Acaricidal and repellent effects of myrtacean essential oils and their major constituents against Tetranychus urticae (Tetranychidae)

Nineteen plant essential oils (EOs) extracted from the family Myrtaceae growing in Australia were screened for their acaricidal and repellent activities against two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), in the laboratory by dipping method and choice- and no-choice tests. Acaricidal bioassays showed that five EOs of Callistemon viminalis, Eucalyptus bicostata, Eucalyptus maidenii, Eucalyptus sideroxylm and Eucalyptus approximans significantly increased the mortality of female adult mites and decreased the total number of eggs. In a choice test, Callistemon sieberi, E. bicostata, Eucalyptus ovata, E. sideroxylm, Eucalyptus mannifera, Eucalyptus dives, Eucalyptus elata, Eucalyptus condonocarpa, Kunzea ericoides, Melaleuca armillaris and Melaleuca fulgens demonstrated good repellency to the mite. In another test, C. sieberi, E. bicostata, E. mannifera, E. condonocarpa, K. ericoides, M. armillaris, and M. fulgens EOs decreased the egg production of the females significantly. In the acaricidal and repellent tests, E. bicostata and E. sideroxylon EOs showed both acaricidal and repellent effects (choice test) and decreased the number of eggs on treated bean leaves. The gas chromatograph/mass spectroscopy analyses revealed that the major components of E. bicostata and E. sideroxylon were 1,8-cineole, limonene, and α-pinene. The 1,8-cineole and limonene showed significant repellent effects on the mites, resulting in reduced numbers of eggs in the choice test. Hence, EOs of E. bicostata and E. sideroxylon and limonene and 1,8-cineole may be potential agents to be used in the sustainable management of T. urticae.     

Psoralen activity and binding sites in melanotic and amelanotic human melanoma cells

The biological activity and specific binding sites of 8-methoxypsoralen (8-MOP) are assayed using two human melanoma cell lines, melanotic SK-Mel 28 and amelanotic C32TG. Long-term (72 hr) treatment with 8-MOP at a concentration of 10(-4)M results in an increase in melanogenesis and a decrease in proliferation, similar in both cell lines. Daily exposure of these cells to ultraviolet A (UVA) irradiation (1.28 mJ/cm(2)) does not enhance the response to the compound. Daily pulse application (30 min daily) of 8-MOP does not promote any response. However, in combination with UVA, 8-MOP pulse treatment becomes as effective as the long-term treatment. A decrease in cell proliferation in the constant presence of 8-MOP is not coupled with apoptosis, since no increase in the number of apoptotic nuclei was observed after the treatment. The flow cytometry indicates that 8-MOP arrests the cells at the G0/G1 phase, irrespective of the presence or absence of UVA light. In view of the lack of epidermal growth factor (EGF) receptors in both cell lines, it is not likely that such an arrest is associated with the down-regulation of EGF receptors by 8-MOP. It is noted that this compound elicits a biphasic cell response, since cell proliferation increases after the first 24-hr treatment, whereas it decreases in the subsequent 48 hr and thereafter. Competition binding assays using 3H-8-MOP disclosed: 1) the specific binding of the compound in both cell lines occurs in the presence or absence of UVA light, and 2) a higher binding rate at low concentrations of the compound is in SK-Mel 28 (72%) rather than C32TG (58%) cells. The competition assays in the presence of UVA suggest a possible occurrence of covalent bindings between psoralen and receptor, as DNA covalent binding accounted to only 3-5% of the total binding in both cell lines.     

Antibiofilm activity of selected plant essential oils and their major components

The aim of the study was to examine the antibiofilm activity of selected essential oils (EO): Lavandula angustifblia (LEO), Melaleuca alternifolia (TTO), Melissa officinalis (MEO) and some of their major constituents: linalool, linalyl acetate, alpha-terpineol, terpinen-4-ol. Biofilms were formed by Staphylococcus aureus ATCC 29213 and Escherichia coli NCTC 8196 on the surface of medical biomaterials (urinary catheter, infusion tube and surgical mesh). TTC reduction assay was used for the evaluation of mature biofilm eradication from these surfaces. Moreover, time-dependent eradication ofbiofilms preformed in polystyrene 96-well culture microplates was examined and expressed as minimal biofilm eradication concentration (evaluated by MTT reduction assay). TTO, alpha-terpineol and terpinen-4-ol as well as MEO, showed stronger anti-biofilm activity than LEO and linalool or linalyl acetate. Among the biomaterials tested, surgical mesh was the surface most prone to persistent colonization since biofilms formed on it, both by S. aureus and E. coli, were difficult to destroy. The killing rate studies of S. aureus biofilm treated with TTO, LEO, MEO and some of their constituents revealed that partial (50%) destruction of 24-h-old biofilms (MBEC50) was achieved by the concentration 4-8 x MIC after 1 h, whereas 2-4 x MIC was enough to obtain 90% reduction in biomass metabolic activity (MBEC90) after just 4 h of treatment. A similar dose-dependent effect was observed for E. coli biofilm which, however, was more susceptible to the action of phytochemicals than the biofilms of S. aureus. It is noteworthy that an evident decrease in biofilm cells metabolic activity does not always lead to their total destruction and eradication.     

