14 We have proposed our own guidelines for some constituents that, at the time of writing, are not restricted by some regulatory agencies. In other cases we give guidelines that are less restrictive than existing ones. The reasons for this are explained in the Toxicity chapter. Table 14.1 presents a comparison of restrictions for some important toxic constituents. Table 14.1 Our restrictions for toxic constituents compared to those of some regulatory agencies aThe percentage of administered diluted oil = (V1) x 100 / (V1 + V2); where V1 = volume of essential oil and V2 = volume of carrier oil, both in mL. bNote that wormseed oil, which contains ascaridole, is prohibited in cosmetics by IFRA, the EU, and Health Canada cThis limit is for skin sensitization eAssuming dermal penetration of 20% fSafrole is prohibited by Health Canada, except ‘when naturally occurring in plant extracts’ There are many different types of isomer. In essential oils, those usually encountered are: • structural isomers: isomers that have identical numbers and types of constituent atoms, but different connections between them (e.g., dill and parsley apiole). Structural isomers have different physical properties, such as boiling points • geometric isomers: isomers that have identical numbers and types of constituent atoms, and the same connections between them, but different arrangements either side of a carbon–carbon double bond (e.g., nerol and geraniol, see Figure 2.3). Geometric isomers have different physical properties, such as boiling points • optical isomers: pairs of molecules containing one chiral center, which have the same numbers and types of atoms and connections between them, but whose atoms are arranged differently in space. They are non-identical mirror images of one another, rather like a pair of gloves. Generally, optical isomers (also known as enantiomers) have the same chemical and physical properties, but when in solution, rotate the plane of polarized light to the same extent, but in opposite directions. One optical isomer will rotate it clockwise (the (+)- or d-isomer), the other anti-clockwise (the (−)- or l-isomer). Despite their chemical similarities, optical isomers can have very different pharmacological and toxicological properties, as well as different tastes and odors (e.g., (+)- and (−)-carvone) • diastereoisomers are similar to enantiomers, but possess more than one chiral center, and hence are usually not mirror images Systematic name: 1-Phenylethanone Chemical class: Benzenoid ketone Note: Also found as a minor or trace component of orris, and several other essential oils. Pharmacokinetics: The metabolism of acetophenone in animals has been extensively studied. In both rabbits and dogs it is metabolized both by reduction and oxidation (Scheline 1991 p. 114). Adverse skin reactions: In a modified Draize procedure on guinea pigs, acetophenone was non-sensitizing when used at 20% in the challenge phase (Sharp 1978). Tested at 2% on the skin of human volunteers, acetophenone was not sensitizing (Opdyke 1978 p. 99–100). Acute toxicity: Acute oral LD50 in rats 3.2 g/kg (Jenner et al 1964); acute dermal LD50 in guinea pigs > 20 mL/kg. No rats died after exposure to an atmosphere saturated (0.45%) with acetophenone (Opdyke 1978 p. 99–100). Subacute and subchronic toxicity: No adverse effects were observed after 1,000, 2,500 or 10,000 ppm fed to rats in the diet for 17 weeks (Hagan et al 1967). Mutagenicity and genotoxicity: Acetophenone was not mutagenic in the Ames test (Florin et al 1980; Ishidate et al 1984). Synonyms: Helenin. Elecampane camphor. Eupatal. 