Pyrrolizidine Alkaloids in Tea (Camellia sinensis L.) from Weeds through Weed-Soil-Tea Transfer and Risk Assessment of Tea Intake.

Pyrrolizidine alkaloids (PAs) have been detected in tea and can threaten human health. However, the specific source of PAs in tea is still unclear. Here, 88 dried tea products collected from six major tea-producing areas in Anhui Province, China, were analyzed. The detection frequency was 76%. The content of total PAs in dried tea was between 1.1 and 90.5 µg/kg, which was all below the MRL recommended by the European Union (150 µg/kg). In the Shexian tea garden, PAs in the weeds and weed rhizospheric soil around tea plants and the fresh tea leaves were analyzed. Intermedine (Im), intermedine-N-oxide (ImNO), and jacobine-N-oxide (JbNO) were transferred through the weed-to-soil-to-tea route into the fresh tea leaves; only Im and ImNO were detected in dried tea samples. Potential risk of the total PAs in the tea infusion was assessed according to the margin of exposure method, and it might be a low concern for public health.

Species difference in toxicokinetics and safety assessment of senecionine N-oxide in a UDP-glucuronosyltransferase 1A4 humanized mouse model.

Pyrrolizidine alkaloids (PAs) are naturally occurring hepatotoxins, and herbs containing PAs are of high concern. PAs are normally found in tertiary amines and N-oxide forms (PA N-oxides), yet the latter are less evaluated for their toxicokinetics. As a continuation of our investigation into the safety assessment of PA-containing herbal medicines, the toxicity and toxicokinetic characteristics of senecionine N-oxide (a representative toxic PA N-oxide) were investigated by using the UDP-glucuronosyltransferase 1A4 humanized mouse model (hUGT1A4 mouse model) and compared with those in wild-type mice simultaneously. Results show that the toxicity caused by senecionine N-oxide exposure was evidently decreased in hUGT1A4 mice as approved by pathology and biochemistry assays. In addition, a N-glucuronidation conjugate was exclusively found in hUGT1A4 mice but not in wild-type (WT) mice. In vitro studies proved that senecionine N-oxide initially reduced to the corresponding tertiary amine alkaloid (senecionine) and then underwent N-glucuronidation via human UGT1A4. The variation in toxicokinetic characteristics was also observed between hUGT1A4 mice and WT mice with a notably enhanced clearance of senecionine N-oxide and senecionine, and accordingly less formation of pyrrole-protein adducts in hUGT1A4 mice, which finally led to the detoxification of senecionine N-oxide exposure in hUGT1A4 mice. Our results provided the first in vivo toxicity data and toxicokinetic characteristics of senecionine N-oxide in a humanized animal model and revealed that human UGT1A4 plays an important role in the detoxification of senecionine N-oxide.

Risk assessment of short-term intake of pyrrolizidine alkaloids in food: derivation of an acute reference dose.

Pyrrolizidine alkaloids (PA) are phytochemicals that are known to act as human hepatotoxins and are also considered to be genotoxic carcinogens. Several plant-derived foods are frequently contaminated with PA, like teas and herbal infusions, spices and herbs or certain food supplements. With respect to the chronic toxicity of PA, the carcinogenic potential of PA is generally regarded as the critical toxicological effect. The risk assessment of the short-term toxicity of PA, however, is internationally less consistent. The characteristic pathological syndrome of acute PA toxicity is hepatic veno-occlusive disease. High PA exposure levels may lead to liver failure and even death as documented by several case reports. In the present report, we suggest a risk assessment approach for the derivation of an acute reference dose (ARfD) for PA of 1 µg/kg body weight per day based on a sub-acute animal toxicity study in rats after oral PA administration. The derived ARfD value is further supported by several case reports describing acute human poisoning following accidental PA intake. The here derived ARfD value may be used for PA risk assessment in cases where the short-term toxicity of PA is of interest in addition to the assessment of the long-term risks.

Effect of Adulteration on Quality and Preliminary Risk Assessment of the Decoction Pieces of Farfarae Flos Based on the Determination of Hepatotoxic Pyrrolizidine Alkaloids by UHPLC-MS/MS.

