or Zuotai to alter their physiochemical properties distinguishing them from environmental metals. The metals found in Ayurveda are mainly from the intentional addition in the form of Bhasma or Zuotai. Bhasma and Zuotai are often used in combination with other herbals and/or animal-based products as mixtures. The advanced technologies are now utilized to characterize herbo-metallic preparations as Quality Assurance/Quality Control. The bioaccessibility, absorption, distribution, metabolism, and elimination of herbo-metallic preparations are different from environmental metals. The pharmacological basis of Bhasma in Ayurveda and Zuotai in Tibetan medicines and their interactions with drugs require scientific research. Although the toxic potentials of Bhasma and Zuotai differ from environmental metals, the metal poisoning case reports, especially lead (Pb), mercury (Hg), and arsenic (As) from inappropriate use of traditional medicines, are increasing, and pharmacovigilance is desired. In risk assessment, chemical forms of metals in Bhasma and Zuotai should be considered for their disposition, efficacy, and toxicity.

A review of cinnabar (HgS) and/or realgar (As4S4)-containing traditional medicines

ETHNOPHARMOCOLOGICAL RELEVANCE

Herbo-metallic preparations have a long history in the treatment of diseases, and are still used today for refractory diseases, as adjuncts to standard therapy, or for economic reasons in developing countries.

AIM OF THE REVIEW

This review uses cinnabar (HgS) and realgar (As₄S₄) as mineral examples to discuss their occurrence, therapeutic use, pharmacology, toxicity in traditional medicine mixtures, and research perspectives.

MATERIALS AND METHODS

A literature search on cinnabar and realgar from PubMed, Chinese pharmacopeia, Google and other sources was carried out. Traditional medicines containing both cinnabar and realgar (An-Gong-Niu-Huang Wan, Hua-Feng-Dan); mainly cinnabar (Zhu-Sha-An-Shen Wan; Zuotai and Dangzuo), and mainly realgar (Huang-Dai Pian; Liu-Shen Wan; Niu-Huang-Jie-Du) are discussed.

RESULTS

Both cinnabar and realgar used in traditional medicines are subjected to special preparation procedures to remove impurities. Metals in these traditional medicines are in the sulfide forms which are different from environmental mercurials (HgCl₂, MeHg) or arsenicals (NaAsO₂, NaH₂AsO₄). Cinnabar and/or realgar are seldom used alone, but rather as mixtures with herbs and/or animal products in traditional medicines. Advanced technologies are now used to characterize these preparations. The bioaccessibility, absorption, distribution, metabolism and elimination of these herbo-metallic preparations are different from environmental metals. The rationale of including metals in traditional remedies and their interactions with drugs need to be justified. At higher therapeutic doses, balance of the benefits and risks is critical. Surveillance of patients using these herbo-metallic preparations is desired.

CONCLUSION

Chemical forms of mercury and arsenic are a major determinant of their disposition, efficacy and toxicity, and the use of total Hg and As alone for risk assessment of metals in traditional medicines is insufficient.

Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines

The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines.

Properties of realgar bioleaching using an extremely acidophilic bacterium and its antitumor mechanism as an anticancer agent

Realgar is a naturally occurring arsenic sulfide (or Xionghuang, in Chinese). It contains over 90% tetra-arsenic tetra-sulfide (As4S4). Currently, realgar has been confirmed the antitumor activities, both in vitro and in vivo, of realgar extracted using Acidithiobacillus ferrooxidans (A. ferrooxidans). Bioleaching, a new technology to greatly improve the use rate of arsenic extraction from realgar using bacteria, is a novel methodology that addressed a limitation of the traditional method for realgar preparation. The present systematic review reports on the research progress in realgar bioleaching and its antitumor mechanism as an anticancer agent. A total of 93 research articles that report on the biological activity of extracts from realgar using bacteria and its preparation were presented in this review. The realgar bioleaching solution (RBS) works by inducing apoptosis when it is used to treat tumor cells in vitro and in vivo. When it is used to treat animal model organisms in vivo, such as mice and Caenorhabditis elegans, tumor tissues grew more slowly, with mass necrosis. Meanwhile, the agent also showed obvious inhibition of tumor cell growth. Bioleaching technology greatly improves the utilization of realgar and is a novel methodology to improve the traditional method.

Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats

Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl₂) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl₂ (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl₂ and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl₂ and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl₂ and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl₂ and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden.

Mercury sulfides are much less nephrotoxic than mercury chloride and methylmercury in mice

Mercury sulfides (α-HgS, β-HgS) are frequently included in traditional medicines. Mercury is known for nephrotoxicity, their safety is of concern. To address this question, mice were orally administrated with Zuotai (54% β-HgS, 30mg/kg), α-HgS (HgS, 30mg/kg), HgCl₂ (33.6mg/kg), or MeHgCl (3.1mg/kg) for 7days, and nephrotoxicity was examined. Animal body weights were decreased by HgCl₂ and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl₂ and MeHg produced renal tubular vacuolation, interstitial inflammation and cell degeneration with protein cysts in the tubular lumen, while these pathological lesions were mild in Zuotai and HgS-treated mice. Electron microscopy showed that HgCl₂ and MeHg produced spotted swelling endothelium reticulum, while these lesions were mild or absent in Zuotai and HgS-treated mice. Renal Hg contents reached 250-300ng/mg kidney in HgCl₂ and MeHg groups as compared to 2-3ng/mg in Zuotai and HgS groups. The expression of kidney injury biomarkers, kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (Ngal), were increased after HgCl₂ and MeHg, but unaltered after Zuotai and HgS. The expression of renal influx transporters Oat3 and Oatp4c1 was decreased, while the expression of renal efflux transporter such as Mrp2, Mrp4, and Mate2 was increased following HgCl₂ and MeHg. These gene expressions were unchanged after Zuotai and HgS. In summary, both α-HgS and β-HgS are less nephrotoxic than HgCl₂ and MeHg, indicating that chemical forms of mercury are a major determinant of mercury disposition and toxicity.

The Tibetan medicine Zuotai differs from HgCl2 and MeHg in producing liver injury in mice

Zuotai is composed mainly of β-HgS, while cinnabar mainly contains α-HgS. Both forms of HgS are used in traditional medicines and their safety is of concern. This study aimed to compare the hepatotoxicity potential of Zuotai and α-HgS with mercury chloride (HgCl2) and methylmercury (MeHg) in mice. Mice were orally administrated with Zuotai (30 mg/kg), α-HgS (HgS, 30 mg/kg), HgCl2 (33.6 mg/kg), or CH3HgCl (3.1 mg/kg) for 7 days, and liver injury and gene expressions related to toxicity, inflammation and Nrf2 were examined. Animal body weights were decreased by HgCl2 and to a less extent by MeHg. HgCl2 and MeHg produced spotted hepatocyte swelling and inflammation, while such lesions are mild in Zuotai and HgS-treated mice. Liver Hg contents reached 45-70 ng/mg in HgCl2 and MeHg groups; but only 1-2 ng/mg in Zuotai and HgS groups. HgCl2 and MeHg increased the expression of liver injury biomarker genes metallothionein-1 (MT-1) and heme oxygenase-1 (HO-1); the inflammation biomarkers early growth response gene (Egr1), glutathione S-transferase (Gst-mu), chemokine (mKC) and microphage inflammatory protein (MIP-2), while these changes were insignificant in Zuotai and HgS groups. However, all mercury compounds were able to increase the Nrf2 pathway genes

NAD(P)H

quinone oxidoreductase 1 (Nqo1) and Glutamate-cysteine ligase, catalytic subunit (Gclc). In conclusion, the Tibetan medicine Zuotai and HgS are less hepatotoxic than HgCl2 and MeHg, and differ from HgCl2 and MeHg in hepatic Hg accumulation and toxicological responses.