Isolation and Insecticidal Activity of Essential Oil from Artemisia lavandulaefolia DC. against Plutella xylostella.

Many plants show significant biological activity against pests due to their unique chemical constituents. It is important to identify effective constituents for their development and utilization as botanical pesticides. Our previous study showed that Artemisia lavandulaefolia essential oil had biological activity against Plutella xylostella. Here, we isolated and identified the constituents of essential oil from A. lavandulaefolia by silica gel column chromatography. The main constituents identified were eucalyptol and caryophyllene oxide, and they were confirmed by gas chromatography-mass spectrometry (GC-MS). Eucalyptol and caryophyllene oxide showed strong contact toxicity against P. xylostella larvae after 24 h of application (Median lethal dose, LD50 = 76.97 µL/mL and 20.71 mg/mL. Furthermore, the two active constituents against P. xylostella adults showed significant fumigant activity (Mmedian lethal concentration, LC50 = 3.25 µL/L and 1.06 mg/L, respectively. Finally, we measured the detoxification enzymes and acetylcholinesterase of the larvae treated with active constituents. The eucalyptol-treated larvae displayed enhanced carboxylesterase (CarE) and glutathione-S-transferase (GST) activities in an in vivo experiment, but it was lower for acetylcholinesterase (AchE) activity. The activities of the CarE and GST significantly decreased when exposed to caryophyllene oxide. In general, the two active constituents, eucalyptol and caryophyllene oxide, showed high insecticidal activity, which demonstrates their potential to be used as natural insecticides.

Chemical Composition and Anticholinesterase Activity of the Essential Oil of Leaves and Flowers from the Ecuadorian Plant Lepechinia paniculata (Kunth) Epling.

This work aimed to study the chemical composition, cholinesterase inhibitory activity, and enantiomeric analysis of the essential oil from the aerial parts (leaves and flowers) of the plant Lepechinia paniculata (Kunth) Epling from Ecuador. The essential oil (EO) was obtained through steam distillation. The chemical composition of the oil was evaluated by gas chromatography, coupled to mass spectrometry (GC-MS) and a flame ionization detector (GC-FID). The analyses led to the identification of 69 compounds in total, of which 40 were found in the leaves and 29 were found in the flowers of the plant. The major components found in the oil were 1,8-Cineole, ß-Pinene, δ-3-Carene, α-Pinene, (E)-Caryophyllene, Guaiol, and ß-Phellandrene. Flower essential oil showed interesting selective inhibitory activity against both enzymes AChE (28.2 ± 1.8 2 µg/mL) and BuChE (28.8 ± 1.5 µg/mL). By contrast, the EO of the leaves showed moderate mean inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), with IC50 values of 38.2 ± 2.9 µg/mL and 47.4 ± 2.3 µg/mL, respectively.

Anti-quorum sensing and antibiofilm potential of 1,8-cineole derived from Musa paradisiaca against Pseudomonas aeruginosa strain PAO1.

Pseudomonas aeruginosa is one of the vulnerable opportunistic pathogens associated with nosocomial infections, cystic fibrosis, burn wounds and surgical site infections. Several studies have reported that quorum sensing (QS) systems are controlled the P. aeruginosa pathogenicity. Hence, the targeting of QS considered as an alternative approach to control P. aeruginosa infections. This study aimed to evaluate the anti-quorum sensing and antibiofilm inhibitory potential of Musa paradisiaca against Chromobacterium violaceum (ATCC 12472) and Pseudomonas aeruginosa. The methanol extract of M. paradisiacsa exhibits that better antibiofilm potential against P. aeruginosa. Then, the crude methanol extract was subjected to purify by column chromatography and collected the fractions. The mass-spectrometric analysis of a methanol extract of M. paradisiaca revealed that 1,8-cineole is the major compounds. 1, 8-cineole significantly inhibited the QS regulated violacein production in C. violaceum. Moreover, 1,8-cineole significantly inhibited the QS mediated virulence production and biofilm formation of P. aeruginosa without affecting their growth. The real-time PCR analysis showed the downregulation of autoinducer synthase and transcriptional regulator genes upon 1,8-cineole treatment. The findings of the present study strongly suggested that metabolite of M. paradisiaca impedes P. aeruginosa QS system and associated virulence productions.

