Chemical Characterization of the Essential Oil Compositions of Mentha spicata and M. longifolia ssp. cyprica from the Mediterranean Basin and Multivariate Statistical Analyses.

This present study aims to characterize the essential oil compositions of the aerial parts of M. spicata L. and endemic M. longifolia ssp. cyprica (Heinr. Braun) Harley by using GC-FID and GC/MS analyses simultaneously. In addition, it aims to perform multivariate statistical analysis by comparing with the existing literature, emphasizing the literature published within the last two decades, conducted on both species growing within the Mediterranean Basin. The major essential oil components of M. spicata were determined as carvone (67.8%) and limonene (10.6%), while the major compounds of M. longifolia ssp. cyprica essential oil were pulegone (64.8%) and 1,8-cineole (10.0%). As a result of statistical analysis, three clades were determined for M. spicata: a carvone-rich chemotype, a carvone/trans-carveol chemotype, and a pulegone/menthone chemotype, with the present study result belonging to the carvone-rich chemotype. Carvone was a primary determinant of chemotype, along with menthone, pulegone, and trans-carveol. In M. longifolia, the primary determinants of chemotype were identified as pulegone and menthone, with three chemotype clades being pulegone-rich, combined menthone/pulegone, and combined menthone/pulegone with caryophyllene enrichment. The primary determinants of chemotype were menthone, pulegone, and caryophyllene. The present study result belongs to pulegone-rich chemotype.

A comprehensive assessment of the cholinergic-supporting and cognitive-enhancing effects of Rosa damascena Mill. (Damask rose) essential oil on scopolamine-induced amnestic rats.

INTRODUCTION: Alzheimer's disease (AD) is a neurodegenerative condition characterized by gradual loss of cognitive abilities (dementia) and is a major public health problem. Here, we aimed at investigating the effects of Rosa damascena essential oil (RDEO) on learning and memory functions in a rat model of amnesia induced by scopolamine, as well as on changes in acetylcholinesterase (AChE) activity, M1 muscarinic acetylcholine receptor (mAChR) expression, and brain-derived neurotrophic factor (BDNF) levels in the extracted brain tissues. METHODS: The control, amnesia (scopolamine, 1 mg/kg/i.p.) and treatment (RDEO, 100 µL/kg/p.o. or galantamine, 1.5 mg/kg/i.p.) groups were subjected to Morris water maze and new object recognition tests. AChE activity was assayed by ELISA, and M1 mAChR and BDNF concentration changes were determined by western blotting. Also, using computational tools, human M1 mAChR was modeled in an active conformation, and the major components of RDEO were docked onto this receptor. RESULTS: According to our behavioral tests, RDEO was able to mitigate the learning and memory impairments caused by scopolamine in vivo. Our in vitro assays showed that the observed positive effects correlated well with a decrease in AChE activity and an increase in M1 mAChR and BDNF levels in amnestic rat brains. We also demonstrated in an in silico setting that the major components of RDEO, specifically -citronellol, geraniol, and nerol, could be accommodated favorably within the allosteric binding pocket of active-state human M1 mAChR and anchored here chiefly by hydrogen-bonding and alkyl-π interactions. CONCLUSION: Our findings offer a solid experimental foundation for future RDEO-based medicinal product development for patients suffering from AD.

In Vitro Antiviral Evaluations of Coldmix®: An Essential Oil Blend against SARS-CoV-2.

Coldmix® is a commercially available Eucalyptus aetheroleum and, Abies aetheroleum blend for medicinal applications. In this present study, the in vitro antiviral potential of Coldmix®, and its major constituents 1,8-cineole and α-pinene were evaluated by using the in vitro ACE2 enzyme inhibition assay as well as the direct contact test against SARS-CoV-2. The observed ACE2 enzyme inhibitory activity of Coldmix®, 1,8-cineole, and α-pinene were 72%, 88%, and 80%, respectively; whereas in the direct contact test in the vapor phase, the destruction of the virus was 79.9% within 5 min and 93.2% in the 30th min, respectively. In a similar Coldmix® vapor phase setup using the in vitro cytotoxicity cell assay, E6 VERO healthy cells were experimentally not affected by toxicity. According to the promising initial antiviral results of Coldmix® and the individually tested constituents, detailed further in vivo evaluation using different virus classes is suggested.

