clove and humulene

The present study describes the possibility of using some essential oils and monoterpens as bioagents against the growth of Ralstonia solanacearum, a causal bacterium of potato brown rot disease. Eight isolates of the bacterium were recovered from infected potato tubers, showing typical symptoms of the disease, Isolates were identified as R.solanacearum phylotype II, based on biochemical and physiological characteristics, as well as, at the molecular level through PCR analysis. Three essential oils extracted from Corymbia citriodora (leaves), Cupressus sempervirens (aerial parts), and Lantana camara (aerial parts) were evaluated for their antibacterial activity against eight isolates of R. solanacearum phylotype II. Results demonstrated that L. camara essential oil (concentration 5000 μg/mL) had the highest effects against the RsMo2, RsSc1 and Rs48, with inhibition zone (IZ) values of 17.33, 16.33, and 17.50 mm, respectively, also against Rs2 (IZ 14.33 mm), and RsIs2 (IZ 16 mm). C. citriodora oil showed the highest activity against RsBe2 (IZ 14 mm), RsFr4 (IZ 13.66 mm) and RsNe1 (IZ 13.66 mm). Gas Chromatography-Mass Spectrometry (GC-MS-FID) analyzed the chemical composition of these essential oils. It was proved that L. camara leaves contains mainly trans-caryophyllene (16.24%) and α-humulene (9.55%), in C. citriodora oil were α-citronellal (56.55%), α-citronellol (14.89%), and citronellol acetate (13.04%), and in Cup. sempervirens aerial parts were cedrol (22.17%), and Δ3-carene (18.59%). Five monoterpenes were evaluated against the most resistance Ralstonia isolate RsFr5 to the three studied essential oils and found that limonene had the highest effect against it compared with the lowest thymol. The results proved the strong bio effects of the essential oil from L. camara leaves as a natural product contained monoterpenes that can inhibit the growth of tested R. solanacearum phylotype II isolates.

Topics: Acyclic Monoterpenes; Aldehydes; Anti-Bacterial Agents; Cupressus; DNA, Bacterial; Gas Chromatography-Mass Spectrometry; Lantana; Microbial Sensitivity Tests; Monocyclic Sesquiterpenes; Monoterpenes; Myrtaceae; Octanols; Oils, Volatile; Plant Diseases; Plant Extracts; Plant Leaves; Ralstonia solanacearum; Sesquiterpenes; Solanum tuberosum

Topics: Aedes; Animals; Anopheles; Biological Control Agents; Culex; Female; Insecticides; Larva; Monocyclic Sesquiterpenes; Mosquito Vectors; Myrtaceae; Oils, Volatile; Oviposition; Plant Leaves; Polycyclic Sesquiterpenes; Sesquiterpenes; Syzygium

Lophostemon suaveolens is a relatively unexplored endemic medicinal plant of Australia. Extracts of fresh leaves of L. suaveolens obtained from sequential extraction with n-hexane and dichloromethane exhibited antibacterial activity in the disc diffusion and MTT microdilution assays against Streptococcus pyogenes and methicillin sensitive and resistant strains of Staphylococcus aureus (minimum bactericidal concentration < 63 μg/mL). The dichloromethane extract and chromatographic fractions therein inhibited nitric oxide in RAW264.7 murine macrophages (IC50 3.7-11.6 μg/mL) and also PGE2 in 3T3 murine fibroblasts (IC50 2.8-19.7 μg/mL). The crude n-hexane, dichloromethane and water extracts of the leaves and chromatographic fractions from the dichloromethane extract also showed modest antioxidant activity in the ORAC assay. GC-MS analysis of the n-hexane fraction showed the presence of the antibacterial compounds aromadendrene, spathulenol, β-caryophyllene, α-humulene and α-pinene and the anti-inflammatory compounds β-caryophyllene and spathulenol. Fractionation of the dichloromethane extract led to the isolation of eucalyptin and the known anti-inflammatory compound betulinic acid.