5,11(13)-Eudesmadien-12,8-olide Chemical class: Tricyclic sesquiterpenoid alkene lactone Adverse skin reactions: Sesquiterpene lactones from Compositae plants are notorious skin sensitizers (Ross et al 1993; Goulden & Wilkinson 1998). Alantolactone is a hapten that reacts with free amino acids, and with purified protein fractions taken from skin tissue (Dupuis & Brisson 1976). It elicited positive patch-test responses in sensitized guinea pigs, and four of 25 dermatitis patients were sensitized to it with a single patch test using a 1% concentration (Opdyke 1976 p. 307–308). Alantolactone was dose-dependently cytotoxic to leukocytes taken from individuals not sensitive to it (Dupuis & Brisson 1976). Based on literature published in German, alantolactone was classified as Category A, a significant contact allergen, by Schlede et al (2003). Carcinogenic/anticarcinogenic potential: Alantolactone dose-dependently induces the detoxifying enzymes quinone reductase, glutathione reductase, glutathione S-transferase, γ-glutamylcysteine synthase and heme oxygenase (Seo et al 2008a). Alantolactone is cytotoxic in vitro against cell lines for human leukemia (IC50 0.7 μM; 162 μg/L), human gastric adenocarcinoma (IC50 6.9 μM; 1,600 μg/L), human uterus carcinoma (IC50 6.9 μM; 1,600 μg/L), and mouse melanoma (IC50 4.7 μM; 1,090 μg/L) (Lawrence et al 2001; Konishi et al 2002). Alantolactone induces apoptosis in Jurkat leukemia T cells (Dirsch et al 2001). Synonyms: Allyl isosulfocyanate. 3-Isothiocyanato-1-propene Chemical class: Aliphatic alkene thiocarbonyl compound Pharmacokinetics: Allyl isothiocyanate is metabolized to mercapturic acids (Ioannou et al 1984; Mennicke et al 1983; Bollard et al 1997) and conjugated with N-acetylcysteine (Jiao et al 1994). In rats and mice ~ 75% was excreted in the urine, ~ 13–15% in the expired air and 1–5% in the feces (Ioannou et al 1984). It appears that allyl isothiocyanate can be transported around the body as inactive (−)-cysteine or glutathione conjugates and then released in the reactive form at another site, to cause damage there (Bruggeman et al 1986). Allyl isothiocyanate stimulates liver fat production in rats (Muztar et al 1979a) and strongly depresses plasma glucose (Muztar et al 1979b). It was goitrogenic in rats at 2–4 mg po (Langer & Stolc 1965). Increases urate excretion rate (Huque & Ahmad 1975). Speeds up blood clotting in rats (Idris & Ahmad 1975). Adverse skin reactions: A severe irritant to mucous membranes and skin (Evans & Schmidt 1980; Budavari 1989). Only two of 259 dermatitis patients (0.8%) with suspected ACD from vegetables and food had a + allergic reaction to allyl isothiocyanate, but 43 (16.6%) had a ? + reaction, which might be due to the irritancy of the compound (Lerbaek et al 2004). Acute toxicity: Acute oral LD50 in rats reported as 490 mg/kg and as 340 mg/kg; mouse oral LD50 310 mg/kg (Jenner et al 1964; Vernot et al 1977). Acute sc LD50 80 mg/kg in mice (Klesse & Lukoschek 1955); acute dermal LD50 in rabbits 88 mg/kg (Vernot et al 1977). A rat oral LD50 value of 112 mg/kg is frequently cited on MSDS for allyl isothiocyanate, but we could find no citation for this. Subacute and subchronic toxicity: Given to rats at 50 mg/kg in the diet for 20 days, allyl isothiocyanate caused acute to subacute stomach ulceration in all animals. At 20 mg/kg for 20 days, ulceration occurred in 50% of animals. At 50 mg/kg for 14 days, it caused thickening of the mucosal lining of the stomach in both rats and mice, and thickening of the urinary bladder wall in male mice. No gross or microscopic lesions were seen after feeding allyl isothiocyanate to rats and mice for 13 weeks at 25 mg/kg (National Toxicology Program 1982). Given to rats in the diet for 26 weeks at 1,000, 2,500 or 10,000 ppm there were no observable adverse effects (Hagan et al 1967). Reproductive toxicity: Allyl isothiocyanate caused embryonic death and decreased fetal weight in pregnant rats when given at doses of 50 mg/kg subcutaneously on two consecutive days (Nishie & Daxenbichler 1980). Hepatotoxicity: Orally administered allyl isothiocyanate and its glutathione and N-acetylcysteine conjugates are considerably toxic to rat liver cells. Because the glutathione conjugate is incapable of crossing cell membranes, its cytotoxicity is believed to be due to its conversion back to the parent isothiocyanate (Bruggeman et al 1986; Temmink et al 1986; Masutomi et al 2001). Mutagenicity and genotoxicity: In the Ames test, allyl isothiocyanate has been reported as mutagenic (Eder et al 1982; Neudecker & Henschler 1985) and non-mutagenic (Eder et al 1980; Kasamaki et al 1982; Azizan & Blevins 1995; Kono et al 1995). In Neudecker & Henschler’s study, modified pre-incubation