A New Eucalyptol-Rich Lavender (Lavandula stoechas L.) Essential Oil: Emerging Potential for Therapy against Inflammation and Cancer.

BACKGROUND/AIM: natural products are a potential source for drug discovery and development of cancer chemoprevention. Considering that drugs currently available for the treatment of inflammatory and cancer conditions show undesirable side effects, this research was designed to evaluate, for the first time, the in vitro anticancer activity of Algerian Lavandula stoechas essential oil (LSEO) against different cancer cell lines, as well as its in vitro and in vivo topical and acute anti-inflammatory properties. MATERIALS AND METHODS: the LSEO was extracted by steam distillation, and chemical composition analysis was performed using gas chromatography. The main compounds identified in LSEO were oxygenated monoterpenes, such as 1,8-Cineole (61.36%). LSEO exhibited a potent anti-inflammatory activity using the xylene-induced mouse ear edema model. RESULTS: LSEO (200 and 20 mg/kg) was able to significantly reduce (p < 0.05) the carrageenan-induced paw edema with a similar effect to that observed for the positive control. Topical application of LSEO at doses of 82 and 410 mg/kg significantly reduced acute ear edema in 51.4% and 80.1% of the mice, respectively. Histological analysis confirmed that LSEO inhibited the skin inflammatory response. Moreover, LSEO was tested for its antitumor activity against different cancer cell lines. LSEO was found to be significantly active against human gastric adenocarcinoma (AGS), Melanoma MV3, and breast carcinoma MDA-MB-231 cells, with median inhibitory concentration (IC50) values of 0.035 ± 0.018, 0.06 ± 0.022 and 0.259 ± 0.089 µL/mL, respectively. Altogether, these results open a new field of investigation into the characterization of the molecules involved in anti-proliferative processes. CONCLUSION: We suggest that LSEO, with 1,8-Cineole as the major active component, is a promising candidate for use in skin care products with anti-inflammatory and anticancer properties. The results of this study may provide an experimental basis for further systematic research, rational development, and clinical utilization of lavender resources.

Selection of Optimal Operating Conditions for Extraction of Myrtus Communis L. Essential Oil by the Steam Distillation Method.

Myrtus communis L. is one of the important aromatic and medicinal species from the Mediterranean area. It is used in various fields such as culinary, cosmetic, pharmaceutical, therapeutic, and industrial applications. Thus, a Box-Wilson experimental plan was used in this study to select the optimal operating conditions in order to obtain high volumes of essential oils. The factorial design method was applied to evaluate at an industrial scale the effect of major process variables on the essential oil extraction from Myrtus communis L. herbs by the steam distillation method. The input variables considered as significant operating conditions were: X1-boiler occupancy rate (boilers were filled to 50%, 75%, and 100%), X2-distillation duration (distillation was continued 60, 75, and 90 min), and X3-particle size (herbs were cut in sizes of 10, 20, and 30 mm via guillotine). The dependent variable selected, coded as Y, was the essential oil volume obtained (mL). The steps of the classical statistical experimental design technique were complemented with the Taguchi method to improve the extraction efficacy of essential oil from Myrtus communis L., and the optimum parameter conditions were selected: boiler occupancy rate 100%, distillation duration 75 min, and particle size 20 mm. Following the optimum parameters, the GC-MS assay revealed for the Myrtus communis L. essential oil two predominant components, α-pinene-33.14% and eucalyptol-55.09%.

Proapoptotic Activity of Achillea membranacea Essential Oil and Its Major Constituent 1,8-Cineole against A2780 Ovarian Cancer Cells.

