CONCLUSION
Cortical oleoresin of lateral shoots and needle essential oils from four Silver fir (Abies alba Mill.) populations scattered in natural forests in Albania were analysed by GC/MS. Seventy compounds were detected in the needle essential oil while thirty-seven compounds were detected in the cortical oleoresin of all trees. The monoterpenes a-pinene, camphene, b-pinene, limonene and bornyl acetate were the main components of the characteristic chemical profile in essential oil. Three monoterpene - a-pinene, b-pinene and limonene and two sesquiterpenes - b-caryophyllene and germacrene D comprise the majority of cortical oleoresin. Among the provenance's great quantitative differences can be found in the terpene composition. Two different chemical profiles were obtained.
Silver fir, an ecologically valuable and indigenous tree species in many European Mountains forest presently is one of the most important conifers in Albania occupying an area of about 16060 ha or 9.3% of conifer forests.
The taxonomy, distribution and the variation of Albanian fir are not elucidated yet. In the framework of our chemical and biological investigations on the volatile metabolites of Greek endemic and Mediterranean conifers (Roussis et al., 1999; Petrakis and Roussis, 1997) we recently were able to collect and study a significant number of Abies alba growing in Albania.
Materials and methods
Plant material from natural distributions of silver fir forest (Abies alba Mill.) was sampled at four locations: Lumebardhe (Puka district), Liqeni i Zi (Bulqiza district), Drenova - Bozdovec (Korca district) and Llogara (Vlora district). These areas covered a representative sample of the natural population of the species in the country.
The trees selected for this study were in good condition and without visible symptoms of disease or infestation. The sampling criteria were as follows: a] Trees between 15-30 year of age; b] Trees at least 50 m apart; c] Only last year branches were considered.
Cortical rather than xylem oleoresin was sampled. Drops of oleoresin were collected from cortical tissue by excising branch buds at about 10 mm or less from the tips. Exuded oleoresin was diluted with cyclohexane and frozen until they were analysed.
The needles were hydrodistilled in a Clevenger apparatus for three hours. The GC analyses were performed on a Varian 3300 Gas Chromatograph equipped with an on column injector and a flame ionisation detector as well as on a Hewlett Packard 5973-6890 GC-MS system operating in EI mode. The Statistical Package for Social Sciences (SPSS) for windows version 8.0 was used for the statistical analysis.
Cortical oleoresin of lateral shoots and needle essential oil were analyzed by Gas Chromatography/Mass Spectrometry for four populations of European silver fir (Abies alba Mill.) scattered in the area of natural distribution of this species in Albania. Based on the geographical variation observed between the populations and the seasonal variation within the provenances regarding the terpenoids from needle essential oil and cortical oleoresin it was possible to shed light on the chemotaxonomy and adaptation of this species in Albania.
Cortical oleoresin
The results of the GC and the GC/MS analyses revealed the presence of thirty-seven compounds, including mono- and sesquiterpenoids. Thirty-three of these compounds were identified, representing approximately 95-97% of the cortex oleoresin.
Essential oil variability
The chemical composition of European silver fir (A. alba) which is naturally grown in Albania, was found to be similar to that of the same tree growing in the other geographical areas previously reported. These results were consistent with all the previous studies, as regards the importance of major monoterpenes, especially a-pinene, camphene, b-pinene and limonene.
b-Pinene was found to be the most abundant compound in the needle essential oil, representing 14.5% to 31.60% of the total terpene content. This value was slightly higher from that reported by Wolf (1994) for different provenances from Poland (19.6% to 23.6%), former-Czechoslovakia (3.4% to 30.6%), and Southeast Europe (15.4% to 30.9%). However, in other provenances from the Carpathian and Hercynic regions of Poland and Ex-Czechoslovakia, the mean concentration of b-pinene was found to be between 12.8% to 25.2% with a coefficient of variation between 22-120% (Paule et al, 1988). b-Pinene seems to be the principal component in the essential oil of other Abies species such, as A. balsamea, where the mean of b-pinene obtained through solvent extraction varies between 34.2% to 38.9% (Ross et al., 1996) and 45.4% to 48.2% (Regimbal et al., 1994) and A. cilicica spp. isaurica with mean of b-pinene equal to 29% (Ba?ci et al., 1999). Compared with other Abies species grown in the Balkan Peninsula, A. alba has a slightly lower content than A. cephalonica (21.3%) but almost twice that of A. borisii regis. (11.4 %) (Roussis et al., 1999).