conditions were employed which would lead to increased levels of a reactive epoxide intermediate, as well as the known mutagen, acrolein. A further report gave both positive and negative findings (Mortelmans et al 1986). Allyl isothiocyanate was weakly genotoxic in tests on Chinese hamster cells in vitro (Kasamaki et al 1982). In a bone marrow micronucleus test involving three daily ip injections, the compound was not genotoxic in mice (Shelby et al 1993). Carcinogenic/anticarcinogenic potential: In a 2 year carcinogenesis study, food-grade allyl isothiocyanate (> 93% purity) was fed at 12 or 25 mg/kg five times a week to groups of 50 rats and 50 mice of each sex. It was carcinogenic in the male rats, causing papillomas in the urinary bladder. In female rats there was equivocal evidence of subcutaneous fibrosarcomas. This effect may be attributed to chronic irritation of the bladder epithelium by high concentrations of allyl isothiocyanate and its cysteine conjugate in the bladder (Bechtel et al 1998). However, in a different assay allyl isothiocyanate was not carcinogenic in either male or female mice (National Toxicology Program 1982). Allyl isothiocyanate can cause hyperplasia and transitional cell papillomas in male rats (Dunnick et al 1982). It showed moderate chemopreventive action against nitrosamine-induced carcinogenesis in rat tissues (Chung et al 1984) and significant chemopreventive action (92.5% inhibition) against pulmonary metastasis induced by melanoma cells in mice (Manesh & Kuttan 2003). Regulatory guidelines: IFRA recommends that allyl isothiocyanate is not used as a fragrance ingredient (IFRA 2009). Allyl isothiocyanate is prohibited as a cosmetic ingredient in the EU and Canada (Anon 2003a; Health Canada Cosmetic Ingredient Hotlist, March 2011). In a preliminary report by an ECETOC taskforce, allyl isothiocyanate was provisionally classified as a moderate allergen (on a scale of extreme, strong, moderate and weak) likely to elicit a sensitization reaction if present at 1% or more (Kimber et al 2003). Synonyms: cis-Ambrettolide. (Z)-7-Hexadecen-16-olide. Ambrettolic acid lactone Systematic name: (Z)-Oxacycloheptadec-8-en-2-one Chemical class: Monocyclic sesquiterpenoid alkene lactone Adverse skin reactions: Ambrettolide was not irritating when tested full strength on rabbit skin, and was neither irritating nor sensitizing when tested at 1% on human subjects (Opdyke 1975 p. 707). Acute toxicity: Both the acute oral LD50 in rats, and the acute dermal LD50 in rabbits exceeded 5 g/kg (Opdyke 1975 p. 707). Summary: Limited data, but the structure of the compound does not raise any red flags. Synonyms: trans-Anethole. p–trans-Propenylanisole. Anise camphor Systematic name: (E)-4-Methoxy-(1-propenyl)benzene Chemical class: Phenylpropenoid ether Pharmacokinetics: (E)-Anethole is distributed and metabolized in a similar way in rats, rabbits and humans (Le Bourhis 1970) with most of an orally administered dose being excreted within 48 hours in mice (Strolin-Benedetti & Le Bourhis 1972). However, it is not distributed uniformly in the body. After intravenous dosing in mice, most of the (E)-anethole accumulated in the liver, lungs and brain. In some studies it is poorly absorbed from the gastrointestinal tract, with most of an administered dose remaining in the mouse stomach (Le Bourhis 1968). In another study very good absorption after oral dosing was seen (Sangster et al 1984a). These differences may be due to the methodologies chosen. In both rats and mice given 250 mg/kg of (E)-anethole, > 95% of the dose was recovered, the majority in the 0–24 hour urine, from which 18 metabolites were identified. The metabolism and toxicity of (E)-anethole have recently been reviewed (Newberne et al 1999). (E)-Anethole undergoes biotransformation by three principle pathways: O-demethylation, N-oxidation and epoxidation. The latter, which can lead to toxic metabolites, is only a minor pathway (~ 3%) in humans (Sangster et al 1987; Solheim & Scheline 1973; Bounds & Caldwell 1996). In animals, (E)-anethole is metabolized differently depending on dose (Caldwell et al 1983; Sangster et al 1984b), but not in human studies (Caldwell & Sutton 1988). Rats produce metabolites from ingested (E)-anethole that other species do not (Bounds & Caldwell 1996). A study using doses of (E)-anethole close to those found in the diet revealed that the major route of excretion is via the urine; carbon dioxide is formed as a by-product and is excreted in the expired air. Nine urinary metabolites are produced, all oxidation products. Most urinary metabolites are also detected in bile, suggesting that biliary excretion is an important route for the removal of (E)-anethole (Leibman & Ortiz 1973). Adverse skin reactions: Tested at 2% on human subjects (E)-anethole was neither irritating nor sensitizing (Opdyke 1973, p. 863–864). Of 15 dermatitis patients who tested positive to 1.0% star anise oil, five were sensitive to (E)-anethole (Rudzki & Grzywa 1976). On standing uncovered for 90 days, synthetic anethole (which generally contains 2–3% of (Z)-anethole) was found to contain (E)-anethole 90.5%, (Z)-anethole 1%, plus anisaldehyde 3.5% and anisic ketone 3.5%, which are considered products of autoxidation (Kraus & Hammerschmidt 1980). It is not known whether oxidized anethole is significantly skin sensitizing. Acute toxicity: Acute oral LD50 2.09–3.20 g/kg in rats, 1.82–5.00 g/kg in mice, 2.16 g/kg in guinea pigs (Jenner et al 1964; Newberne et al 1999). The ip and oral LD50 values were 650 mg/kg and 900 mg/kg, respectively, in mice, and 0.9 g/kg and 3.2 g/kg, respectively, in rats (Boissier et al 1967). Subacute and subchronic toxicity: Given to rats in the diet at 10,000 ppm for 15 weeks (E)-anethole caused slight hydropic changes of hepatic cells in males only; at 2,500 ppm for one year there were no effects (Hagan et al 1967). Human toxicity: In reviewing the toxicity of (E)-anethole, Newberne et al (1999) conclude that the substance poses no risk to human health when used as a food flavoring. Cardiovascular effects: (E)-Anethole shows strong antiplatelet aggregation activity in vitro (Yoshioka & Tamada 2005). Reproductive toxicity: (E)-Anethole has estrogen-like effects in vitro, many times weaker than endogenous estrogens (Zondek & Bergmann 1938; Albert-Puleo 1980). There is some discussion about whether this weak activity is due to (E)-anethole itself or a polymer of the compound (Albert-Puleo 1980). The anethole metabolite, 4-hydroxy-1-propenylbenzene, weakly displaced 17β-estradiol from ERα receptors with an IC50 value of 10− 5 M, and promoted the proliferation of cultured human MCF-7 cells at 10− 8–10− 6 M. In the latter assay, anethole had no effect up to 10− 5 M (Nakagawa & Suzuki 2003). (E)-Anethole did bind to estrogen receptors in recombinant yeast cells, but did not have estrogenic activity in either an estrogen-responsive human cell line (below cytotoxic concentrations) or a yeast screen for androgenic and anti-androgenic compounds (Howes et al 2002). Sweet fennel tea (containing (E)-anethole) has shown in vivo estrogenic effects in humans (Türkyilmaz et al 2008). Oral doses of 50, 70 and 80 mg/kg of (E)-anethole, given to pregnant albino Charles Foster rats on gestational days 1–10, resulted in 33.3%, 66.6% and 100% reduction in implantation, respectively. It is suggested that this may be related to a disruption of hormonal balance. Given at 80 mg/kg/day for three days, (E)-anethole caused a significant increase in uterine weight in immature female rats, suggesting an estrogenic action (Dhar 1995). These results were not supported in an earlier study, in which female Crl:CD BR rats were given (E)-anethole at 25, 175 or 350 mg/kg by gavage for 7 days prior to mating and until day four of lactation. There was no reproductive toxicity at the lower doses, while some increase in mortality, stillbirths and reduction in body weight at birth was seen in the high dose group (ARL 1992, cited in Newberne et al 1999). In a four generation reproduction study, (E)-anethole was given at 1% in the diet to male and female rats from weaning to 3 months of age. No treatment-related adverse effects were observed in any generation (Le Bourhis 1973a, cited in Newberne et al 1999). Hepatotoxicity: Rompelberg et al (1993) reported that 125 or 250 mg/kg/day (E)-anethole by gavage for 10 days had no effect on total CYP content of rat liver microsomes, nor on the levels of EROD and PROD. Reed & Caldwell (1992) found that 300 mg/kg/day ip of (E)-anethole for 7 days caused a 45% increase in microsomal CYP in rats, and dietary administration at 0%, 0.25%, 0.5% or 1.0% caused a dose-dependent increase which was statistically significant at the two higher doses. Considering the results of both studies, it seems that lower doses have little or no effect. (E)-Anethole is dose-dependently cytotoxic to rat liver cells in culture, and causes glutathione depletion. Both these effects are seen at high doses, and are due to anethole 1′,2′-epoxide (AE), a reactive metabolic intermediate (Marshall & Caldwell 1992, 1993). In rats, dietary (E)-anethole has no adverse effect at 0.25% in the diet, causes mild hepatic changes at 0.5%, mostly enzyme induction of no pathological consequence (Newberne et al 1989). Hepatotoxicity caused by (E)-anethole is primarily due to AE, and female Sprague Dawley rats metabolize more (E)-anethole to AE than either mice or humans. At low levels of exposure, (E)-anethole is efficiently detoxified in rodents and humans primarily by O-demethylation and omega-oxidation, respectively, while epoxidation is only a minor pathway. At high doses in rats, particularly females, a metabolic shift occurs resulting in increased epoxidation and formation of AE. Lower activity of the ‘fast acting’ detoxication enzyme epoxide hydrolase in females is associated with more pronounced hepatotoxicity compared to that in males (Newberne et al 1999). Mutagenicity and genotoxicity: (E)-Anethole was mutagenic in the Ames test, but not in the Bacillus subtilis DNA repair assay without S9 (Sekizawa & Shibamoto 1982). It was mutagenic in a mouse lymphoma assay but not in the Ames test (Hsia et al 1979; Mortelmans et al 1986; Gorelick 1995). AE has also been reported as both mutagenic and non-mutagenic in Ames tests (Marshall & Caldwell 1993; Kim SG et al 1999). UDS assays in rat hepatocytes with (E)-anethole have been either inconclusive or negative (Müller et al 1994; Marshall & Caldwell 1996). There is, at most, a low level of genotoxic activity (Phillips et al 1984; Randerath et al 1984; Howes et al 1990) but no significant carcinogenicity (Miller et al 1983; Truhaut et al 1989). (E)-Anethole inhibited the actions of various genotoxic compounds given by gavage to mice at doses of 40–400 mg/kg, and in one case, exerted a protective effect (Abraham 2001). Carcinogenic/anticarcinogenic potential: When (E)-anethole was fed to mice at 0.46% in the diet for 12 months, there was no increase in tumors after 18 months, unlike mice fed similar doses of safrole or estragole (Miller et al 1983). One metabolite, 3’-hydroxyanethole, is not carcinogenic (Miller et al 1983). However, AE induced hepatomas and papillomas in mice (Kim SG et al 1999). In rats, 1% dietary (E)-anethole was associated with a low level of hepatocellular neoplasms. However, the slightly increased tumor incidence was seen in only the highest dose group of female rats, not in male rats, and also not in mice. (E)-Anethole is metabolized similarly in mice and humans (Newberne et al 1989). In a novel assay for carcinogens, groups of male rats were dosed for 2, 14 or 90 days with 0.2 or 2.0 mmol/kg/day (296 mg/kg/day) of (E)-anethole, and hepatic tissue was analyzed for precancerous changes in gene expression. The results strongly suggest that (E)-anethole is not hepatocarcinogenic in male rats (Auerbach et al 2010). (E)-Anethole was cytotoxic to the leukemic cell lines K562 and U937, reaching 77% and 82% cell death, respectively, at 10 mM (1.48 g/L) (Duvoix et al 2004). At oral doses of 0.50 and 1.00 g/kg, (E)-anethole caused significant reductions in the size and weight of Ehrlich ascites tumors in the mouse paw (Al-Harbi et al 1995). In male and female mice given 24 ip injections of (E)-anethole in impure tricaprylin in a total dose of 2.4 or 12.0 g/kg over 24 weeks the incidence of primary lung tumors was no higher than in the control group (Stoner et al 1973). The anticarcinogenic action of (E)-anethole may be due to the promotion