Mode of action of pulegone on the urinary bladder of F344 rats

Toxicity Potential of Nutraceuticals

During the past few decades and especially during and after the COVID-19 pandemic, the use of nutraceuticals has become increasingly popular in both humans and animals due to their easy access, cost-effectiveness, and tolerability with a wide margin of safety. While some nutraceuticals are safe, others have an inherent toxic potential. For a large number of nutraceuticals, no toxicity/safety data are available due to a lack of pharmacological/toxicological studies. The safety of some nutraceuticals can be compromised via contamination with toxic plants, metals, mycotoxins, pesticides, fertilizers, drugs of abuse, etc. Knowledge of pharmacokinetic/toxicokinetic studies and biomarkers of exposure, effect, and susceptibility appears to play a pivotal role in the safety and toxicity assessment of nutraceuticals. Interaction studies are essential to determine efficacy, safety, and toxicity when nutraceuticals and therapeutic drugs are used concomitantly or when polypharmacy is involved. This chapter describes various aspects of nutraceuticals, particularly their toxic potential, and the factors that influence their safety.

Risk Assessment of Pulegone in Foods Based on Benchmark Dose-Response Modeling

This study presents a new risk assessment of pulegone, a substance classified as possibly carcinogenic to humans (Group 2B) by the WHO International Agency for Research on Cancer (IARC). The analysis used data from a two-year carcinogenicity studies in rats and mice conducted by the National Toxicology Program (NTP) in 2011. Because of the absence of a no-observed adverse effect level (NOAEL) in these studies, the benchmark dose (BMD) approach was employed as an alternative risk assessment method. The lowest BMD lower confidence level (BMDL) of 4.8 mg/kg b.w./day among the eight endpoints served as the point of departure for calculating an acceptable daily intake (ADI) of 48 μg/kg b.w./day. This new ADI is significantly lower than the previously established tolerable daily intake of 0.1 mg/kg b.w./day set in 1997. The analysis also considered various genotoxicity studies, which indicate that pulegone's effects follow a nongenotoxic, thresholded mechanism. The estimated intake levels of pulegone in the European Union and USA were below the newly calculated ADI, suggesting a low health risk based on current consumption patterns.

Mentha Pulegium: A Plant with Several Medicinal Properties

The species Mentha Pulegium L. (M. pulegium L.) belongs to the family Lamiaceae, native to Europe, North Africa, and the Middle East, and the genus Mentha. It has been traditionally used in food, cosmetics, and medicines. It is a perennial, fragrant, well-liked, herbaceous plant that can grow up to half a meter tall. It is extensively used as a food flavoring, particularly for Moroccan traditional drinks. Chewing mint and M. pulegium, a relaxing and refreshing plant, can be used to treat hiccups and act as an anticonvulsant and nerve relaxant. Pennyroyal leaves that have been crushed have a pungent, spearmint-like scent. Pennyroyal is used to make herbal teas, which, while not proven to be harmful to healthy adults in small doses, are not recommended due to their liver toxicity. Infants and children can die if they consume it. Pennyroyal leaves, both fresh and dried, are particularly effective at repelling insects. Pennyroyal essential oil should never be taken internally because it is highly toxic, even in small doses, it can be fatal. This plant is used in traditional Moroccan medicine to treat a wide range of conditions, including influenza, rheumatism, migraine, infertility, ulcer, pain, gastrointestinal problems, fever, diabetes, obesity, mental and cardiac disorders, constipation, respiratory ailments, and cough. M. pulegium is a great candidate for contemporary therapeutic usage since it contains a wide variety of biologically active compounds, including terpenoids, flavonoids, alkaloids, tannins, and saponins in all its parts. Among the different parts used are the whole plant, the aerial part, the stem, and the leaves. More interestingly, the entire plant contains a variety of compounds including Pulegone, Isomenthone, Carvone, Menthofuran, Menthol, 1,8-Cineole, Piperitone, Piperitenone, Neomenthol, -humulene, and 3-octanol. Eriocitrin, Hesperidin, Narirutin, Luteolin, Isorhoifolin, Galic acid, and Rosmarinic acid are found in the leaves. p-hydroxybenzoic acid, Ferulic acid, Caffeic acid, Vanillic acid, Syringic acid, Protocatechuic acid, Cinnamic acid, Phloretic acid, o-coumaric acid, p-coumaric acid, Catechin, Epicatechin, Chrysin, Quercetin, Naringenin, Carvacrol are all found in the areal part. Alterporriol G, Atropisomer, Alterporriol H, Altersolanol K, Altersolanol L, Stemphypyrone, 6-O-methylalaternin, Macrosporin, Altersolanol A, Alterporriol E, Alterporriol D, Alterporriol A, Alterporriol B, and Altersolanol J are also found in the stem of fungus. Pulegone, Piperitone, p-Menthane-1,2,3- triol, β-elemenene, guanine (cis-), Carvacrol acetate, and Phenyl ethyl alcohol are all components of this plant's essential oils. Moreover, the study also sought to investigate and document all currently available evidence and information on the nutritional composition and therapeutic uses of this plant ornamental. Its pharmacological applications include antimicrobial, antioxidant, antihypertensive, antidiabetic, anti-inflammatory, antiproliferative, antifungal, anticancer, burn wound healing, antispasmodic, and hepatotoxicity. Finally, toxicological studies have revealed that while low doses of extracts of the plant M. pulegium are not toxic, however, its essential oils of it are extremely toxic. In order to evaluate future research needs and investigate its pharmacological applications through clinical trials, the current assessment focuses on the distribution, chemical composition, biological activities, and primary uses of the plant.