BACKGROUND: Farfarae Flos (FF) is a frequently used traditional herbal medicine with outstanding antitussive actions. The adulteration of FF decoction pieces is common. OBJECTIVE: This study aimed to study the effect of adulteration on the safety and quality of FF decoction pieces. METHODS: The proportion of impurities was conducted by cone quartering method. A simple and accurate ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was established to simultaneous determinate three pyrrolizidine alkaloids (PAs) as endogenous toxic compounds in FF. The traditional medicinal parts (flower bud), impurities (pedicel and rhizome) and unselected samples were determined respectively. The values of estimated daily intake (EDI) and margin of exposure (MOE) were used for risk assessment. RESULTS: Twenty batches of samples were collected from different habitats, and the proportion of impurities ranged from 17.51% to 41.27%. Pedicel and rhizome were the main impurities, accounting for more than 87.40% of the total impurities. The content of PAs in impurities was significantly higher. The EDI value range was 5.34 to 16.59 µg/kg bw/day, which was much higher than the standard safety value of 7.00 × 10-3 µg/kg bw/day. The MOE values ranges for life long time and shorter exposure were 14.29 to 44.37 and 371.53 to 1153.63, respectively, indicating that at least 80% of the samples had safety risks. Correlation analysis showed that the proportion of adulterated impurities had significant correlation with the values of EDI and MOE. CONCLUSIONS: Adulteration of non medicinal parts may significantly increase the risk of medications of FF decoction pieces. HIGHLIGHTS: This study provides an efficient methodology reference for the control of PAs and a basis for adulteration to affect the safety and quality of FF decoction pieces.

Assessment of Distribution and Diversity of Pyrrolizidine Alkaloids in the Most Prevalent Boraginaceae Species in Macedonia.

Systematic study of extraction efficiency of pyrrolizidine alkaloids (PAs) and corresponding pyrrolizidine alkaloid N-oxides (PANOs) from plant material for subsequent LC/MS analysis was carried out. The optimal extraction was achieved with methanol and one clean up step using SPE C18 column. With the optimized LC-ESI-MS/MS method using ion trap, the distribution and diversity of PAs and PANOs in plant material (leaves, flowers and stems) obtained from wild-growing E. vulgare, E. italicum, S. officinale L., C. creticum and O. heterophylla species from Macedonia was assessed. These widespread Boraginaceae species contain various PAs and PANOs and 25 of them were identified. Based on these qualitative and quantitative analyses, the profiles of 1,2-unsaturated PAs for each sample were obtained and their toxic potential was estimated. The toxic potential of O. heterophylla and C. creticum were assumed to be highest (containing up to 4753 mg/kg and 3507 mg/kg), followed by E. vulgare (up to 1340 mg/kg), S. officinale L. (up to 479 mg/kg) and E. italicum (up to 16 mg/kg). This method can be used for monitoring the inclusion of these secondary metabolites in the food chain in order to contribute in their risk management.

Detection, dietary exposure assessment and risk evaluation of quinolones and pyrrolizidine alkaloids in commercial honey from Brazil.

Pyrrolizidine alkaloids are secondary plant metabolites that have already been designated as a potential health risk due to their toxicity. Quinolones are antimicrobials related to bacterial resistance, one of the world's largest contemporary public health problems. This study searched for 22 pyrrolizidine alkaloids and 7 quinolones in honey available for sale in the state of Rio de Janeiro - Brazil - employing an analytical method based on LC-Q-TOF-HRMS. No quinolones were identified, while pyrrolizidine alkaloids were found in 39 out of 80 samples, mainly erucifoline (detected in 17% of the samples) and intermedine/lycopsamine (quantified in 27% of the samples). Considering the highest value found, 141.8 µg kg-1 for senecionine and a consumption of 20 g of honey per person per day, the dietary exposure reached 47.3 ng kg-1, resulting in a MOE value of 5.010, that might lead to a risk for human health.