Evaluation of Antibacterial and Antifungal Effects of Calcium Hydroxide Mixed with Two Different Essential Oils.

BACKGROUND: Calcium hydroxide is a routinely used material for root canal disinfection during root canal treatment. Natural products have great potential in terms of their antibacterial effects. This study aimed to establish an effective alternative intracanal medicament using Origanum dubium (O. dubium) and Mentha spicata (M. spicata) essential oils. MATERIALS AND METHODS: O. dubium and M. spicata, collected from Lefke, Cyprus, were separately subjected to hydrodistillation. The obtained essential oil compositions were analysed simultaneously by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The compositions were then divided into groups and mixed with calcium hydroxide at a 1:1 concentration; after that, the pastes were tested on Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans), which are the most common resistant pathogenic microorganisms in the root canal. The antibacterial activity of the pastes was measured using a disk diffusion assay. RESULTS: The GC and GC-MS analyses revealed that O. dubium and M. spicata had major compositions of carvacrol (75.8%) and carvone (71.3%), respectively. Antimicrobial activity was found to be significantly higher when study groups with O. dubium essential oil were applied to both E. faecalis and C. albicans. The results also show that M. spicata, together with calcium hydroxide, demonstrated a significant antifungal effect on C. albicans when incubated for 72 h. CONCLUSIONS: M. spicata was found to be an effective antimicrobial agent on C. albicans, whereas O. dubium was found to be very effective on both E. faecalis and C. albicans. These data demonstrate that these natural essential oils may be promising candidates for alternative intracanal medicament in future routine clinical applications.

Comparative Studies on Essential Oil and Phenolic Content with In Vitro Antioxidant, Anticholinesterase, Antimicrobial Activities of Achillea biebersteinii Afan. and A. millefolium subsp. millefolium Afan. L. Growing in Eastern Turkey.

The potential applications of Achillea species in various industries have encouraged the examination of their phytochemical components along with their biological potential. In the present study, phenolic contents and essential oil compositions together with the in vitro biological activities of the aerial parts from Achillea biebersteinii Afan. and Achillea millefolium subsp. millefolium Afan. collected from Turkey were evaluated. Different solvent extracts (n-hexane, chloroform, methanol, water) were prepared and their antimicrobial, anticholinesterase, and antioxidant activities were studied. The LC-MS/MS results revealed the presence of 16 different phenolic compounds, including chlorogenic acid, rutin, quercetin, and luteolin glycosides, in methanolic extracts. According to GC-FID and GC/MS results, the primary components of the oils were identified as 1,8-cineole (32.5%), piperitone (14.4%), and camphor (13.7%) in A. biebersteinii and 1,8-cineole (12.3%) and ß-eudesmol (8.9%) in A. millefolium subsp. millefolium. The infusion and methanolic extracts of both species were found to be rich in their total phenolic content as well as their antioxidant and anticholinesterase activity. In contrast, the n-hexane and chloroform extracts of both species showed strong antimicrobial activity with MIC values ranging from 15 to 2000 µg/mL. Our findings suggest that the investigated Achillea species could be evaluated as potent natural agents, and further studies into the promising extracts are needed.