Among the hundreds of reported Achillea species, A. membranacea (Labill.) DC. is one of the six that grow in Jordan. Many species of this genus are used in folk medicine to treat a variety of ailments and several biological and pharmacological activities have been ascribed to their essential oil (EO). For this study, the EO obtained from a specimen of A. membranacea grown in Jordan was analyzed by GC-MS. Ninety-six compounds were detected, of which oxygenated monoterpenes was the predominant class (47.9%), followed by non-terpene derivatives (27.9%), while sesquiterpenes represented 14.2% of the total composition. The most abundant compound in the EO was 1,8-cineole (21.7%). The cytotoxic activity of the EO was evaluated against three cancer cell lines (MCF7, A2780 and HT29), and one normal fibroblast cell line (MRC5) by MTT assay. Significant growth inhibition was observed in EO-exposed A2780 and HT29 cells (IC50 = 12.99 and 14.02 µg/mL, respectively), while MCF7 and MRC5 were less susceptible. The EO induced apoptosis and increased the preG1 events in A2780 cells. 1,8-Cineole, the major constituent of the EO, exhibited submicromolar cytotoxicity against A2780 cells, and was 42 times more selective against MRC5 cells. Its cytotoxicity against A2780 cells was comparable with that of doxorubicin, but 1,8-cineole was more selective for MRC5 normal cells. Interestingly, 1,8-cineole enhanced apoptosis in A2780, and caused a remarkable dose-dependent increase in preG1 events. Thus, 1,8-cineole has demonstrated promising cytotoxic and proapoptotic properties.

Trichome Density in Relation to Volatiles Emission and 1,8-Cineole Synthase Gene Expression in Thymus albicans Vegetative and Reproductive Organs.

1,8-Cineole is the main volatile produced by Thymus albicans Hoffmanns. & Link 1,8-cineole chemotype. To understand the contribution of distinct plant organs to the high 1,8-cineole production, trichome morphology and density, as well as emitted volatiles and transcriptional expression of the 1,8-cineole synthase (CIN) gene were determined separately for T. albicans leaves, bracts, calyx, corolla and inflorescences. Scanning electron microscopy (SEM) and stereoscope microscopy observations showed the highest peltate trichome density in leaves and bracts, significantly distinct from calyx and corolla. T. albicans volatiles were collected by solid phase micro extraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC/MS) and by GC for component identification and quantification, respectively. Of the 23 components identified, 1,8-cineole was the dominant volatile (57-93 %) in all T. albicans plant organs. The relative amounts of emitted volatiles clearly separated vegetative from reproductive organs. Gene expression of CIN was assigned to all organs analyzed and was consistent with the relatively high emission of 1,8-cineole in leaves and bracts. Further studies will be required to analyze monoterpenoid biosynthesis by each type of glandular trichome.

Solubility-physicochemical-thermodynamic theory of penetration enhancer mechanism of action.

The hypothesis for the investigation was that the overall mechanism of action of skin penetration enhancers is best explained by the Solubility-Physicochemical-Thermodynamic (SPT) theory. To our knowledge, this is the first report of the application of SPT theory in transdermal/topical/enhancer research. The SPT theory puts forward the concept that the mode of action of enhancers is related to solubility parameters, physicochemical interactions and thermodynamic activity. This paper discusses these concepts by using experimentally derived permeation data, various physicochemical and solubility parameters (ingredient active gap (IAG), ingredient skin gap (ISG), solubility of active in the formulation (SolV) and the formulation solubility in the skin (SolS)) generated by using FFE (Formulating for Efficacy™ - ACT Solutions Corp) software. These studies suggest that there is an inverse relationship between measured flux and IAG values given that there is an optimum ingredient skin gap, SolV and SolS ratio. The study demonstrated that the flux is actually proportional to a gradient of thermodynamic activity rather than the concentration and maximum skin penetration and deposition can be achieved when the drug is at its highest thermodynamic activity.

