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Multivariate Statisdcal Analysis of the Variability ofEssential Oils from the Leaves of Eucalyptus torellianaAcclimatised in Congo-BrazzavilleThomas Silou a , Aubin Nestor Loumouamou a , Armand Roger Makany a , Faustin Dembi a ,Gilles Figuérédo b & Jean-Claude Chalchat ca Equipe Pluridisciplinaire de Recherche en Alimentation et Nutrition (EPRAN), Pôled’Excellence Régional AUF , BP 389 , Brazzaville , Congob LEXVA Analytique, 460 rue du Montant, 63110 BeaumontAVAHEA , 38 avenue deClémensat , 63540 , Romagnat , Francec Laboratoire de Chimie des Hétérocycles et des Glucides, Chimie des Huiles Essentielles,Campus des Cézeaux , 63177 , Aubiére , France AVAHEA , 38 avenue de Clémensat , 63540 ,Romagnat , FrancePublished online: 12 Mar 2013.

To cite this article: Thomas Silou , Aubin Nestor Loumouamou , Armand Roger Makany , Faustin Dembi , Gilles Figuérédo& Jean-Claude Chalchat (2010) Multivariate Statisdcal Analysis of the Variability of Essential Oils from the Leaves ofEucalyptus torelliana Acclimatised in Congo-Brazzaville, Journal of Essential Oil Bearing Plants, 13:4, 503-514, DOI:10.1080/0972060X.2010.10643855

To link to this article: http://dx.doi.org/10.1080/0972060X.2010.10643855

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Multivariate Statistical Analysis of the Variability of Essential Oils from theLeaves of Eucalyptus torelliana Acclimatised in Congo-Brazzaville

Thomas Silou 1*, Aubin Nestor Loumouamou 1, Armand Roger Makany 1

Faustin Dembi 1, Gilles Figuérédo 2 and Jean-Claude Chalchat 3

1 Equipe Pluridisciplinaire de Recherche en Alimentation et Nutrition (EPRAN),Pôle d’Excellence Régional AUF, BP 389, Brazzaville, Congo

2 LEXVA Analytique, 460 rue du Montant, 63110 BeaumontAVAHEA,38 avenue de Clémensat, 63540 Romagnat, France

3 Laboratoire de Chimie des Hétérocycles et des Glucides, Chimie des HuilesEssentielles, Campus des Cézeaux, 63177, Aubière, France AVAHEA,

38 avenue de Clémensat, 63540 Romagnat, France

Abstract: Hydrodistillation of leaves from the Eucalyptus torelliana tree native to Australiaand acclimatised to Congo-Brazzaville gave essential oils with an average yield of about 0.3 %. Toevaluate the variability of their chemical composition, 19 samples were studied. In these, 97 constituentswere detected of which 69 were identified. Two profiles were found, one rich in terpene hydrocarbons(α-pinene, caryophyllene and aromadendrene), and one rich in oxygenated sesquiterpenes(caryophyllene oxide, globulol and viridiflorol). The essential oils studied were composed essentiallyof the same constituents in contrasting proportions, and formed a relatively homogeneous population.Distinction between the two types was essentially due to constituent contents in oils.

Key words: Eucalyptus torelliana, essential oil, α-pinene, caryophyllene,aromadendrene, caryophyllene oxide, globulol, viridiflorol, Congo-Brazzaville.

Introduction: The Eucalyptus genus contains more than 630 species, for the majority,of Australia. The eucalyptus were planted for commercial purposes in different countries, inparticular in Brazil, China, India, Sri Lanka and Africa (South Africa, Burundi, Congo, Mali,Morocco, Madagascar)1. In Congo, about sixty species (divided into 7 sub-genera:Syphyomyrtus, Corymbia, Monocalyptus, Telocalyptus, Blakela, Eudesmia and Idiogenes)were submitted to acclimatization tests for forest setting, wood production and fight againsterosions. The introduction of these species, from Australia, was done in a progressive waybetween 1953 and 1986 2,3,4 .