Diuron and its metabolites induce mitochondrial dysfunction-mediated cytotoxicity in urothelial cells

In the environment, or during mammalian metabolism, the diuron herbicide (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is transformed mainly into 3-(3,4-dichlorophenyl)-1-methylurea (DCPMU) and 3,4-dichloroaniline (DCA). Previous research suggests that such substances are toxic to the urothelium of Wistar rats where, under specific exposure conditions, they may induce urothelial cell degeneration, necrosis, hyperplasia, and eventually tumors. However, the intimate mechanisms of action associated with such chemical toxicity are not fully understood. In this context, the purpose of the current in vitro study was to analyze the underlying mechanisms involved in the urothelial toxicity of those chemicals, addressing cell death and the possible role of mitochondrial dysfunction. Thus, human 1T1 urothelial cells were exposed to six different concentrations of diuron, DCA, and DCPMU, ranging from 0.5 to 500 µM. The results showed that tested chemicals induced oxidative stress and mitochondrial damage, cell cycle instability, and cell death, which were more expressive at the higher concentrations of the metabolites. These data corroborate previous studies from this laboratory and, collectively, suggest mitochondrial dysfunction as an initiating event triggering urothelial cell degeneration and death.

Amended Safety Assessment of Mentha piperita (Peppermint)-Derived Ingredients as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of M piperita (peppermint)-derived ingredients. The Panel reviewed data relevant to the safety of these ingredients. Because final product formulations may contain multiple botanicals, each containing the same constituent(s) of concern, formulators are advised to be aware of these constituents and avoid reaching levels that may be hazardous to consumers. Industry should continue to use good manufacturing practices to limit impurities that could be present in botanical ingredients. The Panel concluded that M piperita (Peppermint) Oil, Extract, Leaf, and leaf-derived ingredients are safe in cosmetics in the present practices of use and concentration when formulated to be non-sensitizing, and that the available data are insufficient for determining that M piperita (Peppermint) Flower/Leaf/Stem Extract, M piperita (Peppermint) Flower/Leaf/Stem Water, and M piperita (Peppermint) Meristem Cell Culture are safe under the intended conditions of use in cosmetic formulations.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

In vitro biological potential of the essential oil of some aromatic species used in Iranian traditional medicine

