Simultaneous determination of five aristolochic acids and two aristololactams in Aristolochia plants by high-performance liquid chromatography

Chemical profiling of principle active and toxic constituents in herbs containing aristolochic acids

Objective

To clear the amounts of the principal active/toxic components in herbs containing aristolochic acids (HCAAs), which are still used as medicine and/or seasoning in many ethnic minority areas of China.

Methods

In this study, six major active and toxic components in HCAAs were extracted with ultrasonic extraction. With 6-O-methyl guanosine as internal standard, the target compounds were analyzed qualitatively and quantitatively by using ultrahigh performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) with multiple reaction monitoring-information dependent acquisition-enhanced production ion scanning mode (MRM-IDA-EPI) combined with dynamic background subtraction (DBS) function.

Results

The method showed good linearity in the linear range of the six analytes. The limit range of detection was from 0.01 ng/mL to 0.27 ng/mL. All of the detection repeatability, extraction repeatability and accuracy of the method were good. After extraction, the samples remained stable at 15 °C within 24 h. Six analytes were all found in samples except aristolactam (AL) in sample 2, and the contents varied greatly. The contents of these compounds decreased in fruits, leaves and stems of Aristolochia delavayi successively.

Conclusion

This method has the advantages of less sample dosage, simple operation, short analysis cycle, high sensitivity, specificity and accuracy. It laid a good foundation for guiding the safety of HCAAs, the in-depth study of pharmacological and toxicological effects and the scientific and standardized processing and compatibility of HCAAs.

Aristolochic acid IVa forms DNA adducts in vitro but is non-genotoxic in vivo

Aristolochic acids (AAs) are a family of natural compounds with AA I and AA II being known carcinogens, whose bioactivation causes DNA adducts formation. However, other congeners have rarely been investigated. This study aimed to investigate genotoxicity of AA IVa, which differs from AA I by a hydroxyl group, abundant in Aristolochiaceae plants. AA IVa reacted with 2'-deoxyadenosine (dA) and 2'-deoxyguanosine (dG) to form three dA and five dG adducts as identified by high-resolution mass spectrometry, among which two dA and three dG adducts were detected in reactions of AA IVa with calf thymus DNA (CT DNA). However, no DNA adducts were detected in the kidney, liver, and forestomach of orally dosed mice at 40 mg/kg/day for 2 days, and bone marrow micronucleus assay also yielded negative results. Pharmacokinetic analyses of metabolites in plasma indicated that AA IVa was mainly O-demethylated to produce a metabolite with two hydroxyl groups, probably facilitating its excretion. Meanwhile, no reduced metabolites were detected. The competitive reaction of AA I and AA IVa with CT DNA, with adducts levels varying with pH of reaction revealed that AA IVa was significantly less reactive than AA I, probably by hydroxyl deprotonation of AA IVa, which was explained by theoretical calculations for reaction barriers, energy levels of the molecular orbits, and charges at the reaction sites. In brief, although it could form DNA adducts in vitro, AA IVa was non-genotoxic in vivo, which was attributed to its low reactivity and biotransformation into an easily excreted metabolite rather than bioactivation.

Evaluation of the nephrotoxicity and safety of low-dose aristolochic acid, extending to the use of Xixin (Asurum), by determination of methylglyoxal and d-lactate

ETHNOPHARMACOLOGICAL RELEVANCE

Most Aristolochiaceae plants are prohibited due to aristolochic acid nephropathy (AAN), except Xixin (Asarum spp.). Xixin contains trace amounts of aristolochic acid (AA) and is widely used in Traditional Chinese Medicine. Methylglyoxal and d-lactate are regarded as biomarkers for nephrotoxicity.

AIM OF THE STUDY

The use of Xixin (Asarum spp.) is essential and controversial. This study aimed to evaluate tubulointerstitial injury and interstitial renal fibrosis by determining urinary methylglyoxal and d-lactate after withdrawal of low-dose AA in a chronic mouse model.

MATERIALS AND METHODS

C3H/He mice in the AA group (n = 24/group) were given ad libitum access to distilled water containing 3 μg/mL AA (0.5 mg/kg/day) for 56 days and drinking water from days 57 to 84. The severity of tubulointerstitial injury and fibrosis were evaluated using the tubulointerstitial histological score (TIHS) and Masson's trichrome staining. Urinary and serum methylglyoxal were determined by high-performance liquid chromatography (HPLC); urinary d-lactate were determined by column-switching HPLC.

RESULTS

After AA withdrawal, serum methylglyoxal in the AA group increased from day 56 (429.4 ± 48.3 μg/L) to 84 (600.2 ± 99.9 μg/L), and peaked on day 70 (878.3 ± 171.8 μg/L; p < 0.05); TIHS and fibrosis exhibited similar patterns. Urinary methylglyoxal was high on day 56 (3.522 ± 1.061 μg), declined by day 70 (1.583 ± 0.437 μg) and increased by day 84 (2.390 ± 0.130 μg). Moreover, urinary d-lactate was elevated on day 56 (82.10 ± 18.80 μg) and higher from day 70 (201.10 ± 90.82 μg) to 84 (193.28 ± 61.32 μg).

CONCLUSIONS

Methylglyoxal is induced after AA-induced tubulointerstitial injury, so methylglyoxal excretion and metabolism may be a detoxification and repair strategy. A low cumulative AA dose is the key factor that limits tubulointerstitial injury and helps to repair. Thus, AA-containing herbs, especially Xixin, should be used at low doses for short durations (less than one month).