ISSN 0972-060X

*Corresponding author (Thomas Silou)E- mail: < eprancongo@yahoo.fr >

Jeobp 13 (4) 2010 pp 503 - 514 503

Received 11 April 2009; accepted in revised form 18 December 2009

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Experimental plantations (300 ha) were setting up at Pointe Noire (Congo) for thepreservation of this genetic resources. Brézard 3 and Vigneron 2 works gathered biologicaldata, but no systematic study of yield and composition of essential oils is available. Since lastten years, a screening of the essential oils of this Eucalyptus species acclimatized in theCongo-Brazzaville progress in our laboratory. It concern yield and composition of Eucalyptuscitriodora, E. torelliana, E. maculata, E. nesophila, E. polycarpa, E. peltata 5. E.acmenoides, E. miniata, E. phaeotrichia and E. papuana 6,7 and E. citriodora x E.torelliana hybids 8. This study compete those avaliable in the literaure for the same speciesacclimatized in africa: Benin 9,10, Mali 11, Morocco 12, Burundi 13 and Rwanda 14.

With a view to diversifying the uses of the eucalyptus forest at Pointe Noire to includenon-timber products, we undertook a systematic assessment of the potential of Eucalyptustorelliana for essential oil production.

ExperimentalPlant material: The species Eucalyptus torelliana acclimatised in Congo Brazzaville

came from the Atherton plateau in Queensland, eastern Australia (latitude 16-19° S, altitude100-800 m). These trees can reach a height of 25-30 m and a diameter of 90 cm, with aregular bole and dense crown.

Eucalyptus torelliana grows on well-drained, sandy, rich volcanic silts in humidtropical climates with an annual rainfall in the range 1000-1500 mm and a mild dry seasonlasting 3 months. This species tolerates minimum temperatures of 10-16°C and a maximumtemperature of about 29°C. Its wood is brown, hard, with high soil-contact durability andgood mechanical qualities, but it presents gum vessels. This species, often planted for itsamenity value (parks, gardens, tree cover, etc.), can give excellent hybrids with Eucalyptuscitriodora. Easy propagation from cuttings (yield about 90 %) and the average sizecharacteristics of the trees (at 64 months with fertilisation: height 10.6 m and diameter29.1 cm at 1.5 m from the ground) 3 show that the species is well-acclimatised to the localconditions at Pointe Noire in Congo-Brazzaville. The 19 trees (30 years old) studied werelocated in the experimental station of the « Unité de Recherche sur la productivité desPlantations Industrielles (UR2PI, Pointe Noire, Congo-Brazzaville) ». Harvests were carriedin 2002 and 2003, in September (dry season) and May (rainy season) to evaluate possiblevariations of yield and composition of leave essential oils. Leaves were harvestedindiscriminately from adult trees. Essential oils were extracted and analysed. Samplescollected in dry season are noted SS and that one collected in rainy season are noted SP.

Extraction of essential oils: The steam distillation set-up used comprised a steamgenerator in the form of a 2-litre round-bottomed flask surmounted by a 2-litre glass reactorcontaining the plant material, connected to a cooling system to condense the distillate.

A volume of 250 mL of water was heated in the generator flask and 50 g of plantmaterial was placed in the reactor. The essential oil was carried away by the steam and thedistillate was condensed by cooling and collected. The oil was separated by decantation.The extraction took 3 hours and was repeated three times 15.

Oil analysis: GC analyses was performed on a Hewlett-Packard 6890 equipped

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with a split/splitness injector (280°C, split ratio 1:10), using DB-5 column (30 m x 0.25 mm,df : 0.25 μm). The temperature program was 50°C (5 min) rising to 300°C at rate of 5°C/min. Injector and detector temperature was 280°C. Helium was used as carrier gas at aflow rate 1 mL/min. The injection of the sample consisted of 1.0 mL of oil diluted to 10 % v/v with acetone. GC-MS was performed on a Hewlett-Packard 5973/6890 system operatingin EI mode (70 eV), equipped with a split/splitness injector (280°C, split ratio 1:20), usingDB-5 column (30 m x 0.25 mm, df : 0,25 μm). The temperature program was 50°C (5 min)rising to 300°C at rate of 5°C/min. Injector and detector temperature was 280°C. Heliumwas used as carrier gas at a flow rate 1 mL/min.

Retention indices of all constituents were determined according Kovats’ method usingn-alkanes as standards. The constituents were identified by comparison of theirKovats’indices with those of literature 17. Identification were confirmed by comparing massspectra of essential oil constituents with those in data banks1 8, 19 and with the stored laboratorymass spectral library.

Statistical treatment: Statistics were processed using the XLSTAT 2006.2 software,which is a Microsoft Excel add-in (www. xlstat.com).