The goal of this study is to evaluate the chemical compounds, the anti-bacterial/fungal activity, and the cytotoxicity of the essential oil of three species of lamiaceae in Iran. After the extraction of the essential oil implementing the hydrodistillation method, the analysis and identification of the compounds were carried out with a chromatograph coupled with a mass spectrometer. For the evaluation of the anti-bacterial/fungal activity of the essential oils, the measurement of the diameter of inhibition halo, the minimum inhibitory concentration (MIC), bactericidal and fungicidal concentrations (MBC/MFC) were utilized; and for the evaluation of the cytotoxic activity of the essential oils, the 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT) method was used. The results show that the dominant compounds in the Perovskia abrotanoides Kar essential oil were camphor (21.68%), 1,8-cineole (14.26%), and α-pinene (7.23%); moreover, the dominant compounds in the Salvia reuteriana Boiss. Essential oil were benzyl benzoate (27.10%), linalool (13.27%), and sclareol (7.75%); in addition, the dominant compounds in the Ziziphora clinopodioides subsp. rigida (Boiss.) Rech.f. were cyclofenchene (25.29%), pulegone (14.14%), and menthol (7.70%). The largest halo diameter of inhibition halo (~ 22 mm) was against Streptococcus pyogenes and the strongest inhibiting and killing activity was against Candida albicans (MIC and MFC = 125 μg/mL) shown by the S. reuteriana essential oil which, respectively, matched the control antibiotics rifampin and nystatin. The analysis of the MTT test results showed that the Z. clinopodioides subsp. rigida essential oil (with IC50 value of ~ 144.2500) had the strongest cytotoxic activity against human ovarian cancer cells (OVCAR-3). On the whole, the results show that the essential oil of the Lamiaceae family plants is a source for various compounds with potential biological activities which can serve as a possible alternative to produce herbal medicine which are effective on some microorganisms and cancer cell lines.

A regulatory relic: After 60 years of research on cancer risk, the Delaney Clause continues to keep us in the past

The Delaney Clause of the Federal Food, Drug, and Cosmetic Act became law in 1958 because of concerns that potentially harmful chemicals were finding their way into foods and causing cancer. It states, "[n]o additive shall be deemed to be safe if it is found to induce cancer when ingested by man or animal, or if it is found, after tests which are appropriate for the evaluation of the safety of food additives, to induce cancer in man or animal." The United States Food and Drug Administration (US FDA) and United States Environmental Protection Agency (US EPA, prior to implementation of the Food Quality Protection Act) were charged with implementing this clause. Over 60 years, advances in cancer research have elucidated how chemicals induce cancer. Significant advancements in analytical methodologies have allowed for accurate and progressively lower detection limits, resulting in detection of trace amounts. Based on current scientific knowledge, there is a need to revisit the Delaney Clause's utility. The lack of scientific merit to the Delaney Clause was very apparent when recently the US FDA had to revoke the food additive approvals of 6 synthetic flavoring substances because high dose testing in animals demonstrated a carcinogenic response. However, US FDA determined that these 6 synthetic flavoring substances do not pose a risk to public health under the conditions of intended use. The 7th substance, styrene, was de-listed because it is no longer used by industry. The scientific community is committed to improving public health by promoting relevant science in risk assessment and regulatory decision making, and this was discussed in scientific sessions at the American Association for the Advancement of Science (AAAS) 2020 Annual Meeting and the Society of Toxicology (SOT) 2019 Annual Meeting. Expert presentations included advances in cancer research since the 1950s; the role of the Delaney Clause in the current regulatory paradigm with a focus on synthetic food additives; and the impact of the clause on scientific advances and regulatory decision making. The sessions concluded with panel discussions on making the clause more relevant based on 21st-century science.

Historical perspective on the role of cell proliferation in carcinogenesis for DNA-reactive and non-DNA-reactive carcinogens: Arsenic as an example

Our understanding of the etiology of cancer has developed significantly over the past fifty years, beginning with a single-hit linear no-threshold (LNT) conceptual model based on early studies conducted in Drosophila. Over the past several decades, multiple lines of evidence have accumulated to support a contemporary model of chemical carcinogenesis: a multi-hit model involving a prolonged stress environment that over time may drive the mutation of multiple cells into an injured state that ultimately could lead to uncontrolled proliferation via clonal expansion of mutation-carrying daughter cells. Arsenic carcinogenicity offers a useful case study for further exploration of advanced conceptual models for chemical carcinogenesis. A threshold for arsenic carcinogenicity is supported by its mode of action, characterized by repeating cycles of cytotoxicity and cellular regeneration. Furthermore, preliminary meta-analyses of epidemiology dose-response data for inorganic arsenic (iAs) and bladder cancer, correlated to dose-response data measured in vitro, support a threshold of effect in humans on the order of 50-100 μg/L in drinking water. In light of recent developments in our understanding of cancer etiology, we urge strong consideration of the existing mode-of-action evidence supporting a threshold of effect for arsenic carcinogenicity, as well as consideration of the potential methodological pitfalls in evaluating epidemiology dose-response data that could potentially bias in the direction of low-dose linearity.

