Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) to maintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safety has motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/or interrupt propagation of autoxidation. Fat-soluble vitamin E (α-tocopherol) and water-soluble vitamin C (L-ascorbic acid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, often have strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is most often due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), phenolic diterpenes (carnosol, carnosic acid, rosmanol, and rosmadial), flavonoids (quercetin, catechin, naringenin, and kaempferol), and volatile oils (eugenol, carvacrol, thymol, and menthol). Some plant pigments (anthocyanin and anthocyanidin) can chelate metals and donate H to oxygen radicals thus slowing oxidation via 2 mechanisms. Tea and extracts of grape seeds and skins contain catechins, epicatechins, phenolic acids, proanthocyanidins, and resveratrol, all of which contribute to their antioxidative activity. The objective of this article is to provide an overview of natural antioxidants, their mechanisms of action, and potential applications.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1541-4337.2011.00156.x

Natural antioxidants: sources, compounds, mechanisms of action, and potential applications

A list of 1719 chemical compounds identified from headspace samples of floral scent is presented. The list has been compiled from some 270 published papers, including analyses of 991 species of flowering plants and a few gymnosperms, a sample including seed plants from 90 families and 38 orders. The compounds belong to seven major compound classes, of which the aliphatics, the benzenoids and phenylpropanoids, and, among the terpenes, the mono- and sesquiterpenes, occur in most orders of seeds plants. C5-branched compounds, irregular terpenes, nitrogen-containing compounds, and a class of miscellaneous cyclic compounds have been recorded in about two-thirds of the orders. Sulfur-containing compounds occur in a third of the orders, whereas diterpenes have been reported from three orders only. The most common single compounds in floral scent are the monoterpenes limonene, (E)-β-ocimene, myrcene, linalool, α- and β-pinene, and the benzenoids benzaldehyde, methyl 2-hydroxybenzoate (methyl salicylate), benzyl alcohol, and 2-phenyl ethanol, which occur in 54–71% of the families investigated so far. The sesquiterpene caryophyllene and the irregular terpene 6-methyl-5-hepten-2-one are also common and occur in more than 50% of the families. Orchidaceae are by far the best investigated family, followed by several families known to have many species with strongly scented flowers, such as Araceae, Arecaceae, Magnoliaceae, and Rosaceae. However, the majority of angiosperm families are still poorly investigated. Relationships between floral scent and pollination, chemistry, evolution, and phylogeny are briefly discussed. It is concluded that floral scent chemistry is of little use for phylogenetic estimates above the genus level, whereas the distribution and combinations of floral scent compounds at species and subspecific levels is a promising field of investigation for the understanding of adaptations and evolutionary processes in angiosperms.

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Diversity and Distribution of Floral Scent

Essential oils and their volatile constituents are used widely to prevent and treat human disease. The possible role and mode of action of these natural products is discussed with regard to the prevention and treatment of cancer, cardiovascular diseases including atherosclerosis and thrombosis, as well as their bioactivity as antibacterial, antiviral, antioxidants and antidiabetic agents. Their application as natural skin penetration enhancers for transdermal drug delivery and the therapeutic properties of essential oils in aroma and massage therapy will also be outlined.

Pharmaceutical and therapeutic potentials of essential oils and their individual volatile constituents: a review.

Comparative evaluation of 11 essential oils of different origin as functional antioxidants, antiradicals and antimicrobials in foods

