The FEMA GRAS assessment of trans-anethole used as a flavouring substance. Flavour and Extract Manufacturer's Association

FT-IR, FT-Raman and UV spectroscopic investigation, electronic properties, electric moments, and NBO analysis of anethole using quantum chemical calculations

FT-IR and FT-Raman spectra of anethole (1-Methoxy-4-(1-propenyl)benzene), a flavoring agent of commercial value, have been recorded in the regions 4000-400 and 4000-100cm(-1) respectively. The structure of the title molecule has been optimized and the structural parameters have been calculated by DFT/B3LYP method with 6-311++G(d,p) basis set. The fundamental vibrational wavenumbers as well as their intensities were calculated and a good agreement between observed and scaled calculated wavenumbers has been achieved. UV-Vis spectrum of the title compound was recorded in the region 200-500nm and the electronic properties such as HOMO and LUMO energies and associated energy gap were calculated by Time dependent-density functional theory (TD-DFT) approach. Nonlinear optical (NLO) study divulges the nonlinear properties of the molecule. Stability of the title molecule arising from hyper-conjugative interactions and charge delocalization has been investigated using natural bond orbital (NBO) analysis. The theoretical results were found to be in coherence with the measured experimental data.

Characterization of a self-sufficient trans-anethole oxygenase from Pseudomonas putida JYR-1

A novel flavoprotein monooxygenase, trans-anethole oxygenase (TAO), from Pseudomonas putida JYR-1, which is capable of catalyzing the oxidation of trans-anethole to p-anisaldehyde, was heterologously expressed in E. coli and purified. Enzymatic kinetics of diverse substrates and cofactors revealed that TAO is likely to be a novel self-sufficient flavoprotein monooxygenase. Enzyme assays of GST-TAO demonstrated that TAO catalyzed a trans-anethole oxidation reaction without auxiliary component enzyme-like electron-transfer flavin reductases. The single component TAO had the ability to reduce flavin cofactors and simultaneously oxidize trans-anthole to p-anisaldehyde. In the processes of reduction of flavin and oxidation of trans-anethole, TAO accepted various flavin and NAD(P)H cofactors. TAO also catalyzed oxidation of isoeugenol, O-methyl isoeugenol, and isosafrole, all of which contain the 2-propenyl functional group on the aromatic ring structure with different catalytic efficiency. TAO had the greatest catalytic efficiency (k_cat/K_m) with the original substrate, trans-anethole. Investigation about partially deleted mutants of TAO indicated that reductase active sites appeared to be located near the N terminal. Site directed mutagenesis studies also proved that the proposed flavin binding sites, Trp-38, Thr-43, Tyr-55, were critical for flavin reduction. However, disruption of any portion of TAO eliminated the oxygenase activity.

Anethum graveolens: An Indian traditional medicinal herb and spice

Anethum graveolens L. (dill) has been used in ayurvedic medicines since ancient times and it is a popular herb widely used as a spice and also yields essential oil. It is an aromatic and annual herb of apiaceae family. The Ayurvedic uses of dill seeds are carminative, stomachic and diuretic. There are various volatile components of dill seeds and herb; carvone being the predominant odorant of dill seed and α-phellandrene, limonene, dill ether, myristicin are the most important odorants of dill herb. Other compounds isolated from seeds are coumarins, flavonoids, phenolic acids and steroids. The main purpose of this review is to understand the significance of Anethum graveolens in ayurvedic medicines and non-medicinal purposes and emphasis can also be given to the enhancement of secondary metabolites of this medicinal plant.