A multi-parameter evaluation of the neuroprotective and cognitive-enhancing effects of Origanum onites L. (Turkish Oregano) essential oil on scopolamine-induced amnestic rats.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive deterioration of cognitive functions (dementia) and represents a growing public health concern since the population in the age groups at risk is increasing. The latter raises an urgent need to translate research findings in the basic brain and behavioral sciences into anti-AD drugs and disease-modifying therapies. Origanum onites (L.), also called Turkish oregano, is a perennial and herbaceous plant species grown for centuries for medicinal, cosmetic and culinary purposes. This is the first study to investigate the putative neuroprotective and pro-cognitive activities of O. onites essential oil (OOEO) against scopolamine-induced amnesia of AD-type in Wistar albino rats. The results of behavioral tests revealed that OOEO administration was able to significantly alleviate learning and memory impairments induced by scopolamine in vivo. The observed effects could be attributed to inhibition of acetylcholinesterase activity, attenuation of oxidative stress and prevention of neuronal apoptosis in the hippocampus and frontal cortex of AD rats. Modulation of pro-inflammatory enzymes, including cyclooxygenase-2, inducible nitric oxide synthase and myeloperoxidase, might further contribute to the neuroprotective properties of OEOO, as predicted by our in silico models. These findings offer novel insights into the therapeutic potential of OEOO in patients with AD.

Volatile constituents of three Thymus sipyleus Boiss. subspecies from different sites in Turkey.

This study was designed to reveal the chemical diversity of some Thymus sipyleus subspecies growing wild in Turkey and to compare the volatile compound profiles by using micro(hydro)distillation technique. For this purpose, volatile compounds isolated by microdistillation from nine samples (three plant samples collected from different regions in Antalya) of Thymus sipyleus Boiss. subsp. sipyleus var. sipyleus, T. sipyleus Boiss. subsp. sipyleus var. davisianus Ronniger, and T. sipyleus Boiss. subsp. rosulans (Borbas) Jalas were analyzed by GC and GC-MS systems. 1,8-Cineole, p-cymene, α-terpineol and carvacrol were identified as major compounds in T. sipyleus subsp. sipyleus var. sipyleus samples. Geranial, neral, 1,8-cineole and ß-caryophyllene, and α-terpineol and geranial were the main compounds in T. sipyleus subsp. sipyleus var. davisianus samples. ß-Caryophyllene, intermedeol, 1,8-cineole and α-terpineol, α-pinene were the major compounds in T. sipyleus subsp. rosulans samples. As known, thymol is the main compound in most Thymus species in Turkey, but, according to our study, chemical polymorphism has been found among the T. sipyleus subspecies.

Antibacterial Activities of Herbal Toothpastes Combined with Essential Oils against Streptococcus mutans.

In recent years, people have become more conscious about the side-effects of fluoride toothpastes and herbal products have drawn attention as alternatives in the struggle against caries. Studies have focused on the benefits of essential oils obtained from herbs because of their antibacterial effects. The aim of this study was to evaluate and compare the antibacterial activity of Origanum dubium and Cinnamomum cassia oils combined with herbal toothpastes against Streptococcus mutans. The antibacterial activity of the test materials was determined using the agar well diffusion method before and after the addition of essential oils. We tested the efficacy of Splat Organic and Splat Biocalcium against S. mutans (12 mm and 11 mm, respectively) doubled in combination with Origanum dubium (23 mm for both toothpastes) and tripled with Cinnamomum cassia (38 mm and 36 mm, respectively). Jack N' Jill toothpaste, which did not initially show any antibacterial effect, exhibited the largest inhibition zones after the addition of the essential oils (38 mm for Origanum dubium and 39 mm for Cinnamomum cassia). The results of this study pointed out that herbal toothpastes exhibit statistically higher antibacterial activity against Streptococcus mutans (p < 0.05) than their initial forms after the addition of essential oils.

Rhanterium epapposum Oliv. essential oil: Chemical composition and antimicrobial, insect-repellent and anticholinesterase activities.

The essential oil (EO) of the aerial parts of Rhanterium epapposum Oliv. (Asteraceae), was obtained by hydrodistillation. The oil was subsequently analyzed by both GC-FID and GC-MS, simultaneously. Forty-five components representing 99.2% of the oil composition were identified. The most abundant compounds were camphene (38.5%), myrcene (17.5%), limonene (10.1%) and α-pinene (8.7%). Referring to the ethnobotanical utilization, an insecticidal assay was performed, where the oil repelled the yellow fever mosquito Aedes aegypti L. at a minimum effective dose (MED of 0.035 ± 0.010 mg/cm2) compared to the positive control DEET (MED of 0.015 ± 0.004 mg/cm2). Additionally, the in vitro antimicrobial activity against a panel of pathogens was determined using a microdilution method. The acetyl- and butyrylcholine esterase inhibitory activities were measured using the colorimetric Ellman method. The bioassay results showed that the oil was rather moderate in antimicrobial and cholinesterase inhibitions when compared to the standard compounds.

