Fennel, fenchone

Fenchone, Cj Hj O, is found in fennel oil and in the oil of Lavandula Stoechas, in its deirtro-rotatory form, and as laevo-fenchone in oil of thuja leaves. It can be extracted from these oils by treating the fraction boiling at 190° to 195° with nitric acid, or permar anate of potassium, and then steam distilling the unaltered fenchone. 

Mention has already been made of the fact that thujone and fenchone do not react with sodium sulphite consequently the method is useless for tansy, thuja, wormseed, and fennel oils. 

The two enantiomers of fenchone occur in a number of essential oils. Optically pure (15) (-f)-fenchone has been detected in bitter fennel oil Foeniculum vulgare var. vulgare) and in sweet fennel oil F. vulgare var. dulce) from various sources.It has also been reported to exist in... 

Fenchon (l,3,3 Trimethyl-2-norcamphanone), CtoHjoO mw 152.23 colorless oil with camphor-like odor, sp gr 0.9465 at 19°, fr p 5-6°, bp 193—95° insol in w, v sol in ale or eth. This ketone is found as dextro-fenchone in oil of fennel, and as levo-fenchone in oil of tuja. It is a solvent for NC forming a molecular compd in solns and has been used as moderator and gelatinizing agent in single-base or double-base proplnts Refs 1) Beil 7, 96 2) C. Claessen, USP... 

Fenchone is used to prepare artificial fennel oils and to perfume household products. 

Bitter fennel Foeniculum vulgare MU , subsp. vulgare var. vulgare ( )-Anethole (55-75), fenchone (12-26), limonene (1-5)... 

Foeniculum officinale All. F vulgare Mill. Xiao Hui Xiang (Fennel) (fruit) Anethol, d-fenchone, anisaldehyde, methylchavicol.33 Restore normal functioning of the stomach. 

Fennel Foeniculum vulgare (Umbelliferae/ Apiaceae) ripe fruit 2-5 anethole (50-70) fenchone (10-20) estragole (3-20) flavour, carminative, aromatherapy... 

Fennel oil contains anethole and fenchone, which reduce bloating and in higher concentrations act as antispasmodics. 

In a comparative study on hydrodistillation and supercritical C02 (SC-COJ extraction of ground fennel seeds, the former possessed a less intense fennel seed aroma than extracts obtained by SC-C02 from organoleptic tests (Damjanovid et al., 2005). Optimal conditions of SC-C02 extraction (high percentage of trans-anethole, with significant content of fenchone and reduced content of methylchavicol and... 

The root essential oil contains (on average) a-pinene (1.0%), p-cymene (0.3%), /f-lenchyl-acetate (1.0%), trans-anethole (1.6%), eugenol (0.2%), myristicin (3%) and dillapiole (87%). On the other hand, the root and bulbous stem base of Florence fennel contains less than 1% of dillapiole but 70% of trans-anethole, giving a very different taste. The herbage contains 1.00—2.55% essential oil, up to 75% of which is trans-anethole. Anethole and fenchone... 

The metabolism of 7-endo-fenchol to ci-fenchone in fennel has been studied in quite some detail by Croteau and co-workers (Croteau and Felton, 1980). Croteau et al. (1980a) later reported a soluble enzyme preparation from the leaves of fennel which catalysed the cation-dependent cyclization of both geranyl pyrophosphate and neryl pyrophosphate to the bicyclic rearranged monoterpene 1-enc/o-fenchol. Croteau et al. (1980b) found that (+)-(lS)-fenchone, an irregular bicyclic monoterpene ketone thought to be derived... 

Many techniques are followed to identify and quantify the components of fennel essential oil. Krizman et al. (2006) developed a headspace-gas chromatography method for analysing the major volatile constituents in fennel fruits and leaves — a-pinene, a-phellandrene, limonene, fenchone, estragole and trans-anethole. 

This is distilled from the fruit of F. dulce, its main constituents being limonene (20-25%), fenchone (7-10%) and transanethole (4—6%). Arctander (1960) placed the oil in the sweet, non-floral, candy-flavoured group. In the USA, the regulatory status generally recognized as safe has been accorded to fennel oil, GRAS 2481, and sweet fennel oil, GRAS 2483. 

In summary, Foeniculum is stated to have three species, F. vulgare (fennel), F. azoricum Mill. (Florence fennel) and F. dulce (sweet fennel). Fennel is widely cultivated, both in its native habitat and elsewhere, for its edible, strongly flavoured leaves and seeds. The flavour is similar to, but milder than, that of anise and star anise. Anethole and fenchone are the major constituents of the solvent extract of seed phenols, free fatty acids, carbohydrates, proteins, vitamins and minerals have been reported in varying proportions. In the mature fruit, up to 95% of the essential oil is located in the fruit, greater amounts being found in the fully ripe fruit. Approximately 45 constituents have been determined from fennel seed oil, the main constituents being frans-anethole, fenchone, estragol (methyl chavicol), limonene, camphene, a-pinene and other monoterpenes, fenchyl alcohol and... 

Croteau, R., Felton, M. and Ronald, R.C. (1980a) Biosynthesis of monoterpenes conversion of the acyclic precursors geranyl pyrophosphate and neryl pyrophosphate to the rearranged monoterpenes fenchol and fenchone by a soluble enzyme preparation from fennel (Foeniculum vulgare). Archives of Biochemistry and Biophysics 200(2), 524-533. 