The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system

Anise (Pimpinella anisum L.; Apiaceae) and its essential oil have been widely used in folk medicine, pharmacy and food industry. Since there are some data about the impact of anise on functions of central nervous system (CNS), the issue of possible interactions with drugs acting in CNS should be considered. This survey aimed to examine the influence of aniseed essential oil (EO) intake on the effects of drugs that act in CNS. The chemical profile of essential oil determined by GC-MS revealed as the main components: trans-anethole (88.49%), γ-himachalene (3.13%), cis-isoeugenol (1.99%), and linalool (1.79%). The effects of codeine, diazepam, midazolam, pentobarbital, imipramine and fluoxetine were tested in mice after 5days of peroral pretreatment with human equivalent dose of aniseed EO (0.3mg/kg). The intake of EO led to significant increase of analgesic effect of codeine. The motor impairment caused by midazolam was enhanced in the group treated by EO. The application of diazepam decreased the number and percentage of entries in open arm in elevated maze plus test in the group pretreated with EO indicating augmented effect of drug on motor activity. EO pretreatment caused significant shortage of pentobarbital induced sleeping time when compared to control. The decrease in antidepressant effect of imipramine and fluoxetine was diminished by the pretreatment with aniseed EO. Based on the results of this study we conclude that concomitant intake of aniseed EO preparations and drugs that act on CNS should be avoided due to potential herb-drug interactions, which also need further clinical confirmation.

Isolation of a gene responsible for the oxidation of trans-anethole to para-anisaldehyde by Pseudomonas putida JYR-1 and its expression in Escherichia coli

A plasmid, pTA163, in Escherichia coli contained an approximately 34-kb gene fragment from Pseudomonas putida JYR-1 that included the genes responsible for the metabolism of trans-anethole to protocatechuic acid. Three Tn5-disrupted open reading frame 10 (ORF 10) mutants of plasmid pTA163 lost their abilities to catalyze trans-anethole. Heterologously expressed ORF 10 (1,047 nucleotides [nt]) under a T7 promoter in E. coli catalyzed oxidative cleavage of a propenyl group of trans-anethole to an aldehyde group, resulting in the production of para-anisaldehyde, and this gene was designated tao (trans-anethole oxygenase). The deduced amino acid sequence of TAO had the highest identity (34%) to a hypothetical protein of Agrobacterium vitis S4 and likely contained a flavin-binding site. Preferred incorporation of an oxygen molecule from water into p-anisaldehyde using (18)O-labeling experiments indicated stereo preference of TAO for hydrolysis of the epoxide group. Interestingly, unlike the narrow substrate range of isoeugenol monooxygenase from Pseudomonas putida IE27 and Pseudomonas nitroreducens Jin1, TAO from P. putida JYR-1 catalyzed isoeugenol, O-methyl isoeugenol, and isosafrole, all of which contain the 2-propenyl functional group on the aromatic ring structure. Addition of NAD(P)H to the ultrafiltered cell extracts of E. coli (pTA163) increased the activity of TAO. Due to the relaxed substrate range of TAO, it may be utilized for the production of various fragrance compounds from plant phenylpropanoids in the future.

Anethole isomerization and dimerization induced by acid sites or UV irradiation

The formation of cis-anethole and various dimers as a result of the exposure of trans-anethole to microporous solid acids (dealuminated HY zeolites), or UV-Vis irradiation was established by means of high resolution gas chromatography coupled to mass spectrometry. 3,4-bis-(4-Methoxyphenyl)-(E)-hex-2-ene was the most abundant compound among eight different methoxyphenyl-disubstituted hexenes produced by electrophilic addition and elimination reactions induced by HY zeolites. (1a,2a,3b,4b)-1,2-bis(4-Methoxyphenyl)-3,4-dimethylcyclobutane was the principal component in the mixture of 5 methoxyphenyl-disubstituted cyclobutanes found, together with cis-anethole, after UV-Vis irradiation of a trans-anethole solution in toluene.