Support for Regulatory Assessment of Percutaneous Absorption of Retronecine-type Pyrrolizidine Alkaloids through Human Skin.

1,2-unsaturated pyrrolizidine alkaloids are found naturally in Symphytum officinale, well known as comfrey, which has a longstanding use for the topical treatment of painful muscle and joint complaints. Pyrrolizidine alkaloids (PA) are a relevant concern for the safety assessment due to their liver genotoxicity profile, and close attention is paid during manufacturing to minimizing their levels. Current regulatory risk assessment approaches include setting limits that derive from toxicity data coming from the oral route of exposure. This study investigated to what extent pyrrolizidine alkaloids are bioavailable following topical exposure, assessing penetration of retronecine-type PAs in an in vitro human skin model. A single comfrey root formulation was spiked with 3 different congeners (a 7R-monoester, an open-chained 7R-diester, and a cyclic diester) and percutaneous absorption measured per OECD guidelines and good laboratory practices. The measured penetration for all 3 PAs was low and compared favourably with existing in vitro data. Although consideration of different regulatory guidance influences the determination of dermally absorbed dose, these data facilitate the understanding of absorption differences following topical exposure, which in turn can be taken into account in the risk assessment.

Novel Insights into Pyrrolizidine Alkaloid Toxicity and Implications for Risk Assessment: Occurrence, Genotoxicity, Toxicokinetics, Risk Assessment-A Workshop Report.

This paper reports on the major contributions and results of the 2nd International Workshop of Pyrrolizidine Alkaloids held in September 2020 in Kaiserslautern, Germany. Pyrrolizidine alkaloids are among the most relevant plant toxins contaminating food, feed, and medicinal products of plant origin. Hundreds of PA congeners with widespread occurrence are known, and thousands of plants are assumed to contain PAs. Due to certain PAs' pronounced liver toxicity and carcinogenicity, their occurrence in food, feed, and phytomedicines has raised serious human health concerns. This is particularly true for herbal teas, certain food supplements, honey, and certain phytomedicinal drugs. Due to the limited availability of animal data, broader use of in vitro data appears warranted to improve the risk assessment of a large number of relevant, 1,2-unsaturated PAs. This is true, for example, for the derivation of both toxicokinetic and toxicodynamic data. These efforts aim to understand better the modes of action, uptake, metabolism, elimination, toxicity, and genotoxicity of PAs to enable a detailed dose-response analysis and ultimately quantify differing toxic potencies between relevant PAs. Accordingly, risk-limiting measures comprising production, marketing, and regulation of food, feed, and medicinal products are discussed.

Characterization and Lifetime Dietary Risk Assessment of Eighteen Pyrrolizidine Alkaloids and Pyrrolizidine Alkaloid N-Oxides in New Zealand Honey.

Pyrrolizidine alkaloids (PAs) are a large group of botanical toxins of concern, as they are considered genotoxic carcinogens, with long-term dietary exposure presenting an elevated risk of liver cancer. PAs can contaminate honey through honeybees visiting the flowers of PA-containing plant species. A program of monitoring New Zealand honey has been undertaken over several years to build a comprehensive dataset on the concentration, regional and seasonal distribution, and botanical origin of 18 PAs and PA N-oxides. A bespoke probabilistic exposure model has then been used to assess the averaged lifetime dietary risk to honey consumers, with exposures at each percentile of the model characterized for risk using a margin of exposure from the Joint World Health Organization and United Nations Food and Agriculture Organization Expert Committee on Food Additives (JECFA) Benchmark Dose. Survey findings identify the typical PA types for New Zealand honey as lycopsamine, echimidine, retrorsine and senecionine. Regional and seasonal variation is evident in the types and levels of total PAs, linked to the ranges and flowering times of certain plants. Over a lifetime basis, the average exposure an individual will receive through honey consumption is considered within tolerable levels, although there are uncertainties over high and brand-loyal consumers, and other dietary contributors. An average lifetime risk to the general population from PAs in honey is not expected. However, given the uncertainties in the assessment, risk management approaches to limit or reduce exposures through honey are still of value.