of detoxifying enzymes. It also targets various transcription factors that inhibit uncontrolled cell growth. For example, it inhibits TNF-induced cellular responses, such as NF-κB activation (Chainy et al 2000). The results of a gene expression study suggest potent anticarcinogenic and antimetastatic activity for (E)-anethole (Choo et al 2011). Summary: The continuous dietary intake of high doses of (E)-anethole (i.e. cumulative exposure) induces a continuum of cytotoxicity, cell necrosis and cell proliferation in rodents. In chronic dietary studies in rats, hepatotoxicity was observed when the estimated daily hepatic production of AE exceeded 30 mg/kg body weight. In female rats, chronic hepatotoxicity and a low incidence of liver tumors were reported at a dietary intake of 550 mg (E)-anethole/kg/day. Under these conditions, daily hepatic production of AE exceeded 120 mg/kg body weight (Newberne et al 1999). (E)-Anethole inhibits platelet aggregation. The weight of evidence supports the conclusion that (E)-anethole is not genotoxic, and that hepatocarcinogenic effects in the female rat occur via a non-genotoxic mechanism and are secondary to hepatotoxicity caused by continuous exposure to high hepatocellular concentrations of AE (Newberne et al 1999). (E)-anethole undergoes efficient metabolic detoxication in humans at low levels of exposure. There is evidence of a weak estrogenic action, but there is some doubt about what would be a safe dose in humans. Regulatory guidelines: JECFA has set an ADI of 2 mg/kg bw for (E)-anethole (JECFA 1998). (E)-Anethole has has been given GRAS status based on its use as a flavoring agent. In reviewing the compound’s GRAS status the FEMA expert panel cited, among other considerations, the (E)-anethole NOAEL of 120 mg/kg/day in the female rat reported in a 2 + year study which produces a level of AE (i.e., 22 mg AE/kg body weight/day) at least 10,000 times the level (0.002 mg AE/kg body weight day) produced from the intake of (E)-anethole from use as a flavoring substance (Newberne et al 1999). However, this review does not cite the paper by Dhar (1995), in which 50 mg/kg of (E)-anethole had an anti-implantation effect in pregnant rats. Our safety advice: We consider that there is sufficient evidence of an estrogenic action for (E)-anethole, and that administration of essential oils containing a high proportion of it should be avoided by any route in pregnancy, breastfeeding, endometriosis and estrogen-dependent cancers. Because of its antiplatelet aggregation activity, oral dosing of essential oils high in (E)-anethole is cautioned in conjunction with anticoagulant drugs, major surgery, childbirth, peptic ulcer, hemophilia or other bleeding disorders (see Box 7.1 for more detail). Synonyms: cis-Anethole. p–cis-Propenylanisole Systematic name: (Z)-4-Methoxy-(1-propenyl)benzene Chemical class: Phenylpropenoid ether Note: This isomer is significantly more toxic than the common (E)-isomer. Acute toxicity: The ip LD50 values of (Z)-anethole were 135 mg/kg in mice and 93 mg/kg in rats (Boissier et al 1967). Carcinogenic/anticarcinogenic potential: Unlike α-asarone or β-asarone, four ip injections of 90% (Z)-anethole/10% (E)-anethole given prior to weaning did not cause hepatomas to develop in mice after 18 months (Wiseman et al 1987). Synonyms: Anisaldehyde. Anisic aldehyde Systematic name: 4-Methoxybenzaldehyde Chemical class: Benzenoid ether aldehyde Pharmacokinetics: Anisaldehyde is metabolized by glucuronide conjugation in rabbits, and is also metabolized to anisic alcohol and anisic acid in rats (Scheline 1991). Anisaldehyde prolongs the pentobarbital-induced sleeping time in rats, probably by modulating the barbiturate’s metabolism by CYP (Marcus & Lichtenstein 1982). Adverse skin reactions: Tested at 10% on human subjects, anisaldehyde was neither irritating nor sensitizing. (Opdyke 1974 p. 823–824). Acute toxicity: Acute oral LD50 in rats 1.51 g/kg, 1.26 in guinea pigs (Jenner et al 1964), acute dermal LD50 in rabbits > 5 g/kg (Opdyke 1974 p. 823–824). Subacute and subchronic toxicity: Given to rats in the diet for 15 weeks, 10,000 ppm anisaldehyde produced no effects, nor did 