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Essential oils: General aspects
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
For some other oils, their major allergens can tentatively be identified on the basis of their general composition and co-reactions to important ingredients in patch testing as documented in literature. For example, 50% of 94 patients allergic to clove oil co-reacted to eugenol, which is the major ingredient (>82%) of this essential oil (35). Eugenol is also an important component of bay oil (40–55%). Of seven patients reacting to bay oil and tested with eugenol, five (71%) co-reacted to eugenol (36). In the case of lemongrass oil, of 67 patients reacting to this oil, 34 (51%) also reacted to citral (35). Citral consists of geranial + neral, both of which are the dominant ingredients of lemongrass oils (1). Similar combinations include geraniol and geranium oil (23), geraniol and rose oil (23), cinnamal and cinnamon oil, cinnamal and cassia oil, menthol and peppermint oil, and carvone and spearmint oil.
Metabolism of Terpenoids in Animal Models and Humans
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Both natural and synthetic citral are isomeric mixtures of geranial and neral, in which geranial is usually the predominant isomer. Major amounts are found in the essential oils of Cymbopogon sp., Backhousia citriodora, Litsea cubeba, Verbena officinalis, or Melissa officinalis. Moreover, it is found in many citrus oils. Because of its intense lemon aroma, citral has been extensively used for flavoring food, cosmetics, and detergents (O'Neil, 2006; Bornscheuer et al., 2014). Studies in rats have shown that citral is rapidly metabolized into several acids and a biliary glucuronide and excreted, with urine as the major route of elimination of citral, followed by expired air and feces. As demonstrated in Figure 10.10, seven urinary metabolites were isolated and identified (Diliberto et al., 1990). Based on the rat study mentioned above, extensive biotransformation of citral in human subjects is highly suggested.
Monoterpenes-Based Pharmaceuticals: A Review of Applications In Human Health and Drug Delivery Systems
Published in Megh R. Goyal, Durgesh Nandini Chauhan, Plant- and Marine-Based Phytochemicals for Human Health, 2018
Irina Pereira, Aleksandra Zielińska, Francisco J. Veiga, Ana C. Santos, Izabela Nowak, Amélia M. Silva, Eliana B. Souto
Citral exists in lemon oil and citrus flavors.52 Owing to its strong, lemonlike fragrance, it can be successfully used in the food chemistry or perfumery industry,84 as well as for the production of vitamin A. Citral is chemically unstable and readily biodegraded into geranic acid and 6-methyl-5-heptene2-on over time in aqueous solutions. It has been confirmed that citral can be transformed into 2-formylmethy l-2-methyl-5-(1-hydroxy-1-methylethy)tetrahydrofuran under oxygen atmosphere in aqueous acidic condition. According to Organization for Economic Co-operation and Development, almost 92 wt.% of citral can be degraded after 28 days. Furthermore, the degradation rate of citral is also dependent on pH. The half-life time for neral is 9.54 days at pH 4 and for geranial 9.81 days at the same pH. In turn, at pH 7, citral was slowly degraded and the half-life time of neral is 230 days, and geranial 106 days. Finally, in the alkaline solution (pH around 9) the half-life time of neral was 30.1 and 22.8 days.
Review of Antimicrobial and Other Health Effects in 5 Essential Oil Producing Grass Species
Published in Journal of Dietary Supplements, 2023
These species contain essential oils used worldwide in the perfume industry and have been found to have antimicrobial plus other health uses. The main essential oil in lemongrass is citral and accumulates in oil cells inside leaf tissue (Lewinsohn et al. 1998). Essential oil is reported to be found in lemongrass roots, stalks, and leaves at concentrations of 8.7, 27.8, and 35.1%, respectively (Olayemi 2017). Wen et al. (2012) reported that essential oil content declined as leaf blades decreased, however essential oil increased with increasing biomass. Oven drying lemongrass leaves increased the essential oil percentage (2.45%) which was higher than shade drying (2.12%) and sun drying (2.1%) (Hanaa et al. 2012). Palmerosa oil is found in aerial and root portions of palmerosa grass (Verma et al. 2019). Geranium grass oil occurs in leaves (Saggu et al. 2019). Vetiver oil is produced in vetiver grass roots (Del Giudice et al. 2008), however scented top oil occurs in the inflorescence of scented top grass (Verma et al. 2012). This paper discusses several health effects based on an extensive literature review of lemongrass, palmarosa grass, geranium grass, vetiver grass, and scented top grass.
Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)
Published in Pharmaceutical Development and Technology, 2020
Aleksandra Zielińska, Nuno R. Ferreira, Agnieszka Feliczak-Guzik, Izabela Nowak, Eliana B. Souto
The released profiles monoterpenes-loaded SLN shown in Figure 2 enable the identification of a burst release within the first 15 min, while the process was monitored up to 24 h. During the first 15 min almost 16% of α-pinene was immediately released, followed by 6% of citral and geraniol, while for limonene the released profile reached 3.5% during the same time-period. Burst release has been attributed to the different chemical properties of monoterpenes (Huang and Brazel 2001). As a result of the faster release profile of α-pinene-SLN, a faster therapeutic effect could be estimated for these formulations. Within the first hour, besides α-pinene-SLN, citral-SLN also achieved more than 13% of drug release, which can also be linked to the high volatility of these monoterpenes (Marcus et al. 2013; Bilia et al. 2014). However, citral-SLN released only about 30% of the drug within the first 8 h, which means that 70% of the administered monoterpene would not have any therapeutic effect. In addition, the formulation containing citral released the highest percentage of the drug (∼36%) within the whole study lasting 24 h. Besides the particle size, the release is also dependent on the way the volatile compounds are entrapped within the lipid matrix, i.e. if in the inner core, if dissolved in the solid lipid or if placed closer to the surface. The lower the particle size, the higher the surface area of the particles offering higher exposure to the environment and therefore a higher release – in this case, higher volatility.
Citral presents cytotoxic and genotoxic effects in human cultured cells
Published in Drug and Chemical Toxicology, 2020
Ana C. S. Souza, Laís K. Silva, Thais B. Queiroz, Eduardo S. Marques, Clélia A. Hiruma-Lima, Isabel O. M. Gaivão, Edson L. Maistro
Citral (3,7-dimethyl-2,6 octadienal), a mixture of two isomers (cis-isomer neral and trans-isomer geranial), is a monoterpene aldehyde widely used as an aromatic supplement for cosmetics and food industry because of its pleasant lemon scent and flavor (Opdyke 1979; Choi et al.2010). It is the major constituent (65–85%) of the lemongrass (Cymbopogon citratus) leaves oil (Saddiq and Khayyat 2010). This plant is popularly used in tropical and subtropical regions, especially in Brazil, as a spasmolytic, analgesic, antihypertensive, anti-inflammatory, antipyretic, diuretic, and tranquilizer (Ferreira 1984; Carbajal et al.1989; Boukhatem et al.2014; Costa et al.2016). Hypoglycemic, hypolipidemic (Adeneye and Agbaje 2007), anti-Leishmania (Machado et al.2012), antifungal (Boukhatem et al.2014), antitumor, immunomodulatory (Bao et al.2015) and gastroprotective activities were also reported (Sagradas et al.2015). A large part of the pharmacological activities of this plant is attributed to the presence of citral.