8 years post-marketing surveillance between Asari Radix and hepatocellular carcinoma: Nationwide population-based evidence against an association

ETHNOPHARMACOLOGICAL RELEVANCE

Asari Radix (Xixin, Asarum heterotropoides Fr. Schmidt var. mandshuricum Kitag., Asarum sieboldii Miq., or Asarum sieboldii Miq. var. seoulense Nakai, Asarum spp.) is the only herbal medicine containing aristolochic acid that can be used in medical practice. However, scientific evidence regarding its safe use in relation to hepatocellular carcinoma (HCC) is lacking.

AIM OF THE STUDY

The aim of this study was to use post-marketing surveillance to provide a scientific understanding of the relationship between Asari Radix and the development of HCC and suggest the maximum allowable amount of Asari Radix.

MATERIALS AND METHODS

A retrospective, population-based cohort study was conducted, with patients randomly selected and divided into three cohorts: a non-hepatitis B virus (HBV)/hepatitis C virus (HCV) cohort, a HBV cohort, and a HCV cohort. Data were retrieved from the National Health Insurance Research Database of Taiwan from January 1, 1997 to December 31, 2013. The study period covered the initial 10 years of exposure to persistent HBV or HCV, followed by exposure to Asari Radix for an additional 8 years.

RESULTS

After propensity score matching, 106,942, 3818, and 928 patients were included in the non-HBV/HCV, HBV, and HCV cohorts, respectively. These cohorts included 75, 50, and 42 HCCs and 1,564,943, 30,956, and 6938 person-years, respectively. All hazard ratios of exposure to 1-30 g, 31-60 g, 61-100 g, and 101-200 g of Asari Radix in these three cohorts showed negative associations between Asari Radix exposure and HCC development. Furthermore, the three cohorts demonstrated that exposure to under 200 g of Asari Radix was safe.

CONCLUSIONS

Post-marketing surveillance showed that Asari Radix has no relationship with HCC development at an intake of under 200 g. The study is persuasive in furthering our knowledge of the maximum allowable amount of Asari Radix.

Systematic Overview of Aristolochic Acids: Nephrotoxicity, Carcinogenicity, and Underlying Mechanisms

Aristolochic acids (AAs) are a group of toxins commonly present in the plants of genus Aristolochia and Asarum, which are spread all over the world. Since the 1990s, AA-induced nephropathy (AAN) and upper tract urothelial carcinoma (UTUC) have been reported in many countries. The underlying mechanisms of AAN and AA-induced UTUC have been extensively investigated. AA-derived DNA adducts are recognized as specific biomarkers of AA exposure, and a mutational signature predominantly characterized by A→T transversions has been detected in AA-induced UTUC tumor tissues. In addition, various enzymes and organic anion transporters are involved in AA-induced adverse reactions. The progressive lesions and mutational events initiated by AAs are irreversible, and no effective therapeutic regimen for AAN and AA-induced UTUC has been established until now. Because of several warnings on the toxic effects of AAs by the US Food and Drug Administration and the regulatory authorities of some other countries, the sale and use of AA-containing products have been banned or restricted in most countries. However, AA-related adverse events still occur, especially in the Asian and Balkan regions. Therefore, the use of AA-containing herbal remedies and the consumption of food contaminated by AAs still carry high risk. More strict precautions should be taken to protect the public from AA exposure.

Phytochemical Screening and Toxicological Study of Aristolochia baetica Linn Roots: Histopathological and Biochemical Evidence

Aristolochia baetica (A. baetica) is a wild species of Aristolochiaceae family; its roots are used by Moroccan people against cancer for many years ago. The objective of the study was to investigate the phytochemical screening, acute and subacute toxicity of A. baetica roots growing in the north of Morocco. Qualitative and quantitative analyses of A. baetica roots were performed using standard methods; the acute toxicity of the root extract of the studied plant was assessed in mice by gavage of single doses of 1, 2, and 4 g/kg body weight for 14 days; by the time the subacute toxicity was done using repeated doses 1, 1.5, and 2 g/kg/day for 28 days. Histological changes and biochemical parameters as markers of kidney and liver function were evaluated. The results of phytochemical screening showed the presence of polyphenols, tannins, alkaloids, flavonoids, saponins, and the absence of anthraquinones, sterols, and terpenes. The results of acute toxicity showed the absence of mortality and signs of toxicity in groups treated with 1 and 2 g/kg; however, the clinical signs of toxicity were important and the rate of mortality was estimated at 16 % in the group treated with 4 g/kg. The results of subacute toxicity showed several changes of serum parameters registered in groups treated with 1.5 and 2 g/kg/day, respectively. The results showed also the absence of histological injuries in groups treated with 1 and 1.5 g/kg/day; meanwhile, the histological alterations were remarkable in treated group with the highest dose administered of 2 g/kg/day. The outcome of this work showed that the roots' extract of the studied plant was toxic in mice with repeated doses, but no toxic effect was observed with a single dose under 4g/kg.

Rapid Identification and Simultaneous Quantification of Aristolochic Acids by HPLC-DAD and Confirmations by MS in Aristolochia chilensis Using a Limited Biomass

Six aristolochic acids were identified in the Chilean species Aristolochia chilensis using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) and subsequent confirmation with mass spectrometry (MS). The fractions of each signal were collected and injected directly into an Orbitrap mass detector model Q Exactive Focus (Thermo Scientific). The acids extraction was done with 0.10-0.50 g of lyophilized and pulverized sample and concentrated in Soxhlet extraction equipment. The liquid-liquid separations and a subsequent solid phase extraction (SPE) C18 were performed using 100 µL of the extract that contains the aristolochic acids present in the Aristolochia chilensis plant. The HPLC conditions used a single mobile phase acetonitrile : water (1 : 1) acidified with 0.1% acetic acid and an isocratic elution to 1 mL·min^-1. The column InertSustain C18 250 × 4.6 mm and 3 µm was used, the injection volume was 20 µL, and the time of run was reduced to 15 min. Calibration curves were constructed with r² being 0.9997. The quantification limit for AAI was 0.138 ± 0.010 µg/mL, and for AAII, it was 0.558 ± 0.042 µg/mL.