Eugenol inhibit 7,12-dimethylbenz[a]anthracene-induced genotoxicity in MCF-7 cells: Bifunctional effects on CYP1 and NAD(P)H:quinone oxidoreductase

Typically, chemopreventive agents either inhibit the cytochrome P450s (CYPs) that are essential for the metabolism of carcinogens or induce phase II detoxifying enzymes. This study examined the chemopreventive effect of eugenol on 7,12-dimethylbenz[a]anthracene (DMBA)-induced DNA damage in MCF-7 cells. Eugenol inhibited the formation of the DMBA-DNA adduct in a dose dependent manner. CYP1A1 and CYP1B1 activity, which catalyze the biotransformation of DMBA, were strongly inhibited by eugenol. Eugenol also suppressed the CYP1A induction by DMBA through decreased aryl hydrocarbon receptor activation and subsequent DNA binding. Furthermore, eugenol increased the expression and activity of NAD(P)H:quinone oxidoreductase (QR), a major detoxifying enzyme for DMBA, through NF-E2 related factor2 binding to antioxidant response element in QR gene. Therefore, eugenol has a potent protective effect against DMBA-induced genotoxicity, presumably through the suppression of the DMBA activation and the induction of its detoxification. These results suggest that eugenol has potential as a chemopreventive.

Inhibitory effect of anethole on T-lymphocyte proliferation and interleukin-2 production through down-regulation of the NF-AT and AP-1

Anethole is a naturally occurring alkenylbenzene found in a variety of foods and essential oils. In the present study, we investigated the effect of anethole on T-cell function and the regulatory mechanism of its effect. Direct addition of anethole to B6C3F1 mouse splenocyte cultures produced a concentration-dependent inhibition of the lymphoproliferative response to concanavalin A stimulation. Anethole inhibited phorbol 12-myristate 13-acetate (PMA) plus ionomycin (Io)-induced interleukin-2 (IL-2) mRNA expression and protein secretion in EL4 mouse T-cells as determined by quantitative/competitive RT-PCR and ELISA, respectively. To further characterize the mechanism for the transcriptional regulation of IL-2, an electrophoretic mobility shift assay was performed to evaluate the binding activity of the nuclear factor of activated T-cells (NF-AT), activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), and octamer binding protein (Oct) in PMA/Io-stimulated EL4 cells. Anethole decreased the NF-AT and AP-1 binding activity, but no significant effect was observed on NF-kappaB or Oct binding activity. These results suggest that anethole suppress T-cell proliferation and IL-2 production and that the inhibition is mediated, at least in part, through the down-regulation of NF-AT and AP-1.

Synthesis and antioxidant, anti-inflammatory and gastroprotector activities of anethole and related compounds

Some derivatives of trans-anethole [1-methoxy-4-(1-propenyl)-benzene] (1) were synthesized, by introducing hydroxyl groups in the double bond of the propenyl moiety. Two types of reactions were performed: (i) oxymercuration/demercuration that formed two products, the mono-hydroxyl derivative, 1-hydroxy-1-(4-methoxyphenyl)-propane (2) and in lesser extent the dihydroxyl derivative, 1,2-dihydroxy-1-(4-methoxyphenyl)-propane (3) and (ii) epoxidation with m-chloroperbenzoic acid that also led to the formation of two products, the dihydroxyl derivative (3) and the correspondent m-chloro-benzoic acid mono-ester, 1-hydroxy-1(4-methoxyphenyl)-2-m-chlorobenzoyl-propane (4). The structures of these compounds were confirmed mainly by mass, IR, 1H and 13C NMR spectral data. The activity of anethole and hydroxylated derivatives was evaluated using antioxidant, anti-inflammatory and gastroprotector tests. Compounds (2) and (3) were more active antioxidant agents than (1) and (4). In the anti-inflammatory assay, anethole showed lower activity than hydroxylated derivatives. Anethole and in lesser extent its derivatives 2 and 4 showed significant gastroprotector activity. All tested compounds do not alter significantly the total number of white blood cells.