Chemical composition and phagocyte immunomodulatory activity of Ferula iliensis essential oils.

Essential oil extracts from Ferula iliensis have been used traditionally in Kazakhstan for treatment of inflammation and other illnesses. Because little is known about the biologic activity of these essential oils that contributes to their therapeutic properties, we analyzed their chemical composition and evaluated their phagocyte immunomodulatory activity. The main components of the extracted essential oils were (E)-propenyl sec-butyl disulfide (15.7-39.4%) and (Z)-propenyl sec-butyl disulfide (23.4-45.0%). Ferula essential oils stimulated [Ca2+]i mobilization in human neutrophils and activated ROS production in human neutrophils and murine bone marrow phagocytes. Activation of human neutrophil [Ca2+]i flux by Ferula essential oils was dose-dependently inhibited by capsazepine, a TRPV1 channel antagonist, indicating that TRPV1 channels mediate this response. Furthermore, Ferula essential oils stimulated Ca2+ influx in TRPV1 channel-transfected HEK293 cells and desensitized the capsaicin-induced response in these cells. Additional molecular modeling with known TRPV1 channel agonists suggested that the active component is likely to be (Z)-propenyl sec-butyl disulfide. Our results provide a cellular and molecular basis to explain at least part of the beneficial therapeutic properties of FEOs.

Modulation of Human Neutrophil Responses by the Essential Oils from Ferula akitschkensis and Their Constituents.

Essential oils were obtained by hydrodistillation of the umbels+seeds and stems of Ferula akitschkensis (FAEOu/s and FAEOstm, respectively) and analyzed by gas chromatography and gas chromatography-mass spectrometry. Fifty-two compounds were identified in FAEOu/s; the primary components were sabinene, α-pinene, ß-pinene, terpinen-4-ol, eremophilene, and 2-himachalen-7-ol, whereas the primary components of FAEOstm were myristicin and geranylacetone. FAEOu/s, ß-pinene, sabinene, γ-terpinene, geranylacetone, isobornyl acetate, and (E)-2-nonenal stimulated [Ca(2+)]i mobilization in human neutrophils, with the most potent being geranylacetone (EC50 = 7.6 ± 1.9 µM) and isobornyl acetate 6.4 ± 1.7 (EC50 = 7.6 ± 1.9 µM). In addition, treatment of neutrophils with ß-pinene, sabinene, γ-terpinene, geranylacetone, and isobornyl acetate desensitized the cells to N-formyl-Met-Leu-Phe (fMLF)- and interleukin-8 (IL-8)-induced [Ca(2+)]i flux and inhibited fMLF-induced chemotaxis. The effects of ß-pinene, sabinene, γ-terpinene, geranylacetone, and isobornyl acetate on neutrophil [Ca(2+)]i flux were inhibited by transient receptor potential (TRP) channel blockers. Furthermore, the most potent compound, geranylacetone, activated Ca(2+) influx in TRPV1-transfected HEK293 cells. In contrast, myristicin inhibited neutrophil [Ca(2+)]i flux stimulated by fMLF and IL-8 and inhibited capsaicin-induced Ca(2+) influx in TRPV1-transfected HEK293 cells. These findings, as well as pharmacophore modeling of TRP agonists, suggest that geranylacetone is a TRPV1 agonist, whereas myristicin is a TRPV1 antagonist. Thus, at least part of the medicinal properties of Ferula essential oils may be due to modulatory effects on TRP channels.

Chemical Composition and Biological Activity of Centaurea baseri: New Species from Turkey.