Comparative studies on the multi-component pharmacokinetics of Aristolochiae Fructus and honey-fried Aristolochiae Fructus extracts after oral administration in rats

Background

Aristolochiae Fructus (AF) and honey-fried Aristolochiae Fructus (HAF) have been used in China for a long time as anti-tussive and expectorant drugs. Few clinical cases have been reported to be associated with the toxicity of AF and HAF, although relatively high amounts of aristolochic acids (AAs) have been found in them. Our previous experiments have verified from the chemical changes and from traditional toxicology that honey-processing can significantly reduce the toxicity of AF. To further elucidate the detoxification mechanism of honey-processing, comparative pharmacokinetics of AAs in AF and HAF are performed in this study.

Methods

An HPLC-MS/MS (high-performance liquid chromatography-tandem mass spectrometry) method was developed and validated for the determination of AA I, AA II, AA C, AA D and 7-OH AA I in rat plasma. The multi-component pharmacokinetics of AAs in AF and HAF extracts were investigated after the oral administration of three doses to rats. The relative pharmacokinetic parameters were compared systematically.

Results

The five AAs shared a similar nonlinear PK (pharmacokinetic) process. They involve rapid absorption and elimination, and they were fit into a two-compartmental open model. Some significant pharmacokinetic differences were observed between the AF and HAF groups: the C_max and AUC values of AA I and AA II in the AF groups were much higher than those of the HAF groups.

Conclusions

Honey-frying technology can reduce the toxicity of AF by significantly decreasing the absorption of AA I and AA II. The PK parameters obtained in this work could provide valuable references for the toxicity research and clinical use of Aristolochiaceae herbs, including AF and HAF.

Graphical abstract

Process diagram of comparative pharmacokinetics study

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1626-2) contains supplementary material, which is available to authorized users.

Expression of Renal Aquaporins in Aristolochic Acid I and Aristolactam I-Induced Nephrotoxicity

BACKGROUND

Exposure to aristolochic acid (AA) can cause AA nephropathy, which is characterized by extensive proximal tubular damage and polyuria.

METHODS

To test the hypothesis that polyuria might be induced by altered regulation of aquaporins (AQPs) in the kidney, different doses of AA-I or aristolactam I (AL-I) were administered intraperitoneally to Sprague-Dawley rats, and urine, blood, and kidney samples were analyzed. In addition, AQP1, AQP2, AQP4 and AQP6 expression in the kidney were determined.

RESULTS

The results showed dose-dependent proximal tubular damage and polyuria in the AA-I- and AL-I-treated groups, and the nephrotoxicity of AL-I was higher than that of AA-I. The expression of renal AQP1, AQP2 and AQP4, but not AQP6 were significantly inhibited by AA-I and AL-I. Comparison of the inhibition potencies of AA-I and AL-I showed that AL-I was a stronger inhibitor of AQP1 expression than AA-I, while there was no difference in their effects on AQP2 and AQP4.

CONCLUSION

These results suggested that AA induced renal damage and polyuria were associated with a specific decrease in the expression of renal AQP1 AQP2 and AQP4, and AL-I showed higher nephrotoxicity than AA-I, which might be attributable to the differences in their inhibition of AQP1.

Temporal Variation of Aristolochia chilensis Aristolochic Acids during Spring

In this communication, we report the springtime variation of the composition of aristolochic acids (AAs) in Aristolochia chilensis leaves and stems. The dominant AA in the leaves of all samples, which were collected between October and December, was AA-I (1), and its concentration varied between 212.6 ± 3.8 and 145.6 ± 1.2 mg/kg and decreased linearly. This decrease occurred in parallel with the increase in AA-Ia (5) concentration from 15.9 ± 0.8 mg/kg at the beginning of October to 96.8 ± 7.8 mg/kg in mid-December. Both acids are enzymatically related by methylation-demethylation reactions. Other AAs also showed important variations: AA-II (2) significantly increased in concentration, reaching a maximum in the first two weeks of November and subsequently decreasing in mid-December to approximately the October levels. The principal component in the AA mixture of the stems was also AA-I (1); similar to AA-II (2), its concentration increased beginning in October, peaked in the second week of November and subsequently decreased. The concentrations of AA-IIIa (6) and AA-IVa (7) in the leaves and stems varied throughout the study period, but no clear pattern was identified. Based on the variation of AAs in A. chilensis leaves and stems during the study period, the reduced contents of non-phenolic AAs and increased concentrations of phenolic AAs are likely associated with a decrease in this plant’s toxicity during the spring.