1,000 ppm for 28 weeks (Hagan et al 1967). Mutagenicity and genotoxicity: Anisaldehyde inhibited the mutagenic activity of compound 4-NQO in a hamster cell line at 0.2–1.0 g/L (Kim et al 2001), and was not mutagenic in the Ames test (Ishidate et al 1984; Kasamaki et al 1982; Florin et al 1980). It has been reported as non-genotoxic, weakly genotoxic and antigenotixic in tests using cultured Chinese hamster cells (Kasamaki et al 1982; Ishidate et al 1984; Imanishi et al 1990). In mouse bone marrow cells, anisaldehyde reduced CA induced by X-rays (Sasaki et al 1990). Carcinogenic/anticarcinogenic potential: Anisaldehyde inhibited the growth of human lung, liver and stomach carcinoma cells at similar concentrations (Kim et al 2001). It also inhibited the activation of carcinogenic nitrosamines in mouse hepatic and pulmonary microsomes (Morse et al 1995). Comments: Anisaldehyde may be an oxidation product rather than a true constituent of essential oils. Summary: There are currently no safety concerns associated with anisaldehyde. Systematic name: 4-Methoxybenzyl alcohol Chemical class: Benzenoid ether alcohol Note: Can also be present in vanilla absolute. Adverse skin reactions: In a modified Draize procedure on guinea pigs, anisyl alcohol was non-sensitizing when used at 10% in the challenge phase (Sharp 1978). There were no positive reactions when anisyl alcohol was tested at 5% on 115 dermatitis patients (Remaut 1992). In other European studies, 1/1,503, and 1/2,004 dermatitis patients (total reactions 0.06%) tested positive to 1% anisyl alcohol (Heisterberg et al 2011, Schnuch et al 2007a). Of 167 dermatitis patients suspected of fragrance sensitivity 3 (1.8%) reacted to 5% anisyl alcohol on patch testing (Larsen et al 1996b). When tested at 5% on 20 fragrance-sensitive dermatitis patients, anisyl alcohol induced 4 (20%) positive reactions (Larsen 1977). Acute toxicity: Acute oral LD50 values of 1.34 g/kg for rats, and 1.78 g/kg for mice have been reported (Adams et al 2005c). Mutagenicity and genotoxicity: Anisyl alcohol was not mutagenic in S. typhimurium strain TA100 (Ball et al 1984). Carcinogenic/anticarcinogenic potential: Anisyl alcohol was not carcinogenic in male mice when a total dose of 3.75 μmol (518 μg) was injected ip in increasing doses on days 1, 8, 15 and 22 prior to weaning (Miller & Miller 1983). Comments: In a review of the data, including some not cited here, Hostýnek and Maibach (2003a) conclude that, due to various flaws in the research, there is no convincing evidence that anisyl alcohol has a significant skin sensitizing potential. Since anisyl alcohol is found in only one essential oil, at 0–3.5%, the matter is somewhat academic in our context. Systematic name: 1-(2-Propenyl)-2,3-dimethoxy-4,5-methylenedioxybenzene Chemical class: Bicyclic phenylpropenoid ether Note: Sensitive to decomposition on storage. Mutagenicity and genotoxicity: Dill apiole has a very low level of genotoxicity (Phillips et al 1984; Randerath et al 1984). Carcinogenic/anticarcinogenic potential: Dill apiole was not carcinogenic in male mice when a total dose of 4.75 μmol (1.05 mg) was injected ip in increasing doses on days 1, 8, 15 and 22 prior to weaning (Miller & Miller 1983). Synonyms: Apiole. Parsley apiol. Parsley camphor. Apioline Systematic name: 1-(2-Propenyl)-2,5-dimethoxy-3,4-methylenedioxybenzene Chemical class: Bicyclic phenylpropenoid ether Note: Sensitive to decomposition on storage. Pharmacokinetics: Metabolism involves extensive oxidation in both rabbits and dogs (Scheline 1991). Acute toxicity: When 12 mice were administered a single gavage dose of 10 mL/kg parsley apiole, all died within 60 hours. There were gross and microscopic signs of liver and kidney toxicity (Amerio et al 1968). Subacute and subchronic toxicity: The lowest total dose of parsley apiole causing death in adult humans is 4.2 g (2.1 g/day for 2 days) (D’Aprile 1928); the lowest fatal daily dose is 770 mg, which was taken for 14 days (Lowenstein & Ballew 1958); the lowest single fatal dose is 8 g (Barni & Barni 1967). At least 19 g has been survived (D’Aprile 1928). Common symptoms of parsley apiole poisoning are fever, severe