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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).
Sources of Pulping and Bleaching Derived Chemicals in Effluents
Published in Mark R. Servos, Kelly R. Munkittrick, John H. Carey, Glen J. Van Der Kraak, and PAPER MILL EFFLUENTS, 2020
Removal in biological treatment systems can be due to microbial degradation, physio-chemical processes such as adsorption, or air stripping. In some cases, microbial degradation may not be complete, resulting in compounds being partially metabolized. This results in the formation and discharge of new compounds. For example, early studies showed that some monoterpenes discharged to biological treatment systems can be converted to camphor or fenchone (Wilson and Hrutfiord 1975). Recent studies report that resin acids can be hydroxylated (Wilkins et al. 1988; Zender et al. 1993) or, under anaerobic conditions, undergo reduction (McFarlane and Clark 1988; Zender et al. 1993). Surveys of aerobically treated effluents in the United States showed detectable levels of 13-abieten-18-oic acid (NCASI 1989; NCASI unpublished data) and 7-oxodehydroabietic acid (NCASI unpublished data). NCASI has also surveyed several additional mill effluents for 7-isopimarenic acid and found the compound present only once at just above the detection limit (NCASI 1993; NCASI unpublished data). Additional studies would be required to determine how significant these findings are, but the low levels detected indicate these reduced and oxidized resin acids may not be a problem in well-operated aerobic treatment systems.
Terpenoids Against Cardiovascular Diseases
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Monoterpenes can be classified into three subgroups: monocyclic (terpinolene and α-terpineol), acyclic (linalool, geraniol, myrcene) and bicyclic (thujone, fenchone, camphor, α-pinene) (Santos et al. 2011). There are other classifications in each of these subgroups: tropolonas (γ-thujaplicin), aldehydes and ketones (carvone, myrtenal), alcohols (menthol), lactones (monoterpene lactones are called iridoids, for example, nepetalactone) and unsaturated hydrocarbons (limonene) (Simões et al. 2004). Monoterpenes along with diterpenes and sesquiterpenes are known as secondary metabolites because they are categorized as being nonessential for viability; nevertheless, they conciliate vital interactions between plants and their surroundings (Santos et al. 2011). Interestingly, several studies have found that monoterpenes have diverse pharmacological characteristics such as antibacterial, antifungal, anti-spasmodic, anti-oxidant and anticancer properties (Santos et al. 2011). In addition to those properties, monoterpenes are known to produce remarkable results on the cardiovascular system, enhancing amid other actions such as hypotension, reduced heart rate and vasodilation (Peixoto-Neves et al. 2010). Santos et al. (2011) surveyed 33 monoterpenes, 16 of them had been previously studied for their effects on the cardiovascular system: perillyl alcohol, citronellol, p-cymene, carvacrol, myrtenal, eucalyptol (1,8-cineole), α-terpineol, linalool, rotundifolone (piperitenone oxide), α-terpinen-4-ol, menthol, myrtenol, α-pinene, sobrerol, thymol and α-limonene. Consequently, monoterpenes are already often seen as beneficial therapeutic agents for the cure and prevention of CVDs (Figure 9.1).
The role of the intermediate state in angle-resolved photoelectron studies using (2 + 1) resonance-enhanced multiphoton ionization of the chiral terpenes, α-pinene and 3-carene
Published in Molecular Physics, 2021
Hassan Ganjitabar, Dhirendra P. Singh, Richard Chapman, Adrian Gardner, Russell S. Minns, Ivan Powis, Katharine L. Reid, Arno Vredenborg
In accordance with Yang's theorem [10] the photoelectron angular distribution, Eq. (1), for ionization of an initially randomly oriented sample would be limited to no more than the 2nd Legendre polynomial term; the significant presence of terms up to the 5th order polynomial is a clear indication that at least three photons are absorbed, contributing their angular momentum to the net anisotropy in the process. For the assumed (2 + 1) REMPI mechanism, a two-photon resonant intermediate excitation is supposed to be followed a single photon ionization of the intermediate. Additional anisotropy for the latter photoemission step comes from preferential molecular axis alignment in the excited intermediate. Theoretical models that attempt to capture such a two-photon induced intermediate alignment have proven to offer a semi-quantitative account of experimental MP-PECD results in the case of camphor [14] and fenchone [37]. The current results for α-pinene, with very substantial b3–b5 coefficients that cannot be present in the photoionization of a randomly oriented intermediate state, presents as a very strong test-case for further refinement of theoretical treatments.