New Approaches for Biomonitoring Exposure to the Human Carcinogen Aristolochic Acid

Aristolochic acids (AA) are found in all Aristolochia herbaceous plants, many of which have been used worldwide for medicinal purposes for centuries. AA are causal agents of the chronic kidney disease entity termed aristolochic acid nephropathy (AAN) and potent upper urinary tract carcinogens in humans. AAN and upper urinary tract cancers are endemic in rural areas of Croatia and other Balkan countries where exposure to AA occurs through the ingestion of home-baked bread contaminated with Aristolochia seeds. In Asia, exposure to AA occurs through usage of traditional Chinese medicinal herbs containing Aristolochia. Despite warnings from regulatory agencies, traditional Chinese herbs containing AA continue to be used world-wide. In this review, we highlight novel approaches to quantify exposure to AA, by analysis of aristolactam (AL) DNA adducts, employing ultraperformance liquid chromatography-electrospray ionization/multistage mass spectrometry (UPLC-ESI/MSⁿ). DNA adducts are a measure of internal exposure to AA and serve as an important end point for cross-species extrapolation of toxicity data and human risk assessment. The level of sensitivity of UPLC-ESI/MSⁿ surpasses the limits of detection of AL-DNA adducts obtained by ³²P-postlabeling techniques, the most widely employed methods for detecting putative DNA adducts in humans. AL-DNA adducts can be measured by UPLC-ESI/MS³, not only in fresh frozen renal tissue, but also in formalin-fixed, paraffin-embedded (FFPE) samples, an underutilized biospecimen for assessing chemical exposures, and in exfoliated urinary cells, a non-invasive approach. The frequent detection of AL DNA adducts in renal tissues, combined with the characteristic mutational spectrum induced by AA in TP53 and other genes provides compelling data for a role of AA in upper urothelial tract cancer.

Chinese herbs containing aristolochic acid associated with renal failure and urothelial carcinoma: a review from epidemiologic observations to causal inference

Herbal remedies containing aristolochic acid (AA) have been designated to be a strong carcinogen. This review summarizes major epidemiologic evidence to argue for the causal association between AA exposure and urothelial carcinoma as well as nephropathy. The exposure scenarios include the following: Belgian women taking slimming pills containing single material Guang Fang Ji, consumptions of mixtures of Chinese herbal products in the general population and patients with chronic renal failure in Taiwan, occupational exposure in Chinese herbalists, and food contamination in farming villages in valleys of the Danube River. Such an association is corroborated by detecting specific DNA adducts in the tumor tissue removed from affected patients. Preventive actions of banning such use and education to the healthcare professionals and public are necessary for the safety of herbal remedies.

Development of an Eastern blotting technique for the visual detection of aristolochic acids in Aristolochia and Asarum species by using a monoclonal antibody against aristolochic acids I and II

INTRODUCTION

Aristolochic acids (AAs) are naturally occurring nephrotoxicants and human carcinogens. Aristolochic acid I (AA-I) and aristolochic acid II (AA-II) are two important AAs with clear toxicity.

OBJECTIVE

To obtain a monoclonal antibody (MAb) recognising AA-I and AA-II and develop an Eastern blotting technique for the specific visualisation and easy determination of AA-I and AA-II in plant extracts or tissues of Aristolochia and Asarum species.

METHODS

A hybridoma secreting MAb against AAs was prepared by cell fusion with splenocytes derived from a mouse immunised with AA-I-keyhole limpet haemocyanin (KLH) conjugate and the myeloma cell line SP2/0-Ag14. AA-I and AA-II were separated by thin-layer chromatography (TLC) and then blotted onto a positively charged polyethersulphone (PES) membrane using a modified carbodiimide method. The resulting membrane-bound AA-protein conjugates were linked to the newly prepared MAb and then to the secondary antibody labelled with peroxidase. 4-Chloro-1-naphthol was then added as the peroxidase substrate for staining.

RESULTS

MAb 2A10-10B showed a high specificity for AA-I (100%) and AA-II (69.3%) and low cross reactivity (≤ 2.2%) toward analogues that may disrupt detection of AA-I and AA-II in plants. An established Eastern blotting method was applied to the immunohistolocalisation of AA-I and AA-II in dry plant tissues, and this analysis showed that the phelloderm, cortex and phloem of Aristolochia manshuriensis stem may contain higher amounts of total AA-I and AA-II as compared with the pith and xylem.

CONCLUSION

This method was extremely useful for the visual screening of AA-I and AA-II among easily mistaken herbal medicines.

Fate of Ingested Aristolactams from Aristolochia chilensis in Battus polydamas archidamas (Lepidoptera: Papilionidae)

We performed a sequestration study of aristolactams (ALs) from Aristolochia chilensis in Battus polydamas archidamas (Lepidoptera: Papilionidae) by examining the AL content of the plant, fifth instar larvae, osmeterial secretion, pupae, exuviae and feces. Aristolactam-I (AL-I) and aristolactam-II (AL-II) present in A. chilensis are sequestered by fifth instar larvae of B. polydamas archidamas. There is a preferential sequestration of AL-II, or a more efficient metabolization and excretion of AL-I, by the larva. No ALs were found in the osmeterial secretion, pupae and exuviae; in addition, little AL-I and no AL-II were found in larval frass. The two lactams, particularly AL-I, are extensively metabolized to other products in the larva. A reasonable hypothesis is that the ingested ALs are oxidized to their respective aristolochic acids.

Occupational exposure to herbs containing aristolochic acids increases the risk of urothelial carcinoma in Chinese herbalists

PURPOSE

Aristolochic acid can cause urothelial carcinoma. Herbal remedies containing aristolochic acids were previously categorized as proven group 1 human carcinogens by the WHO cancer agency, the International Agency for Research on Cancer. However, the health effect on workers exposed to aristolochic acid is unclear. Fangchi, a representative herb containing aristolochic acid, is commonly used in the Chinese herbal medicine industry. We determined whether workers exposed to fangchi are at increased risk for urothelial carcinoma.

