Gerhard Buchbauer

Phase‐I metabolism mediated by cytochrome P450 (CYP) enzymes represents a major route of elimination of many drugs that can compete for the same CYP enzyme. The bioactivity of essential oils (EOs) and their flavour and fragrance constituents have been known since ancient times, and like any other physiological process in the human body the activity of CYP enzymes can also be influenced (increased and/or decreased) by these natural compounds. This review discusses the effects of EO constituents on important drug‐metabolizing CYP enzymes. Exposure to EO constituents through commonly used products via cutaneous, oral, and inhalation routes is outlined, and the impact of some important EO constituents on CYP enzymes is described in more detail. In particular, the simultaneous application of EO constituents with drugs or the excessive use of EOs and their constituents can lead to unexpected adverse effects.

The use of essential oils (EOs) worldwide continues to rise, and EOs are already established in folk and western medicine as remedies against inflammation, respiratory diseases, and infections, and are used for aromatherapy, insect repellents, food preservatives, and in the perfume and cosmetics industries. Pesticide residues are already present in the environment, however, and are thus also found in the aromatic plants used for EO production. The control of pesticides in EOs is therefore essential, especially with the recent trends in EO consumption. This paper is an overview on possible methods used for the determination of pesticide residues in EOs, covering the work of the scientific community in the last 20–25 years.

Essential oils (EOs) exhibit a wide range of pharmacological properties, which have been reported over the years in various studies. The aim of this literature review is to present the latest findings of the immunomodulatory effects of EOs. From 2008 to 2016in vivo- and/orin vitro-studies, most of which were published in the last couple of years, have been selected based on their topic relevance, namely immunomodulatory, anti-inflammatory, antileishmanial, antiallergic, and anticancer effects of various EOs. These findings show modulation of pro- and anti-inflammatory cytokines, antiproliferative, chemotactic properties and also exert antiparasitic effects by inhibiting the pro, axenic and intramacrophagic amastigote forms of Leishmania parasites or by modulating the T_H1 and T_H2 immune responses. Furthermore, the EOs of some plants show the ability to reduce the mast cell degranulation and improve the airway inflammation and mucus obstruction in the cases of immediate hypersensitivity in murine models. Additionally, the cytotoxicity of some EOs against human melanoma, hepatoma, lung, prostate and breast cancer cell lines proposed their potential antitumor effect by an increased immunosuppressive (cytostatic) activity.

A well‐functioning sense of smell is essential not only for human wellbeing and the quality of life, it is also important to protect the organism from harmful influences it is exposed to, such as gas, toxic agents or rotten food. Various drugs interfere with human olfaction and are able to elicit olfactory dysfunction, but little is known about the underlying mechanisms. To date, a wide range of drugs have not been sufficiently investigated with respect to their impact on olfaction. This review provides an overview of drugs that have been identified as inducing olfactory disorders and discusses underlying causes and mechanisms.

The use of body odours, emitted in the form of volatile organic compounds (VOCs), has become the focus of scientific research in recent years.Diseases such as cancer, metabolic disorders, infections and some other diseases can change the components of daily VOCs, often leading to the production of disease‐specific VOCs that might be used as diagnostic biomarkers if detected early enough. We summarize here scientific publications (2003–2013) related to the study of VOCs in human diseases. Copyright © 2014 John Wiley & Sons, Ltd.

The antimicrobial activity of essential oils is discussed in this review taking in account studies which were published in the period of time from 2008 until September 2010. Furthermore, the most important methods to examine the antimicrobial efficiency of essential oils are presented. The studies are divided into the following two groups, namely antibacterial and antifungal active agents depending on the activity of the applied essential oil against the test microorganisms. Various interesting possible applications are revealed such as the use of essential oils instead of synthetic drugs to circumvent the increasing resistance of some pathogens. Moreover, they could not only be used for the therapy of infectious illnesses, but also as preservatives in the food industry. A further possibility is, among others, the application of essential oils in skin products in order to treat or avoid dermal infections. Additionally, the prevalent constituents of the individual antimicrobial active essential oils are elaborated. Copyright © 2011 John Wiley & Sons, Ltd.

Studies regarding pheromes consisting of essential oil components of various plants and released by insects and arachnids (pests) were compiled for this review. For example, verbenol and verbenone were found to be an essential part of the bark beetle's aggregation pheromone, released with the intent to round up its conspecifics. Concerning plant lice, aphids use (E)‐β‐farnesene as an alarm pheromone. Furthermore, nepetalactol and nepetalactone, two essential oil components of the cat mint (Lamiaceae), occur as an aphid‐released sex pheromone, emitted to induce mating behaviour. On the other hand, some bees imitate a linalool‐containing orchid odour as their sex pheromone and thus attract their mating partners. The sand fly, responsible for the American visceral leishmaniasis, uses derivatives of either α‐himachalene, germacrene D or cembrene as a sex pheromone. Studies about termites reveal a large amount of different presumable pheromone compounds that also appear as essential oil components, e.g. neocembrene as a part of the trail pheromone, (E,E)‐α‐farnesene as an alarm pheromone and other terpenes, such as for example γ‐cadinene as primer pheromone, enforcing the effect of the juvenile hormone and therefore determining about caste development. Concerning the pest insects, management strategies, conducted with pheromone traps, are presented or compared. Regarding arachnids, studies about spider pheromones are rare, whereas more information is available about mites, which release neral and geranial as an alarm pheromone. Copyright © 2011 John Wiley & Sons, Ltd.