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| Tricyclene |
0.04
|
0.06
|
0.03
|
0.01
|
0.00
|
0.00
|
0.07
|
0.02
|
| a -Pinene |
26.28
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42.91
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12.16
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23.09
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35.99
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38.62
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37.33
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47.12
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| Camphene |
0.73
|
0.90
|
0.27
|
0.38
|
0.64
|
0.38
|
0.87
|
0.66
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| b -Pinene |
35.67
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26.65
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14.90
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18.28
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32.58
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29.93
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36.61
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30.00
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| Myrcene |
1.38
|
1.73
|
1.55
|
2.60
|
1.54
|
1.63
|
1.38
|
1.37
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| Limonene |
6.88
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10.18
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35.30
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41.45
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10.22
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10.26
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6.73
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5.46
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| a -Terpinolene |
0.07
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0.02
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0.02
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0.03
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0.11
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0.04
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0.11
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0.05
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| a -Terpinol |
0.09
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0.00
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0.00
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0.00
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0.10
|
0.01
|
0.08
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0.00
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| Linalyl acetate |
0.06
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0.02
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0.00
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0.02
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0.00
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0.00
|
0.08
|
0.00
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| Bornyl acetate |
0.21
|
0.07
|
1.14
|
0.08
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0.02
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0.00
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0.15
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0.09
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|
|
0.55
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0.19
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1.16
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0.20
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0.12
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0.03
|
0.44
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0.13
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| a -Longipinene |
0.30
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0.10
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0.29
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0.05
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0.03
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0.02
|
0.26
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0.04
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| Neryl acetate |
0.19
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0.10
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0.02
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0.10
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0.00
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0.02
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0.13
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0.04
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| E-Caryophyllene |
5.04
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3.60
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8.87
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3.89
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3.87
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3.25
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3.43
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3.65
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| a -Himachalene |
0.29
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0.08
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0.06
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0.01
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0.02
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0.02
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0.26
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0.02
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| UN 1 |
0.12
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0.04
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0.00
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0.00
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0.00
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0.00
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0.04
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0.00
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| a -Humulene |
2.36
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1.75
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3.90
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1.89
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1.85
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1.59
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1.59
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1.79
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| E-b -Farnesene |
0.10
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0.03
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0.00
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0.02
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0.09
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0.03
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0.08
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0.01
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| g -Gurjenene |
0.06
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0.00
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0.01
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0.00
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0.00
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0.00
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0.10
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0.00
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| g -Murolene |
0.61
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0.14
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0.32
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0.07
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0.37
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0.02
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0.30
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0.04
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| Germacrene D |
12.48
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9.20
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15.23
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6.90
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6.58
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12.15
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5.94
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8.35
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| b -Selinene |
0.11
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0.00
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0.00
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0.00
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0.02
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0.00
|
0.18
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0.00
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| b -cis-Guajene |
0.62
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0.05
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0.21
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0.05
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0.08
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0.02
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0.71
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0.13
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| a -Selinene |
0.27
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0.16
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0.02
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0.04
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0.14
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0.05
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0.09
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0.02
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| b -Himachalene |
0.25
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0.10
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0.05
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0.05
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0.13
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0.09
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0.19
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0.03
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| Germacrene A |
0.06
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0.01
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0.09
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0.02
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0.01
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0.05
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0.08
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0.01
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| UN S.Q |
0.68
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0.08
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0.00
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0.01
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0.55
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0.16
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0.46
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0.17
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| g -Cadinene |
0.61
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0.27
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0.18
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0.13
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0.30
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0.10
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0.20
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0.19
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| d -Cadinene |
1.06
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0.26
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0.90
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0.10
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0.60
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0.07
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0.56
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0.13
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| Cadina-1,4-diene |
0.09
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0.02
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0.00
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0.00
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0.04
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0.02
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0.03
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0.01
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| a -Cadinene |
0.59
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0.16
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0.64
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0.31
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0.49
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0.38
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0.28
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0.25
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| E-Nerolidol |
0.19
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0.00
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0.10
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0.00
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0.16
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0.02
|
0.06
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0.00
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| 10-epi-g -Eudesmol |
1.36
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1.07
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1.95
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0.16
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1.39
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0.41
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0.85
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0.04
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| epi-a -Cadinol |
0.17
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0.00
|
0.02
|
0.00
|
0.40
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0.03
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0.21
|
0.00
|
| Cubenol |
0.08
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0.00
|
0.09
|
0.00
|
0.40
|
0.00
|
0.03
|
0.00
|
| Unknown 3 |
0.19
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0.03
|
0.24
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0.10
|
0.32
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0.19
|
0.08
|
0.01
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| E,E-Farnesol |
0.08
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0.14
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0.13
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0.00
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0.20
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0.30
|
0.19
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0.20
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| Unknown 4 |
0.04
|
0.00
|
0.84
|
0.05
|
0.47
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0.00
|
0.03
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0.00
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The analyses revealed a high number of compounds and a high variation among the different provenances for the majority of the identified terpenes. Concerning the essential oil yield, which is mostly subject to environmental factors, the Bulqiza provenance showed the highest yield during both seasons. Monoterpenes were the major compounds of both needle essential oil and cortical oleoresin.
The pattern of variation revealed by the components in needle monoterpenes may have been due to a great interaction among the stages of development, environmental factors and, probably, the interaction process applied and its duration. In addition, most variation might have been due to genetic diversity since the silver fir possess a rather high variability within the individual populations, much higher than in the other conifers which were subject to similar investigations. This latter fact can be explained to some extent by the higher variation within the species (Paule et al., 1988).
Bagci E., Baser K.H.C., Kurkçuoglu M., Babaç T., and Çelik S. (1999): Study of the essential oil composition of two subspecies of Abies cilicica (Ant. et Kotschy) Carr. from Turkey. Flavour Fragrance Journal, 14, 47-49.
Paule L., Yazdani R. and Gomory D. (1988): Monoterpene composition of Silver fir (Abies alba Mill.) foliar oleoresin. In: IUFRO-Tannensymposium, Zvolen, pp 49-66. Paule, L and Korpel, S. (eds).
Petrakis P. and Roussis V. (1997): Evolution in Mediterranean climate regions. TREE, vol. 12, no. 3.
Regimbal J.M. and Collin G. (1994): Essential oil analysis of Balsam fir Abies balsamea (L.) Mill. Journal of Essential Oil Research, 6, 229-238.
Wolf H. (1994): Die Variation des Monoterpenmusters im Nadelharz verschiederner Herkünften der Weisstanne (Abies alba Mill.). In: Weisstannen - Herkünften: Neue resultate zur Provenienzversuch bei Abies alba Mill., pp. 45-77. Wolf H. (ed).
Roussis V., Couladis M., Tzakou O., and Loukis A. (2000): A comparative study on the needle volatile constituents of three Abies species grown in South Balkans. J. Ess. Oil Res. 12, 41.