MATERIALS AND METHODS

We designed a case-control study based in a national representative cohort of Chinese herbalists. This study analyzed 6,564 Chinese herbalists employed between 1985 and 1998. All incident cases of urothelial carcinoma that occurred between 1988 and 2001 were defined as the case group. Controls were selected from the baseline cohort in a randomized manner. A total of 24 cases and 140 controls were included in analysis. Information about fangchi exposure was obtained in a questionnaire survey administered in 2002.

RESULTS

Processing, selling or dispensing herbs containing fangchi significantly increased the risk of urothelial carcinoma (HR 2.4, 95% CI 1.1-5.3, p = 0.03). This relationship was independent of cigarette smoking or potential arsenic exposure from drinking water from deep wells.

CONCLUSIONS

Exposure to the Chinese herbal drug fangchi increases the risk of urothelial carcinoma in herbalists. Appropriate medical monitoring is warranted for workers who have similar exposure.

Proteome alterations in response to aristolochic acids in experimental animal model

Strong indications have been presented that dietary poisoning with aristolochic acids (AA) is responsible for Endemic Nephropathy (EN) and AA associated cancer of the upper urinary tract (UUTC). Our recent investigation showed drastic urinary proteome changes in AA treated mice. This study was designed to identify proteome changes associated with AA nephrotoxicity in experimental animal model. The DBA and C57BL mice, which differ in AA sensitivity, were exposed to AA for 4 days. The strategy for urinary, plasma and kidney tissue proteome study of AA exposed and control mice integrated gel-based and in-solution tryptic digestion combined with LC-ESI-MS/MS. To maximize proteome coverage, plasma fractionation scheme was developed and MS compatible sequential tissue extraction procedure was established. Proteomic analyses of urinary, plasma and kidney tissue tryptic digests resulted in identification of several cytoskeletal proteins, as well as proteins involved in kidney development and inflammatory response, that are differentially expressed in both AA exposed and control mice. These proteins are consistent with renal pathogenesis of endotoxicity and cancer. This proteomic strategy could be effectively translated for unbiased discovery of potential biomarkers for EN and associated UUTC in humans. At the same time, these results highlight the significance of AA exposure with EN. This article is part of a Special Issue entitled: Integrated omics.

Comparative study of the contents of analogues of aristolochic acid in two kinds of Aristolochiae Fructus by high-performance liquid chromatography

Aristolochiae Fructus ("Madouling") is derived from the fruits of Aristolochia contorta and A. debilis (Aristolochiaceae). These two species contain potentially nephrotoxic constituents, but are officially used in China. Distinction of constituents and toxicity between these two species remains unclear. A high-performance liquid chromatography method was developed and validated for the simultaneous determination of seven analogues of aristolochic acid (aristolochic acids I, II, IIIa, IVa and VIIa), as well as aristololactams I and II in Aristolochiae Fructus. Chromatographic separation was achieved on a Zorbax SB-C(18) column with a gradient mobile phase comprising acetonitrile and 1 % acetic acid-30 mM triethylamine (20:1, v/v) buffer. Analytes were detected with a diode array detector at 250 and 260 nm. The contents of seven constituents in samples (11 batches of A. contorta fruits, 15 batches of A. debilis fruits and 33 commercial samples of Madouling) were determined. The content of aristolochic acid IVa was higher than that of aristolochic acid VIIa in A. contorta fruits, whereas the opposite was true in A. debilis fruits. This feature can be used to distinguish the two species from each other and identify the resource plant of Madouling. Through a morphological method and a newly found principle based on the ratio AA-IVa/AA-VIIa, we found that the 33 commercial samples collected from 12 provinces in China were all derived from the fruits of A. contorta.

Production, Characterization of a Monoclonal Antibody against Aristolochic Acid-II and Development of its Assay System

Aristolochic acid-II (AA-II) conjugated with bovine serum albumin (BSA) was used as an antigen for immunizing BALB/c mice. Isolated splenocytes from the immunized mice were fused with an aminopterin-sensitive mouse myeloma cell line, SP2/0-Ag14, to produce hybridoma cells that secreted a monoclonal antibody (MAb) against AA-II. The selected hybridoma was subsequently cloned by limited dilution method. For MAb, the isotype and an estimated dissociation constant ( K D ) of the MAb were determined. The MAb was used to establish an ELISA method. Accuracy and variation assays, as well as determinations of the specificity and sensitivity, were also carried out and the linear range was 0.19–13 μg/ml. The anti-AA-II MAb showed a very high specificity for AA-II and had low cross-reactivities against the other aristolochic acid (AAs) (CR: AA-I, 3.4%; AA-VIIa, 0.86%) or aristololactam-I (AL-I) (CR < 0.07%) except AA-IIIa which has 17% of cross activity. Anti-AA-II MAb also showed negligible cross-reactivity (< 0.5%) toward other natural compounds with different chemical structures including barbaloin, sennoside A, rutin, glycyrrhizin, caffeic acid etc. This is the first time that an ELISA method was successfully established for the application of anti-AA-II MAb.

Increased risks of upper tract urothelial carcinoma in male and female chinese herbalists

BACKGROUND/PURPOSE

It has been shown that herbs that contain aristolochic acid induce urological cancer. Chinese herbalists have easy access to such herbs. Our previous mortality study has shown a significantly increased risk of urological cancer in female but not male herbalists. To re-examine this risk in male herbalists, the incidence of urological cancer was analyzed.

METHODS

We enrolled all 6550 Chinese herbalists in Taiwan registered during 1985-2000, and we retrospectively followed the development of cancer until 2001 by analysis of data collected from the Taiwan Cancer Registry. Standardized incidence ratios (SIRs) were calculated for urological cancers in herbalists and compared with those for the general population in Taiwan.