The genus Centaurea L. is one of the largest and important genera of Asteraceae family. Centaurea species have been widely used as herbal remedies in folk medicine for their antidandruff, antidiarrheic, antirheumatic, anti-inflammatory, choleretic, diuretic, digestive, stomachic, astringent, antipyretic, cytotoxic, and antibacterial properties. Centaurea baseri Kose & Alan is a recently described local endemic species in Turkey and this is the first study on the chemical composition and bioactivity of its hydrodistilled essential oil and the crude extract. According to chromatospectral analysis, hexadecanoic acid (42.3%), nonacosane (8.2%), and heptacosane (8.0%) were the main compounds of the essential oil, while 16 compounds were determined in the MeOH extract using LC/MS. Furthermore, antimicrobial, antioxidant, and cytotoxic effects of the essential oil and the extract were evaluated in comparison with the standard agents. The extract showed strong antifungal effect against Candida utilis at the concentration of 60 µg/ml (MIC) where the EO showed growth inhibition at the concentration of 47.00 µg/ml (MIC) against pathogen Bacillus cereus. Both the essential oil and the extract did not show any selective antioxidant properties. The extract showed remarkably selective cytotoxic properties against MCF-7, PANC-1, A549, and C6 glioma cells.

Essential Oil Composition of Helichrysum conglobatum from Cyprus.

The essential oil of aerial parts of Helichrysum conglobatum (Viv.) Steudel. (Asteraceae) from Cyprus was analyzed by GC and GC-MS. The essential oil yield was 0.01, v/w. Forty five compounds were identified in the oil comprising 96.1% of the total. The essential oil was mainly composed of sesquiterpene type compounds and oxygenated sesquiterpene derivatives. The main components of the oil were P-caryophyllene (14.6%), Y-curcumene (14.1%), hexadecanoic acid (13.5%), tetradecanoic acid (7.5%), rosifoliol (5.4%) and 6-cadinene (5.3%). This is the first report on the essential oil composition of H. conglobatum from Cyprus.

Antiprotozoal Effect of Artemisia indica Extracts and Essential Oil.

Diverse solvent extracts of Artemisia indica leaves originating from the West Bengal region (India) were assessed for the content of artemisinin and characteristic Artemisia polymethoxyflavonoids, namely eupatin (1), casticin (2), chrysoplenetin (3), cirsilineol (4), chrysophenol-D (5), and artemetin (6). HPLC-DAD and HPLC-MS were used to investigate the extracts macerated by solvents of increasing polarity, i.e., petroleum ether, n-hexane, dichloromethane, acetone, MeOH, or EtOH (either 96, 80, or 60 % v/v), and hot water. Artemisinin was absent in all extracts. The acetone and EtOH extracts comprised the highest levels of polymethoxyflavonoids, whereas no flavonoid could be detected in the infusion. None of the remaining extracts contained chryosphenol-D (5) or artemetin (6), while chrysoplenetin (3) was found in all extracts. The essential oil of the plant was also obtained by hydrodistillation and analysed by gas chromatography and gas chromatography-mass spectrometry simultaneously. Of the 92 compounds detected in the oil, camphor (13.0 %) and caryophyllene oxide (10.87 %) were the major components. All solvent extracts and the volatile oil showed in vitro antimalarial activity, plus a potential malaria prophylactic effect by inhibiting at least two recombinant plasmodial fatty acid biosynthesis (PfFAS-II) enzymes. Except for the infusion, all extracts were also active against other parasitic protozoa and displayed low cytotoxicity against mammalian cells. This is the first detailed study investigating both artemisinin and polymethoxyflavonoid content as well as in vitro malaria prophylactic and detailed antiprotozoal potential of A. indica extracts against a panel of protozoan parasites. This is also the first report of antiparasitic activity of the essential oil of the plant.

DPPH scavenging, PRAP activities and essential oil composition of edible Lathyrus ochrus L. (Cyprus Vetch, Luvana) from Cyprus.

