Essential oils of some amazonian Mikania species

Terpenoid constituents were identified in the essential oils of Mikania banisteriae and M. congesta. M. amara contains aliphatic alcohols, aldehydes and acids besides p-cymene and thymol.     

Essential oils from micropropagated plants of Lavandula viridis

The essential oils of Lavandula viridis were analysed by GC and GC-MS. Comparisons were made between three types of plant material from the same clone: field-grown plant, in vitro shoot cultures and micropropagated plants of the same clone. The most common components usually found in lavender oils were present in the oil samples analysed and more than 45 constituents were identified, representing more than 80% of the essential oil. The essential oils analysed consisted mainly of monoterpenes (75.4-76.3%), where oxygenated and hydrocarbons identified ranged from 41.8 to 57.3% and 18.1 to 34.2%, respectively. The major components found were 1.8-cineole (18.2-25.1%), camphor (9.1-15.7%), alpha-pinene (8.8-14.1%), borneol (4.1-4.8%), beta-pinene (1.2-5.6%), delta 3-carene (1.0-6.5%) and alpha-terpineol (0.8-4.2%). The monoterpene fraction of the in vitro shoot cultures showed different relative amounts of hydrocarbons and oxygenated components in relation to the parent plant and to micropropagated plants. In the sesquiterpene hydrocarbon fraction of the oil samples analysed (6.1-8.2%), 7-epi-alpha-selinene (1.6-4.8%) was the most important component and the oxygenated sesquiterpenes were found in small amounts (1.1-1.7%). The essential oils from field-grown plants of L. viridis, when compared with those obtained from in vitro shoot cultures or micropropagated plants of the same clone, demonstrated that the same major components were found without significant compositional variations.     

The use of essential oils in veterinary ectoparasite control: a review

There is a growing body of evidence indicating the potential value of essential oils as control agents against a range of arthropod ectoparasites, particularly lice, mites and ticks. Toxicity has been demonstrated following immersion and physical contact with treated surfaces, as well as after exposure to the vapour of these oils; the last of these factors implies that there is a neurotoxic, rather than simply a mechanical, pathway in their mode of action. However, the volatile nature of essential oils suggests that their residual activity is likely to be short‐lived. A possible advantage of essential oils over conventional ectoparasite treatments may refer to their reported ovicidal efficacy, although it is unclear whether this results from neurotoxicity or mechanical suffocation. There are many difficulties in comparing the findings of existing studies of essential oil toxicity. One major issue is the wide variation among batches in the relative concentrations of oil constituents. A second issue concerns the fact that many experimental designs make it difficult to confirm that the effect seen is attributable to the oil; in many cases inappropriate controls mean that the effects of the excipient on mortality cannot be distinguished. Hence, it is important that an excipient‐only control is always included in these bioassays. Furthermore, in direct contact assays, when attempting to identify the toxicity pathway of the essential oil tested, it is important to include a hydrophobic control. Without this, it is impossible to distinguish simple mechanical effects from neurological or other cellular toxicity. The use of essential oils in the control of veterinary ectoparasites is an area which holds considerable potential for the future and research into their use is still at an early stage. More extensive field trials, the standardization of components, the standardization of extraction, the standardization of good experimental design, mammalian toxicology profiling and excipient development, as well as further investigation into the residual activities and shelf‐lives of these oils are all required to allow the full realization of their potential.     

Genetic transformation of yeast protoplasts with DNA encapsulated in liposomes

Abstract Protoplasts of auxotrophic strains of Saccharomyces cerevisiae could be transformed to prototrophy with plasmid DNA encapsulated in liposomes. With negatively charged liposomes, the transformation efficiency was higher than with naked DNA.     

Essential oils enhance the toxicity of permethrin against Aedes aegypti and Anopheles gambiae

Insecticide resistance and growing public concern over the safety and environmental impacts of some conventional insecticides have resulted in the need to discover alternative control tools. Naturally occurring botanically‐based compounds are of increased interest to aid in the management of mosquitoes. Susceptible strains of Aedes aegypti (Linnaeus) (Diptera: Culicidae) and Anopheles gambiae (Meigen) (Diptera: Culicidae) were treated with permethrin, a common type‐I synthetic pyrethroid, using a discriminate dose that resulted in less than 50% mortality. Piperonyl butoxide (PBO) and 35 essential oils were co‐delivered with permethrin at two doses (2 and 10 µg) to determine if they could enhance the 1‐h knockdown and the 24‐h mortality of permethrin. Several of the tested essential oils enhanced the efficacy of permethrin equally and more effectively than piperonyl butoxide PBO, which is the commercial standard to synergize chemical insecticide like pyrethroids. PBO had a strikingly negative effect on the 1‐h knockdown of permethrin against Ae. aegypti, which was not observed in An. gambiae. Botanical essential oils have the capability of increasing the efficacy of permethrin allowing for a natural alternative to classic chemical synergists, like PBO.     

