Essential oil research: past, present and future

Abstract

Essential oil plants and essential oils (EOs) have been used since early human history to fl avour and treat food and beverages as aroma chemicals and, empirically, as preservatives, to cover unpleasant odours, to attract other individuals or to control sanitary problems. In this way they contribute to communication between individuals, infl uence the well-being of humans and animals and show a long socio-cultural and socio-economic tradition.Discovering and elucidating thousands of new EO compounds over the last few decades, we have learned to understand the complexity and enormous diversity in this group of natural products, which consists of mono-and sesquiterpenes, phenylpropenes and other volatile compounds. In addition, the in vitro and in vivo activity of these substances has been studied extensively, and new fi elds of application have been discovered. This was consistently and necessarily followed by a number of national and international regulations concerning the quality, safety and effi cacy of EOs, the risk-benefi t assessment of their use in food and feed additives, as fl avourings and cosmetic ingredients and also as biocides. The Convention on Biological Diversity (CBD), guidelines concerning good agricultural and collection practices (GA/C/P) and the GMO discussion are also infl uencing not only the proper use but also research on essential oils. Taking these items into consideration, the following four areas had and still have a signifi cant infl uence on EO research:• Development of analytical methods.• Biodiversity studies.• Biosynthesis and '-omics' research.• In vitro and in vivo studies on eff ect and effi cacy. Development of Analytical MethodsProbably the most important step in the analysis of secondary plant products has been the introduction of chromatographic methods, of which thin-layer chromatography (TLC) and gas chromatography (GC) have had the highest impact on EO analysis. TLC is still a valid tool for rapidly obtaining phytochemical fi ngerprints of complex matrices, and is especially useful in fi eld research, away from well-equipped laboratory facilities. In combination with densitometric and spectroscopic methods, (HP)TLC has actually made a comeback in quality control. [1] GC in its beginnings, with packed columns, had shown only limited resolution, [2] but was nevertheless the fi rst technique enabling quantitative analysis of highly complex mixtures, as EOs are. Today, GC is the most commonly used method in this fi eld, advanced and highly sophisticated, with enantioselective capillary columns and coupled with mass spectroscopy (MS) or mass selective detectors (MSDs). [3] Headspace sampling and solid-phase microextraction (HS-SPME), in addition, enables the analysis of even the content of single oil glands, ducts or cavities, showing, for example, that the chemical composition diff ers between leaf insertions and leaf regions and also between the peltate and capitate oil glands of Salvia spp. [4,5] much more than in oregano [6] or peppermint. [7] This indicates the necess...

Stability of Essential Oils: A Review

“…Isman () as well as Adorjan and Buchbauer () pointed out their application as plant and crop protectants. Moreover, promising approaches have been reported using essential oils or components thereof in medicinal products for human or veterinary use (Buchbauer and Jirovetz ; Shahi and others ; Bakkali and others ; Franz ; Woronuk and others ; Lang and Buchbauer ). Therefore, in recent times, essential oils have gained great popularity as consumers have developed a particular ever‐growing awareness toward the use of natural ingredients, especially in food, household, and cosmetic products (Yamamoto ; Jiang and others ).…”

Sulphur-containing compounds in the essential oil ofFerula alliacearoots and their mass spectral fragmentation patterns

“…Previous research also unveiled a number of medicinal properties form Ferula spp. including antibacterial, antifungal, antioxidant, anti-inflammatory, antinociceptive, anticonvulsant, antispasmodic and hypotensive activities (Bakkali et al 2008;Asili et al 2009;Maggi et al 2009;Bagheri et al 2010;Franz 2010;Chibani et al 2012;Labed-Zouad et al 2015).…”

Chemical Composition, an Antioxidant, Cytotoxic and Microbiological Activity of the Essential Oil from the Leaves of Aeollanthus suaveolens Mart. ex Spreng

“…Brazil has a huge biodiversity, where much of the native plant species has not been studied. It is estimated that about 3000 essential oils are known, of which about three hundred are commercially important, intended mainly for the fragrance market [2, 3]. …”