Estragole: a weak direct-acting food-borne genotoxin and potential carcinogen

Bio-organic fertilizers promote yield, chemical composition, and antioxidant and antimicrobial activities of essential oil in fennel (Foeniculum vulgare) seeds

The aromatic fennel plant (Foeniculum vulgare Miller) is cultivated worldwide due to its high nutritional and medicinal values. The aim of the current study was to determine the effect of the application of bio-organic fertilization (BOF), farmyard manure (FM) or poultry manure (PM), either individually or combined with Lactobacillus plantarum (LP) and/or Lactococcus lactis (LL) on the yield, chemical composition, and antioxidative and antimicrobial activities of fennel seed essential oil (FSEO). In general, PM + LP + LL and FM + LP + LL showed the best results compared to any of the applications of BOF. Among the seventeen identified FSEO components, trans-anethole (78.90 and 91.4%), fenchone (3.35 and 10.10%), limonene (2.94 and 8.62%), and estragole (0.50 and 4.29%) were highly abundant in PM + LP + LL and FM + LP + LL, respectively. In addition, PM + LP + LL and FM + LP + LL exhibited the lowest half-maximal inhibitory concentration (IC50) values of 8.11 and 9.01 μg mL-1, respectively, compared to L-ascorbic acid (IC50 = 35.90 μg mL-1). We also observed a significant (P > 0.05) difference in the free radical scavenging activity of FSEO in the triple treatments. The in vitro study using FSEO obtained from PM + LP + LL or FM + LP + LL showed the largest inhibition zones against all tested Gram positive and Gram negative bacterial strains as well as pathogenic fungi. This suggests that the triple application has suppressive effects against a wide range of foodborne bacterial and fungal pathogens. This study provides the first in-depth analysis of Egyptian fennel seeds processed utilizing BOF treatments, yielding high-quality FSEO that could be used in industrial applications.

Facing energy limitations - approaches to increase basil (Ocimum basilicum L.) growth and quality by different increasing light intensities emitted by a broadband LED light spectrum (400-780 nm)

Based on the current trend towards broad-bandwidth LED light spectra for basil productions in multi-tiered controlled-environment horticulture, a recently developed white broad-bandwidth LED light spectrum (400-780 nm) including far-red wavelengths with elevated red and blue light fractions was employed to cultivate basil. Four Ocimum basilicum L. cultivars (cv. Anise, cv. Cinnamon, cv. Dark Opal and cv. Thai Magic) were exposed to two different rising light intensity conditions (I_Low and I_High). In dependence of the individual cultivar-specific plant height increase over time, basil cultivars were exposed to light intensities increasing from ~ 100 to ~ 200 µmol m^-2 s^-1 under I_Low, and from 200 to 400 µmol m^-2 s^-1 under I_High (due to the exponential light intensity increases with decreasing proximity to the LED light fixtures). Within the first experiment, basils' morphological developments, biomass yields and time to marketability under both light conditions were investigated and the energy consumptions were determined to calculate the basils' light use efficiencies. In detail, cultivar-dependent differences in plant height, leaf and branch pair developments over time are described. In comparison to the I_Low light conditions, I_High resulted in accelerated developments and greater yields of all basil cultivars and expedited their marketability by 3-5 days. However, exposure to light intensities above ~ 300 µmol m^-2 s^-1 induced light avoidance responses in the green-leafed basil cultivars cv. Anise, cv. Cinnamon and cv. Thai Magic. In contrast, I_Low resulted in consumer-preferred visual qualities and greater biomass efficiencies of the green-leafed basil cultivars and are discussed as a result of their ability to adapt well to low light conditions. Contrarily to the green-leafed cultivars, purple-leafed cv. Dark Opal developed insufficiently under I_Low, but remained light-tolerant under I_High, which is related to its high anthocyanin contents. In a second experiment, cultivars' volatile organic compound (VOC) contents and compositions over time were investigated. While VOC contents per gram of leaf dry matter gradually decreased in purple-leafed cv. Dark Opal between seedling stage to marketability, their contents gradually increased in the green cultivars. Regardless of the light treatment applied, cultivar-specific VOC compositions changed tremendously in a developmental stage-dependent manner.