Principal component analysis (PCA) and ascending hierarchical classification (AHC)were used to compress the data and thereby simplify interpretation. PCA is a method forprocessing data that is in the form of a table of individual items (lines) versus quantitativevariables (columns). It allows a large mass of data to be reduced to a more manageable sizeby replacing some of the initial variables by linear combinations of others. These newvariables are termed principal components. They can be taken, under certain conditions, asa best possible reduction of the starting data. PCA is thus a method of data compression. Itenables us to use simple graphics to visualise links between variables and similarities betweenindividuals: a correlation circle for links between variables and the plane formed by the firsttwo principal component axes (F1 and F2) for similarities between individuals.

AHC is used to cluster objects on the basis of their description by a set of variables,or from a matrix describing the similarity or dissimilarity of the objects.

It is an iterative classification method based on a simple principle. We calculate thesimilarity between N objects, starting by grouping the two that minimise a chosen aggregationcriterion. This forms the first class. We then calculate the dissimilarity between this classand the remaining N - 2 objects. We group the first class and the next object that minimisesthe aggregation criterion. Grouping is continued until we obtain a class that includes all theobjects. In this way we construct a binary classification tree called a dendrogram. The treecan then be partitioned in different ways according to purpose.

The XLSTAT 2006.2 software used, besides the plots, provides criteria to check thereliability of the procedure: percentage of variability attributable to the different principalcomponents, correlation matrix for the variables, cosine-squared variables, etc.

Results and discussion: The essential oil contents of 19 samples collected in thedry and rainy seasons were in the ranges 0.0-0.2 % and 0.1-0.5 % respectively. We foundthe production of essential oil of Eucalyptus torelliana to be small in both dry and rainyseasons. The oil contents found were always below 1 %, as in the great majority of the

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species in this genus 7,20. Our previous results on Congolese eucalyptus show that the yeildof hydroditillation of leaves of E. acmenoïdes, E. miniata, E. phaeotrichia, E. papuanaof E. torelliana, E. Nesophila and E. polycarpa is lower than 1 % 5,6,7. E. Maculata oilcontent is higher than 2 %, those of E. Citriodora can reach 6 % 5,7. The values ofrefractive index (n = 1.4616) and optical rotation (+3°2< a <+4°9) obtained are in conformitywith those usually observed for essential oils of Eucalyptus in the literature 1, 20. The 19samples, corresponding to material collected in the dry and rainy season, were analysed; 97compounds were detected, of which 69 were identified. Table 1 gives the list of constituentsidentified. The most important constituents found were: α-pinene, citronellyl acetate, globuloland viridiflorol. Other compounds such as β-pinene, β-caryophyllene, aromadendrene,spathulenol, caryophyllene oxide and α-eudesmol also occurred in relatively large amounts:1- 15 % (Table 2). Figure 1 shows the chromatogram of one essential oil of Eucalyptustorelliana.

Fig 1. Typical chromatogram of an essential oil from leaves of Eucalyptus torellialana

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Inspection of Table 1 reveals that: (i) the first four major constituents (α-pinene, globulol,citronellyl acetate and viridiflorol) show a wide individual variation of amplitude 22< min-max <78 % in the dry season, (ii) the same behaviour is observed in the rainy season forthese major components, except for citronellyl acetate, the content of which falls below 2%, thereby providing an indicator of harvesting season, and (iii) the six minor constituents(individual content <13 % : β-pinene, spathulenol, α-eudesmol, aromadendrene, β-caryophyllene and caryophyllene oxide) have low min-max amplitudes, of the order of 10%, reflecting a narrow variability between trees, irrespective of harvesting season.

The PCA representation of variables and items on the first F1 F2 plane constructedwith the 69 identified constituents, which accounts for only 35 % of the variability, did notsignificantly facilitate interpretation. The same treatment for the 26 constituents occurringat levels of at least 1 % in at least one sample increased the amount of variability accountedfor in the first principal F1 F2 plane (43.2 %) and revealed a very close correlation betweencertain variables (Figure 2). Eliminating closely correlated variables and restricting them tothe first six major constituents (α-pinene, caryophyllene oxide, globulol, viridiflorol, guaioland α-eudesmol) yielded the same representation of the variables, while at the same timeimproving the cumulated proportion of variation accounted for: 64.8 % (Figures 3 and 4).

