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Thymol Based Nanoemulsions
Published in Ramesh Raliya, Nanoscale Engineering in Agricultural Management, 2019
Sarita Kumari, R.V. Kumara Swamy, Ram Chandra Choudhary, Savita Budhwar, Ajay Pal, Ramesh Raliya, Pratim Biswas, Vinod Saharan
Essential oils contain a complex mixture of non-volatile and volatile compounds, produced by aromatic plants as secondary metabolites, with a wide-spectrum of biological activities (Esmaeili and Asgari 2015). The fact that essential oils are considered as “natural” components makes them highly desirable for use in many food products, since there is growing consumer demand for natural rather than synthetic additives. The major constituents in commercial essential oils can be classified into three classes: Phenols, terpenes and aldehyde (Chang et al. 2012). Thymol (2-isopropyl-5-methylphenol) (Fig. 1) is a major essential oil phenolic component (EOCs) of the thyme oil extracted from the herb Thymus vulgaris and is classified as generally recognized as safe (GRAS) by the U.S. Food and Drug Administration. It is also known as “hydroxy cymene” because it is biosynthesized by the aromatization of γ-terpinene to p-cymene followed by hydroxylation of p-cymene. The antimicrobial efficacy of thymol has been known for decades (Poulose and Croteau 1978).
Terpenoids Against Infectious Diseases
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Sanhita Ghosh, Kamalika Roy, Chiranjib Pal
In 2014, Bukvicki et al. studied the effect of Satureja horvatii oil against certain Gram-positive and -negative bacteria in vitro. According to his work, Satureja horvatii oil showed significant effects against Staphylococcus aureus, Salmonella typhimurium, Listeria monocytogenes and Escherichia coli (Bukvicki et al. 2014). The major constituents of this oil were p-cymene (33.14%) and thymol (26.11%) (Table 8.1). In a singular experiment, a minimal concentration of p-cymene completely inhibited the growth of Escherichia coli, Vibrio parahaemolyticus, Listeria monocytogenes and Salmonella enterica. Similarly, at a concentration of 6 mg/mL, Staphylococcus aureus, Streptococcus mutans and, at a concentration of 3 mg/mL, Streptococcus sanguinis, were found to be inhibited. Moreover, p-cymene was found to exert synergistic effects along with 4-terpineol, linalool and α-terpineol (Table 8.1), against Salmonella enterica, Staphylococcus aureus and Streptococcus sanguinis (Marchese et al. 2017).
Surface Acidity and Catalytic Activity
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
The occurrence in clay minerals of both Brønsted and Lewis acid sites, and their involvement in organic catalysis, have been the subject of many reports. Brown and Rhodes (1997a), for example, found that an acid-treated montmorillonite, exchanged with various polyvalent cations, could mediate the Brønsted acid-catalyzed conversion of α-pinene to camphene as well as the Lewis acid-catalyzed rearrangement of camphene hydrochloride to isobornyl chloride. Brønsted acidity peaked following thermal activation of the clay catalyst at 150°C, while maximum Lewis acidity was measured after heating at 200°C–300°C. That Brønsted and Lewis acidity may operate competitively has been suggested by Frenkel and Heller-Kallai (1983) during the high-temperature transformation of limonene in the presence of Na+-, Mg2+-, Al3+-, and H+/Al3+-exchanged montmorillonites. The isomerization-disproportionation of limonene is apparently controlled by Brønsted acidity, which in turn is influenced by the nature of the interlayer cations. On the other hand, the formation of p-cymene by oxidation (of limonene) is a Lewis acid catalyzed reaction. Similarly, Motokura et al. (2007) have proposed that the high activity of Al3+-montmorillonite in catalyzing the α-benzylation of 1,3-dicarbonyl compounds with primary alcohols is due to cooperation between Brønsted and Lewis acid sites in the interlayer space. Synergy between Brønsted and Lewis acidities may also lie behind the high efficiency of Fe3+- and Zn2+-(K10) montmorillonites in catalyzing the Friedel–Crafts acylation of aromatic ethers with acetic anhydride as compared with the Cu2+-, Al3+-, and Co2+-exchanged samples (Choudary et al. 1998).
The product of interaction of elemental sulfur and dimethylphosphate 1,3-dimethylimidazolium is a new green initiator of formaldehyde polymerization
Published in Green Chemistry Letters and Reviews, 2021
Natalia Tarasova, Alexey Zanin, Efrem Krivoborodov, Mikhail Motyakin, Irina Levina, Valerie Dyatlov, Ilya Toropygin, Victor Dyakonov, Yaroslav Mezhuev
The initiating system was obtained by dispersing 1.46 g (5.7×10–3 mol) of S8 and 1 mL (5.7×10–3 mol) of 1,3-dimethylimidazolium dimethylphosphate in 50 mL of benzene at a temperature of 298 K and stirring for 1 h. All reagents were produced by Sigma-Aldrich. The dark-brown product of the interaction of the ionic liquid and elemental sulfur accumulates in the lower layer as a result of phase separation, so that its quantitative isolation, accompanied by complete regeneration of benzene, was possible with the help of a dividing funnel. Benzene can be replaced with p-cymene, as a green alternative. It is assumed that the formation of the initiating system is accompanied by the opening of the S8 ring as a result of a nucleophilic attack by a dimethylphosphate anion (Scheme 1). At least, ionic liquids that do not contain a dimethylphosphate anion (and its homologs) did not interact with S8, and the opening of the S8 ring when interacting with dimethylphosphate-containing ionic liquids was confirmed earlier by high-resolution mass spectroscopy data and the appearance of an additional oxygen atom signal in the 17O NMR spectra (10–12).
Synthesis, characterization, and antimicrobial studies of half-sandwich η6-toluene ruthenium complexes with N,N′-bidentate ligands
Published in Journal of Coordination Chemistry, 2020
Joel M. Gichumbi, Holger B. Friedrich, Bernard Omondi, Hafizah Y. Chenia
Arene-ruthenium complexes play an important role in organometallic chemistry among various metal complexes. They have been shown to exhibit antimicrobial activity against drug-resistant pathogenic microorganism [5, 8, 9]. The increased activity of these ruthenium complexes in antimicrobial, antibiotic, and anticancer applications has greatly contributed to the interest in synthesizing new ruthenium complexes and investigating their possible uses [5, 8, 9]. Although a large number of Ru(II)-arene compounds have been developed and extensively investigated, most studies have focused on [(η6-arene)RuCl(L)Cl]+ (where arene is η6-C6H6, p-cymene, and L the ligand) type complexes [8]. This work therefore is a contribution to half-sandwich ruthenium complexes where arene is η6-C6H5-CH3. Toluene was chosen because it has properties between benzene and p-cymene. This was expected to have an influence on the properties when compared to benzene and p-cymene; due to the presence of one methyl group it has a different ability to provide electron density to the ruthenium metal ion.
A brief insight into the use of plant products as green inhibitors for corrosion mitigation of aluminium and aluminium alloys
Published in Canadian Metallurgical Quarterly, 2022
K Namitha, Padmalatha Rao, Suma A. Rao
Umoren et al. evaluated [58] corrosion inhibition properties of Pachylobus edulis exudate gum for aluminium in 0.1 M HCl in the presence of halide ions Cl–, Br– and I–. The phytochemical components present are sabinene, terpene-4-ol, -pinene, and p-cymene (Figure S6 (a-d)). The objective of adding halide ions is to demonstrate enhanced synergism. After the addition of halide ions, inhibition efficiency increased from 41% to 63%. The halide ions improved exudate gum cations adsorption by forming metal bridges between metal and organic compounds.