Determination of Toxic Pyrrolizidine Alkaloids in Traditional Chinese Herbal Medicines by UPLC-MS/MS and Accompanying Risk Assessment for Human Health.

Pyrrolizidine alkaloids (PAs) are a class of natural toxins with hepatotoxicity, genotoxicity and carcinogenicity. They are endogenous and adulterated toxic components widely found in food and herbal products. In this study, a sensitive and efficient ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was used to detect the PAs in 386 kinds of Chinese herbal medicines recorded in the Chinese Pharmacopoeia (2020). The estimated daily intake (EDI) of 0.007 µg/kg body weight (bw)/day was adopted as the safety baseline. The margin of exposure (MOE) approach was applied to evaluate the chronic exposure risk for the genotoxic and carcinogenic potential of PAs. Results showed that PAs was detected in 271 out of 386 samples with a content of 0.1-25,567.4 µg/kg, and there were 20 samples with EDI values above the baseline, 0.007 µg/kg bw/day. Beyond that, the MOE values for 10 out of 271 positive samples were below 10,000. Considering the actual situation, Haber's rule was used to assume two weeks exposure every year during lifetime, and still the MOE values for four out of 271 positive samples were under 10,000, indicating these products may have potential health risk. The developed method was successfully applied to detect the PAs-containing Chinese herbal medicines. This study provides convincing data that can support risk management actions in China and a meaningful reference for the rational and safe use of Chinese herbal medicines.

Quantitative CT assessment by histogram and volume ratio in pyrrolizidines alkaloids-induced hepatic sinusoidal obstruction syndrome.

OBJECTIVE: To quantitatively assess hypoattenuation volume ratio and hepatic parenchymal hypoattenuation on contrast enhanced computed tomography (CECT) in patients with pyrrolizidines alkaloids (PAs)-induced hepatic sinusoidal obstruction syndrome (HSOS), and evaluate the correlations of the CT-based quantitative values with clinical factors. METHODS: Thirty-five patients with PAs-induced HSOS who underwent CECT were retrospectively enrolled. The ratio of hypoattenuation volume to total liver volume, and changes in damaged area-to-normal liver density ratio (ΔDR) derived from histogram on portal venous phase were quantitatively measured. Heterogeneous hypoattenuation (CT score) scored by hypoattenuation volume ratio and ΔDR were calculated. The correlation between imaging findings and clinical factors was analyzed using Pearson correlation test. RESULTS: Liver function tests were abnormal in most patients, the mean Hounsfield unit (HU) of damaged area (58.68 ± 17.3) was significantly lower (P < 0.001) than the corresponding normal liver (82.27 ± 23.97). Heterogeneous hypoattenuation were mild in 13 patients (37 %), moderate in 16 patients (46 %), and severe in 6 patients (17 %). ΔDR derived from histogram was positively correlated (weakly to moderately) with total bilirubin (r = 0.341, P = 0.045), direct bilirubin (r = 0.385, P = 0.022), and alkaline phosphatase (r = 0.491, P = 0.003), while such correlation was not observed in hypoattenuation volume ratio. The severity of heterogeneous hypoattenuation scored by hypoattenuation volume ratio and ΔDR was positively correlated (weakly) with prothrombin time (r = 0.357, P = 0.035), international normalized ratio (r = 0.363, P = 0.032), alkaline phosphatase (r = 0.359, P = 0.034), and model for end-stage liver disease (MELD) score (r = 0.347, P = 0.041). CONCLUSION: Heterogeneous hypoattenuation scored by volume ratio and ΔDR on CECT provides a non-invasive approach in evaluating the severity of PAs-induced HSOS.

Comparative Risk Assessment of Three Native Heliotropium Species in Israel.