Mentha pulegium L.: A Plant Underestimated for Its Toxicity to Be Recovered from the Perspective of the Circular Economy

The aim of the study was to investigate the micromorphology of Mentha pulegium leaves and flowers harvested in three different Sicilian (Italy) areas with peculiar pedo-climatic conditions, and to characterize the phytochemical profile, the phytotoxic activity, and the eco-compatibility of their essential oils (EOs) for potential use as safe bioherbicides. Light microscopy (LM) and scanning electron microscopy (SEM) highlighted that M. pulegium indumentum consists of non-glandular and glandular trichomes of different types. Peltate trichomes of plants from the different sites showed few significant differences in dimension and abundance, but they were characterized by a surprisingly high number of secretory cells both in leaves and flowers. Phytochemical analyses showed that oxygenated monoterpenes were the most abundant class in all the EOs investigated (92.2-97.7%), but two different chemotypes, pulegone/isomenthone and piperitone/isomenthone, were found. The complex of morphological and phytochemical data indicates that soil salinity strongly affects the expression of the toxic metabolite pulegone, rather than the EO yield. Phytotoxicity tests showed a moderate activity of EOs against the selected species as confirmed by α-amylase assay. Moreover, the low toxicity on brine shrimp provided a rationale for the possible use of investigated EOs as eco-friendly herbicides.

Ecological and Plant Community Implication on Essential Oils Composition in Useful Wild Officinal Species: A Pilot Case Study in Apulia (Italy)

The study focused on the effects of ecology (plant communities and topographical data) on composition of essential oils (EOs) of some officinal wild plant species (Lamiales): Clinopodium suaveolens, Salvia fruticosa subsp. thomasii, Satureja montana subsp. montana, and Thymbra capitata, in different environments of Apulia (Italy). C. suaveolens and S. fruticosa subsp. thomasii are rare species of conservation interest, while S. montana subsp. montana and T. capitata, have a wide distribution and are used in traditional medicine or as spices. Results showed that the ecological context (phytosociological and ecological features) may influence the composition of EOs of the studied species. High differences in the compound composition have been found in S. montana subsp. montana, whereas minor effects were observed in C. suaveolens, S. fruticosa subsp. thomasii, and T. capitata accessions. The understanding of such aspects is necessary for providing optimal conditions to produce EOs rich in compounds known for their biological activities. The results are of great interest also for EOs producers and at the same time to improve our knowledge and valorize wild officinal plants.

Selected essential oils and their mechanisms for therapeutic use against public health disorders. An overview

Today, the numbers of people suffering from lifestyle diseases like diabetes, obesity, allergies and depression increases mainly in industrialised states. That does not only lower patients' quality of life but also severely stresses the health care systems of these countries. Essential oils (EO) have been in use as therapeutic remedies for centuries against various complaints, but still their effectiveness is being underestimated. In the last decades, a great number of controlled studies have supported efficacy of these volatile secondary plant metabolites for various therapeutic indications. Besides others, EO has antidepressant, anti-obesity, antidiabetic, antifirogenic and antiallergic effects. In this review the pharmacological mechanisms for selected EO are summarised and discussed with the main attention on their impact against public health disorders. Additionally, toxicity of these oils as well as possible drug interactions is presented.

