The enantiomeric ratios of camphor have been determined in authentic essential oils, using heptakis(6-O-t-butylsilyl-2,3-di-O-ethyl)-beta-cyclodextrin as the chiral stationary phase. An enantiomeric excess of (1S)-(-) within 72-75% is characteristic of coriander oil (Coriandrum sativum L.). Contrary, an enantiomeric excess of (1R)-(+) characterizes the essential oil of sage (> 90% for Salvia sclarea L. and 50-70% for Salvia officinalis L.) and of basil (> 94% for Ocimum basilicum L.)

E. De Dominicis

F. Tateo

M. Bononi

V. Fumagalli

AIR Universita degli studi di Milano

    C o m m u n i c a t i o nUpdate on enantiomeric composition of (1R)-(+)- and(1S)-(2)-camphor in essential oils by enantioselective gaschromatographyF. Tateo,* M. Bononi, E. De Dominicis and V. FumagalliDepartment of Plant Physiology and Agricultural Chemistry, Agrifood and EnvironmentalAnalytical Chemistry Section, Milan State University, 2 Via Celoria, 20133 Milan, ItalyReceived 19th February 1998, Accepted 12th March 1998The enantiomeric ratios of camphor have been determinedin authentic essential oils, using heptakis(6-O-t-butylsilyl-2,3-di-O-ethyl)-b-cyclodextrin as the chiral stationary phase.An enantiomeric excess of (1S)-(2) within 72–75% ischaracteristic of coriander oil (Coriandrum sativum L.).Contrary, an enantiomeric excess of (1R)-(+) characterizesthe essential oils of sage ( > 90% for Salvia sclarea L. and50–70% for Salvia officinalis L.) and of basil ( > 94% forOcimum basilicum L.).IntroductionStudies by various authors have concentrated on evaluation ofthe enantiomeric distribution of chiral compounds in variousessential oils1–22 and chirality evaluation of some essential oilcompounds has been adopted for quality assurance as anindicator of genuineness.The enantiomeric forms (1R)-(+) and (1S)-(2) of camphorpresent no significant differences from the point of view ofsensorial analysis: both enantiomers present the same profile23characterized by a pungent camphorous smell with a hint ofmintiness and a fresh, bitter taste.24,25Bicchi et al.,26 in particular, have published a review of thechirality subject, relating to the period 1989–1994, but thequotations concerning camphor in the bibliography are verylimited. Kreis and Mosandl,11 using enantioselective multi-dimensional gas chromatography, reported the stereodiffer-entiation of camphor in essential oils of Lavandula species.Experimental papers published to date on the enantiomericratio of camphor concern mainly the essential oils of Cinnamo-mum camphora (L.) by J. Presl, Ocimum canum by Sims,Sassafras albidum (Nutt.) by Nees, in which the enantiomer(1R)-(+)24,25,27 is prevalent, and of Salvia grandiflora, Salviatriloba L., Artemisia herba alba by Asso, and Artemisiaferganensis, Artemisia austrachanica, Lippia adoensis, Blumeabalsamifera, which reveal an enantiomeric excess of (1S)-(2).27,28According to Ravid et al.,10 only (1S)-(2)-camphor ispresent in Chrysanthemum parthenium L., while the speciesSalvia tomentosa Mill. contains (±)-camphor, and Furia andBellanca24 have also encountered camphor with a racemicdistribution in Chrysanthemum japonicum sinense.In three of the six samples of Salvia officinalis L. analyzed,Ravid et al.10 encountered an enantiomeric excess of (1S)-(2)-camphor, and in the other three an excess of the form (1R)-(+). We have carried out further research in this area.Evaluations have therefore been made of camphor in absolutelyreliable essential oils relating to the species Salvia officinalis L.At the same time, evaluations have been made of theenantiomeric distributions of camphor in three other types ofessential oil not referred to, so far, in the bibliography.Identification of the two enantiomeric forms has been madeby various authors with different GC systems and columns (b org-cyclodextrin). With the heptakis(6-O-t-butyldimethylsilyl-2,3-di-O-acetyl)-b-cyclodextrin11 column, the (1S)-(2) form iseluted first, followed by (1R)-(+), while for the octakis(3-O-butyryl-2,6-di-O-pentyl)-g-cyclodextrin (Lipodex E)10,29,30 col-umn, the opposite is true. The experiments referred to here werecarried out with heptakis(6-O-t-butylsilyl-2,3-di-O-ethyl)-b-cyclodextrin as the chiral stationary phase.ExperimentalThe results obtained refer to pure essential oils of Salviaofficinalis L. and