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Natural Variability of Essential Oil Components
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Unfortunately, molecular biological studies on volatile accumulation in connection with plant development and morphogenetic changes have been limited until today. Grausgruber-Grüger et al. (2012) investigated the connection between the accumulation of main monoterpenes and transcript levels of their synthases during the vegetation cycle of garden sage (Salvia officinalis). It has been established that terpene synthase mRNA expression and the level of the respective end products were in significant correlation in the cases of 1,8-cineole (correlation coefficients r = 0.51 and 0.67 for the two investigated cultivars) and camphor (r = 0.75 and 0.82), which indicated a transcriptional control of the process. The same correlation, however, could not be proved for α- and β-thujones, which shows the possible role of other regulation mechanisms in their accumulation. In lavender, the gene responsible for the formation of linalool is strongly expressed in essential oil glands of the flowers and shows the peak expression at 70% flowering stage. After that, LinS gene transcription decreases, but the level of the product linalool still remains high (Lane et al., 2010). The authors concluded that the production of linalool in lavender is transcriptionally regulated but other regulatory mechanisms (e.g., transcriptional upregulation of other genes, post-transcriptional regulatory mechanisms) may also be involved. Sarker and Mahmoud (2015) cloned and functionally characterized two monoterpene acetyltransferases from Lavandula x intermedia glandular trichomes which are capable of synthesizing geranyl acetate, lavandulyl acetate, and neryl acetate from their respective monoterpene substrates. They demonstrated that transcripts of their genes were significantly more abundant in flowers compared to leaf tissues, which corresponds to the higher accumulation rate of these components in the flowering parts.
Variability, toxicity, and antioxidant activity of Eupatorium cannabinum (hemp agrimony) essential oils
Published in Pharmaceutical Biology, 2016
Asta Judzentiene, Rasa Garjonyte, Jurga Budiene
Toxicity test of the six oil samples 3, 4, 17, 18, 21, and 22 showed that lethality (LC50) of brine shrimp (Artemia sera) larvae ranged from 16.3 to 22.0 μg/mL (Table 4). These data revealed that essential oils of E. cannabinum containing appreciable amounts of germacrene D (≤22.0%) and neryl acetate (≤19.7%) were notably toxic. There are some reports concerning toxicity of volatile oils rich in germacrene D (Dubey et al., 2007; Haber et al., 2008; Kiran & Devi, 2007; Ogutcu et al., 2008). The leaf essential oils of Talauma gloriensis with the most abundant components germacrene D (43.5%) also showed notable brine shrimp toxicity (LC50 value = 14.1 μg/mL) (Haber et al., 2008). Essential oils from Eupatorium cannabinum, Chloroxylon swietenia, and Trachyspermum ammi containing among main constituents germacrene D displayed remarkable mosquitocidal, larvicidal, and broad spectrum of fungitoxic activities (Dubey et al., 2007; Kiran & Devi, 2007). Volatile oils of Salvia limbata with major constituent spathulenol (29.3%) and germacrene D (24.7%) exhibited antimicrobial, antioxidant, and antiviral activities (Ogutcu et al., 2008).