RESULTS

There were 30 newly diagnosed cases of urological cancer and most of them were transitional cell carcinoma (93.1%). The mean age at diagnosis for urothelial carcinoma was 51.6 years, and 51.9% were in the upper urinary tract. After adjustment for age and sex, the SIR for all urological cancers was 3.51 [(95% confidence interval (CI): 2.37-5.01]. When stratified by location, the SIRs for kidney and upper urinary tract cancers and bladder cancer were 4.24 (95% CI: 2.47-6.80) and 2.86 (95% CI: 1.52-4.89), respectively. When analyzed by sex, the SIRs for all urological cancers, kidney and upper urinary tract cancers, and bladder cancer were also significantly increased in male herbalists.

CONCLUSION

The significant risk of urothelial carcinoma noted in male herbalists increases our suspicion that this is an occupational disease that renders regular health assessment of herbalists an urgent necessity.

Aristolochic acid nephropathy: variation in presentation and prognosis

BACKGROUND

Aristolochic acid nephropathy (AAN) is a worldwide problem and one of the common causes of chronic kidney disease (CKD) in China.

METHODS

Three hundred patients diagnosed as AAN from 1997 to 2006 were enrolled. Medical histories of Chinese herb ingestion, clinical-pathological features and risk factors for renal failure were recorded. Patients were followed up for 2-156 months. Factors involved in the prognosis of AAN were investigated.

RESULTS

The 300 patients with AAN manifested three clinical subtypes, including acute kidney injury (acute AAN) in 13 patients, abrupt tubular dysfunction with normal serum creatinine (Scr) levels in seven cases and chronic tubulointerstitial nephropathy with decreased estimated glomerular filtration rate (eGFR) (chronic AAN) in 280 cases. The acute AAN cases had the highest aristolochic acid (AA)-I intake per day and developed progressive kidney failure during 1-7 years follow-up. The tubular dysfunction AAN patients had the lowest cumulative AA-I intake and were able to keep normal Scr levels during 2-8 years follow-up. The chronic AAN patients took the lowest AA-I dose per day but with the longest period and the highest cumulative dosage and exhibited a very large range of eGFR changing rate (from -21.6 to 5.2, median -3.5 mL/min/year). The cumulative AA-I intake (r = 0.330, P = 0.045) and the time course from the termination of AA medication to the start of follow-up (r = -0.430, P = 0.009) were found to be independent factors correlated with the decrease rate of eGFR in the chronic AAN patients. AA and the metabolites could be detected in a high frequency in patients who had stopped herbal medication for 1 year, which indicates a rather long washout time for these chemicals.

CONCLUSIONS

AAN has variant phenotypes with distinct prognosis, which is determined by the variable AA medications. With better understanding of toxic and environmental causes for kidney injury, there would be a better chance to uncover the causal factors of cases of 'CKD without known causes' which is crucial for improving the disease outcomes.

Regular use of nephrotoxic medications is an independent risk factor for chronic kidney disease--results from a Chinese population study

BACKGROUND

Prescription drug abuse is an important global health concern. Our previous survey in Beijing indicates that nephrotoxic medication use is independently associated with chronic kidney disease (CKD).

METHODS

In the present study, the study population consisted of participants from our previous survey with a confirmed history of nephrotoxic medication use. Nephrotoxic mediations included three antipyretic analgesics (58.2%) and three Chinese traditional medicines containing aristolochic acids (CTM-AAs, 47.3%). Prevalence of CKD (defined by presence of albuminuria and/or reduced estimated glomerular filtration rate) as well as markers of tubular injury was analysed, and compared with 109 age- and sex-matched controls.

RESULTS

The prevalence of CKD was higher among medication users compared with controls, which was 18.3% and 8.5%, respectively. Among participants with medication use without CKD, markers of tubular injury including N-acetyl-β-d-glucosaminidase, transferrin and α(1)-microglobulin, were present in 26.6%. CKD was associated with CTM-AA use (cumulative AA-I dose > 0.5 g, OR = 5.625, P < 0.05) and antipyretic analgesic use (cumulative dose > 2.0 kg, OR = 3.848, P = 0.063) in a dose-dependent manner. Albuminuria and tubular injury persisted among CTM-AA users, but not among analgesic users after cessation of drug.

CONCLUSIONS

Our study suggests that education about rational analgesic use and CTM-AA banning may constitute an effective CKD prevention strategy.

A Three-Stage-Integrative Approach for the Identification of Potential Hepatotoxic Compounds From Botanical Products

With the increasing use of herbal medicines and dietary supplements, intensive concerns about their potential toxicities have been raised. Screening and identifying the toxic compounds from these botanical products composed by hundreds of components have become a critical but challenging problem. In this study, 3 methods, including fraction separation, an in-house-developed fluorescein diacetate-based automatic microscopy screening (FAMS) platform, and liquid chromatography-mass spectrometry-based compounds identification were integrated within the Three-Stage-Integrative (TSI) approach for the identification of potential hepatotoxicants from botanical products. The sensitivity and linear range of FAMS assay was validated and compared with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay by previously reported hepatotoxic compounds. The success of TSI approach was further demonstrated by its application to Fructus aristolochiae. Aristolochic acid IVa and aristolodione were tentatively identified to be potential hepatotoxicants in this plant. These applications suggested that our TSI approach provides an effective tool for identifying potential toxic compounds from botanical products.