Antiproliferative effects of nitrosulindac on human colon adenocarcinoma cell lines

Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the incidence of colon cancer, but their use is limited by toxicity in the gastrointestinal tract. The coupling of a nitric oxide-releasing moiety to NSAIDs strongly reduces these side effects. We demonstrated that the NO-releasing sulindac (nitrosulindac) has much more potent effects on colon adenocarcinoma cell lines compared to sulindac. Moreover, it could inhibit the growth of cells in soft agar experiments, demonstrating the antineoplastic activity at low concentration of nitrosulindac. However, this reduction in the growth of colon cancer cells seemed to be independent of the classical apoptosis pathway and could be explained by a cytostatic effect. Nitrosulindac caused a light perturbation of the cell cycle parameters not linked to a modification of the levels of p21 or the proliferating cell nuclear antigen. Moreover, neither sulindac, nor nitrosulindac, were able to inhibit the NF-kappa B pathway. These data suggested that nitrosulindac could be a better solution compared to other NSAIDs in the treatment of colon cancer.     

Monoclonal antibody against a melanosomal protein in melanotic and amelanotic human melanoma cells

BALB/c mice were immunized with tyrosinase, partially purified in two stages from a human melanoma cell line. A hybridoma was obtained which produced monoclonal antibody (MoAb 1C11) reactive with 8/10 melanoma cell lines and 10/10 primary cultures of human melanocytes, neval cells, and melanomas. Immunoreactivity correlated to a certain extent with tyrosinase activity but not with melanin content. No crossreactivity was obtained with neuroblastoma, medulloblastoma, fibroblasts, keratinocytes, lymphoid cells, or murine melanomas. Purification of the antigen directly from cell lysates with a MoAb 1C11 CNBr-Sepharose affinity column gave a green-brown protein of 56 kDa with no detectable tyrosinase activity. This protein was therefore different from 60 kDa active tyrosinase, identified by enzyme activity and Western blotting with a MoAb derived previously (MoAb 5C12). Unlike 5C12, 1C11 reactivity was not destroyed by pretreatment of the antigen with periodate. Immunogold labelling showed that the 1C11-reactive antigen was associated with melanosomes, and there was close correlation between 5C12 and 1C11 reactivity in resistance to trypsin and in staining various melanocytic cell populations. MoAb 1C11 may therefore recognise a polypeptide epitope in a molecule closely linked to melanin biosynthesis.     

Acetylcholinesterase and butyrylcholinesterase inhibitory activity of Pinus species essential oils and their constituents

This study aimed to investigate the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity of the essential oils from Pinus nigra subsp. nigra, P. nigra var. calabrica, and P. heldreichii subsp. leucodermis. This activity is relevant to the treatment of Alzheimer’s disease (AD), since cholinesterase drugs are currently the only drugs available to treat AD. P. heldreichii subsp. leucodermis exhibited the most promising activity, with IC₅₀ values of 51.1 and 80.6?μg/mL against AChE and BChE, respectively. An interesting activity against AChE was also observed with P. nigra subsp. nigra essential oil, with an IC₅₀ value of 94.4?μg/mL. Essential oils were analyzed by GC and GC-MS with the purpose of investigating their relationships with the observed activities. Among the identified constituents, terpinolene, β-phellandrene, linalyl acetate, trans-caryophyllene, and terpinen-4-ol were tested. trans-Caryophyllene and terpinen-4-ol inhibited BChE with IC₅₀ values of 78.6 and 107.6?μg/mL, respectively. β-Phellandrene was selective against AChE (IC₅₀ value of 120.2?μg/mL).     