The Volatile Phytochemistry of Seven Native American Aromatic Medicinal Plants

As part of our evaluation of essential oils derived from Native American medicinal plants, we have obtained the essential oils of Agastache foeniculum (Pursch) Kuntze (Lamiaceae), Gaultheria procumbens L. (Ericaceae), Heliopsis helianthoides (L.) Sweet (Asteraceae), Liatris spicata (L.) Willd. (Asteraceae), Pycnanthemum incanum (L.) Michx. (Lamiaceae), Smallanthus uvedalia (L.) Mack. ex Mack. (Asteraceae), and Verbena hastata L. (Verbenaceae) by hydrodistillation. The essential oils were analyzed by gas chromatographic techniques. The essential oil of A. foeniculum was dominated by estragole (88–93%), while methyl salicylate (91%) dominated the G. procumbens essential oil. Germacrene D was the major component in H. helianthoides (42%) and L. spicata (24%). 1,8-Cineole (31%) and α-terpineol (17%) were the main compounds in P. incanum essential oil. The essential oil of S. uvedalia showed α-pinene (24%), perillene (15%), and β-caryophyllene (17%) as major components. Verbena hastata essential oil was rich in 1-octen-3-ol (up to 29%) and palmitic acid (up to 22%). Four of these essential oils, H. helianthoides, L. spicata, P. incanum, and V. hastata, are reported for the first time. Additionally, the enantiomeric distributions of several terpenoid components have been determined.

Gas Chromatography-Mass Spectrometry-Based Classification of 12 Fennel (Foeniculum vulgare Miller) Varieties Based on Their Aroma Profiles and Estragole Levels as Analyzed Using Chemometric Tools

Fennel (Foeniculum vulgare Miller) is a popular aromatic plant native to the Mediterranean basin and cultivated worldwide that is valued for the nutritional and health benefits of its fruits. Headspace solid-phase microextraction of 12 fennel accessions of cultivated (F. vulgare subsp. vulgare) and wild forms (F. vulgare subsp. piperitum) of different origins was carried out for assessing their volatile distribution. Fifty-four volatiles were identified, with ethers amounting for the major class at ca. 52-99% attributed to the abundance of (E)-anethole and estragole. Several subsp. vulgare accessions proved to be excellent sources of the chief aroma (E)-anethole (95.9-98.4%), whereas high levels of estragole at ca. 72% were observed in subsp. piperitum from Minia and Khartoum and must be considered in the safety assessment of fennel. Other volatile classes were detected including ketones, esters, aldehydes, alcohols, and hydrocarbons (monoterpenes, sesquiterpenes, and diterpenes). Fenchone exceeded 15% of the total volatiles in some fennel specimens, linked to a conspicuous bitter aftertaste. The members of subsp. piperitum were more enriched in monoterpene hydrocarbons with sabinene found exclusively in these, while subsp. vulgare comprised a higher content of ethers. Principle component analysis determined isoterpinolene as a special component in subsp. piperitum. In all specimens from the same group, estragole was the most distinguished volatile compound according to the findings from orthogonal partial least squares-discriminant analysis. The highest estimated estragole levels were detected in subsp. piperitum from Minia at 89.8 mg/g. This comparative study provides the first comprehensive insight into volatile profiling of 12 fennel fruit varieties.

Metabolome-Based Analysis of Herbal Cough Preparations Via Headspace Solid-Phase Microextraction GC/MS and Multivariate Data Analyses: A Prospect for Its Essential Oil Equivalency

Liquid cough preparations containing essential oils pose a challenge for isolating and quantifying their volatile components from such a complex matrix enriched with nonvolatile constituents and excipients. This study aims to develop a strategy integrating QC analysis of seven natural cough preparations in the Egyptian market and to assess volatile variation among the preparations using multivariate data analyses. Cough preparations were subjected to headspace solid-phase microextraction (HS-SPME) for determination of their essential oil composition mediating for their actions and to assess volatile differences among them. HS-SPME is a suitable technique for sample preparation that allows for extraction and enrichment of volatiles from complex nonvolatile matrices and their direct desorption into the gas chromatography analytical system. A total of 88 volatile components were identified belonging to seven classes, viz. aromatics, aliphatic hydrocarbons, mono/sesquiterpene hydrocarbons, and oxygenated mono/sesquiterpenes. Oxygenated monoterpenes, viz., menthol, cineole, thymol, and (E)-anethole, were the major volatiles identified in five cough preparations (79.5-98.6%), whereas aromatics, chiefly cinnamate derivatives, constituted the second class amounting for 50.5 and 27.4% in the other two cough preparations. Meaningful results regarding the products' efficacy and safety were extrapolated from this analytical procedure, where artificial preservatives (parabens) were detected in five cough preparations. This study established an efficient strategy for exploring volatile profiling and defining different markers among the different cough preparations. Additionally, authenticity of listed herbal ingredients in the cough preparations was also confirmed in certain preparations, while other formulations failed to show representative volatile components. Volatile variation among preparations was assessed using multivariate data analyses in an attempt to prioritize cough preparations for usage, suggesting the preference of Bronchicum and Babetone among examined cough products.