Criteria for the safety evaluation of flavoring substances

The current status of the GRAS evaluation program of flavoring substances operated by the Expert Panel of FEMA is discussed. The Panel maintains a rigorous rotating 10-year program of continuous review of scientific data related to the safety evaluation of flavoring substances. The Panel concluded a comprehensive review of the GRAS (GRASa) status of flavors in 1985 and began a second comprehensive review of the same substances and any recently GRAS materials in 1994. This second re-evaluation program of chemical groups of flavor ingredients, recognized as the GRAS reaffirmation (GRASr) program, is scheduled to be completed in 2005. The evaluation criteria used by the Panel during the GRASr program reflects the significant impact of advances in biochemistry, molecular biology and toxicology that have allowed for a more complete understanding of the molecular events associated with toxicity. The interpretation of novel data on the relationship of dose to metabolic fate, formation of protein and DNA adducts, enzyme induction, and the cascade of cellular events leading to toxicity provides a more comprehensive basis upon which to evaluate the safety of the intake of flavor ingredients under conditions of intended use. The interpretation of genotoxicity data is evaluated in the context of other data such as in vivo animal metabolism and lifetime animal feeding studies that are more closely related to actual human experience. Data are not viewed in isolation, but comprise one component that is factored into the Panel's overall safety assessment. The convergence of different methodologies that assess intake of flavoring substances provides a greater degree of confidence in the estimated intake of flavor ingredients. When these intakes are compared to dose levels that in some cases result in related chemical and biological effects and the subsequent toxicity, it is clear that exposure to these substances through flavor use presents no significant human health risk.

Identification of syn- and anti-anethole-2,3-epoxides in the metabolism of trans-anethole by the newly isolated bacterium Pseudomonas putida JYR-1

Bacterial strain JYR-1, which utilizes high concentrations (up to 100 mM) of trans-anethole as the sole source of carbon and energy, was isolated from soil. It grew to OD(600)(nm) = 2.6 with a doubling time of 8 h when grown on 20 mM trans-anethole. Strain JYR-1 was identified as Pseudomonas putida based on the partial gene sequence of its 16S rDNA. Elution profiles of culture extracts were examined by high-performance liquid chromatography and showed that four metabolites were produced from the bacterial culture containing trans-anethole that were not detected in control experiments. LC-MS analysis showed molecular weights of 138.2, 164.5, 164.3, and 152.3. The metabolites with molecular weights at 152.3 and 138.2 were confirmed to be p-anisic acid and p-hydroxybenzoic acid, respectively, when compared with HPLC retention times and molecular weights of authentic compounds. The metabolites with molecular weights at 164.5 and 164.3 were further analyzed by NMR and were proved to be stereoisomer syn- and anti-anethole epoxides. Therefore, strain JYR-1 most likely initiates the metabolism of trans-anethole through the formation of epoxides on the propene group of the compound.

A procedure for the safety evaluation of natural flavor complexes used as ingredients in food: essential oils

A scientifically based guide has been developed to evaluate the safety of naturally occurring mixtures, particularly essential oils, for their intended use as flavor ingredients. The approach relies on the complete chemical characterization of the essential oil and the variability of the composition of the oil in the product intended for commerce. Being products of common plant biochemical pathways, the chemically identified constituents are organized according to a limited number of well-established chemical groups called congeneric groups. The safety of the intake of the each congeneric group from consumption of the essential oil is evaluated in the context of data on absorption, metabolism, and toxicology of members of the congeneric group. The intake of the group of unidentified constituents is evaluated in the context of the consumption of the essential oil as a food, a highly conservative toxicologic threshold, and toxicity data on the essential oil or an essential oil of similar chemotaxonomy. The flexibility of the guide is reflected in the fact that high intake of major congeneric groups of low toxicologic concern will be evaluated along with low intake of minor congeneric groups of significant toxicological concern (i.e., higher structural class). The guide also provides a comprehensive evaluation of all congeneric groups and constituents that account for the majority of the composition of the essential oil. The overall objective of the guide is to organize and prioritize the chemical constituents of an essential oil in order that no reasonably possible significant risk associated with the intake of essential oil goes unevaluated. The guide is, however, not intended to be a rigid checklist. The Flavor and Extract Manufacturers Association (FEMA) Expert Panel will continue to evaluate each essential oil on a case by case basis applying their scientific judgment to insure that each natural flavor complex is exhaustively evaluated.

