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

Long-term toxicity evaluation of aristolochic acid-IIIa in mice

Aristolochic acid (AA)-IIIa is an AA analog present in Aristolochiaceae plants. To evaluate the chronic toxicity of AA-IIIa, mice were intragastrically administered with media control, 1 mg/kg AA-IIIa, and 10 mg/kg AA-IIIa, and designated as the control (CTL), AA-IIIa low dose (AA-IIIa-L), and AA-IIIa high dose (AA-IIIa-H) groups, respectively. AA-IIIa was administered three times a week, every other day, for 24 weeks (24-week time point). Thereafter, some mice were sacrificed immediately, while others were sacrificed 29 or 50 weeks after AA-IIIa withdrawal (53- or 74-week time point). Serum and organs were collected for biochemical and pathological analyses, respectively. Whole-genome sequencing was performed on the kidney, liver, and stomach tissues of AA-IIIa-treated mice for single-nucleotide polymorphism (SNP) detection. AA-IIIa-H mice died at 66 weeks, and the remaining mice showed moribund conditions at the 69 weeks. AA-IIIa induced minor kidney tubule injury, fibroblast hyperplasia, and forestomach carcinoma in mice. Bladder, intestine, liver, heart, spleen, lung, and testis tissues were not pathologically altered by AA-IIIa. In addition, AA-IIIa increased the C:G > A:T mutation in the kidney; however, no SNP mutation changes were observed in the liver and forestomach tissues of AA-IIIa-H mice at the 24-week time point compared with control mice. Therefore, we suspect that AA-IIIa is potentially mutagenic for mice after overdose and long-term administration. On the other hand, the forestomach is a unique organ in mice, but it does not exist in humans; thus, we hypothesize that the stomach toxicity induced by AA-IIIa is not a suitable reference for toxicological evaluation in humans. We recommend that Aristolochiaceae plants containing AA-IIIa should be properly supervised, and overdosing and long-term administration of drugs containing AA-IIIa should be avoided.

Rapid simultaneous determination of thirteen aristolochic acids analogs in Aristolochiaceae plants by Ultra-High-Performance liquid Chromatography- tandem mass spectrometry in dynamic multiple reaction monitoring mode

Asarum and Aristolochia are two large genera of Aristolochiaceae plants containing typical toxicant aristolochic acid analogs(AAAs), AAAs can be deemed as toxicity markers of Aristolochiaceae plants. Based on the least AAAs in dry roots and rhizomes of Asarum heterotropoides, Asarum sieboldii Miq and Asarum sieboldii var, all of which are enrolled in the Chinese pharmacopeia up to now. AAAs distribution in Aristolochiaceae plants, especially Asarum L. plants, is still obscure and controversial due to few AAAs measured, unverified species of Asarum, and complicated pretreatment in analytical samples making the results more challenging to reproduce. In the present study, a simple ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method in dynamic multiple reaction monitoring mode for simultaneous determination of thirteen AAAs was developed for evaluating the distribution of toxicity phytochemicals in Aristolochiaceae plants. The sample was prepared by extracting Asarum and Aristolochia powder with methanol, and the supernatant was analyzed using the Agilent 6410 system on an ACQUITY UPLC HSS PFP column with gradient elution of water and acetonitrile, containing 1% v/v formic acid (FA) each, at a flow rate of 0.3 mL/min. The chromatographic condition provided good peak shape and resolution. The method was linear over the specific ranges with the coefficient of determination (R²) > 0.990. Satisfactory intra- and inter-day precisions were achieved with RSD less than 9.79%, and the average recovery factors obtained were in the range of 88.50%～105.49%%. The proposed method was successfully applied for simultaneous quantification of the 13 AAAs in 19 samples from 5 Aristolochiaceae species, especially three Asarum L. species enrolled in the Chinese Pharmacopoeia. Except Asarum heterotropoides, the results supported that the Chinese Pharmacopoeia (2020 Edition) adopting the root with rhizome as medicinal parts of Herba Asari instead of the whole herb for drug safety by providing scientific data.

Quantitative Determination and Toxicity Evaluation of Aristolochic Acid Analogues in Asarum heterotropoides F. Schmidt (Xixin) and Traditional Chinese Patent Medicines