The essential oil of the aerial parts of edible Lathyrus ochrus L. was investigated by simultaneous GC, GC/MS analyses under the same conditions. Trace amount of oil (0.01> mL) obtained by hydro distillation of 200 g fresh plants was trapped in 1 mL n-hexane. Twenty components were detected representing 91.55 ± 0.56 % of the oil. The main components were phytol 49.39 ± 0.44 %, hexadecanoic acid 20.64 ± 0.89 % and pentacosane 4.20 ± 0.09 %. Essential oil solution (1% oil: n-hexane) afforded similar DPPH scavenging activity (9.28 ± 1.30 %) when compared with positive controls α-tocopherol (9.74 ± 0.21 %) and BHT (7.79 ± 0.26 %) at the same concentrations. Antioxidant activity of the oil was determined using a new HPTLC-PRAP assay. The oil afforded two fold higher reducing activity of phosphomolybdenum complex (594.85 ± 5.14 AU) when compared with positive controls α- tocopherol (271.10 ± 2.86 AU) and BHT (210.53 ± 1.81 AU) at the same concentration.

Molecular and phytochemical investigation of Angelica dahurica and Angelica pubescentis essential oils and their biological activity against Aedes aegypti, Stephanitis pyrioides, and Colletotrichum species.

In this study, Angelica dahurica and Angelica pubescentis root essential oils were investigated as pest management perspectives, and root samples were also analyzed genetically using the nuclear ribosomal internal transcribed spacer (ITS) region as a DNA barcode marker. A. pubescentis root essential oil demonstrated weak antifungal activity against Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides, whereas A. dahurica root essential oil did not show antifungal activity. Conversely, A. dahurica root essential oil demonstrated better biting deterrent and insecticidal activity against yellow fever mosquito, Aedes aegypti, and azalea lace bugs, Stephanitis pyrioides, than A. pubescentis root oil. The major compounds in the A. dahurica oil were found as α-pinene (46.3%), sabinene (9.3%), myrcene (5.5%), 1-dodecanol (5.2%), and terpinen-4-ol (4.9%). α-Pinene (37.6%), p-cymene (11.6%), limonene (8.7%), and cryptone (6.7%) were the major compounds found in the A. pubescentis oil. In mosquito bioassays, 1-dodecanol and 1-tridecanol showed antibiting deterrent activity similar to the positive control DEET (N,N-diethyl-3-methylbenzamide) at 25 nmol/cm(2) against Ae. aegypti, whereas only 1-tridecanol showed repellent activity in human-based cloth patch bioassay with minimum effective dosages (MED) of 0.086 ± 0.089 mg/cm(2) (DEET = 0.007 ± 0.003 mg/cm(2)). In larval bioassays, 1-tridecanol was more toxic with an LC50 value of 2.1 ppm than 1-dodecanol having an LC50 value of 5.2 ppm against 1-day-old Ae. aegypti larvae. 1-Dodecanol and 1-tridecanol could be useful for the natural mosquito control agents.

The in vivo evaluation of anti-angiogenic effects of Hypericum essential oils using the chorioallantoic membrane assay.

CONTEXT: Hypericum species including Hypericum confertum Choisy, H. hircinum L., H. hyssopifolium Chaix. subsp. elongatum (Ledeb.) Woron var. microcalycinum (Boiss. & Heldr.) Boiss. and H. perforatum L. (Clusiaceae) are used as medicinal plants in Turkey. OBJECTIVE: The anti-angiogenic evaluation of Hypericum essential oils using the chick embryo chorioallantoic membrane (CAM) assay are performed with this study for the first time. MATERIALS AND METHODS: The anti-angiogenic activity of Hypericum essential oils (0.5-5.0 mg/ml) was evaluated in vivo using the CAM assay, compared to standard anti-angiogenic substances at the same concentrations, in trice replicated independent assays. GC and GC-MS analyses were carried out simultaneously to identify the chemical compositions of the Hypericum essential oils. RESULTS: The CAM treated with H. perforatum essential oil showed anti-angiogenic effect (score 0.6 ± 0.3) at 50 µg/pellet concentration, whereas other tested Hypericum essential oils showed no effect compared to the standards (e.g. suramin score 0.5 ± 0.2). Furthermore, the tested oils showed neither membrane toxicity nor irritation at the tested concentrations. The major compound of the essential oil of H. confertum was identified as germacrene D (30.2%). The major compound of the essential oils of the H. hircinum. H. hyssopifolium subsp. elongatum var. microcalycinum and H. perforatum was identified as α-pinene (88.3, 57.8, 33.3%), respectively. DISCUSSION AND CONCLUSION: Hypericum species and in particular H. perforatum essential oil may have important effect toward wound healing and various inflammations. The data obtained in this experiment suggest further investigations on various cancers due to its anti-angiogenic effects observed.