The representation of individual items on the principal F1F2 plane showed two principalgroups of equal size on each side of the F1 axis, and a small group of three individuals fairlyclose to one of the two principal groups.

Fig. 2. Representation with 26 variables (constituents) byPCA for the first two principal components F1, F2

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Fig 3. Representation with 6 variables (constituents) byPCA for the first two principal components F1, F2

Fig 4. Representation by PCA of individuals, with6 constituents,for the first two principal components F1, F2

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AHC, which automatically classifies items by progressive clustering, gave the sameend result: in particular, we identify the two near-equivalent classes even more clearly(Figure 5). AHC analysis confirmed the classes identified in the PCA. In addition, thismethod provides details on the class structure (Table 3). Class 1 contains 9 objects withsample SP5 as the central object, i.e., the one most representative of the class. It is anessential oil made up mainly of oxygenated sesquiterpenes (viridiflorol, globulol, caryophylleneoxide and spathulenol). Class 2 contains 10 objects with SS7 as central object, made upmainly of terpene hydrocarbons (α-pinene, β-caryophyllene and aromadendrene).

We might have expected a major rainy season type (SP5) and a major dry seasontype (SS7), but the samples of the two seasons were found to be distributed near-evenlybetween the two classes. Hence there was no correlation between the chemical compositionof the oils and the harvest season. We also note that the oils from trees 1, 2, 3 and 5, andfrom trees 6, 7, 8 and 9, fell into the same class. This indicates a stable composition irrespectiveof the harvest period. Only the composition of tree 4 changed significantly between therainy season (class 1) and the dry season (class 2). We also note that none of the trees hadits two oils grouped by AHC, possibly because the compositions were too close, resulting ina close similarity of oils from different trees. We can conclude that the oils studied made upa relatively homogeneous population. Overall, they had the same qualitative composition.The quantitative variation in the constituents gives two chemical profiles with an inversionof the proportions of these constituents in the different oils.

Table 4 presents the oils from the samples in class 2. They are made up of terpenehydrocarbons, and in particular α-pinene, β-caryophyllene and aromadendrene. In theessential oils presented in Table 5 sesquiterpene alcohols predominate over the hydrocarbons,although these are still present in appreciable amounts.

E. torelliana belongs to Corymbia subgenus; and our previous results 5,6,7 on congolesespecies which belongs to this subgenus show that α and β-pinenes are the major constituents

Fig 5. Distribution of individuals by ascending hierarchical clustering

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in E. nesophila, E. polycarpa, following by sesquiterpene alcohol, and respectivly, viridifloroland citronellyle acetate in E. maculata and E. nesophila. Brophy et al.21 works on 30 otherspecies of the Corymbia sub-genus, shows that α-pinene is the major component and E.citriodora is a very typical species in this subgenus.

References1. Boland, J., Brophy, J. and House, A.P. (1991). Eucalyptus leaf oils. Use,

Chemistry, Distillation and Marketing. Inkata Press, Melbourne, Australia.2. Vigneron, Ph. (1987). Les Eucalyptus introduits au Congo, supplément de 1982 a

1986. Note interne CTFT-Congo, 35.3. Gouma, R., Dembi, F.J., Vigneron, Ph. and Saya, A.R. ( 2002). Les Eucalyptus

introduits au Congo de 1987 à 2002, Note interne UR2PI, 53.4. Brézard, J.M. (1982). Les Eucalyptus introduits au Congo de 1953 à 1981. Note

interne CTFT-Congo,5. Silou, T., Loumouamou, A.N., Loukakou, E., Chalchat, J.C. and Figuérédo,

G. (2008). Intra and interspecific variations of yield and chemical composition ofessential oils from five Eucalyptus species growing in the Congo-Brazzaville. Corymbiasubgenus, J. Essent. Oils Res., 21(3): 203-210.

6. Loumouamou, A.N., Silou, T., Loukakou, E. , Chalchat, J.C. and Figuérédo,G. (2007). Rendement et composition des huiles essentielles de Eucalypyusacmenoides et de Eucaluptus miniata aclimatés au Congo-Brazzaville. Annales del’Université Marien Ngouabi 8(4): 94-98.

7. Loumouamou, A.N. (2008).Variabilité chimiques des huiles essentielles d’eucalyptusdu sous genre Corymbia acclimatés au Congo-Brazzaville : Approche statistique, Thèsede Doctorat Université Marien Ngouabi, Brazzavillv 166 p.