The influence of terpinen-4-ol and eucalyptol - The essential oil components - on fungi and plant sterol monolayers.

Antifungal and herbicidal activity of terpenes, being the components of the essential oils, is directly related to the incorporation of these compounds into cellular membranes. Thus, the differences in the lipid composition of various pathogenic membranes may be the factor determining the activity of these molecules. One of the class of lipids, which form the membrane environment are sterols. The aim of this work was to compare the effect of two terpenes: terpinen-4-ol and eucalyptol on the monolayers formed by ergosterol and ß - sitosterol, which are the components of fungi and plant membranes, respectively. The modifications in the sterol monolayer properties were investigated in the surface pressure-area measurements and penetration studies as well as in a micrometer scale (Brewster angle microscopy experiments) and in nanoscale (GIXD technique). It was evidenced that although at higher surface pressure the terpene molecules are in part removed from the interface, they are able to substantially modify the condensation, morphology and molecular organization of the sterol film. It was also found that the incorporation of terpenes into sterol films is comparable for both sterols, however, ß - sitosterol monolayers properties are affected more strongly than ergosterol films. Finally, the analysis of the results of the studies performed on model membrane systems and the results of antimicrobial studies reported in literature, enabled us to suggest that the activity of terpenes depends on the membrane composition and that the sterol concentration may be important from the point of view of antifungal effect of terpinen-4-ol and eucalyptol.

Post-harvest management control of Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae): new insights through essential oil encapsulation in cyclodextrin.

BACKGROUND: Essential oils are reported to be bio-insecticides. However, problems related to their volatility, oxidation and poor water solubility need to be solved before they can be considered as replacement pest control methods. Thus, an appropriate formulation is needed for commercial use. In this work, a new control method based on the use of a powdered cyclodextrin (CD)/1,8-cineole inclusion complex was assessed against larvae and adults of Ectomyelois ceratoniae (Zeller) in comparison with two Rosmarinus officinalis (L.) essential oils, free 1,8-cineole (oils major compound) and a mixture of 50% CD/1,8-cineole inclusion complex and 50% free 1,8-cineole. RESULTS: Solid CD/1,8-cineole complex was more toxic against E. ceratoniae larvae than the two crude essential oils. At a concentration of 15 µL liter-1 air, the respective mortalities were 94.12%, 35.29% and 19.61% for solid CD/1,8-cineole complex, Thala and Cap Zbib oils after 37 days of exposure. Moreover, the solid CD/1,8-cineole complex achieved 5% adult emergence versus 68.33% for Cap Zbib and 55% for Thala oils. The half-life of solid CD/1,8-cineole inclusion complex (10.98 days) was considerably longer than that of the mixture (7.53 days) or free 1,8-cineole (3.43 days). CONCLUSION: This work highlights the utility of essential oil encapsulation in CD to overcome restrictions when used to control the date moth E. ceratoniae during storage. © 2019 Society of Chemical Industry.

Studies on the Behavior of Eucalyptol and Terpinen-4-ol-Natural Food Additives and Ecological Pesticides-in Model Lipid Membranes.

Effective application of the essential oils requires detailed exploration of their mechanism of action and the origin of diverse activity of their components. In this work, the influence of eucalyptol and terpinen-4-ol on artificial membranes was studied to verify whether the differences in the activity of these compounds are related to their effect on membranes. The properties of monolayers formed from structurally different lipids in the presence of terpenes were examined based on the results of the surface pressure-area measurements, penetration studies, and Brewster angle microscopy experiments. Both compounds were able to incorporate into the membrane and alter lipid/lipid interactions, making the monolayer less stable and more fluid. These effects were determined by monolayer composition (but not by its condensation per se) and the resulting rheological properties and were stronger in the presence of terpinen-4-ol. These findings confirm the hypothesis that differences in the antimicrobial potency of these terpenes are membrane-related, and membrane composition may determine their selectivity.