Pyrrolizidine alkaloids (PAs) are genotoxic carcinogenic phytotoxins mostly prevalent in the Boraginaceae, Asteraceae and Fabaceae families. Heliotropium species (Boraginaceae) are PA-producing weeds, widely distributed in the Mediterranean region, that have been implicated with lethal intoxications in livestock and humans. In Israel, H. europaeum, H. rotundifolium and H. suaveolens are the most prevalent species. The toxicity of PA-producing plants depends on the PA concentration and composition. PAs occur in plants as mixtures of dozens of various PA congeners. Hence, the risk arising from simultaneous exposure to different congeners has to be evaluated. The comparative risk evaluation of the three Heliotropium species was based on recently proposed interim relative potency (iREP) factors, which take into account certain structural features as well as in vitro and in vivo toxicity data obtained for several PAs of different classes. The aim of the present study was to determine the PA profile of the major organ parts of H. europaeum, H. rotundifolium and H. suaveolens in order to assess the plants' relative toxic potential by utilizing the iREP concept. In total, 31 different PAs were found, among which 20 PAs were described for the first time for H. rotundifolium and H. suaveolens. The most prominent PAs were heliotrine-N-oxide, europine-N-oxide and lasiocarpine-N-oxide. Europine-N-oxide displayed significant differences among the three species. The PA levels ranged between 0.5 and 5% of the dry weight. The flowers of the three species were rich in PAs, while the PA content in the root and flowers of H. europaeum was higher than that of the other species. H. europaeum was found to pose a higher risk to mammals than H. rotundifolium, whereas no differences were found between H. europaeum and H. suaveolens as well as H. suaveolens and H. rotundifolium.

In vitro biotransformation of pyrrolizidine alkaloids in different species: part II-identification and quantitative assessment of the metabolite profile of six structurally different pyrrolizidine alkaloids.

Pyrrolizidine alkaloids (PA) exert their toxic effects only after bioactivation. Although their toxicity has already been studied and metabolic pathways including important metabolites were described, the quantification of the latter revealed a large unknown portion of the metabolized PA. In this study, the qualitative and quantitative metabolite profiles of structurally different PAs in rat and human liver microsomes were investigated. Between five metabolites for europine and up to 48 metabolites for lasiocarpine were detected. Proposals for the chemical structure of each metabolite were derived based on fragmentation patterns using high-resolution mass spectrometry. The metabolite profiles of the diester PAs showed a relatively good agreement between both species. The metabolic reactions were summarized into three groups: dehydrogenation, oxygenation, and shortening of necic acid(s). While dehydrogenation of the necine base is considered as bioactivation, both other routes are considered as detoxification steps. The most abundant changes found for open chained diesters were dealkylations, while the major metabolic pathway for cyclic diesters was oxygenation especially at the nitrogen atom. In addition, all diester PAs formed several dehydrogenation products, via the insertion of a second double bond in the necine base, including the formation of glutathione conjugates. In rat liver microsomes, all investigated PAs formed dehydropyrrolizidine metabolites with the highest amount formed by lasiocarpine, whereas in human liver microsomes, these metabolites could only be detected for diesters. Our findings demonstrate that an extensive analysis of PA metabolism can provide the basis for a better understanding of PA toxicity and support future risk assessment.

Radioiodination and in vivo assessment of the potential of newly synthesized pyrrolizine-5-carboxamides derivative in tumor model.

Recently, pyrrolizine derivatives have been reported to possess numerous anticancer activities. In a previous study, (EZ)-6-((4-chlorobenzylidene)-amino)-7-cyano-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine carboxamide (EZPCA) compound was synthesized and the cytotoxic activity of EZPCA toward COX-2 enzyme (overexpressed in cancer cells) was reported. In order to assess the suitability of this compound as a promising pilot structure for in vivo applications, EZPCA was radiolabeled with radioiodine-131 (131I) and various factors affecting radiolabeling process were studied. Quality control studies of [131I]iodo-EZPCA were performed using paper chromatography and HPLC was used as a co-chromatographic technique for confirming the radiochemical yield. Biodistribution studies of [131I]iodo-EZPCA were undertaken in normal and tumor bearing mice. The radiochemical yield percentage of [131I]iodo-EZPCA was 94.20 ± 0.12%. The biodistribution results showed evident tumor uptake of [131I]iodo-EZPCA with promising target/non-target (T/NT) ratios. As a conclusion, these data suggest that [131I]iodo-EZPCA had high binding efficiency, high tumor uptake and sufficient stability to be used be used in diagnostic studies.