Asarum (Xixin), which contains analogues of aristolochic acid (AA), is the only species of the genus Aristolochia included in the Chinese Pharmacopoeia 2020. However, the contents and nephrotoxic effects of AA analogs in Asarum (Xixin) and its formulations have not been clarified. An automatic, effective solid phase extraction process and UPLC-MS/MS method were established for the pretreatment and quantitative detection of AA analogues in commercially available traditional Chinese patent medicines. The cytotoxicity and DNA damage induced by five analogues of AA were evaluated by CCK8 using human kidney cells (HK-2) and comet assays. HPLC was used to detect the analogues of AA in Asarum heterotropoides F. Schmidt (Xixin). The results showed that the contents of AA I, AA II, and AA IIIa were below the detection limit, while AA IVa and AL I presented relatively high contents of Asarum heterotropoides F. Schmidt (Xixin), within the range of 66.50–121.03 μg/g and 19.73–43.75 μg/g, respectively. The levels of AA analogues were in the nanogram-per-gram level in the main traditional Chinese patent medicines. AA I and AL I exhibited relatively high cytotoxicity at 48 h in CCK8 assays, while AA II, AA IIIa, and AA IVa showed weak cytotoxicity even at 800–1,000 μM. AA I induced significant pathological alterations and direct DNA damage at 40 mg/kg and 20 mg/kg, respectively. No distinct nephrotoxicity or hepatotoxicity was observed in mice treated with AA II, AA IIIa, AA IVa, or AL I at 40 mg/kg in this study. Consumption of Asarum heterotropoides F. Schmidt (Xixin) with controlled doses and periods is relatively safe as the contents of AA analogues in Asarum heterotropoides F. Schmidt (Xixin) and its formulations were far below those causing acute toxicity in this study. But, the long-term toxicity of Asarum heterotropoides F. Schmidt (Xixin) still needs further study.

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.

An Overview on Analytical Methods for Quantitative Determination of Aristolochic Acids

Background:

Aristolochic acids are chemically linked to nitrophenanthrene carboxylic acids which are found in aristolochia plants. These compounds are intrinsically carcinogenic, while they have been used in traditional medicine from a long time ago. Despite the beneficial effects of herbals for treating some diseases, they possess some side effects.

Methods:

Therefore, the development of a sensitive and selective procedure for the determination of these harmful components in various complicated samples is an important task for health systems and drug authorities. In the past years, ultra-pressure liquid chromatography, high performance liquid chromatography and capillary electrophoresis with different detection systems were used for determination of aristolochic acids in various samples.

Results:

In this review, different analytical methods have been discussed in brief and applications of them in diverse samples have been summarized.

Conclusion:

Different approaches are compared from point of sensitivity, selectivity, and extraction efficiency.

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.

Characterization and quantitation of aristolochic acid analogs in different parts of Aristolochiae Fructus, using UHPLC-Q/TOF-MS and UHPLC-QqQ-MS

Aristolochiae Fructus, a Chinese herbal medicine derived from the fruit of Aristolochia contorta Bge., contains nephrotoxic aristolochic acid analogues (AAAs). According to ancient medical texts, various medicinal parts of the fruit of A. contorta were ever used. In order to reveal which part could be safely and effectively used, it is necessary to analyze the chemical profiles of different medicinal parts. Herein we compared the chemical compositions and determined aristolochic acid I (AA-I) and aristolochic acid II (AA-II) in the four parts viz. outer pericarp, inner pericarp, septum, and seed. Ultra-high performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was applied for chemical profiling. Ultra-high performance liquid coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS) was employed to quantify AA-I and AA-II in different parts. It was found that the chemical compositions of the four parts varied both qualitatively and quantitatively. A total of 10 AAAs, including 5 aristolochic acids and 5 aristolactams, together with 3 alkaloids, were unambiguously or tentatively identified by UHPLC-QTOF-MS. The quantitatively analytical results obtained by UHPLC-QqQ-MS showed that AA-I and AA-II exclusively accumulate in the seeds of A. contorta. These findings provide supporting data for the rational selection of medicinal parts.

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.

Risk assessment of plant food supplements and other herbal products containing aristolochic acids using the margin of exposure (MOE) approach

After the incidences of induction of aristolochic acid nephropathy after consumption of herbal weight loss preparations that accidentally contained aristolochic acids (AAs), several countries defined national restrictions on the presence of AAs in food, including plant food supplements (PFS) and herbal products. This study investigates whether the risks associated with exposure to AAs via PFS and herbal products are at present indeed negligible. Data reported in literature on AA levels in PFS and other herbal products and also obtained from a new series of PFS in the present study were used to calculate the estimated daily intakes (EDIs) and corresponding margins of exposure (MOEs). Available literature data revealed that 206 out of 573 samples were found to contain aristolochic acid I (AAI) and/or aristolochic acid II (AAII). The results obtained from recently collected PFS revealed that both AAI and AAII were detected in three out of 18 analysed PFS at levels up to 594.8 and 235.3 µg g^-1, respectively, being in line with the levels reported in literature. The EDIs resulting from intake of these PFS resulted in MOEs that were generally below 10,000, corroborating the priority for risk management. Although these results refer to PFS collected by targeted sampling strategies, the data reveal that AA-containing PFS are still freely available. When considering that the use of these samples may be limited to shorter periods of time, the EDIs might be lower, but MOE values would still be lower than 10,000 for more than 50% of the AA-containing PFS and herbal products. In conclusion, the presence of AAs in PFS and herbal products even several years after instalment of the legal restrictions still raises concern, especially for people who frequently use the respective PFS and herbal products.