Chemical composition, antifungal and insecticidal activities of Hedychium essential oils.

The antimicrobial properties of essential oils have been documented, and their use as "biocides" is gaining popularity. The aims of this study were to analyze the chemical composition and assess the biological activities of Hedychium essential oils. Oils from 19 Hedychium species and cultivars were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques. The antifungal and insecticidal activities of these oils were tested against Colletotrichum acutatum, C. fragariae, and C. gloeosporioides, and three insects, the azalea lace bug (Stephanitis pyrioides), the yellow fever mosquito (Aedes aegypti), and the red imported fire ant (Solenopsis invicta). Hedychium oils were rich in monoterpenes and sesquiterpenes, especially 1,8-cineole (0.1%-42%), linalool (<0.1%-56%), a-pinene (3%-17%), b-pinene (4%-31%), and (E)-nerolidol (0.1%-20%). Hedychium oils had no antifungal effect on C. gloeosporioides, C. fragariae, and C. acutatum, but most Hedychium oils effectively killed azalea lace bugs. The oils also show promise as an adult mosquito repellent, but they would make rather poor larvicides or adulticides for mosquito control. Hedychium oils acted either as a fire ant repellent or attractant, depending on plant genotype and oil concentration.

Biting deterrence, repellency, and larvicidal activity of Ruta chalepensis (Sapindales: Rutaceae) essential oil and its major individual constituents against mosquitoes.

The essential oil from aerial parts of Ruta chalepensis L. (Sapindales: Rutaceae) was obtained by hydrodistillation, and its chemical profile was identified using gas chromatography and gas chromatography-mass spectrometry. Compounds, 2-undecanone (43.2%), 2-nonanone (27.9%), and 2-nonyl acetate (10.6%) were the major constituents of the oil. Biting deterrent activity of R. chalepensis essential oil at 10 and 50 microg/cm2, 2-undecanone at 8.5 microg/cm2, 2-nonanone at 9 microg/cm2, and 2-nonyl acetate at 9.3 microg/cm2 was similar to DEET (N, N-diethyl-meta-toluamide) at 4.8 microg/cm2, against Aedes aegypti L. Biting deterrent activity of R. chalepensis oil at 50 microg/cm2 against Anopheles quadrimaculatus Say was statistically similar to DEET at 4.8 microg/cm2, whereas the activity was lower in the other compounds tested. In cloth patch assay, R. chalepensis essential oil was effective at 187 microg/cm2, whereas 2-undecanone was effective at 108.9 microg/cm2 against Ae. aegypti. In larval bioassays, 2-undecanone showed similar toxicity whereas toxicity of R. chalepensis essential oil and 2-nonanone was higher at 24-h posttreatment at the LD50 in An. quadrimaculatus than Ae. aegypti. This study revealed that R. chalepensis essential oil and its major compounds were active biting deterrents against Ae. aegypti at higher application rates whereas only the essential oil showed activity similar to DEET against An. quadrimaculatus. 2-undecanone was the most active compound in in vivo repellency bioassay against Ae. aegypti. Chemical composition of R. chalepensis essential oil varies because of plant production and harvest practices, and the activity level of the essential oil may depend on the source of the sample.