Chemodiversity of Essential Oils in Seseli libanotis (L.) W.D.J.Koch (Apiaceae) in Central Europe.

Seseli libanotis is an aromatic umbelliferous plant distributed sporadically on dry grassland edges in Europe and Western Asia. The essential oil composition in the different plant parts was studied from plants collected on nine sites in Austria and one site in Alto Adige, Italy. Monoterpenes such as α-pinene, sabinene and ß-myrcene and the sesquiterpene germacrene D were present in all essential oils from the aerial parts. Inflorescences and fruits had the highest essential oil contents. These essential oils from four sites were rich in acorenone B, while from other three sites they had carotol as a major component. Osthole as furocoumarin occurred in some oils. The root essential oils were dominated by α-pinene. The essential oil variability has been studied by principal component analysis (PCA) and discriminant analysis (DA) with plant parts or sampling site as a priori groups. PCA could well separate inflorescence and fruit essential oil samples from leaf and stem essential oil samples. DA differentiated well between the plant parts and most of the sampling sites.

Antifungal potential and structure activity relationship of carrot seed constituents.

The aim of this study was to evaluate in vitro antifungal potential of carrot seed extracts, its essential oil, different fractions, isolated compounds, and their derivatives against three phytopathogenic rice fungi (Fusarium moniliforme, Bipolaris oryzae, and Rhizoctonia solani) using poisoned food technique. Carrot seed essential oil was extracted using hydrodistillation method and extracts were prepared using different solvents viz. dichloromethane, hexane, and methanol. The pure compounds daucene, carotol, and daucol were isolated using column chromatography and derivatized using different reagents. The study demonstrated that antifungal potential of all tested compounds varied in a dose dependent manner. Structure activity relationship of isolated and derivatized compounds showed that polar moieties possessed more antifungal potential as compared to non-polar moieties. The results suggested that carrot seed methanol extract and carotol possessed strong antifungal potential as compared to other components tested. PRACTICAL APPLICATIONS: Phytopathogenic fungi are the major problems causing harmful damage to the rice crop. Only available control of these diseases is synthetic fungicides but their repeated use led to serious environmental issues, residual toxicity, and development of resistance. Therefore, it's better to find some natural alternatives. The current study was conducted to evaluate in vitro antifungal potential of carrot seed essential oil, its constituents and extracts against phytopathogenic fungi of rice. The methanol extract and carotol possessed highest antifungal potential which might be due to their polar nature. This information may add a new dimensions to biological activity of these natural molecules mainly in the field of agriculture as fungal diseases are found to be associated with major losses in agriculture. Hence these compounds can act as natural antifungal agents against rice fungi.

Repellent Activity of Carrot Seed Essential Oil and Its Pure Compound, Carotol, Against Mosquitoes.

In our natural products screening program for mosquitoes, carrot seed essential oil showed high repellency. The gas chromatography (GC)/flame ionization detector and GC/mass spectrometry analysis of the essential oil revealed the presence of 47 compounds. Carotol was more than 75% w/w, followed by muurolene (4.86%), (Z)-ß-farnesene (2.9%), and diepicedrene (1.1%). Systematic bioassay-guided fractionation of the essential oil was performed to identify active repellent compounds. In both Klun and Debboun (K&D) and Ali and Khan (A&K) bioassays, carotol showed biting deterrent activity similar to N,N-Diethyl-3-methylbenzamide (deet) and carrot seed essential oil against both Aedes aegypti and Anopheles quadrimaculatus, while in in vivo cloth patch bioassay, the minimum effective dose (MED) of deet was lower (12.5 µg/cm2) than the essential oil and carotol (25 µg/cm2) against Ae. aegypti. In the A&K bioassay, the MED values were similar, whereas the values of the mixtures of deet with essential oil and carotol was lower (6.25 + 6.25 = 12.5 µg/cm2) than their individual treatments (25 µg/cm2). In direct skin application bioassay, both the essential oil and carotol provided good repellency. The mixtures of deet and essential oil or carotol significantly increased the residual activity, indicating synergism. Mosquito repellency of the essential oil and carotol is reported for the 1st time. These data indicate the potential of these natural products to be developed as commercial repellents.