Introduction, K. Husnu Can Bas,er and G. Buchbauer History and Sources of Essential Oil Research, K.-H. Kubeczka Sources of Essential Oils, C. Franz and J. Novak Production of Essential Oils, E. Schmidt Chemistry of Essential Oils, C. Sell Analysis of Essential Oils, B. d'Acampora Zellner, P. Dugo, G. Dugo, and L. Mondello Safety Evaluation of Essential Oils: A Constituent-Based Approach, T.B. Adams and S.V. Taylor Metabolism of Terpenoids in Animal Models and Humans, W. Jager Biological Activities of Essential Oils, G. Buchbauer Effects of Essential Oils in the Central Nervous System Part I: Central Nervous System Effects of Essential Oils in Humans, E. Heuberger Part II: Psychopharmacology of Essential Oils, D. Savio Nunes, V. de Moura Linck, A. Lourenco da Silva, M. Figueiro, and E. Elisabetsky Phytotherapeutic Uses of Essential Oils, B. Harris In Vitro Antimicrobial Activities of Essential Oils Monographed in the European Pharmacopoeia 6th Edition, A. Pauli and H. Schilcher Aromatherapy with Essential Oils, M. Lis-Balchin Biotransformation of Monoterpenoids by Microorganisms, Insects, and Mammals, Y. Noma and Y. Asakawa Biotransformation of Sesquiterpenoids, Ionones, Damascones, Adamantanes, and Aromatic Compounds by Green Algae, Fungi, and Mammals, Y. Asakawa and Y. Noma Industrial Uses of Essential Oils, W.S. Brud Encapsulation and Other Programmed Release Techniques for Essential Oils and Volatile Terpenes, J. Karlsen Aroma-Vital Cuisine, M.M. Kettenring and L.M. Vucemilovic Essential Oils Used in Veterinary Medicine, K. Husnu Can Ba,ser and C. Franz Trade of Essential Oils, H. Bovill Storage and Transport of Essential Oils, K.-D. Protzen Recent EU Legislation on Flavors and Fragrances and its Impact on Essential Oils, J.C.R. Demyttenaere Index

Handbook of Essential Oils : Science, Technology, and Applications

The antioxidant activity of a commercial rectified clove leaf essential oil (Eugenia caryophyllus) and its main constituent eugenol was tested. This essential oil comprises in total 23 identified constituents, among them eugenol (76.8%), followed by beta-caryophyllene (17.4%), alpha-humulene (2.1%), and eugenyl acetate (1.2%) as the main components. The essential oil from clove demonstrated scavenging activity against the 2,2-diphenyl-1-picryl hydracyl (DPPH) radical at concentrations lower than the concentrations of eugenol, butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA). This essential oil also showed a significant inhibitory effect against hydroxyl radicals and acted as an iron chelator. With respect to the lipid peroxidation, the inhibitory activity of clove oil determined using a linoleic acid emulsion system indicated a higher antioxidant activity than the standard BHT.

Chemical Composition and Antioxidant Properties of Clove Leaf Essential Oil

In the last few years more and more studies on the biological properties of essential oils have been published and it seemed worthwhile to compile the studies of 2009, 2008 and the second part of 2007. Such an overview covering the scientific literature mainly from 2000 onwards, up to the first half of the year 2007, has been published recently. The focus of this overview lies on the anti-nociceptive, anticancer, anti-inflammatory, penetration-enhancing, insect repellent, antiviral and antioxidative properties of essential oils. Many essential oils have been used for centuries in folk medicine and in recent years the biological properties of various essential oils have been proved by a number of studies. Their use in the treatment of pain, inflammation, viral diseases and cancer and their potential to enhance the penetration of other drugs, their insect repellent activity and their antioxidative effects were confirmed. Nonetheless, more studies are necessary to analyse the biological properties of other essential oils or to prove their mechanism of action. Copyright © 2010 John Wiley & Sons, Ltd.

Biological properties of essential oils: an updated review

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.

Gerhard Buchbauer

Papers

Handbook of Essential Oils : Science, Technology, and Applications

Chemical Composition and Antioxidant Properties of Clove Leaf Essential Oil

Biological properties of essential oils: an updated review

A review on recent research results (2008–2010) on essential oils as antimicrobials and antifungals. A review.

Characterisation of various grape seed oils by volatile compounds, triacylglycerol composition, total phenols and antioxidant capacity.