8. Loumouamou, A.N, Silou, T., Mapola, G., Chalchat, J.C. and Figuérédo, G.(2009). Yield and composition of essential oils from Eucalyptus citriodora xEucalyptus torelliana, a hybrid species growing in Congo-Brazzaville. J. Essent. OilRes., 21: 295 -299.

9. Sohounhloué, D.K., Dangou, J., Gnomhossou, B., Garneau, F.X., Gagnon, H.and Jean, F.I. (1996). Leaf oils of three Eucalyptus species from Benin: E. torellianaF. Muell., E. citriodora Hook and E. tereticornis Smith. J. Essent. Oil Res., 8: 11-113.

10. Moudachirou, M., Gbénou, J.D., chalchat, J.C., Chabard, J.L. and Lartigue,C. (1999). Chemical composition of essential oils of Eucalyptus from Benin: E.citriodora and E. camaldulensis. Influence of location, harvest time, storage ofplants and time of steam distillation. J. Essent. Oil Res. 11: 109-118.

11. Chalchat, J.C., Garry, R.Ph., Sidibé, L. and Harama, M. (2000). Aromatic Plantsof Mali (V): Chemical composition of Essential oils of four Eucalyptus Speciesimplanted in Mali : E. camaldulensis, E. citriodora, E. torelliana and E. tereticornis.J. Essent. Oil Res., 12: 695-701.

12. Zrira, S.S., Benjilali, B.B., Fechtalv, M.M. and Richard, H.H. (1992). Essentialoils of twenty-seven Eucalyptus species grown in Morocco. J. Essent. Oil Res., 4:259-264.

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13. Dethier, M., Nduwimana, A., Cordier, Y., Menut, C. and Lamaty, G., (1994).Aromatic plants of tropical Central Africa. XVI. Studies on Essential oils of fiveEucalyptus species grown in Burundi.. J. Essent. Oil Res., 6: 469-473.

14. Chalchat, J.C, Ph. Garry, R., Muhayimana, A., Habimana, J.B. and Chabard,J.L. (1997). Aromatic plants of Rwanda. II. Chemical composition of Essential Oilsof Ten Eucalyptus Species Growing in Ruhande Arboretum, Butare, Rwanda. J.Essent.Oil Res.,9 : 159-165.

15. Mapola, G. (2006). Optimisation des conditions de culture de Eucalyptus citriodorapour la production des huiles essentielle, Thèse de Doctorat Univresité marien Ngouabi,Brazzaville, 129 p.

16. AFNOR, (1996). Huiles essentielles, normes françaises, Paris.17. Jemings, W. and Shibamoto, T. (1980). Qualitative analysis of flavour and fragrance

volatiles by glass capillary chromatography. Academic Press New York.18. Adams, R.P. (1995). Identification of Essential Oil Components by Gas Chromato-

graphy/Mass Spectroscopy; Allured Publishing Corporation, Carol Stream, Illinois, USA.19. McLafferty, F.W., Stauffer, D.B. (1989). The Wiley/NBS Registry of Mass Spectral

Data; John Wiley and Sons, New York.20. Coppen, J.J.W. (2002). Eucalyptus: the genus eucalyptus, London.21. Brophy, J.J., Forster, P.I., Goldsack, R.J. and Hibbert, D.B. (1998).The essential

oils of the yellow bloodwood eucalypts (Corymbia, section Ochraria, Myrtaceae).Biochemical Systematics and Ecology. 26(2): 239-249.

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Table 1. List of constituents identified in the 19 samplesof Eucalyptus torelliana collected in the dry and rainy season

1 α-Pinene 24 β-Gurjunene 47 5-epi-7-epi-α-Eudesmol2 β-Pinene 25 Aromadendrene 48 Humulene epoxide II3 myrcene 26 Seline-5,11-diene 49 1,10-Diepicubenol4 para-Cymene 27 α-Humulene 50 iso-Leptospermone5 Limonene 28 allo-Aromadendrene 51 10-epi-γ-Eudesmol6 1,8-Cineole 29 9-epi-(E)-Caryophyllene 52 1-epi-Cubenol7 α-Pinene oxide 30 γ-Gurjunene 53 Eremoligenol8 α-Campholenal 31 β-Selinene 54 γ-Eudesmol9 trans-Pinocarveol 32 Viridiflorene 55 β-Acorenol

