Biological effects of essential oils – A review
Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, medicinal and cosmetic applications, especially nowadays in pharmaceutical, sanitary, cosmetic, agricultural and food industries. Because of the mode of extraction, mostly by distillation from aromatic plants, they contain a variety of volatile molecules such as terpenes and terpenoids, phenol-derived aromatic components and aliphatic components. In vitro physicochemical assays characterise most of them as antioxidants. However, recent work shows that in eukaryotic cells, essential oils can act as prooxidants affecting inner cell membranes and organelles such as mitochondria. Depending on type and concentration, they exhibit cytotoxic effects on living cells but are usually non-genotoxic. In some cases, changes in intracellular redox potential and mitochondrial dysfunction induced by essential oils can be associated with their capacity to exert antigenotoxic effects. These findings suggest that, at least in part, the encountered beneficial effects of essential oils are due to prooxidant effects on the cellular level. 
Stability of Essential Oils: A Review
In recent years, consumers have developed an ever‐increasing interest in natural products as alternatives for artificial additives or pharmacologically relevant agents. Among them, essential oils have gained great popularity in the food, cosmetic, as well as the pharmaceutical industries. Constituting an array of many lipophilic and highly volatile components derived from a great range of different chemical classes, essential oils are known to be susceptible to conversion and degradation reactions. Oxidative and polymerization processes may result in a loss of quality and pharmacological properties. Despite their relevance for consumers, there is a paucity of information available addressing this issue. Therefore, the present review provides a comprehensive summary on possible changes in essential oils and factors affecting their stability. Focusing on individual essential oils, the various paths of degradation upon exposure to extrinsic parameters are outlined. Especially temperature, light, and oxygen availability are recognized to have a crucial impact on essential oil integrity. Finally, analytical methods to assess both genuine as well as altered essential oil profiles are evaluated with respect to their suitability to track chemical alterations. It is believed that only a careful inspection of essential oils by a set of convenient methods allows profound quality assessment that is relevant to producers and consumers alike. 
Effect of Essential Oils on Pathogenic Bacteria
The increasing resistance of microorganisms to conventional chemicals and drugs is a serious and evident worldwide problem that has prompted research into the identification of new biocides with broad activity. Plants and their derivatives, such as essential oils, are often used in folk medicine. In nature, essential oils play an important role in the protection of plants. Essential oils contain a wide variety of secondary metabolites that are capable of inhibiting or slowing the growth of bacteria, yeasts and moulds. Essential oils and their components have activity against a variety of targets, particularly the membrane and cytoplasm, and in some cases, they completely change the morphology of the cells. This brief review describes the activity of essential oils against pathogenic bacteria. 
Essential Oils Isolated from Myrtaceae Family as Natural Insecticides
An interest in natural products from plants has been increased due to the disruption of natural biological control systems, undesirable effects on non-target organisms, environmental hazards, and the development of resistance to synthetic insecticides, which are applied in order to reduce the populations of insects. Essential oils (EOs) from plants may be an alternative source of insect control agents, since they constitute a rich source of bioactive compounds that are biodegradable into nontoxic products and potentially suitable for use in integrated management programs. These materials may be applied to food crops shortly before harvest without leaving excessive residues. Furthermore, medically safe of these plant derivatives has emphasized also. For these reasons, much effort has been focused on plant EOs and their constituents as potential sources of insect control agents. In this context, Myrtaceae family would rank among the most important families of plants. In the last few years more and more studies on the insecticidal properties of EOs from Myrtaceae family have been published and it seemed worthwhile to compile them. Therefore, the subject matter of this paper lies on the insecticidal effects of EOs from Myrtaceae and their compounds in insect pest’s control. Natural essences of Myrtaceae plants owe its insecticidal action to the presence in its composition of terpenic derivatives such as 1.8-cineole, limonene, linalool, myrcene, terpineol, thymol and α-pinene, which have introduced as potential insecticides. These review indicated that pesticides based on Myrtaceae essential oils could be used in a variety of ways to control a large number of insect pests. 
Role of Natural Essential Oils in Sustainable Agriculture and Food Preservation
Research on humans, animals or plants about anti-inflammatory, anticancer, antiviral, repellent, antibacterial, antifungal or antioxidant activities of the essential oils corroborated the biological characteristics of aromatic plants and their use since ancient times for their preservative and medicinal properties. These mixtures of natural compounds are valuable ingredients in perfumery, food, agricultural and pharmaceutical industries. Currently, consumer demand natural products, effective, safe and environmentally friendly. Among them, essential oils may be natural alternatives of synthetic herbicides for organic farming systems, solving serious environmental problems due to their low persistence in the field as well as the incidence of resistance in both weeds and some pathogens. Correlations between the principal compounds of essential oils with herbicidal effect than explain their use in a sustainable agriculture or their antibacterial activity against food borne pathogens, food spoiling bacteria and bacterial virulence factors as biofilm formation for the use as natural food preservative are the main focus of this review. 
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 Ebadollahi, A. (2013) “Essential Oils Isolated from Myrtaceae Family as Natural Insecticides”, Annual Research & Review in Biology, 3(3), pp. 148-175. Available at: https://journalarrb.com/index.php/ARRB/article/view/24663 (Accessed: 11December2020).
 Blázquez, M. A. (2014) “Role of Natural Essential Oils in Sustainable Agriculture and Food Preservation”, Journal of Scientific Research and Reports, 3(14), pp. 1843-1860. doi: 10.9734/JSRR/2014/11376.