Spread of Jacobaea vulgaris and Occurrence of Pyrrolizidine Alkaloids in Regionally Produced Honeys from Northern Germany: Inter- and Intra-Site Variations and Risk Assessment for Special Consumer Groups.

Pyrrolizidine alkaloids (PA) and PA N-oxides (PANO) are secondary plant metabolites exhibiting genotoxic and carcinogenic properties. Apart from the roots and leaves, PA/PANO are particularly present in pollen and nectar. Therefore, the spread of Jacobaea vulgaris in certain regions of northern Germany has an impact on the safety of honey produced in that region. In this study, raw honey samples (n = 437) were collected from usually three individual beehives per site (n = 73) in the district of Ostholstein and analyzed for 25 PA/PANO. The results reveal mean levels of 8.4, 1.5, and 72.6 µg/kg and maximum levels of 111, 59.4, and 3313 µg/kg, depending on the season (summer 2015 and spring/summer 2016, respectively). As far as individual data are concerned, sites near areas with J. vulgaris growth did not necessarily result in high PA/PANO values. Furthermore, intra-site investigations revealed remarkable differences in PA/PANO levels of raw honey collected by different bee colonies at the same site. Consumption of these regionally produced honeys entails an increased exposure to PA/PANO, especially in children and high consumers. Margin of exposure values of <10,000 and an exceedance of the health-based guidance value highlight that regionally produced and marketed honey must be considered with care for a proper risk assessment and risk management.

Occurrence and Risk Assessment of Pyrrolizidine Alkaloids in Spices and Culinary Herbs from Various Geographical Origins.

Pyrrolizidine alkaloids (PA) and their N­oxides (PANO) are a group of toxic secondary plant metabolites occurring predominantly as contaminants in (herbal) teas, honeys and food supplements, as well as in spices and culinary herbs. Depending on the botanical origin of the contaminating plant, the pattern of PA/PANO can strongly vary within a sample. The current study aimed to broaden the existing data on the occurrence of PA/PANO in spices and culinary herbs. For this, 305 authentic samples covering 15 different matrices mainly harvested in 2016 or 2017 and originating from 36 countries were investigated for the presence of 44 PA/PANO. Fifty-eight percent of the samples contained at least one PA/PANO. The average sum content over all samples was 323 µg/kg (median of 0.9 µg/kg, 95% percentile of 665 µg/kg). The highest amount of 24.6 mg/kg was detected in an oregano sample. Additionally, conspicuous analyte patterns were discovered in samples from similar cultivation regions, indicating related botanical sources of PA/PANO contaminations. Particularly, oregano and cumin from Turkey often contained high amounts of PA/PANO. The results were used to assess the acute and chronic health risks related to PA/PANO intake via spices and culinary herbs, indicating a potential health risk in particular for adults and children with high consumption or when considering worst­case contamination scenarios of a sum content of 5500 µg/kg.

Detection of pyrrolizidine alkaloids in jamu available on the Indonesian market and accompanying safety assessment for human consumption.

The occurrence and accompanying risks of pyrrolizidine alkaloids (PAs) in Indonesian jamu were evaluated. PAs were detected in 34 out of 35 jamu containing PA-producing botanicals, in the range of 12.3-235,376 µg/kg. A total PA level of 5.9-3,421 µg/kg was found in 17 out of 23 jamu made of non-PA-producing botanicals pointing to contamination with PA-producing plants. Short-time consumption of jamu is unlikely to result in acute toxic effects, although one sample would exceed an intake of 10 µg PA/kg bw/day which may cause hepatic veno-occlusive disease (HVOD) in humans. The risk assessment for the genotoxic and carcinogenic potential of PAs revealed Margin of Exposure (MOE) values below 10,000 for 27 out of all samples analysed (46.6%), indicating a priority for risk management when assuming daily lifelong consumption. Assuming consumption for two weeks every year during a lifetime, and using Haber's rule, 13 out of 35 jamu samples containing PA-producing botanicals (37%) still pose a priority, while the jamu consisting of non-PA-producing botanicals would be of low priority (MOE>10,000). This study provides data that can support risk management actions in Indonesia to minimize the potential health risk for jamu consumers due to the occurrence of toxic PAs in these products.