10 trans-Verbenol 33 Bicyclogermacrene 56 epi-α-Cadinol11 Citronellal 34 γ-Cadinene 57 epi-α-Muurolol12 α-Terpineol 35 δ-Cadinene 58 α-Muurolol13 Verbenone 36 trans-Calamenene 59 β-Eudesmol14 trans-Carveol 37 α-Calacorene DB5-1744 60 α-Cadinol15 Citronellol 38 Elemol 61 α-Eudesmol16 Isobornyl acetate 39 Lonjipinanol 62 trans-Calamenen-10-ol17 trans-Pinocarvyl acetate 40 Ledol 63 Bulnesol18 Citronellyle acetate 41 Spathulenol 64 Cadalene19 Neryl acetate 42 Caryophyllene oxide 65 (Z,Z)-Farnesol <20 α-Copaene 43 Globulol 66 (E,E)-Farnesol21 Geranyl acetate 44 Viridiflorol 67 (E,Z)-Farnesol22 α-Gurjunene 45 Guaiol 68 (E)-Sesquilavandulyl

acetate23 β-Caryophyllene 46 epi-Globulol 69 Carissone

Table 2. Major constituents in the 19 samples of Eucalyptus torelliana studied

Major constituents dry season content (%) rainy season content (%)

α-Pinene 0.65-55.5 0.1-78.1Citronellyle acetate 10.5-55.5 0.07-1.7Globulol 2.57-24.5 3.5-26Viridiflorol 1.47-34.06 0.38-15.95β-Pinène 0.09-8.31 0.09-12.4Spathulenol 1.2-9.17 0.44-8.41α-Eudesmol 0.45-12.37 0.1-3.87Aromadendrene 0.96-9.19 1.57-6.09β-Caryophyllene 2.4-7.67 0.2-6.69Caryophyllene oxide 0.8-4.75 0.2-11.24

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Table 3. Structures of classes

Class 1 2

Number of objects 9 10Intra-class variance 187.681 1244.214Minimum distance from barycentre 6.686 12.042Mean distance from barycentre 12.092 30.160Maximum distance from barycentre 20.878 55.043

SS 1 SS 4SS 2 SS 6SS 3 SS 7*SS 5 SS 8SP 1 SS 9SP 2 SS 10SP 3 SP 6SP 4 SP 7SP 5* SP 8

SP 9

SS: samples collected in dry season;SP: samples collected in rainy season;

* Central objects

Table 4. Composition (%) of essential oils with predominantterpene hydrocarbons (7 out of 10 objects in class 2*)

Trees ααααα-pinene βββββ-caryophyllene aromadendrene spathulenol globulol

SP6 24.39 4.57 5.41 0.00 5.06SS7 20.26 5.76 6.43 0.00 17.47SS8 17.52 7.67 9.19 9.17 13.02SP7 54.74 12.14 - 1.20 3.40SS4 55.50 8.32 - 2.19 2.57SP9 78.10 7.93 - - -SP9 78.10 7.93 - - -SS6 - - - - -SP8 - - - -

SS10 - - - - -

SS: samples collected in dry seasonSP: samples collected in rainy season*Samples SS6, SP8 and SS10 are misclassified

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Table 5. Composition (%) of essential oils with predominantoxygenated sesquiterpenes (8 out of 9 objects in class 1*)

Trees A B C D E F G H

SP2 - 6.69 4.63 8.41 - 8.35 12.63 3.87SP3 - - 6.03 - 9.08 9.09 7.69 -SP5 2.99 - - 5.77 9.18 9.31 14.5 2.43SP1 5.45 - - - 11.24 10.76 15.95 -SP4 10.2 - - 7.69 10.03 8.24 7.23 -SS3 15.09 6.16 - - 5.54 7.87 12.25 -SS2 24.68 4.82 - - - 6.74 17.58 -SS1 12.51 3.72 - - 3.29 9.75 34.06 -SS5 - - - - - - - -

SS: samples collected in dry season; SP: samples collected in rainy season;* SS5 is misclassified. A: α-Pinene B: β-CaryophylleneC: Aromadendrene D: Spathulenol E: Caryophyllene oxideF: Globulol G: Viridiflorol H: α-Eudesmol

Thomas Silou et al. / Jeobp 13 (4) 2010 pp 503 - 514 514

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