Safety evaluation of food flavorings

Food flavorings are an essential element in foods. Flavorings are a unique class of food ingredients and excluded from the legislative definition of a food additive because they are regulated by flavor legislation and not food additive legislation. Flavoring ingredients naturally present in foods, have simple chemical structures, low toxicity, and are used in very low levels in foods and beverages resulting in very low levels of human exposure or consumption. Today, the overwhelming regulatory trend is a positive list of flavoring substances, e.g. substances not listed are prohibited. Flavoring substances are added to the list following a safety evaluation based on the conditions of intended use by qualified experts. The basic principles for assessing the safety of flavoring ingredients will be discussed with emphasis on the safety evaluation of flavoring ingredients by the Food and Agriculture Organization (FAO) and World Health Organization (WHO) Joint Expert Committee on Food Additives (JECFA) and the US Flavor and Extract Manufacturers Expert Panel (FEXPAN). The main components of the JECFA evaluation process include chemical structure, human intake (exposure), metabolism to innocuous or harmless substances, and toxicity concerns consistent with JECFA principles. The Flavor and Extract Manufacturers Association (FEMA) evaluation is very similar to the JECFA procedure. Both the JECFA and FEMA evaluation procedures are widely recognized and the results are accepted by many countries. This implies that there is no need for developing countries to conduct their own toxicological assessment of flavoring ingredients unless it is an unique ingredient in one country, but it is helpful to survey intake or exposure assessment. The global safety program established by the International Organization of Flavor Industry (IOFI) resulting in one worldwide open positive list of flavoring substances will be reviewed.

Chemical composition, toxicity and mosquito repellency of Ocimum selloi oil

Ocimum spp. (Lamiaceae) and their essential oils have been traditionally used to kill or repel insects, and also to flavor foods and oral products, in fragrances, in folk medicine and as condiments. In Brazil, Ocimum selloi has been used to treat stomachaches and as an anti-inflammatory remedy. This study was performed to provide data on the chemical composition, acute toxicity, mutagenicity, skin irritant potential and mosquito repellency of Ocimum selloi oil. GC/MS analysis of Ocimum selloi oil revealed that its major constituents were methyl-chavicol or estragole (55.3%), trans-anethole (34.2%), cis-anethole (3.9%) and caryophyllene (2.1%). Ocimum selloi oil given by gavage to adult Swiss Webster mice produced no adverse effects at doses as high as 1250 mg/kg body weight. Deaths and symptoms (e.g. hypoactivity, ataxia and lethargy) were observed at doses > or =1500 mg/kg body weight, being females apparently more susceptible than males. Genotoxicity of Ocimum selloi oil was evaluated in the Salmonella/microsome assay without and with S9 mixture. The oil, tested up to the toxicity limit (500-700 microg/plate), was not mutagenic to tester strains TA97a, TA98 and TA100. None of 30 volunteers of either sex exposed to undiluted Ocimum selloi oil (4-h patch test) showed a positive skin irritant reaction. A field test (six volunteers, each individual his/her own control) was carried out to evaluate mosquito (Anopheles braziliensis) repellency of Ocimum selloi oil diluted in ethanol (10% v/v). The median number of mosquito bites on volunteers' skin-recorded for 30 min after application of Ocimum selloi oil (2, range 0-3) was much lower than that noted after application of the solvent alone (19.5, 3-25) (Wilcoxon test, P<0.01). In conclusion, results showed that Ocimum selloi oil is an effective mosquito repellent that presents a low acute toxicity, poses no mutagenic risk and seems not to be irritating to human skin.

Disposition and metabolism of isoeugenol in the male Fischer 344 rat

The primary objective of these studies was to determine the absorption, distribution, metabolism and excretion of isoeugenol following oral and intravenous administration to male Fischer-344 rats. Following a single oral dose of [14C]isoeugenol (156 mg/kg, 50 microCi/kg), greater than 85% of the administered dose was excreted in the urine predominantly as sulfate or glucuronide metabolites by 72 h. Approximately 10% was recovered in the feces, and less than 0.1% was recovered as CO(2) or expired organics. No parent isoeugenol was detected in the blood at any of the time points analyzed. Following iv administration (15.6 mg/kg, 100 microCi/kg), isoeugenol disappeared rapidly from the blood. The t(1/2) was 12 min and the Cl(s) was 1.9 l/min/kg. Excretion characteristics were similar to those of oral administration. The total amount of radioactivity remaining in selected tissues by 72 h was less than 0.25% of the dose following either oral or intravenous administration. Results of these studies show that isoeugenol is rapidly metabolized and is excreted predominantly in the urine as phase II conjugates of the parent compound.