abdominal pain, vaginal bleeding, vomiting and diarrhea (D’Aprile 1928; Amerio et al 1968). In the majority of cases, post-mortem examination reveals considerable damage to both liver and kidney tissue, often with gastrointestinal inflammation and sometimes damage to heart tissue (Lowenstein & Ballew 1958; Amerio et al 1968; Colalillo 1974). In one case, contamination of parsley apiole with triorthocresyl phosphate is believed to have contributed to the death of the patient (Hermann et al 1956). Such contamination was not unknown in the 1930s and 1940s, and would generally cause severe neurotoxicity (Lowenstein & Ballew 1958). Reproductive toxicity: Parsley apiole and various preparations of parsley have been used for many years to procure illegal abortion in Italy (Barni & Barni 1967; Marozzi & Farneti 1968; Colalillo 1974). In one fatal case, a woman in her seventh month of pregnancy ingested 14 capsules of parsley apiole (300 mg of apiole per capsule) over 2 days. On the third day, she experienced violent abdominal pains with diarrhea, vomiting and vaginal bleeding. The fetus was expelled with severe menorrhagia. Her cardio-renal signs deteriorated rapidly, with signs of nephritis. The patient’s cardiac function decreased, she became comatose and died (D’Aprile 1928). Out of five cases, all of whom were between two and seven months pregnant, one aborted and later died, one did not abort but died, and three aborted and survived (D’Aprile 1928). In the case which did not abort, the fetus was dead. Post-abortive vaginal bleeding, sometimes profuse, is a feature of these cases. A cumulative effect is apparent, parsley apiole being taken daily for 3–8 days before either death or abortion ensued. One of the cases cited had traces of parsley apiole in her urine 12 days after the last ingestion. Other researchers reported similar cases of apiole intoxication, such as that of a woman who consumed 6 g of parsley apiole over 3 days, aborted, and later died, having suffered massive internal bleeding, convulsions, oliguria and pyrexia (Laederich et al 1932). The lowest daily dose of parsley apiole that induced abortion was 900 mg taken for 8 consecutive days. The inevitable conclusion is that apiole-rich essential oils present a high risk of abortion if taken in oral doses. External use would also seem inadvisable in pregnancy. In animal studies, considerably higher doses of parsley apiole appear to be tolerated. In pregnant guinea pigs, abortion did not occur except at lethal doses, around 2 g (D’Aprile 1928). In pregnant rabbits, abortion was induced by doses of 5–14 g, with severe hemorrhage (Patoir et al 1936). In both types of animal, the dose is equivalent to ~ 100–200 g in a human. This is 20–40 times higher than the amount of apiole causing abortion in humans, and highlights the poor correlation between animals and humans in this area. Carcinogenic/anticarcinogenic potential: Parsley apiole reacts only weakly with DNA and is not associated with tumor development (Phillips et al 1984). It was not carcinogenic in male mice when a total dose of 4.75 μmol (1.05 mg) was injected ip in increasing doses on days 1, 8, 15 and 22 prior to weaning (Miller et al 1983). Parsley apiole is cytotoxic to cells for myelogenous leukemia (K562, IC50 24.1 μg/mL), non-small cell lung cancer (NCI-H460, IC50 43.0 μg/mL) and breast cancer (MCF-7, IC50 36.0 μg/mL) (Di Stefano et al 2011). Our safety advice: The human data suggest that apiole possesses a similar degree of oral toxicity to humans as does pulegone. The lowest single fatal dose of pennyroyal oil is one tablespoon (15 mL, corresponding to 9–12 mL of pulegone), while the lowest single fatal dose of parsley apiole is 8 g (corresponding to approximately 9 mL). Therefore, we recommend a daily oral maximum dose for parsely apiole of 0.4 mg/kg for toxicity, equivalent to 28 mg for an adult. This oral maximum is equivalent to a dermal maximum of 0.76% (Table 14.1)
Constituent profiles
Isomers
Constituent profiles A–Z
Acetophenone
Alantolactone
Allyl isothiocyanate
(Z)-Ambrettolide
(E)-Anethole
(Z)-Anethole
p-Anisaldehyde
Anisyl alcohol
Apiole (dill)
Apiole (parsley)
Constituent profiles