Essential oils: effects of application rate and modality on potential for combating northern fowl mite infestations

The northern fowl mite (NFM), Ornithonyssus sylviarum (Mesostigmata: Macronyssidae), is the primary blood‐feeding ectoparasite found on poultry in the U.S.A. Three experiments were conducted in vitro to test the acaricidal properties of cade, garlic, lavender, lemongrass, pine and thyme essential oils against NFM, and to evaluate whether these effects are altered by adjusting oil application rates and application modality (direct vs. vapour contact). Applied at the rate of 0.21 mg/cm², the essential oils of cade, thyme, lemongrass and garlic resulted in higher NFM mortality at 24 h post‐application than lavender and pine oils, and the untreated and ethanol‐treated controls. Cade and thyme were the most consistent and fast‐acting of the essential oils in terms of toxicity to NFM. Cade applied at 0.21 mg/cm² and 0.11 mg/cm² and thyme applied at 0.21 mg/cm² were effective in eliminating NFM within 2 h through direct contact. The modality of application did not affect the efficacy of cade and thyme essential oils. The results suggest that essential oils may be utilized as alternatives to chemical pesticides and could be used as fumigants for the control of NFM.     

负载噬菌体qdvp001的阳离子脂质体的制备及热稳定性和抗菌活性

[背景]副溶血弧菌噬菌体qdvp001在防治副溶血弧菌污染方面具有巨大的应用潜力,但其对温度的敏感性较高,在较高的温度环境下会失活.[目的]利用阳离子脂质体包埋保护噬菌体qdvp001以提高其热稳定性,同时探究其脂质体包被液的抗菌活性.[方法]制备和表征负载副溶血弧菌噬菌体qdvp001的阳离子脂质体,测定阳离子脂质体...     

Essential oils of three asiatic artemisia species

The steam-distilled essential oils from the aerial parts of three Asiatic Artemisia, A. glabella, A. rupestris and A. persica, were analysed by GC/MS. In all about 100 compounds were identified; davanone is one of the main components of A. persica.     

Essential oils of five Tanacetum vulgare genotypes

The essential oils of five Tanacetum vulgare genotypes were investigated and their main components identified. Artemisia alcohol, γ-campholenol, davanone, lyratol, lyratyl acetate and 4-thujen-2α-yl acetate have not been reported before as constituents of Tanacetum vulgare. This is the first time that γ-campholenol has been isolated from a natural source. 4-Thujen-2α-yl acetate is a novel compound.     

Stealth liposomes: review of the basic science, rationale, and clinical applications, existing and potential

Among several promising new drug-delivery systems, liposomes represent an advanced technology to deliver active molecules to the site of action, and at present several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles ("first-generation liposomes") to "second-generation liposomes", in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. A significant step in the development of long-circulating liposomes came with inclusion of the synthetic polymer poly-(ethylene glycol) (PEG) in liposome composition. The presence of PEG on the surface of the liposomal carrier has been shown to extend blood-circulation time while reducing mononuclear phagocyte system uptake (stealth liposomes). This technology has resulted in a large number of liposome formulations encapsulating active molecules, with high target efficiency and activity. Further, by synthetic modification of the terminal PEG molecule, stealth liposomes can be actively targeted with monoclonal antibodies or ligands. This review focuses on stealth technology and summarizes pre-clinical and clinical data relating to the principal liposome formulations; it also discusses emerging trends of this promising technology.     

Potential dopamine prodrug-loaded liposomes: preparation,characterization, and in vitro stability studies

Dopamine delivery to the central nervous system (CNS) undergoes the permeability limitations of the blood-brain barrier (BBB). Condensation of dopamine with neutral amino acids could afford potential prodrugs able to interact with the BBB endogenous transporters and easily enter the brain. To improve the bioavailability of the dopamine prodrug, 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DOPH), it was encapsulated in unilamellar liposomes of dimiristoylphosphatidylcholine (DMPC) and cholesterol. Vesicles were characterized by dynamic light scattering in order to evaluate their dimensions and vesicle stability, by zeta-potential measurements, by means of electronic microscopy after freeze-fracture and differential scanning calorimetry. The influence of vesicle composition on DOPH chemical and enzymatic stability was also evaluated. The formulated liposome suspensions were found to be stable, monodisperse systems with a negative zeta potential. From the obtained results, it is possible to conclude that, in studied samples, DOPH inclusion in liposomes offers the possibility of preventing photodegradation and of enhancing in vitro plasma stability. These studies suggest the potential of these formulations as a method to prevent DOPH chemical degradation and enzymatic metabolism.     