Potential Toxicity of the Essential Oil from Minthostachys mollis: A Medicinal Plant Commonly Used in the Traditional Andean Medicine in Peru

Medicinal plants are used throughout the world and the World Health Organization supports its use by recommending quality, safety and efficacy. Minthostachys mollis is distributed in the Andes of South America and is used by the population for various diseases. While studies have shown their pharmacological properties, the information about their safety is very limited. Then, the goal of this research was to determine the acute oral toxicity and in repeated doses during 28 days of Minthostachys mollis essential oil (Mm-EO) in rats. For the acute toxicity test two groups of rats, of three animals each, were used. Each group received Mm-EO in a single dose of 2000 or 300 mg/kg of body weight. For the repeated dose toxicity test, four groups of 10 rats each were used. Doses of 100, 250 and 500 mg/kg/day were used, one group was control. With the single dose of Mm-EO of 2000 mg/kg of body weight, the three rats in the group showed immediate signs of toxicity and died between 36 and 72 hours. In the lung, inflammatory infiltrate was observed, predominantly lymphocytic with severe hemorrhage and presence of macrophages with hemosiderin. In the repeated dose study, male rats (5/5) and female rats (2/5) died at the dose of 500 mg/kg/day. The body weight of both male and female rats decreased significantly with doses of 250 and 500 mg/kg/day. The serum levels of AST and ALT increased significantly and the histopathological study revealed chronic and acute inflammatory infiltrate in the lung; while in the liver was observed in 80% of the cases (24/30) mild chronic inflammatory infiltrate and in some of those cases there was vascular congestion and in one case cytoplasmic vacuolization. The Mm-EO presented moderate acute oral toxicity, while with repeated doses for 28 days; there was evidence of toxicity, in a dose-dependent manner, mainly at the hepatic level.

FEMA GRAS assessment of natural flavor complexes: Mint, buchu, dill and caraway derived flavoring ingredients

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. NFC flavor materials include a variety of essential oils and botanical extracts. The re-evaluation of NFCs is conducted based on a constituent-based procedure outlined in 2005 and updated in 2018 that evaluates the safety of NFCs for their intended use as flavor ingredients. This procedure is applied in the re-evaluation of the generally recognized as safe (GRAS) status of NFCs with constituent profiles that are dominated by alicyclic ketones such as menthone and carvone, secondary alcohols such as menthol and carveol, and related compounds. The FEMA Expert Panel affirmed the GRAS status of Peppermint Oil (FEMA 2848), Spearmint Oil (FEMA 3032), Spearmint Extract (FEMA 3031), Cornmint Oil (FEMA 4219), Erospicata Oil (FEMA 4777), Curly Mint Oil (FEMA 4778), Pennyroyal Oil (FEMA 2839), Buchu Leaves Oil (FEMA 2169), Caraway Oil (FEMA 2238) and Dill Oil (FEMA 2383) and determined FEMA GRAS status for Buchu Leaves Extract (FEMA 4923), Peppermint Oil, Terpeneless (FEMA 4924) and Spearmint Oil, Terpeneless (FEMA 4925).

Screening for human urinary bladder carcinogens: two-year bioassay is unnecessary

Screening for carcinogens in general, and for the urinary bladder specifically, traditionally involves a two-year bioassay in rodents, the results of which often do not have direct relevance to humans with respect to mode of action (MOA) and/or dose response. My proposal describes a multi-step short-term (90 day) screening process that characterizes known human urinary bladder carcinogens, and identifies those reported in rodent two-year bioassays. The initial step is screening for urothelial proliferation, by microscopy or by increased Ki-67 labeling index. If these are negative, the agent is not a urinary bladder carcinogen. If either of these is positive, an MOA and dose response analysis are performed. DNA reactivity is evaluated. If the chemical is non-DNA reactive, evaluation for cytotoxicity is performed. This involves examination of the urothelium and urine, the latter to identify the generation of urinary solids (e.g. calculi). If urinary solids are the cause of cytotoxicity, the MOA is not relevant to human cancer, but dose response becomes essential for evaluating potential toxicity to humans. If cytotoxicity occurs but no urinary solids are detected, urinary concentrations of the chemical and its metabolites are evaluated, and compared to in vitro cytotoxicity against rodent and human immortalized urothelial cell lines. Based on this process, a screen for urinary bladder carcinogenicity is reliable, and more importantly, can be based on MOA and dose response analyses useful in the overall risk assessment for possible human bladder cancer. The proposed procedure is shorter, less expensive and more relevant than the two-year bioassay.

Effect of (R)-(+) Pulegone on Ovarian Tissue; Correlation with Expression of Aromatase Cyp19 and Ovarian Selected Genes in Mice

Objective

Pulegone (PGN) is a monoterpene ketone, whose metabolites exert several cytotoxic effects in various tissues. The present study was conducted in order to evaluate the (R)-(+) PGN-induced alterations in ovarian aromatization, proto-oncogenes and estrogen receptorα (ERα) and ERβ receptors expressions.

