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Sapit Diloksumpun Nalin Wongkattiya Kittisak Buaban Tharinee Saleepochn Panawan Suttiarporn Suwaporn Luangkamin 《Molecules (Basel, Switzerland)》2022,27(3)
Eucalyptus oils are widely used for a variety of purposes. This study investigates the terpenoid compositions and antibacterial and antioxidant activities of eucalypt leaf oils extracted from four E. urophylla clones and one E. urophylla × E. camaldulensis hybrid clone grown in Thailand. According to GC/MS analysis, the E. urophylla oils were mainly composed of 1,8-cineole, α-terpinyl acetate, β-caryophyllene, and spathulenol, while 1,8-cineole, α-terpinyl acetate, p-cymene, and γ-terpinene were mostly identified in the hybrid oil. All eucalypt oils exhibited a significant bacteriostatic effect against Gram-positive bacteria, Streptococcus pyogenes, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. Only the hybrid oil had an effect on all Gram-negative bacteria tested, including Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes. These oils have antibacterial properties that vary according to their terpenoid content. Only the hybrid oil had a potent antioxidant effect, with an IC50 value of 4.21 ± 0.35 mg/mL for free radical (DPPH) scavenging. This oil’s antioxidant effect may be a result of the phenolic terpenoids, thymol and carvacrol. As a result, these oils may be a novel source of antibacterial and antioxidant agents. Additionally, the antibacterial and antioxidant capabilities of the E. urophylla × E. camaldulensis hybrid essential oil are reported for the first time. 相似文献
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The three isomeric methylpyridines and the three isomeric cyanopyridines each constitute a photochemical triad. Irradition of each methylpyridine or each cyanopyridine in the vapor phase at 254 nm results in the formation of the other two isomers as primary photoproducts. Dideuteration of the 2-substituted or 3-substituted methyl or cyanopyridines expanded each triad to a pentad. Due to symmetry, 2,6-dideuteration of 4-methyl-or 4-cyanopyridine did not expand the triad. Trideuteration of 4-methylpyridine removed this symmetry and resulted in a photochemical pentad. These results are consistent with a mechanism involving 2,6-photocylization, migration of nitrogen around the five sides of the cyclopentenyl ring, and rearomatization. This mechanism exactly predicts the observed distribution of deuterium in the photoproducts. 相似文献
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2,5-Dideuteriopyrazine (1-2,5-d2) and 2,6-dideuteriopyrazine (1-2,6-d2) phototranspose in the vapor phase to mixtures of 4,6-dideuteriopyrimidine (2-4,6-d2) and 2,5-dideuteriopyrimidine (2-2,5-d2) or 4,5-dideuteropyrimidine (2-4,5-d2) and 2,4-dideuteriopyrimidine (2-2,4-d2), respectively. In each case, a trace quantity of a dideuteriopyridazine (7-d2) photoproduct was also observed. These products are consistent with a diazaprefulvene mechanism involving, 2,6-bonding, one or two nitrogen migrations, and rearomatization. 相似文献
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