and their antidepressant, detoxifying, stimulating, antimicrobial, and calming effects, EO gain huge ad­miration as a natural, secure an efficient therapy for health problems (Tongnuanchan & Benjakul, 2014). EOs are complex, comprises of various chemicals, mostly present in liquid state but very few in solid form also. At normal temperature, these volatile oils may appear colorless to light yellowish in color and are readily absorbed through the skin. EO usually have lower density then water but few volatile oils like cinnamon oil, clove oil, etc. possesses high density than water. They are miscible in vegetable oils, fats, wax, and water and also soluble in diethyl ether, acetone, ethyl acetate, ethanol (Solórzano­Santos & Miranda-Novales, 2012). EOs of same plant may differ completely in aroma and properties from part to part e.g. Geranium plant yields oil from flowers and the leaves, and both oils from different parts differ in constituents, aroma and other properties (Veras et al., 2012; Rivera Calo et al., 2015). In plants, generally volatile oil stored in glands, oil ducts, resin ducts, or glandular trichomes of the plants. The quality of EOs usually affected by various interlinked factors, such as climatic conditions, seasonal and geographical conditions, harvesting time and method of extraction (Pannizi et al., 1993). The oils yield from the various parts of plants could be pretentious at the various stages of the plant growth. EOs is generally used as flavoring ingredient such as in edible products, drinks, perfume industries, pharmaceuticals, and cosmetics manufacturing.

Various compositions of EO make it potential to use them as potent antimicrobial agent with a low risk of microbial resistance occurrence (Bakkali et al., 2008).

et al, 2007; Tabanca, 2007). EOs also contains non-terpenic composites biogenerated via the Phenyl­propanoids pathway, such as eugenol, cinnamaldehyde, and safrole (Modzelewska, 2005).

Terpenoids are naturally occurring hydrocarbons and basically consist of five carbon isoprene units. Terpenoids are the terpenes obtained from the several kinds of plants and flowers in the form of primary constituents of the EOs (Thimmappa, 2014). Within terpenoids; monoterpenoid and sesquiterpenoid families are main because majority of most important components of EOs found in the plants (Ludwic­zuk, 2017). Terpenoids are divided into hemeterpenes (C diterpenes (C terpenes (C

Various Examples of EOs are turpentine, α and β-pinene isolated from Pinus species, geraniol isolated from Rosa damascena, terpinen-4-ol from Melaleuca alternifolia (tea tree oil), linalool from Coriandrum sativum, zingiberol from Zingiber officinale and cineol from Eucalyptus globulus, etc. (Bakkali et al, 2008; Sell, 2010; Chamorro et al., 2012).