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DOI: 10.1055/s-0036-1596460
Chemical composition and antibacterial effect of volatile compounds from different chemotypes of sweet gale (Myrica gale)
Publication History
Publication Date:
14 December 2016 (online)
Sweet gale (Myrica gale L., Myriaceae) is an aromatic shrub distributed at high latitudes in the northern hemisphere. The essential oil of leaves of M. gale have anticatarrhal, mucolytic and cytotoxic activities, and an abortive effect [1, 2]. The aim of this study was to investigate the chemical composition and antibacterial effect of volatile compounds from leaves of 24 Scottish genotypes of M. gale grown in Denmark. Plant material (2 g) was freeze-dried and extracted with CH2Cl2 (10 ml) and analysed by GC-MS and GC-FID. The genotypes were classified into four chemotypes (Table 1). Extracts from representative genotypes of each chemotype were investigated towards a gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria using the agar disc diffusion and liquid culture assays. In the agar diffusion test a 2-fold dilution of the extracts (80 µl extract/disc) showed antibacterial effect against B. subtilis with the following inhibition zone radius (mm): trans-nerolidol (1.83 ± 0.24), 1,8-cineol (1.67 ± 0.24), α-pinene and β-elemenone (1.17 ± 0.24). Antibacterial activity against E. coli was only observed in the liquid culture assay but to a lesser extent than towards B. subtilis. The growth rates in the exponential phase of B. subtilis supplemented with 0.2% v/v extract in the liquid culture assay were (in min-1): 0.49 ± 0.01 (α-pinene), 0.42 ± 0.02 (β-elemenone), 0.29 ± 0.01 (trans-nerolidol), 0.34 ± 0.01 (1,8-cineol) and 0.53 ± 0.02 (negative control culture). The lag-phases (min) were 300 (α-pinene), 450 (β-elemenone), 540 (trans-nerolidol), 540 (1,8-cineol) and 60 (negative control culture). The results show that extracts of all chemotypes have antibacterial effects and predominatly affect the lag-phases of the growth of the gram-positive bacteria B. subtilis. The order of chemotypes with increasing antibacterial activity was α-pinene < β-elemenone < 1,8-cineol < trans-nerolidol.
Major constituent |
RIb |
Average content (µg/g plant material)± GCV (%)a |
|||
α-pinene (9)c |
β-elemenone (8) |
trans-nerolidol (5) |
1,8-cineol (2) |
||
α-Pinene |
1010 |
52.6± 30.0 |
47.4 ± 45.6 |
30.9 ± 55.3 |
54.3 ± 21.6 |
Limonene |
1181 |
17.2 ± 37.2 |
24.3 ± 43.2 |
16.6 ± 26.5 |
24.0 ± 21.3 |
1,8-Cineol |
1191 |
25.4 ± 74.4 |
49.5 ± 42.2 |
37.2 ± 35.2 |
59.1± 16.1 |
p-Cymene |
1251 |
7.1 ± 38.0 |
10.5 ± 39.1 |
7.5 ± 32.0 |
11.8 ± 17.8 |
γ-Elemene |
1619 |
18.9 ± 60.9 |
23.2 ± 88.0 |
14.0 ± 77.1 |
28.8 ± 28.5 |
α-Terpineol acetate |
1677 |
5.6 ± 113 |
13.2 ± 52.3 |
5.0 ± 64.0 |
8.7 ± 118 |
trans-Nerolidol |
2037 |
7.9 ± 184 |
24.2 ± 109 |
68.6± 59.5 |
1.6 ± 37.5 |
β-Elemenone |
2061 |
24.6 ± 93.9 |
66.0± 39.1 |
19.5 ± 101 |
29.9 ± 142 |
Germacrone |
2189 |
4.3 ± 88.4 |
10.9 ± 51.5 |
3.9 ± 82.1 |
5.2 ± 140 |
Total major constituents |
164 ± 53.1 |
269 ± 40.9 |
203 ± 34.9 |
223 ± 35.6 |
|
Total |
234 ± 55.1 |
356 ± 41.3 |
276 ± 29.7 |
325 ± 29.8 |
|
aGCV (%) = genotypic coefficient of variation in% within the same chemotype; bRI = retention index determined on a Zebron ZB-WAXplus capillary GC column (60 m × 0.25 mm × 0.25 µm); cNumber in parentheses refer to the number of genotypes in this chemotype. |
Keywords: Myrica gale, volatile compounds, chemotypes, antibacterial activity.
References:
[1] Svoboda KP, Inglis A, Hampson J, Galambosi B, Asakawa Y. Biomass production, essential oil yield and composition of Myrica gale L. harvested from wild populations in Scotland and Finland. Flavour Fragr J 1998; 13: 367 – 372
[2] Sylvestre M, Legault J, Dufour D, Pichette A. Chemical composition and anticancer activity of leaf essential oil of Myrica gale L. Phytomed 2005; 12: 299 – 304
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No conflict of interest has been declared by the author(s).