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Essential Oils
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Mohd Sajjad Ahmad Khan, Mohd Musheer Altaf
An array of virulence factors viz. adhesions, melanin, calcineurin, hydrolytic enzymes, catalases, lipid signaling molecules including biofilm formation has been observed in fungal pathogenesis. These traits have been addressed under in vitro and in vivo for the development of newer antifungals targeting pathogenicity. It has been shown that some phyto-compounds such as tacrolimus and cyclosporine A impede calcineurin in C. albicans and Cryptococcus neoformans (Liu et al. 1991; Huai et al. 2002). Aureobasdin A and Khafrefungin have been shown to inhibit inositol phosphoryl ceramide synthase in Candida spp., C. neoformans, and Aspergillus spp. (Gauwerky et al. 2009). Hammer et al. (2000) reported inhibitory effects of TTO on germ tube formation (GTF) in C. albicans. They observed that GTF by C. albicans is influenced by the exposure of Candida cells to sub-inhibitory concentrations of TTO. Manoharan et al. (2017) revealed the chemical makeup, antibiofilm, and antihyphal activities of oil from cedar leaf. They observed potential antibiofilm activity of cedar leaf oil against C. albicans. They identified α-thujone, camphor, fenchone, fenchyl alcohol, and borneol as significant inhibitor of biofilm development in C. albicans. As inhibition of hyphal formation is responsible for antibiofilm effects, their transcriptomic analyses revealed camphor and fenchyl alcohol to be downregulating a few hypha-specific and biofilm-related genes (ECE1, ECE2, RBT1, and EED1).
Terpenoids Against Infectious Diseases
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Sanhita Ghosh, Kamalika Roy, Chiranjib Pal
Menthol is a cyclic monoterpene alcohol, found as a major constituent in the essential oils of Mentha canadensis L. (cornmint) and M. × piperita L. (peppermint). The inhibitory capacity of M. piperita oil, which contains menthol (42.8%), menthone (14.6%) and isomenthone (5.9%) as the major constituents, was evaluated in vitro on RC-37 cells against HSV-1 and HSV-2 using a plaque reduction assay and viral suspension test. Peppermint oil showed a time-dependent activity 3 h after incubation. The concentration required to inhibit 50% of HSV plaque formation was found to be 0.002% and 0.0008% for HSV-1 and HSV-2, respectively (Schuhmacher et al. 2003; Kamatou et al. 2013). Isoborneol (Table 8.1), a monoterpene alcohol, was reported to inhibit HSV-1 replication significantly at 0.06% concentrations by interfering with the glycosylation of the viral polypeptides gB and gD. Interestingly, (+)-isoborneol isomer was found most effective against HSV-1, whereas other monoterpenoid alcohols such as borneol (an isomer with respect to the hydroxyl position to isoborneol) (Table 8.1) or eugenol, did not exhibit satisfactory results with inhibitory effects on viral glycosylation (Erdog˘an Orhan et al. 2012; Armaka et al. 1999).
Surface Tracing Methods
Published in Wen-Jei Yang, Handbook of Flow Visualization, 2018
Of the physical methods, we will first consider the sublimation method, which is based on the fact that a coating of a suitable material on the surface of the body in flow is sublimated more strongly in the region of the turbulent boundary layer than in the region of the laminar boundary layer. A basic requirement is that the color of the coating be different from that of the body in the flow. It is then possible to establish the transition boundary between the surface free of the coating, i.e., that portion of the surface where the coating substance is passed into the flowing medium by action of the sublimation, and the surface where the coating remained unaffected. In certain cases the difference between these two portions of the surface is insufficiently distinct, and is properly visible only after intense oblique illumination [26]. The following substances are most frequently used for coatings: hexachloroethane, naphthalene, diphenyl, acenaphthene, hydroquinone, diethylether, fluorene, camphor, borneol [9]. The test surface is coated by dry spraying, using a solvent, e.g., of acetone, light petroleum fractions, benzene, xylene, whenever necessary. The solvent chosen must not be damaging to the body surface being tested.
Synthesis of borneol from α-pinene catalyzed by a SO42−/TiO2–La3+ nanometer rare-earth solid superacid
Published in Inorganic and Nano-Metal Chemistry, 2018
Helin Wang, Lihong Jiang, Yaming Wang, Yane Zheng, Xingxing Jiao, Deng Pan
Borneol (C10H18O) is a terpene and organic component that is widely used to treat encephalopathy and neurological disorders.[1–3] Borneol has multiple biological and pharmacological activities, including the inhibition of acetylcholine-mediated effects,[4] the enhancement of the adsorption of modulation of bone metabolism,[5] and the GABA action.[6] In recent years, with the increasing demand for borneol, natural borneol has been far from the needs of mankind. The borneol was usually prepared industrially in two stages: (1) α-pinene is treated with liquid mineral acids and (2) the resulting borneol or α-terpineol is esterified with acetic anhydride in the presence of the mineral-acidic catalysts.[7,8] The disadvantages of such a process include serious corrosion of equipment, complicated technique, too large amount of catalysts, dramatic reaction which is hard to control, too large raw material consumption, non-recyclability of catalyst, and serious environmental pollution. In view of these reasons, searching for an efficient and environmentally-friendly catalyst has become an important research theme.