Estragole: DNA adduct formation in primary rat hepatocytes and genotoxic potential in HepG2-CYP1A2 cells

Estragole is a natural constituent in herbs and spices and in products thereof such as essential oils or herbal teas. After cytochrome P450-catalyzed hydroxylation and subsequent sulfation, estragole acts as a genotoxic hepatocarcinogen forming DNA adducts in rodent liver. Because of the genotoxic mode of action and the widespread occurrence in food and phytomedicines a refined risk assessment for estragole is needed. We analyzed the time- and concentration-dependent levels of the DNA adducts N²-(isoestragole-3'-yl)-2'-desoxyguanosine (E3'N²dG) and N⁶-(isoestragole-3'-yl)-desoxyadenosine (E3'N⁶dA), reported to be the major adducts formed in rat liver, in rat hepatocytes (pRH) in primary culture after incubation with estragole. DNA adduct levels were measured via UHPLC-ESI-MS/MS using stable isotope dilution analysis. Both adducts were formed in pRH and could already be quantified after an incubation time of 1 h (E3'N⁶dA at 10 μM, E3'N²dG at 1μM estragole). E3'N²dG, the main adduct at all incubation times and concentrations, could be detected at estragole concentrations < 0.1 μM after 24 h and < 0.5 μM after 48 h. Adduct levels were highest after 6 h and showed a downward trend at later time-points, possibly due to DNA repair and/or apoptosis. While the concentration-response characteristics of adduct formation were apparently linear over the whole concentration range, strong indication for marked hypo-linearity was obtained when the modeling was based on concentrations < 1 μM only. In the micronucleus assay no mutagenic potential of estragole was found in HepG2 cells whereas in HepG2-CYP1A2 cells 1 μM estragole led to a 3.2 fold and 300 μM to a 7.1 fold increase in micronuclei counts. Our findings suggest the existence of a 'practical threshold' dose for DNA adduct formation as an initiating key event of the carcinogenicity of estragole indicating that the default assumption of concentration-response-linearity is questionable, at least for the two major adducts studied here.

A Phenotypic Switch of Differentiated Glial Cells to Dedifferentiated Cells Is Regulated by Folate Receptor α

In a previous study, we showed that folate receptor‐α (FRα) translocates to the nucleus where it acts as a transcription factor and upregulates Hes1, Oct4, Sox2, and Klf4 genes responsible for pluripotency. Here, we show that acetylation and phosphorylation of FRα favor its nuclear translocation in the presence of folate and can cause a phenotypic switch from differentiated glial cells to dedifferentiated cells. shRNA‐FRα mediated knockdown of FRα was used to confirm the role of FRα in dedifferentiation. Ocimum sanctum hydrophilic fraction‐1 treatment not only blocks the folate mediated dedifferentiation of glial cells but also promotes redifferentiation of dedifferentiated glial cells, possibly by reducing the nuclear translocation of ~38 kDa FRα and subsequent interaction with chromatin assembly factor‐1. stem cells2019;37:1441–1454

Guidance on the assessment of the biological relevance of data in scientific assessments

EFSA requested its Scientific Committee to prepare a guidance document providing generic issues and criteria to consider biological relevance, particularly when deciding on whether an observed effect is of biological relevance, i.e. is adverse (or shows a beneficial health effect) or not. The guidance document provides a general framework for establishing the biological relevance of observations at various stages of the assessment. Biological relevance is considered at three main stages related to the process of dealing with evidence: Development of the assessment strategy. In this context, specification of agents, effects, subjects and conditions in relation to the assessment question(s): Collection and extraction of data; Appraisal and integration of the relevance of the agents, subjects, effects and conditions, i.e. reviewing dimensions of biological relevance for each data set. A decision tree is developed to assist in the collection, identification and appraisal of relevant data for a given specific assessment question to be answered.

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.

Changes in Volatile Compounds during Aging of Sweet Fennel Fruits-Comparison of Hydrodistillation and Static Headspace Sampling Methods

Two extraction methods for subsequent gas chromatographic (GC) determination of volatiles from freshly harvested and aged fennel fruit samples ( Foeniculum vulgare Mill.,ssp. vulgare var. dulce) have been compared. Hydrodistillation followed by GC-FID and GC-MS analysis was used as a standard method for essential oil characterization, while static headspace followed by GC (SHS-GC-FID) was used as a comparative method for determination of volatile components. As the fennel fruit ages, there is a gradual loss of the volatile components as indicated by the lower yield of essential oil and lower content of volatiles, as indicated by the alternative SHS-GC-FID analysis. Slight differences observed for the main components ( trans-anethole, estragole, fenchone, and limonene) using the two methods are negligible, indicating that these volatiles did not undergo chemical transformation during the sample preparation procedures. A difference in anisaldehyde content was observed when the composition of the hydrodistilled essential oil was compared with the SHS-GC-FIDanalysis of volatiles and explanation for the variation of anisaldehyde content and the origin of other compounds was suggested. Comparison of the obtained results showed that limonene oxides, carvone and carveolare detectable in SHS-GC-FID analysis of the aged fennel fruits, while in hydrodistilled samples analyzed by GC-FID they were not present. Another observed difference was the appearance of products in significant amounts with higher retention times than trans-anethole, namely threo- and erythro-anethole β-hydroxymethylether and anethole glycol that are not detectable in the essential oil obtained by hydrodistillation. So, the relative abundance of the major components is comparable between these two methods for fennel seed up to 3 years from harvest and they can be used interchangeably depending on the purpose and amount of material. Furthermore, SHS-GC-FID can be used for assessment of maximum storage time and quality of fennel fruit suitable for human consumption.