Essential oils as soil biofumigants for the control of the root‐knot nematode Meloidogyne incognita on tomato

The effectiveness of soil fumigation with 50, 100 and 200 µL kg^?1 soil of essential oils (EOs) from the plant species Eucalyptus citriodora, Eucalyptus globulus, Mentha piperita, Pelargonium asperum and Ruta graveolens was assessed against the root‐knot nematode Meloidogyne incognita on potted tomato. Plant growth parameters and number of galls, nematode eggs and juveniles on tomato roots were evaluated after two months of maintenance of the treated plants at 25°C in greenhouse. EOs of E. globulus and P. asperum significantly reduced nematode multiplication and gall formation on tomato roots at all the tested rates, whereas the EOs of E. citriodora, M. piperita and R. graveolens were more suppressive at levels greater than 50 µL kg^?1 soil. Biofumigation with EOs of E. globulus and P. asperum resulted also in the largest increase of tomato plant top and root biomass. The five samples of EOs had a different chemical composition as determined by GC and GC‐MS. Structure–activity relationship based on the main constituents of the tested EOs and their nematicidal effect on M. incognita is discussed.     

Repellency of essential oils against Nephotettix cincticeps: Laboratory and glasshouse assays

Four oils from Piper nigrum, Litsea cubeba, Zanthoxylum bungeanum and Curcuma longa were obtained by ethanol extraction. The repellency of these oils and two major compounds (linalool and piperine) was evaluated against female adult and third‐instar nymphs of the rice pest, Nephotettix cincticeps, under laboratory and glasshouse conditions. Paired‐choice and no‐choice assays were used for each treatment, with essential oils evaluated after 24 and 48 hr of exposure and chemical compounds evaluated after 12 and 24 hr of exposure. The potential effects of essential oils on activities of glutathione S tranferase (GST), carboxyl esterase (CarE) and acetyl cholinesterase (AchE) were also evaluated after 48 hr of exposure to leafhoppers. The constituents of the essential oils were determined using GC‐MS. The results showed that the major components in the oils were piperine (34.75%) for P. nigrum, 9,12‐octadecadienoic acid (Z,Z) (18.74%) for L. cubeba, ethanone, 1‐(2‐hydroxy‐4,6‐dimethoxyphenyl) (18.51%) for Z. bungeanum and turmerone (15.89%) for C. longa. In all cases, the essential oils repelled female adults and third‐instar nymphs of N. cincticeps. The repellency of the tested oils and chemicals compounds in the paired‐choice assay was higher than in the no‐choice assay. In all experimental conditions, P. nigrum and C. longa oils were the most and the least potent, respectively. Linalool was the best repellent among the single‐tested compounds under laboratory conditions. In the glasshouse study, the highest repellency was observed in the mixture of linalool and piperine. GST and CarE activities of leafhoppers were significantly enhanced by exposure to the four essentials oils; AchE activity increased significantly only in the P. nigrum and L. cubeba assays. Our results clearly indicate that the tested oils and chemical compounds are promising agents for developing plant‐based pesticides to control N. cincticeps.     

Enhancement of apparent substrate selectivity of proteinase K encapsulated in liposomes through a cholate-induced alteration of the bilayer permeability

