Foeniculum vulgare Miller, a New Chemotype from Montenegro

Previous studies relating to prolonged and fractionated distillation procedures highlighted essential oils' (EOs) chemical composition to be significantly dependent on the extraction duration and harvesting time. As a continuation, a hydrodistillation procedure was applied to ripe fruit material of fennel, Foeniculum vulgare Miller (Apiaceae), collected from three localities in Montenegro (Podgorica, Nikšić, and Kotor) to furnish a total of 12 EOs. Liquid and vapor phases of the samples were analyzed by Gas Chromatography/Mass Spectrometry and Headspace-Gas Chromatography/Mass Spectrometry techniques, and 18 compounds have been identified. Although both quantitative and qualitative differences between the samples were notable, the phenylpropanoids anethole (ANE) and estragole and the monoterpenoids α-terpineol (TER) and fenchone (FEN) could be singled out as the most abundant constituents. The EOs from Podgorica belong to the most common ANE-rich chemotype, while the predominance of the monoterpenoid fraction is characteristic of the samples from Nikšić and Kotor. The latter is particularly rich in TER (up to 56.5%), with significant amounts of FEN and ANE. This chemical profile could represent a new chemotype of fennel EO. Vapor phases contained mainly monoterpenoids, with increased amounts of FEN and TER, while the number of phenylpropanoids was significantly decreased.

A comparative volatilomic characterization of Florence fennel from different locations: antiviral prospects

The genus Foeniculum is known for its wide ethnobotanical use in the Mediterranean region. Herein, we explored the compositional differences of volatile oils and headspace aroma of Florence fennel (Foeniculum vulgare var. azoricum (Mill.) Thell.) based on its different organs and various geographical origins via gas chromatography coupled with mass spectrometry (GC-MS). Sixty-seven volatile components were detected with phenylpropenes and monoterpenes, including trans-anethole, limonene, α-pinene, trans-β-ocimene, fenchyl acetate, and fenchone, as major constituents. Phenylpropenes were dominant in fennel hydro-distilled oils, whereas monoterpenes were dominant in most of the headspace aroma. The infraspecific variability was assessed using the unsupervised multivariate data analysis tools PCA and HCA, resulting in segregate clustering of accessions from different organs and locations with trans-anethole, limonene, trans-β-ocimene, fenchone, myristicin, and apiole as major phytomarkers contributing to this segregation. The antiviral activities of samples against hepatitis A and C viruses were investigated using the plaque reduction assay, HAV 3C proteinase and HCV NS5B polymerase inhibitory assays with a percentage inhibition between 66% and 85% and IC50 values from 1.8 to 26.7 μg mL-1. In silico molecular docking scores in latter enzyme binding pockets revealed key allosteric interactions with trans-β-ocimene and β-fenchyl acetate showing the best Gibb's free energy. Florence fennel exhibited interesting new perspectives for medicinal and industrial applications.

Changes in Volatile Compounds during Aging of Sweet Fennel Fruits-Comparison of Hydrodistillation and Static Headspace Sampling Methods

Two extraction methods for subsequent gas chromatographic (GC) determination of volatiles from freshly harvested and aged fennel fruit samples ( Foeniculum vulgare Mill.,ssp. vulgare var. dulce) have been compared. Hydrodistillation followed by GC-FID and GC-MS analysis was used as a standard method for essential oil characterization, while static headspace followed by GC (SHS-GC-FID) was used as a comparative method for determination of volatile components. As the fennel fruit ages, there is a gradual loss of the volatile components as indicated by the lower yield of essential oil and lower content of volatiles, as indicated by the alternative SHS-GC-FID analysis. Slight differences observed for the main components ( trans-anethole, estragole, fenchone, and limonene) using the two methods are negligible, indicating that these volatiles did not undergo chemical transformation during the sample preparation procedures. A difference in anisaldehyde content was observed when the composition of the hydrodistilled essential oil was compared with the SHS-GC-FIDanalysis of volatiles and explanation for the variation of anisaldehyde content and the origin of other compounds was suggested. Comparison of the obtained results showed that limonene oxides, carvone and carveolare detectable in SHS-GC-FID analysis of the aged fennel fruits, while in hydrodistilled samples analyzed by GC-FID they were not present. Another observed difference was the appearance of products in significant amounts with higher retention times than trans-anethole, namely threo- and erythro-anethole β-hydroxymethylether and anethole glycol that are not detectable in the essential oil obtained by hydrodistillation. So, the relative abundance of the major components is comparable between these two methods for fennel seed up to 3 years from harvest and they can be used interchangeably depending on the purpose and amount of material. Furthermore, SHS-GC-FID can be used for assessment of maximum storage time and quality of fennel fruit suitable for human consumption.

Simultaneous Determination of Essential Oil Components and Fatty Acids in Fennel using Gas Chromatography with a Polar Capillary Column

Cultivated and wild growing samples of fennel ( Foeniculum vulgare Mill., Apiaceae) from R. Macedonia were studied for their volatiles and fatty acid composition. The main essential oil components isolated via hydrodistillation were: trans-anethole (>80%), estragole (<6%), limonene (<6%), anisaldehyde (<1%) and 0.5 % fenchone. An alternative method for characterization of both the non-polar volatile and non volatile fractions was developed using n-hexane and dichloromethane (3:1, v/v) in a Soxhlet extraction followed by transesterification. The obtained extracts were then characterized and the dominant fatty acid was 18:1 (petroselinic and oleic acid) 75.0–82.8 %, followed by 18:2 (linoleic acid) 10.8–16.2% and other fatty acids: palmitic (4.3–6.9%), stearic (1.2–1.7%) and myristic (0–2.9%). The results for the volatile fraction after Soxhlet extraction and transesterification did not significantly differ from results obtained after hydrodistillation, especially for the main components ( trans-anethole, estragole, fenchone and limonene), implying that the developed method can be used for simultaneous determination of volatiles and fatty acids.

Factors Affecting Chemical Variability of Essential Oils: A Review of Recent Developments

This review, covering mainly papers of the last decade, focuses on recent findings on the different factors affecting the chemical composition of essential oils, such as exogenous and endogenous factors. The endogenous factors are related to anatomical and physiological characteristics of the plants and to the biosynthetic pathways of the volatiles, which might change in either the different tissues of the plants or in different seasons, but also could be influenced by DNA adaptation. The exogenous factors, over a long period, might affect some of the genes responsible for volatiles formation. Those factors lead to ecotypes or chemotypes in the same plant species. In the last few years chemotaxonomy has been widely used to classify plants with essential oils characterized by intra-specific chemical polymorphism. It could be evidenced that chemotypes are frequently genotypes and recently the application of the Random Amplified Polymorphic DNA (RAPD) markers, coupled with powerful statistical methods, appeared to be useful in discriminating the different genotypes. The data presented led to the suggestion that further chemotaxonomic studies should be the result of the analysis of morphological traits combined both with chemical and molecular markers.