Salvia sclarea L., Ocimum basilicum L., andCordiandrum sativum L., obtained from factory-distilled plants,accurately identified by botanists.The essential oils were diluted in ethyl alcohol (10% v/vessential oil–ethyl alcohol), and were subjected to GC chiralanalysis. GC-MS analysis confirmed the peak identity.GC chiral analysis conditionsEnantiomeric ratios of camphor were obtained using a HRGC5160 Mega Series (Carlo Erba Strumentazione, Rodano, Milan,Italy), equipped with a fused-silica capillary column 25 m 30.25 mm id, coated with heptakis(6-O-t-butylsilyl-2,3-di-O-ethyl)-b-cyclodextrin, 0.25 mm film thickness (Mega®,Legnano, Milan, Italy); column temperature, 60 °C (10 min) to120 °C at 3 °C min21, 120 to 230 °C at 4 °C min21; injectortemperature, 200 °C; detector (FID) temperature, 220 °C;injection mode, split; split ratio, 1/20; injection volume, 0.2 ml;carrier gas, H2 0.4 kg cm22.GC MS analysis conditionsAnalyses were performed on a Hewlett-Packard 5971A massselective detector (MSD), equipped with an HP 5890 Series IIgas chromatograph; GC conditions were: an SPBTM-5 fused-silica capillary column, 30 m 3 0.2 mm id, 0.2 mm filmthickness (SUPELCO, Milan, Italy); column temperature, 80 °C(10 min) to 120 °C at 1 °C min21, 120 °C (10 min) to 230 °C at3 °C min21, 230 °C (10 min); injector temperature, 220 °C;injection mode, split; split ratio, 1/20; injection volume, 0.2 ml;carrier gas, He at a constant pressure of 100 3 103 Pa.MS conditions were: GC-MS interface temperature, 280 °C;acquisition parameters, full scan (40–300 u), ionization energy,70 eV.Results and discussionThe results obtained make it possible to acquire the sum datathat had hitherto not been available for basil oil, coriander oil,Anal. Commun., 1999, 36, 149–151 149Downloaded on 10 November 2012Published on 01 January 1999 on http://pubs.rsc.org | doi:10.1039/A901388AView Online / Journal Homepage / Table of Contents for this issueand clary sage oil. Only some of the data obtained to date areconfirmed and concern Salvia officinalis L.Table 1 gives the values of enantiomeric distribution ofcamphor in the essential oil samples analyzed, and Fig. 1 showsthe enantiomeric distribution of camphor in the coriander oilsamples [sample 1, (a)] and basil oil [sample 4, (b)].The essential oils of Salvia sclarea L. present an enantio-meric excess of (1R)-(+) exceeding 90%; the oils of Salviaofficinalis L. also present an enantiomeric excess of (1R)-(+)that is less marked but nevertheless exceeds 50%.Only (1R)-(+)-camphor was found in three of the fivesamples of essential oils of basil analyzed (samples 1,2 and 5),while in the other two, the presence, albeit very limited, of theenantiomer (1S)-(2) was found.In coriander oil, an enantiomeric excess of the form (1S)-(2)was found to be a characteristic.ConclusionsResults concerning enantiomeric excess values obtained by GCchiral analysis of genuine Salvia sclarea L. and Salviaofficinalis L. essential oils with a camphor content extendingover a fairly wide range (0.1–25%), show an enantiomericexcess of the form (1R)-(+)-camphor. The enantiomeric excessvalues, however, seem to be characteristic of the species and,contrary to the results of other authors, have been found toconform to very narrow variability limits.This conclusion is compatible with the biosynthetic pathwayfrom geranyl pyrophosphate (GPP), the last step of which is thetransformation of (1S)-(2)-borneol to (1R)-(+)-camphor by adehydrogenase NAD-dependent.31As regards Ocimum basilicum L. essential oils, with acamphor content below 1%, chiral analysis shows, even in thiscase, an enantiomeric excess of (1R)-(+)-camphor higher than94%.In contrast, results concerning Coriandrum sativum L.essential oils, show an enantiomeric excess of (1S)-(2)-cam-phor with very narrow variability limits.It would seem possible to conclude that even the enantio-meric composition of camphor is a useful factor in assessing thegenuineness, and is a characterizing element, of variousbotanical genuses.References1 F. Tateo, M. Mariotti and M. Bononi, J. Essent. Oil Res., 1998, 10,241.2 F. Tateo and M. Bononi, American Laboratory News, 1997, April,22D.3 F. Tateo, E. Desimoni and M. Bononi, in Wine Nutritional andTherapeutic Benefits, ed. T. R. Watkins, American Chemical Society,Washington, DC, 1997, pp. 