Proteinase K-containing liposomes with highly selective membrane permeability properties were prepared. The selectivity obtained was with respect to the two substrate molecules added to the external aqueous phase of the liposomes: acetyl-L-Ala-Ala-Ala-p-nitroanilide (Ac-AAA-pNA) and succinyl-L-Ala-Ala-Ala-p-nitroanilide (Suc-AAA-pNA). The liposome-forming lipid used was POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and modulation of the membrane permeability was achieved using the detergent cholate. Proteinase K-containing mixed liposomes (PKCL) were prepared by adding cholate to preformed proteinase K-containing POPC liposomes (PKL) at a defined effective cholate/POPC molar ratio in the liposomal bilayer membrane R(e). Proteinase K was kept inside PKCL with a negligible amount of leakage into the bulk aqueous phase at R(e) < or = 0.30. At higher R(e), leakage of proteinase K was pronounced, even under conditions where POPC/cholate mixed liposomes seemed to be still intact (0.30 < R(e) < or = 0.39). At R(e) < or = 0.30, the reactivity of proteinase K in the PKCL measured with the externally added substrate Ac-AAA-pNA increased with increasing R(e), while the reactivity measured with Suc-AAA-pNA remained low, regardless of the R(e) value. This showed that externally added Ac-AAA-pNA molecules permeated the liposomal membrane more easily than Suc-AAA-pNA by modulating the membrane with cholate. Consequently, Ac-AAA-pNA was hydrolyzed in PKCL with considerably higher apparent substrate selectivity in comparison with the cases of proteinase K in PKL and free proteinase K (without liposomal encapsulation). The results obtained clearly demonstrate that the prepared PKCL can be utilized as a kind of nano-scaled bioreactor system which can take up a particular target substrate with high apparent substrate selectively from the external phase of the liposomes. Inside the liposomes, the target substrate is then converted into the corresponding products.     

Sterically stabilized liposomes as a potent carrier for shikonin

The ability of pegylated liposomes (sterically stabilized liposomes-SSL) to localize in solid tumors via the enhanced permeability and retention (EPR) effect, partly depends on their long circulating properties which can be achieved by grafting polyethylene glycol (PEG) to the liposomes’ surface. Alkannin and shikonin (A/S) are naturally occurring hydroxynaphthoquinones with a well-established spectrum of wound healing, antimicrobial, anti-inflammatory, antioxidant, and recently established antitumor activity. The purpose of this work was to prepare and characterize shikonin-loaded pegylated liposomes as a new drug carrier for shikonin, as a continuation of authors’ previous work on conventional shikonin-loaded liposomal formulations. Three new pegylated liposomal formulations of shikonin (DSPC-PEG₂₀₀₀, EPC-PEG₂₀₀₀, and DPPC-PEG₂₀₀₀) were prepared and characterized in terms of physicochemical characteristics, pharmacokinetics, and stability (at 4?°C, for 28?d) and compared with the corresponding conventional ones. Particle size distribution, ζ-potential, entrapment efficiency, and release profile of the entrapped drug were measured. Results indicated the successful incorporation of shikonin into liposomes alongside with their good physicochemical characteristics, high entrapment efficiency, satisfactory in vitro release profile, and good physical stability. The results are considered promising and could be used as a road map for designing further in vivo experiments.     

Essential Oils as Potent Source of Nematicidal Compounds

Bioassay tests were conducted to find out the nematicidal activity of eight essential oils against Meloidogyne incognita (Kofoid and White) Chitwood at four concentrations. Maximum activity was recorded in oils of Eucalyptus citriodora , Eucalyptus hybrida and Ocimum basilicum followed by Pelargonium graveolens , Cymbopogon martinii, Mentha arvensis, Mentha piperita and Mentha spicata oils, respectively. The eucalyptus ( E. citriodora and E. hybrida ) and Indian basil ( O. basilicum ) oils were highly toxic to M. incognita even at the lower concentrations, namely 500 and 250 ppm. The remaining oils were also toxic to the nematode but at different amounts.     

粤北阴香不同器官中精油成分研究

采用水蒸汽同步蒸馏法分别对采自粤北的阴香的果、叶、枝条提取精油,并用气质联用仪对所提取的精油进行了成分分析和鉴定。共鉴定了41种成分,主要成分为龙脑（68．5％～73．8％）、芳香醇、丁子香烯、橙花叔醇、榄香烯、柠檬醛、莰烯、葑醇、愈创烯、香叶烯、枞萜、萜品醇、蒎烯等。阴香不同器官（果、叶、枝）中的精油成分及所占比例均有差异。     

The inhibitory effect of essential oils on herpes simplex virus type-1 replication in vitro

The antiviral effect of 12 essential oils on herpes simplex virus type-1 (HSV-1) replication was examined in vitro. The replication ability of HSV-1 was suppressed by incubation of HSV-1 with 1% essential oils at 4 C for 24 hr. Especially, lemongrass completely inhibited the viral replication even at a concentration of 0.1%, and its antiviral activity was dependent on the concentrations of the essential oil. When Vero cells were treated with the essential oil before or after viral adsorption, no antiviral activity was found, which suggests that the antiviral activity of essential oils including lemongrass may be due to the direct interaction with virions.