Kinetics of aristolochic acid I after oral administration of Radix Aristolochiae or Guanxinsuhe preparation in canines

ETHNOPHARMACOLOGICAL RELEVANCE

Aristolochic acid I (AAI), a major component derived from Aristolochia species, which have been known for a long time and remain in use today, particularly in Asia and Central America. It has been confirmed to induce a type of so-called aristolochic acid nephropathy (AAN) and involved in the development of Balkan endemic nephropathy (BEN).

AIM OF THE STUDY

To investigate the kinetic of AAI in beagle dogs after single-dose oral administration of Radix Aristolochiae or its preparation, Guanxinsuhe, as well as the effects of compound compatibility in traditional Chinese medicine on the pathologic processes of AAN.

MATERIALS AND METHODS

Beagle dogs were orally administrated Radix Aristolochiae (0.3 g/kg/day), Guanxinsuhe preparation (0.9 g/kg/day) (with an identical dosage of AAI), and empty capsules respectively for 180 days. Canines (n=2) were euthanized on day 90, 180, 210, HPLC was established to determine the AAI level in plasma and the kinetic behaviors of AAI in dogs were elucidated after single dosing. Hematoxylin and eosin (H&E)-staining was applied for histopathologic examination to evaluate the pathological status of kidneys.

RESULTS

Compared to canines with Radix Aristolochiae treatment, the Cmax, AUC, Tmax, and t(1/2β) of AAI in Guanxinsuhe preparation group were elevated, while t(1/2α) of AAI was decreased. The results indicated the co-existing components in Guanxinsuhe preparation could increase the absorption, accelerate the distribution, but delay the absorption and elimination of AAI. After long-term dosing, animals treated with Radix Aristolochiae were found with more severe renal impairment and higher AAI level in plasma.

CONCLUSIONS

It was demonstrated that the compound compatibility in Guanxinsuhe preparation can affect the kinetic process of AAI and attenuate the toxic effect on kidney when the duration of treatment was prolonged.

Isolation, Characterization and Quantity Determination of Aristolochic Acids, Toxic Compounds in Aristolochia bracteolata L

BACKGROUND

Aristolochic Acids (AAs) are major components of plants in Aristolochia and have been found to be nephrotoxic, carcinogenic and mutagenic. Herein reported are the isolation, identification and quantity determination methods of Aristolochic Acid-I (AA-I) and Aristolochic Acid-II (AA-II) toxic compounds of Aristolochia bracteolata indigenous to Central Sudan and medicinally used in diverse biological functions including analgesic and diuretic effects, treatment of tumors, malaria and/or fevers.

METHODS AND RESULTS

AAs mixture was extracted with methanol from the defatted material of Aristolochia bracteolata whole plant at room temperature and was isolated from the aqueous methanol extract by chloroform. Moreover, Silica-gel column chromatography and Preparative Thin Layer Chromatography (PTLC) using chloroform/methanol gradient mixtures were used to isolate AAs mixtures as a yellow crystalline solid. A preliminary detection of AAs was made by Thin Layer Chromatography (silica-gel, chloroform: methanol (6:1)). The Rf value of the acids mixture was 0.43-0.46. The presence of AAs in plant sample was confirmed by High Performance Liquid Chromatography/Ultraviolet (HPLC/UV) analysis using 1% acetic acid and methanol (40:60) as mobile phase and maximum absorption wave length of 250 nm. Quantitative determination of AA-II (49.03 g/kg) and AA-I (12.98 g/kg) was also achieved by HPLC/UV.

RECOMMENDATION

It is recommended that the use of Aristolochia bracteolata as a medicinal plant should be extremely limited or strictly prohibited. The chromatograms obtained in this study can serve as fingerprints to identify AAs in plant samples.

Toxicities of aristolochic acid I and aristololactam I in cultured renal epithelial cells

Aristolochic acid nephropathy, a progressive tubulointerstitial renal disease, is primarily caused by aristolochic acid I (AA-I) intoxication. Aristololactam I (AL-I), the main metabolite of AA-I, may also participate in the processes that lead to renal damage. To investigate the role and mechanism of the AL-I-mediated cytotoxicity, we determined and compared the cytotoxic effects of AA-I and AL-I on cells of the human proximal tubular epithelial (HK-2) cell line. To this end, we treated HK-2 cells with AA-I and AL-I and assessed the cytotoxicity of these agents by using the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, flow cytometry, and an assay to determine the activity of caspase 3. The proliferation of HK-2 cells was inhibited in a concentration- and time-dependent manner. Cell-cycle analysis revealed that the cells were arrested in the S-phase. Apoptosis was evidenced by the results of the annexin V/propidium iodide (PI) assay and the occurrence of a sub-G1 peak. In addition, AA-I and AL-I increased caspase 3-like activity in a concentration-dependent manner. These results also suggested that the cytotoxic potency of AL-I is higher than that of AA-I and that the cytotoxic effects of these molecules are mediated through the induction of apoptosis in a caspase 3-dependent pathway.

SELDI-TOF as a method for biomarker discovery in the urine of aristolochic-acid-treated mice

Aristolochic acids (AAs) present in Aristolochia plants are substances responsible for Chinese herbs nephropathy. Recently, strong indications have also been presented, which dietary poisoning with AA is responsible for endemic (Balkan) nephropathy (EN), an enigmatic renal disease that affects rural population living in some countries in Southeastern Europe. A mouse model was applied to follow the effects of two forms of AA, AAI and AAII. SDS-PAGE and SELDI-TOF mass spectrometry with normal phase chips were used to evaluate changes in the urine of treated animals. These two methods are demonstrated to be comparable. The use of SELDI-TOF MS for rapid analysis of a large number of samples and the combination of this method with nano-LC-ESI MS/MS for protein identification were demonstrated. Biomarker discovery after analysis of large cohort of EN patients will be the final aim of these investigations.