Simultaneous Determination of Essential Oil Components and Fatty Acids in Fennel using Gas Chromatography with a Polar Capillary Column

Cultivated and wild growing samples of fennel ( Foeniculum vulgare Mill., Apiaceae) from R. Macedonia were studied for their volatiles and fatty acid composition. The main essential oil components isolated via hydrodistillation were: trans-anethole (>80%), estragole (<6%), limonene (<6%), anisaldehyde (<1%) and 0.5 % fenchone. An alternative method for characterization of both the non-polar volatile and non volatile fractions was developed using n-hexane and dichloromethane (3:1, v/v) in a Soxhlet extraction followed by transesterification. The obtained extracts were then characterized and the dominant fatty acid was 18:1 (petroselinic and oleic acid) 75.0–82.8 %, followed by 18:2 (linoleic acid) 10.8–16.2% and other fatty acids: palmitic (4.3–6.9%), stearic (1.2–1.7%) and myristic (0–2.9%). The results for the volatile fraction after Soxhlet extraction and transesterification did not significantly differ from results obtained after hydrodistillation, especially for the main components ( trans-anethole, estragole, fenchone and limonene), implying that the developed method can be used for simultaneous determination of volatiles and fatty acids.

In vitro toxicological evaluation of essential oils and their main compounds used in active food packaging: A review

Essential oils (EOs) and their main constituent compounds have been extensively investigated due to their application in the food industry for improving the shelf life of perishable products. Although they are still not available for use in food packaging in the market in Europe, considerable research in this field has been carried out recently. The safety of these EOs should be guaranteed before being commercialized. The aim of this work was to review the scientific publications, with a primary focus on the last 10 years, with respect to different in vitro toxicological aspects, mainly focussed on mutagenicity/genotoxicity. In general, fewer genotoxic studies have been reported on EOs in comparison to their main components, and most of them did not show mutagenic activity. However, more studies are needed in this field since the guidelines of the European Food Safety Authority have not always been followed accurately. The mutagenic/genotoxic activities of these substances have been related to metabolic activation. Therefore, in vivo tests are required to confirm the absence of genotoxic effects. Considering the great variability of the EOs and their main compounds, a case-by-case evaluation is needed to assure their safe use in food packaging.

Investigation of the cytotoxic, genotoxic, and apoptosis-inducing effects of estragole isolated from fennel (Foeniculum vulgare)

The present study was undertaken to evaluate, in the HepG2 human hepatoma cell line, the in vitro cytotoxic, genotoxic, and apoptotic activities of estragole (1), contained in the essential oil of Foeniculum vulgare (fennel) and suspected to induce hepatic tumors in susceptible strains of mice. Toward this end, an MTT cytotoxicity assay, a trypan blue dye exclusion test, a double-staining (acridine orange and DAPI) fluorescence viability assay, a single-cell microgel-electrophoresis (comet) assay, a mitochondrial membrane potential (Δψm) assay, and a DNA fragmentation analysis were conducted. In terms of potential genotoxic effects, the comet assay indicated that estragole (1) was not able to induce DNA damage nor apoptosis under the experimental conditions used.

Can estragole in fennel seed decoctions really be considered a danger for human health? A fennel safety update

Fennel (Foeniculum vulgare Mill.) mature fruit (commonly known as seeds) and essential oil of fennel are widely used as flavoring agents in food products such as liqueurs, bread, cheese, and an ingredient of cosmetics and pharmaceutical products. Moreover fennel infusions are the classical decoction for nursing babies to prevent flatulence and colic spasm. Traditionally in Europe and Mediterranean areas fennel is used as antispasmodic, diuretic, anti-inflammatory, analgesic, secretomotor, secretolytic, galactagogue, eye lotion, and antioxidant remedy and integrator. Topically, fennel powder is used as a poultice for snake bites. In Asian cultures fennel was ingested to speed the elimination of poisons. As one of the ancient Saxon people's nine sacred herbs, fennel was credited with the power to cure. Fennel was also valued as a magic herb: in the Middle Ages it was draped over doorways on Midsummer's Eve to protect the household from evil spirits. Recently because of estragole carcinogenicity, fennel has been charged to be dangerous for humans especially if used as decoction for babies. But this allegation do not consider the remedy is prepared as a matrix of substances, and recent researches confirm that pure estragole is inactivated by many substance contained in the decoction.