Materials and Methods

In this experimental study, mature albino mice were divided into experimental (received 25 mg/kg, 50 mg/kg and 100 mg/kg PGN, orally for 35 days) and control (received 2% solution of Tween 80 as a PGN solvent, orally) groups. The mRNA levels of Erα, Erβ, p53, Bcl-2, and cytochrome p450 (Cyp19) as well as ovarian angiogenesis were analyzed through reverse transcription polymerase chain reaction and immunohistochemical techniques, respectively. Moreover, apoptosis of follicular cells, serum estrogen and progesterone levels and mRNA damage were investigated via using terminal transferase and biotin-16-dUTP staining, electrochemilunescence and fluorescent microscopy methods, respectively.

Results

The PGN reduced Erα, Erβ and Cyp19 expression at 50 mg/kg and 100 mg/kg doses, while significantly elevating p53 and reducing Bcl-2 expression. Finally, PGN impaired ovarian angiogenesis, increased apoptosis, elevated follicular atresia and reduced serum levels of estrogen and progesterone.

Conclusion

Chronic exposure to PGN (50 mg/kg and 100 mg/kg), severely affects ovarian aromatization, proto- oncogenes mRNA levels and expression of ERs.

Planimetric and Biomechanical Study of Local Effect of Pulegone on Full Thickness Wound Healing in Rat

Background

Pulegone as principal component of essential oil, reported to have anti-bacterial, antioxidant and anti-inflammatory properties. The present study was aimed to evaluate wound healing activity of pulegone in a rat model.

Method

Forty rats were used for excisional and incisional wound healing models. For each model twenty male white Wistar rats were randomly divided into five groups (n = 4) of control (CG), Sham surgery, E1, E2 and E3. Wound size, hydroxyproline content of wound and biomechanical testing were assessed.

Result

In E2 animals, the wound size was reduced earlier than in E1 and E2 groups (P = 0.035). However, time had significant effect on wound contraction of all wounds. Hydroxyproline contents in the groups CG, sham surgery, E1, E2 and E3 were found to be 51.25 ± 3.40, 58.41 ± 4.62, 68.59 ± 3.53, 86.32 ± 3.18, and 74.26 ± 4.73 mg g^-1, respectively. Hydroxyproline contents were increased significantly in E2 compared to E1 and E3 which implied more collagen deposition compared to other experimental groups (P = 0.001). The biomechanical indices, maximum stored energy, stiffness, ultimate strength and yield strength obtained for E2 group were significantly higher than those obtained for E1 and E2 groups (P = 0.002).

Conclusion

The pulegone showed a reproducible wound healing potential in rats.

Scientific Opinion on Flavouring Group Evaluation 57, Revision 1 (FGE.57Rev1): consideration of isopulegone and three flavouring substances evaluated by JECFA (55th meeting)

The EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), and to decide whether further evaluation is necessary, as laid down in Commission Regulation (EC) No 1565/2000. The present consideration concerns a group of four flavouring substances consisting of isopulegone and three other substances evaluated by JECFA at the 55th meeting. This revision is made due to additional toxicity data available for (1R,2S,5R)‐isopulegol [FL‐no: 02.067]. The substances were evaluated through a stepwise approach that integrates information on structure–activity relationships, intake from current uses, toxicological threshold of concern, and available data on metabolism and toxicity. p‐Mentha‐1,4(8)‐dien‐3‐one [FL‐no: 07.127] is no longer supported by the flavour industry and was not evaluated. In agreement with JECFA, the Panel evaluated the candidate substances in this Flavouring Group Evaluation (FGE) via the B‐side of the Procedure. Based on a no observed adverse effect level (NOAEL) from a 90‐day oral toxicity study on [FL‐no: 02.067], adequate margins of safety for the three candidate substances could be calculated. Therefore, the Panel agrees with the JECFA conclusion, ‘No safety concern at estimated levels of intake as flavouring substances’ based on the maximised survey‐derived daily intake (MSDI) approach. Besides the safety assessment of these flavouring substances, the specifications for the materials of commerce have also been considered and found adequate. For the three substances evaluated in this FGE, use levels have become available and the modified theoretical added maximum daily intakes (mTAMDIs) were estimated. For [FL‐no: 02.067 and 07.067], the mTAMDI exceeds the toxicological threshold of concern for their structural classes and need more refined exposure assessment to finalise the evaluation.