Pyrrolizidine alkaloids in food and phytomedicine: Occurrence, exposure, toxicity, mechanisms, and risk assessment - A review.

Among naturally occurring plant constituents, the 1,2-unsaturated pyrrolizidine alkaloids (in the following termed 'PAs') play a distinct role because of the large number of congeners occurring in nature and the pronounced toxicity of some congeners. Several PAs are hepatotoxic in humans, experimental and farm animals and were shown to be potent hepatocarcinogens in laboratory rodents. Although the general mode of action leading to toxicity has been elucidated, i.e., being mediated by metabolic conversion of the parent molecule into a highly reactive electrophile capable of attacking cellular target molecules, major questions related to the risk assessment of PAs remain unresolved. It was the aim of a workshop held in September 2018 to shed more light on the occurrence, exposure, mode of action, toxicokinetics and -dynamics of PAs to improve the scientific basis for an advanced toxicological risk assessment. The contributions in nine chapters describe the scientific progress using advanced analytical methods, studies in subcellular fractions, cell culture, experimental animals and humans and the use of PBPK modeling and structure-activity relationship considerations aiming at a better understanding of PA toxicity and genotoxicity. Since PAs differ considerably in their toxic potencies and substantial species differences in sensitivity towards PA exposure exist, a special emphasis was placed on these issues.

Integrating physiologically based kinetic (PBK) and Monte Carlo modelling to predict inter-individual and inter-ethnic variation in bioactivation and liver toxicity of lasiocarpine.

The aim of the present study was to predict the effect of inter-individual and inter-ethnic human kinetic variation on the sensitivity towards acute liver toxicity of lasiocarpine in the Chinese and the Caucasian population, and to derive chemical specific adjustment factors (CSAFs) by integrating variation in the in vitro kinetic constants Vmax and Km, physiologically based kinetic (PBK) modelling and Monte Carlo simulation. CSAFs were derived covering the 90th and 99th percentile of the population distribution of pyrrole glutathione adduct (7-GS-DHP) formation, reflecting bioactivation. The results revealed that in the Chinese population, as compared to the Caucasian population, the predicted 7-GS-DHP formation at the geometric mean, the 90th and the 99th percentile were 2.1-, 3.3- and 4.3-fold lower respectively. The CSAFs obtained using the 99th percentile values were 8.3, 17.0 and 19.5 in the Chinese, the Caucasian population and the two populations combined, respectively, while the CSAFs were generally 3.0-fold lower at the 90th percentile. These results indicate that when considering the formation of 7-GS-DHP the Caucasian population may be more sensitive towards acute liver toxicity of lasiocarpine, and further point out that the default safety factor of 3.16 for inter-individual human kinetic differences may not be sufficiently protective. Altogether, the results obtained demonstrate that integrating PBK modelling with Monte Carlo simulations using human in vitro data is a powerful strategy to quantify inter-individual variations in kinetics, and can be used to refine the human risk assessment of pyrrolizidine alkaloids.

Review: Quality of herbal medicinal products: State of the art of purity assessment.

BACKGROUND: The European Pharmacopoeia as well as further legal provisions contain rules for the assessment of potential residues and contaminants in herbal substances and preparations used for the production of herbal medicinal products, e.g. for the assessment of pesticide residues, heavy metals and other elemental impurities, mycotoxins and microorganisms. As a potential contamination caused by weeds, the occurrence of pyrrolizidine alkaloids is being discussed for several years which lead to measures of health authorities limiting the PA content in herbal medicinal products and to measures of industry consisting of reducing the probability of PA occurrence in medicinal plants and the respective products. CONCLUSION: In this context and with regard to all kinds of potential residues or contaminants, collection and evaluation of data from daily analytical practice of manufacturers and suppliers is useful for the assessment of the situation and the definition of testing strategies.