Chemistry of Essential Oils
K. Hüsnü Can Başer, Gerhard Buchbauer in Handbook of Essential Oils, 2020
The two most significant monoterpene aldehydes are citral (71) and its dihydro analogue citronellal (103), both of which are shown in Figure 6.20. The word citral is used to describe a mixture of the two geometric isomers geranial (101) and neral (102) without specifying their relative proportions. Citral occurs widely in nature, both isomers usually being present, the ratio between them usually being in the 40:60 to 60:40 range. Lemongrass contains 70%–90% citral and the fruit of Litsea cubeba contains about 60%–75%. Citral also occurs in Eucalyptus staigeriana, lemon balm, ginger, basil, rose, and citrus species. It is responsible for the characteristic smell of lemons although lemon oil usually contains only a few percent of it. Citronellal (103) also occurs widely in essential oils. E. citriodora contains up to 85% citronellal, and significant amounts are also found in some chemotypes of L. cubeba, citronella Swangi leaf oil, and Backhousia citriodora. Campholenic aldehyde (104) occurs in a limited range of species such as olibanum, styrax, and some eucalypts. Material produced from a-pinene (65) is important as an intermediate for synthesis.
Monoterpenes-Based Pharmaceuticals: A Review of Applications In Human Health and Drug Delivery Systems
Megh R. Goyal, Durgesh Nandini Chauhan in Plant- and Marine-Based Phytochemicals for Human Health, 2018
Citral is classified as αand β-unsaturated aldehydes.139 Therefore, it can be used as a model substance for heterogeneously catalyzed selective hydrogenations. The hydrogenation process of the carbonyl group is insignificant when palladium is put on as an active metal. Then, the conjugated C = C bond is hydrogenated prior to the terminal isolated one. As a result of this reaction, citronellal (CAL) and dihydrocitronellal are obtained as main products.139 The main chemical and physical properties of citral are shown in Table 4.1.55 Physicochemical properties of citral are rare, in spite of that its hydrogenation products influence positively on chemicals and perfume industry.84
Monographs of fragrance chemicals and extracts that have caused contact allergy / allergic contact dermatitis
Anton C. de Groot in Monographs in Contact Allergy, 2021
Citronellal is a colorless to pale yellow clear liquid; its odor type is floral and its odor is described as ‘sweet, floral rosy waxy and citrus green’ (www.thegoodscentscompany.com). Citronellal is used in small amounts for scenting soaps and detergents, is also used as flavor in foods and beverages and is applied as insect repellent. Its principal application, however, is in the preparation of isopulegol, citronellol, and hydroxycitronellol (U.S. National Library of Medicine).
Review of Antimicrobial and Other Health Effects in 5 Essential Oil Producing Grass Species
Published in Journal of Dietary Supplements, 2023
Lemongrass leaves have shown to have anti-inflammatory properties via proteasome inhibition, NF-κB pathway, and cytokine expression (Francisco et al. 2013). Lemongrass extracts have been reported to reduce human lymphoma tumor growth (Philion et al. 2017). A clinical trial using 0.25% lemongrass oil mouthwash showed the highest reduction in plaque and gingival indexes when compared to a 0.2% chlorhexidine mouthwash (Dany et al. 2015). In fact, Subha and Pradeep (2017) showed in a clinical trial that a 0.25% concentration of lemongrass oil aided in chronic periodontitis and reduced markers of cardio-vascular diseases. Gastroprotective effects have been shown in rats fed with lemongrass leaf infusion (Sagradas et al. 2015). Lemongrass oil has been shown to be effective against prostate cancer and glioblastoma cell lines (Bayala et al. 2018). Polysaccharides of lemongrass may help in preventing or treating neurodegenerative diseases where neuro-inflammation is part of the problem (Mediesse et al. 2018). Machado et al. (2015) reported that a lemongrass hexane extract helped control allergic asthma in mice. A 20% solution of lemongrass oil showed an inhibition against Aeromonas salmonicida ssp. salmonicida which causes fish furunculosis disease (Starliper et al. 2015) and the main biochemicals in the lemongrass oil included eugenol α- and β-citral. Citronellal which has been found in lemongrass oil has the potential to prevent atherosclerosis in rats (Lu et al. 2019). Another component of lemongrass oil is linalool which has been reported to lower blood pressure and pulse rate in people with carpal tunnel syndrome (Seol et al. 2016).
Analysis of the clinical effect of olfactory training on olfactory dysfunction after upper respiratory tract infection
Published in Acta Oto-Laryngologica, 2019
Xiao-Feng Qiao, Guo-Ping Wang, Xin Li, Yin-Huan Bai, Wei Zheng
Four reagents with different odors were used, including benzene ethanol (rose), menthol (mint), citronellal (lemon), and eugenol (clove) (all 100%, from Sigma-Aldirch, USA). Each odorant was smelled for 10 s/time, and the interval between two odorants was 10 s. Each olfactory training session lasted for five minutes, and the training frequency was one time before breakfast and one time before sleep everyday [3]. The olfactory function was tested at 1, 3 and 6 months after treatment.
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