Safety assessment of allylalkoxybenzene derivatives used as flavouring substances - methyl eugenol and estragole

This publication is the seventh in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers' Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavouring substances under conditions of intended use. In this review, scientific data relevant to the safety evaluation of the allylalkoxybenzene derivatives methyl eugenol and estragole is critically evaluated by the FEMA Expert Panel. The hazard determination uses a mechanism-based approach in which production of the hepatotoxic sulfate conjugate of the 1'-hydroxy metabolite is used to interpret the pathological changes observed in different species of laboratory rodents in chronic and subchronic studies. In the risk evaluation, the effect of dose and metabolic activation on the production of the 1'-hydroxy metabolite in humans and laboratory animals is compared to assess the risk to humans from use of methyl eugenol and estragole as naturally occurring components of a traditional diet and as added flavouring substances. Both the qualitative and quantitative aspects of the molecular disposition of methyl eugenol and estragole and their associated toxicological sequelae have been relatively well defined from mammalian studies. Several studies have clearly established that the profiles of metabolism, metabolic activation, and covalent binding are dose dependent and that the relative importance diminishes markedly at low levels of exposure (i.e. these events are not linear with respect to dose). In particular, rodent studies show that these events are minimal probably in the dose range of 1-10 mg/kg body weight, which is approximately 100-1000 times the anticipated human exposure to these substances. For these reasons it is concluded that present exposure to methyl eugenol and estragole resulting from consumption of food, mainly spices and added as such, does not pose a significant cancer risk. Nevertheless, further studies are needed to define both the nature and implications of the dose-response curve in rats at low levels of exposure to methyl eugenol and estragole.

Evaluation of the potential effects of ingredients added to cigarettes. Part 3: in vitro genotoxicity and cytotoxicity

Cigarette mainstream smoke from blended cigarettes with and without the addition of ingredients was assayed for its cytotoxicity and genotoxicity. In total, 333 ingredients commonly used in cigarette manufacturing were assigned to three different groups. Each group of ingredients was added at a low and a high level to the test cigarettes. The mutagenicity of the particulate phase of the resulting cigarette smoke was assayed in the Salmonella plate incorporation (Ames) assay with tester strains TA98, TA100, TA102, TA1535 and TA1537. The cytotoxicity of the gas/vapor phase and the particulate phase was determined in the neutral red uptake assay with mouse embryo BALB/c 3T3 cells. Within the sensitivity and specificity of the test systems, the in vitro mutagenicity and cytotoxicity of the cigarette smoke were not increased by the addition of the ingredients.

Anti-genotoxicity of trans-anethole and eugenol in mice

The naturally occurring flavouring agents trans-anethole and eugenol were evaluated for antigenotoxic effects in mice. The test doses of trans-anethole (40-400 mg/kg body weight) and eugenol (50-500 mg/kg weight) were administered by gavage 2 and 20 h before the genotoxins were injected intraperitoneally. Anti-genotoxic effects were assessed in the mouse bone marrow micronucleus test. Pretreatment with trans-anethole and eugenol led to significant antigenotoxic effects against cyclophosphamide (CPH), procarbazine (PCB), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and urethane (URE). In addition, trans-anethole inhibited the genotoxicity of ethyl methane sulfonate (EMS). Both trans-anethole and eugenol exerted dose-related antigenotoxic effects against PCB and URE. There was no significant increase in genotoxicity when trans-anethole (40-400 mg/kg body weight) and eugenol (50-500 mg/kg body weight) were administered alone.