Increased mortality risk for cancers of the kidney and other urinary organs among Chinese herbalists

BACKGROUND

A national survey in Taiwan has shown that Chinese herbal therapy increases the risk of chronic kidney disease. However, it is unknown whether herbal therapy will increase the risk of urological cancers. The purpose of this study was to determine whether Chinese herbalists are at higher risk for urological cancers.

METHODS

We studied all Chinese herbalists in Taiwan that were registered in the Chinese Herbalist Labor Union between 1985 and 2000. We retrospectively followed their survival status and causes of death using the National Mortality Registry Database from 1985 to 2004. Standardized mortality ratios (SMRs) for urological cancers in herbalists were calculated and compared with those of the general population of Taiwan.

RESULTS

A total of 6548 Chinese herbalists were enrolled and 88,289 person-years were accrued during the observation period. After adjustment for age and sex, the SMR for urological cancers was significantly higher for Chinese herbalists than for the general population (SMR = 3.10; 95% CI: 1.41-5.87). When further stratified by location, the SMR for kidney cancer and other urinary organ cancers (SMR = 3.81; 95% CI: 1.39-8.28) except bladder cancer (SMR = 2.26; 95% CI: 0.47-6.59) were significantly higher for the Chinese herbalists. The SMR for chronic and unspecified nephritis, renal failure, and renal sclerosis were also significantly higher for herbalists (SMR = 2.40; 95% CI: 1.40-3.84).

CONCLUSIONS

Chinese herbalists have a significantly higher risk for urological cancers. This increased risk among herbalists highlights the urgent need for safety assessments of Chinese herbs.

Authentication of Radix Aucklandiae and its substitutes by GC-MS and hierarchical clustering analysis

Radix Aucklandiae (Muxiang in Chinese), the dried root of Aucklandia lappa, is used as a medicinal material for digestive system disorders in traditional Chinese medicine for centuries. Owing to the similarity of morphologies and trade names, Radix Vladimiriae (Chuan-Muxiang), the roots of Vladimiria souliei and V. souliei var. cinerea, and Radix Inulae (Tu-Muxiang), the roots of Inula helenium and Inula racemosa, as well as the renal toxic aristolochic acid containing Radix Aristolochiae (Qing-Muxiang), the roots of Aristolochia debilis and Aristolochia contorta, are often used confusedly as the substitutes of Radix Aucklandiae. In order to ensure the effective and safe utility of Radix Aucklandiae, a GC-MS method was developed to generate the chemical profiles of essential oils of Radix Aucklandiae and its substitutes. In addition, hierarchical clustering analysis was used to compare the similarities of these chemical profiles. It was found that all the samples of A. lappa have similar chemical profiles and were clustered into one group, while the samples of Radix Vladimiriae, Radix Inulae, and Radix Aristolochiae were clustered into their own independent groups, respectively, suggesting that together with hierarchical clustering analysis, chemical profiles of essential oils generated by GC-MS could objectively discriminate Radix Aucklandiae from its common substitutes.

A sensitivity enhanced high-performance liquid chromatography fluorescence method for the detection of nephrotoxic and carcinogenic aristolochic acid in herbal medicines

A new, sensitive and selective HPLC method with fluorescence detector (HPLC-FLD) for the determination of nephrotoxic and carcinogenic aristolochic acid (AA) in herbal medicines by using pre-column derivatization with zinc powder in acetic acid is presented. Variables governing the derivatization reaction, such as the amount of zinc powder and acetic acid, as well as the derivatization time were studied and optimized. An extended linear dynamic range over three orders of magnitude was observed for AA-I and AA-II (R(2)>0.9998). Method accuracy at low, medium and high spiked AA levels determined by the percentage mean deviation was below 4.4% and 7.2% for AA-I and AA-II, respectively. The detection limits of 0.39 ng/mL (AA-I) and 0.52 ng/mL (AA-II) were 2 orders of magnitude lower than those obtained from HPLC-MS or CE-ECD analyses, 3-4 orders of magnitude lower than those from HPLC-UV or CE-UV methods. The developed method has been applied for the determination of AA in herbal medicines. Among the tested samples, Guanmutong had the highest AA concentration (2607.0 microg/g AA-I, 711.2 microg/g AA-II). Comparison studies between HPLC-FLD and HPLC-MS/MS demonstrated that the two methods gave similar quantitative results for the selected herb samples.

Characterization and determination of six aristolochic acids and three aristololactams in medicinal plants and their preparations by high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry

Aristolochic acid derivatives (AAs) and aristolactam derivatives (ALs) have been characterized by electrospray ionization mass spectrometry, and their fragmentation pathways are proposed. ALs exhibit a single ionization product [M+H]+, whereas AAs show multiple ionization products. By optimizing the chromatographic separation and mass spectrometric parameters, the precursor ions of the derivatives with the best responses were found, and the sensitivities in the determination of the nine derivatives were improved. Based on the investigation of ionization behaviour, a HPLC-DAD/ESI-MS (high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry) method has been developed for simultaneous analysis of nine derivatives, i.e., AA I, AA II, AA C, AA D, 7-OH AA I, aristolic acid I, AL AII, AL IIIa and AL IVa, in nine medicinal herbs and two preparations. The method appears to be suitable for safety assurance and quality control of commercially available samples with good selectivity and suitable sensitivity.