Topics: 3T3 Cells; Animals; Anti-Bacterial Agents; Anti-Inflammatory Agents; Australia; Azulenes; Betulinic Acid; Bicyclic Monoterpenes; Flavonoids; Mice; Microbial Sensitivity Tests; Monocyclic Sesquiterpenes; Monoterpenes; Myrtaceae; Nitric Oxide; Pentacyclic Triterpenes; Plant Extracts; Plant Leaves; Plants, Medicinal; Polycyclic Sesquiterpenes; RAW 264.7 Cells; Sesquiterpenes; Staphylococcus aureus; Streptococcus pyogenes; Triterpenes; Tumor Necrosis Factor-alpha

Mosquitoes transmit serious pathogens and parasites to humans and animals, including malaria, dengue, Japanese encephalitis and filariasis. The extensive use of chemical pesticides leads to the development of resistance in mosquito vector populations and serious non-target effects on human health and the environment. Myrtaceae plants can be a useful reservoir of natural products effective against Culicidae young instars. In this research, we evaluated the mosquitocidal potential of the essential oil (EO) from Syzygium zeylanicum leaves against larvae of three mosquitoes of medical and veterinary importance, the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus, and the Japanese encephalitis vector Culex tritaeniorhynchus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy. GC-MS revealed that the S. zeylanicum EO contained at least 18 compounds. The major chemical components were α-humulene (37.8.5 %) and β-elemene (10.7 %). The EO had a significant toxic effect against early third-stage larvae of An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus, with LC50 values of 83.11, 90.45, and 97.96 μg/ml, respectively. The two major constituents extracted from the S. zeylanicum EO were tested individually for acute toxicity against larvae of the three mosquito vectors. α-Humulene and β-elemene appeared highly effective against An. subpictus (LC50 = 6.19 and 10.26 μg/ml, respectively), followed by Ae. albopictus (LC50 = 6.86 and 11.15 μg/ml) and Cx. tritaeniorhynchus (LC50 = 7.39 and 12.05 μg/ml). Furthermore, the EO and its major components was safe towards the non-target fish Gambusia affinis; LC50 values were 20374.26, 1024.95, and 2073.18 μg/ml, respectively for EO, α-humulene and β-elemene. Overall, this study highlighted that the acute toxicity of S. zeylanicum EO towards mosquito larvae was mainly due to the presence of α-humulene and β-elemene. Furthermore, we pointed out the concrete possibility to exploit these two compounds from S. zeylanicum EO as highly effective larvicides against young instars of An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus, with little effect on non-target organisms.

Topics: Aedes; Animals; Anopheles; Culex; Gas Chromatography-Mass Spectrometry; Insecticides; Larva; Monocyclic Sesquiterpenes; Mosquito Vectors; Myrtaceae; Oils, Volatile; Plant Leaves; Sesquiterpenes; Syzygium

The leaf essential oils of the two chemotypes of Eugenia reinwardtiana (Blume) DC growing in Australia have been investigated. Chemotype 1, isolated in 0.2% yield, w/w, dry weight, contained major amounts of α-pinene (10-26%), limonene (1-15%), β-caryophyllene (0.7-11%), α-humulene (0.9-16%) and bicyclogermacrene (1-23%). The second chemotype, found only on coastal dunes SW of Lockerbie Qld, and isolated in 0.4-0.6% (w/w, dry weight), contained α-pinene (tr-8.5%) β-caryophyllene (12-27%) and α-humulene (1-17%) as the major terpenes. This chemotype also contained the novel aliphatic diketone, 2-butyl-2,4,4-trimethyl-5-methoxycyclohex-5-en-1,3-dione (18-33%), whose structure determination is reported herein.

Topics: Australia; Cyclohexanones; Cyclohexenes; Eugenia; Limonene; Molecular Structure; Monocyclic Sesquiterpenes; Oils, Volatile; Plant Leaves; Plant Oils; Sesquiterpenes; Terpenes