Critical role of toxicologic pathology in a short-term screen for carcinogenicity

Carcinogenic potential of chemicals is currently evaluated using a two year bioassay in rodents. Numerous difficulties are known for this assay, most notably, the lack of information regarding detailed dose response and human relevance of any positive findings. A screen for carcinogenic activity has been proposed based on a 90 day screening assay. Chemicals are first evaluated for proliferative activity in various tissues. If negative, lack of carcinogenic activity can be concluded. If positive, additional evaluation for DNA reactivity, immunosuppression, and estrogenic activity are evaluated. If these are negative, additional efforts are made to determine specific modes of action in the animal model, with a detailed evaluation of the potential relevance to humans. Applications of this approach are presented for liver and urinary bladder. Toxicologic pathology is critical for all of these evaluations, including a detailed histopathologic evaluation of the 90 day assay, immunohistochemical analyses for labeling index, and involvement in a detailed mode of action analysis. Additionally, the toxicologic pathologist needs to be involved with molecular evaluations and evaluations of new molecularly developed animal models. The toxicologic pathologist is uniquely qualified to provide the expertise needed for these evaluations.

European medicinal and edible plants associated with subacute and chronic toxicity part I: Plants with carcinogenic, teratogenic and endocrine-disrupting effects

In recent decades, the use of herbal medicines and food products has been widely embraced in many developed countries. These products are generally highly accepted by consumers who often believe that "natural" equals "safe". This is, however, an oversimplification because several botanicals have been found to contain toxic compounds in concentrations harmful to human health. Acutely toxic plants are in most cases already recognised as dangerous as a result of their traditional use, but plants with subacute and chronic toxicity are difficult or even impossible to detect by traditional use or by clinical research studies. In this review, we systematically address major issues including the carcinogenicity, teratogenicity and endocrine-disrupting effects associated with the use of herbal preparations with a strong focus on plant species that either grow natively or are cultivated in Europe. The basic information regarding the molecular mechanisms of the individual subtypes of plant-induced non-acute toxicity is given, which is followed by a discussion of the pathophysiological and clinical characteristics. We describe the genotoxic and carcinogenic effects of alkenylbenzenes, pyrrolizidine alkaloids and bracken fern ptaquiloside, the teratogenicity issues regarding anthraquinone glycosides and specific alkaloids, and discuss the human health concerns regarding the phytoestrogens and licorice consumption in detail.

Cytotoxicity and gene expression changes induced by inorganic and organic trivalent arsenicals in human cells

Inorganic arsenic (iAs) is a human urinary bladder, skin and lung carcinogen. iAs is metabolized to methylated arsenicals, with trivalent arsenicals more cytotoxic than pentavalent forms in vitro. In this study, cytotoxicity and gene expression changes for arsenite (iAs(III)), monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)) were evaluated in three human cell types, urothelial (1T1), keratinocyte (HEK001) and bronchial epithelial (HBE) cells, corresponding to target organs for iAs-induced cancer. Cells were exposed to arsenicals to determine cytotoxicity and to study gene expression changes. Affymetrix chips were used to determine differentially expressed genes (DEGs) by statistical analysis. Lethal concentrations (LC50) for trivalent arsenicals in all cells ranged from 1.6 to 10μM. MMA(III) and DMA(III) had 4-12-fold greater potency compared to iAs. Increasing concentrations of iAs(III) induced more genes and additional signaling pathways in HBE cells. At equivalent cytotoxic concentrations, greater numbers of DEGs were induced in 1T1 cells compared to the other cells. Each arsenical altered slightly different signaling pathways within and between cell types, but when altered pathways from all three arsenicals were combined, they were similar between cell types. The major signaling pathways altered included NRF2-mediated stress response, interferon, p53, cell cycle regulation and lipid peroxidation. These results show a similar process qualitatively and quantitatively for all three cell types, and support a mode of action involving cytotoxicity and regenerative proliferation.