94–112.4 F. Tateo and M. Bononi, Chimica analitica degli Aromi, ed. G. M.Ricchiuto, Bussolengo, Verona, 1995, vol. 1, pp. 305–343.5 U. Ravid, Perfum. Flavor., 1998, 23(4), 25.6 U. Ravid, E. Putievsky, I. Katzir, E. Lewinsohn and N. Dudai,Flavour Fragr. J., 1997, 12, 109.7 C. Bicchi, A. D’Amato, V. Manzin and P. Rubiolo, Flavour Fragr. J.,1997, 12, 55.8 U. Ravid, E. Putievsky and I. Katzir, Flavour Fragr. J., 1996, 11,191.9 U. Ravid, E. Putievsky and I. Katzir, Flavour Fragr. J., 1995, 10,281.10 U. Ravid, E. Putievsky and I. Katzir, Flavour Fragr. J., 1993, 8,225.11 P. Kreis and A. Mosandl, Flavour Fragr. J., 1992, 7, 187.12 A. Mosandl and V. Schubert, Z. Lebensm.-Unters.-Forsch., 1990,190, 506.13 A. Mosandl, U. Hener, P. Kreis and H.-G. Schmarr, FlavourFragrance. J., 1990, 5, 193.14 P. Kreis, A. Mosandl and H.-G. Schmarr, Dtsch. Apoth. Ztg., 1990,130, 2579.15 C. Askari, P. Kreis, A. Mosandl and H.-G. Schmarr, Arch. Pharm.,1992, 325, 35.16 C. Askari and A. Mosandl, Phytochem. Anal., 1991, 2, 211.17 V. Schubert and A. Mosandl, Phytochem. Anal., 1991, 2, 171.18 H.-G. Schmarr, A. Mosandl and A. Kaunzinger, J. Microcolumn.Sep., 1991, 3, 395.19 A. Dietrich, B. Maas, V. Karl, P. Kreis, D. Lehmann, B. Weber andA. Mosandl, J. High Resolut. Chromatogr., 1992, 15, 176.20 D. Lehmann, C. Askari, D. Henn, F. Dettmar, U. Hener and A.Mosandl, Dtsch. Lebensm.-Rundsch., 1991, 87, 75.21 V. Karl, H.-G. Schmarr and A. Mosandl, J. Chromatogr., 1991, 587,347.22 A. Mosandl, U. Hener, P. Kreis and H.-G. Schmarr, Flavour Fragr.J., 1990, 5, 193.Table 1 Enantiomeric composition, enantiomeric excess and relativequantity of camphor in authentic essential oils.EnantiomericRelative composition (%)quantity EnantiomericSource (%) (1S)-(2) (1R)-(+) excess (%)Salvia sclarea L.Sample 1 (Italy) 0.1 3.8 96.2 92.4 (1R)Sample 2 (Italy) 0.1 4.9 95.1 90.2 (1R)Salvia officinalis L.Sample 1 (France) 11.8 23.4 76.6 53.2 (1R)Sample 2 (France) 24.9 15.1 84.9 69.8 (1R)Coriandrum sativum L.Sample 1 (Italy) 5.4 86.3 13.7 72.6 (1S)Sample 2 (Italy) 5.1 87.6 12.4 75.2 (1S)Sample 3 (Italy) 5.2 87.0 13.0 74.0 (1S)Ocimum basilicum L.aSample 1 (Italy) 0.9 0 100 100 (1R)Sample 2 (Italy) 0.7 0 100 100 (1R)Sample 3 (Italy) 0.4 2.5 97.5 95.0 (1R)Sample 4 (Italy) 0.5 2.0 98.0 96.0 (1R)Sample 5 (Italy) 0.5 0 100 100 (1R)a Of the basil oil samples analyzed, those of the so-called ‘Genuese type’(samples 1 and 2) show mainly linalool (47–52%) and traces of estragol,while the so-called ‘Neapolitan type’ (samples 3, 4 and 5) show mainlylinalool (47–63%) and between 9 and 12% estragol.Fig. 1 Enantiomer GC separation of camphor isolated from (a) Corian-drum sativum L. and (b) Ocimum basilicum L., using heptakis(6-O-t-butylsilyl-2,3-di-O-ethyl)-b-cyclodextrin as the chiral stationary phase; forfurther conditions, see Experimental section.150 Anal. Commun., 1999, 36, 149–151Downloaded on 10 November 2012Published on 01 January 1999 on http://pubs.rsc.org | doi:10.1039/A901388AView Online23 E. T. Theimer, T. Yoshida and E. M. Klaiber, J. Agric. Food Chem.,1977, 25, 1168.24 Fenaroli’s Handbook of Flavor Ingredients, ed. T. E. Furia and N.Bellanca, CRC Press, Boca Raton, FL, 1975, vol. 2, p. 82.25 K. Bauer and D. Garbe, Common Fragrance and Flavor Material,VCH, Weinheim, 1985, p. 47.26 C. Bicchi, A. D’Amato, V. Manzin and P. Rubiolo, Flavour Fragr. J.,1995, 10, 127.27 J. S. Glasby, Encyclopedia of the Terpenoids, Wiley, Chichester,1982, vol. 1, p. 375.28 Handbook of Terpenoids, ed. S. Dev, CRC Press, Boca Raton, FL,1982, vol. 2, p. 471.29 W. A. König, R. Krebber, P. Evers and G. Bruhn, J. High Resolut.Chromatogr., 1990, 13, 328.30 W. A. König, R. Krebber and P. Mischnick, J. High Resolut.Chromatogr., 1989, 12, 732.31 R. Croteau and J. Shaskus, Archives of biochemistry and biophysics,1985, 236, 535.Paper 9/01388AAnal. Commun., 1999, 36, 149–151 151Downloaded on 10 November 2012Published on 01 January 1999 on http://pubs.rsc.org | doi:10.1039/A901388AView Online

Update on enantiomeric composition of (1R)-(+) and (1S)-(-) camphor in essential oil by enantioselettive gas chromatography

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Update on enantiomeric composition of (1R)-(+) and (1S)-(-) camphor in essential oil by enantioselettive gas chromatography

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