Cyclopentane bicyclic monoterpenoids that occur in the plant kingdom belong to three major skeletal types camphane, iso-camphane, and fenchane (Fig. 7). Camphane-type terpenoid alcohols, (+)-bomeol (Gl) and (—)-isobomeol (G2), have been isolated from Cinnamomum camphora (Lauraceae) and Achillea filipendulina (Asteraceae). A ketone derived from these, (-h)-camphor (G3), is found in the camphor tree Cinnamomum camphora) and in the leaves of rosemary Rosmarinus officinalis) and sage Salvia officinalis, Labiatae). Camphene (G4) and its enantiomer with the isocamphane carbon skeleton are known to occur in the oils of citronella and turpentine. Fenchane-type bicyclic cyclopentane monoterpenoids are commonly found in plants as their ketone derivatives. (—)-Fenchone (G5) occurs in the tree of life Thuja occidentalis, Cupres-saceae). Its enantiomer, (+)-fenchone (G6), has been isolated from the oil of fennel Foeniculum vulgare, Umbelliferae). 

Camphene is a solid terpene. The dextro variety d-camphene is found in camphor, ginger and spike oils, and the levo variety, 1-camphene is in citrondla and valerian oil and in French and American turpentine. Bornylene does not occur in nature but has been prepared from the alcohol corresponding to it known as Borneol or Borneo camphor. This, as previously stated, may be prepared from pinene so that Bornylene itself may be made from pinene. Fenchene, also, is not found in nature but is obtained by reduction of fenchone a terpene ketone found in fennel oil and in Thuja oil. 

Thujone, Fenchone.—Two other ketone derivatives are known, viz., thujone and fenchone. They occur together in thuja oil. Thujone is present also in tansy wormwood and sage oils while fenchone is found in fennel oil. Without taking up the proofs for the constitution of these two ketones we may give their formulas as below ... 

Fennel Oil (Foeniculum vulgare) You can check out Table II in the Anethole section for a good composite of bitter and sweet fennel oils. An even better reference can be seen Table XIX which is the consolidated data of a global survey of fennel seed oil with the sole objectives for quantification being the fenchone, anethole and methyl chavicol contents [2, vol. V,p. 133]. 

The oil varies to a considerable extent according to its origin. The chief constituent of the sweet fennel oil is anethole, to which the taste is due, but, as is frequently the case, even when, as in this oil, the percentage of the chief constituent is as high as 80 to 90 per cent, the taste is modified by the presence of small quantities of other substances, (Compare cassia, and cinnamon, cloves and pimento) fenchone, for example, giving it a camphoraceous odour. 

Japanese fennel fruits somewhat resemble those of anise in appearance, but are more oblong and do not taper to the apex. Umney Pharm. J. 1896, 57, 91) obtained 2.7 per cent of pale yellow oil with the odour of sweet fennel. The solidifying-point was 7° C., melting-point 10°. When fractionated, the following fractions were obtained below 220°, 26 per cent 220-225°, 32 per cent 225-230°, 34 per cent residue, 8 per cent. According to Umney, this oil probably contains 75 per cent of anethole 10 per cent of fenchone (by reduction and acetylisation), with some pinene and dipentene it is not stated how the last two were identified. 

Fennel oils are composed mainly of phenylpropane derivatives, the different anethol isomers making up 60-80% of the oil, followed by fenchone, a bicyclic monoterpene lactone making up 10-35%, and monoterpene hydrocarbons, mainly limonene, with a content of up to 10%. 

Since 2005, the Eur. Pharm. has changed its monograph for Anisi aetheroleum by limiting the source of the oil to Pimpinella anisum L. (formerly P. anisum and Illicium vemm Hook). In general, the monograph conforms with the ISO standard, supplemented by the limitation for foeniculin (max. 0.01%, adulteration with star anise oil) and fenchone (max. 0.01%, mixing or adulteration with fennel oil). 

Composition E-anethole (bitter fennel 55-75%, sweet fennel 80-95%), fenchone (bitter fennel 12-25%, sweet fennel below 1%), methyl chavicol (2-6%), limonene, a-pinene, a-phellandrene, cis-anethole and anisic aldehyde. For further constituents see [99,100]. Ravid et al. ]101] employed chirality GC to prove that enantiomerically pure (-i-)-fenchone is present in fennel oil. 

Foeniculum vulgare Hill (Fennel) Fruits SD 4.0 anethole, fenchone 33,34... 

FENNEL FRUIT Foeniculi fructus The schizocarpic fruit of Foeniculum vul tare, Mill., family Apiaceae, which is a herbaceous plant, endemic to the Mediterranean aera. The fennel fruit contains 2-6% volatile oil, FomicuU aetherokum, which has a bitter camphor-like taste of the optically active (-1-) fenchone (called BITTER FENNEL, Foeniculi amari fructus,) with minimum 60% anethole and 15%, fenchone, and the SWEET FENNEL, Foeniculi dulcis fructus, with trans-anethole 80%. 

Figure 6. Fennel 1 - a-pinene, 2 - P-myrcene, 3 - limonen, 4 - fenchon, 5 - estragol, 6 - trans-anethol.

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