Fumigant toxicity of Apiaceae essential oils and their constituents against Sitophilus oryzae and their acetylcholinesterase inhibitory activity

We evaluated the insecticidal and acetylcholinesterase (AChE) inhibition activities of the essential oils and their constituents of 10 Apiaceae on the adult rice weevil, Sitophilus oryzae. Of the 10 species tested, dill (Anethum graveolens), caraway (Carum carvi), and cumin (Cuminum cyminum) essential oils showed strong fumigant toxicity against adult S. oryzae. LC₅₀ values of caraway, dill, and cumin essential oils were 2.45, 3.29, and 4.75 mg/L air, respectively. Among the test compounds, (+)-carvone, (?)-carvone, cuminaldehyde, dihydrocarvone, linalool oxide, carveol, trans-anethole, and neral demonstrated strong fumigant toxicity against adult S. oryzae with LC₅₀ values of 0.61, 0.84, 1.12, 2.92, 3.76, 4.29, 5.02, and 6.60 mg/L air, respectively. α-Pinene showed the strongest AChE inhibition activity followed by β-pinene and limonene. The measured toxicity of the artificial blends of the constituents identified in dill and cumin oils indicated that (+)-carvone and cuminaldehyde were major contributors to the fumigant toxicity of the artificial blend.     

The effects of essential oils and their major compounds on fish bacterial pathogens – a review

The increased resistance of fish pathogens to conventional treatments has lead researchers to investigate the antibacterial properties of natural resources, such as essential oils (EOs) of plants, in an effort to find products that are less harmful to the environment. The objective of this review is to provide an overview of the studies, in vivo and in vitro, that addressed the use of EOs and their major compounds as antimicrobial agents in fish, to identify the best EOs and compounds to investigate considering feasibility of application and suggest possible future studies. To date, studies suggest that the use of EOs in the prevention and/or treatment of infectious diseases in fish may be a promising strategy to reduce the use of conventional antibiotics in aquaculture, since several EOs effectively reduce or avoid the effects of bacterial infections in fish. The use of EOs through nanotechnology delivery systems, especially in dietary supplementation experiments, is promising. This form of application of the EOs allows a potentiation and targeting of the desired effect of the EOs and also allows the protection of EOs active constituents against enzymatic hydrolysis, deserving further study.     

The inhibition of Candida albicans by selected essential oils and their major components

Many volatile oils are known to possess antifungal properties and are potentially applicable as antimycotic agents. By studying the efficacy of essential oils against different pathogenic mycetes, we have evaluated the in-vitro inhibiting activity of some essential oils and their main constituents against a strain of Candida albicans. Sixteen commercial essential oils and forty-two pure constituents (alcohols, aldehydes, ketons, phenols and hydrocarbons), were tested by using a semisolid agar antifungal susceptibility (SAAS) method. Gas chromatography/mass spectroscopy analyses of the oils tested were performed. The essential oils of Origanum vulgare, Satureja montana, Mentha piperita, Cinnamomum verum, Cymbopogon flexuosus showed maximum inhibitory activity (MIC = 500 ppm) after 7 days. According to the results of the examination of pure constituents, -phellandrene proved to be the most interesting component among cyclic monoterpenic hydrocarbons as it showed a strong activity (MIC = 50 ppm). The most active of phenols was carvacrol (MIC 100 ppm). The open-chain alcohol 1-decanol was the most active of alcohols at 50 ppm. Finally, among aldehydes, a strong activity was shown by trans-cynnamaldehyde (MIC 50 ppm).     

Rapid melanization of bomirski amelanotic melanoma cells in cell culture

Transfer of Bomirski amelanotic melanoma cells from in vivo to in vitro growth conditions results in occurrence of rapid melanization in their cytoplasm. The melanized cells from primary cell culture initiate tumours in hamsters, which do not contain traces of melanin and resemble typical amelanotic melanoma.     

Tyrosinase activity in primary cell culture of amelanotic melanoma cells

After transfer of the Ab amelanotic melanoma cells from in vivo to in vitro growth conditions tyrosinase activity in their soluble fraction rapidly increased. This increase lasted to the middle of the logarithmic phase of growth and was followed by a decrease of tyrosinase activity, which was accompanied by accumulation of melanin in the cells. Calf serum stimulated simultaneously tyrosinase activity, melanin synthesis, and proliferation of the melanoma cells. Acrylamide-gel electrophoresis patterns of soluble tyrosinase from the Ab melanoma cells cultured in vitro consisted of two bands, similarly as soluble tyrosinase from the Ma melanotic melanoma cells freshly isolated from solid tumors.     

Plasmodium falciparum: effect of time in continuous culture on binding to human endothelial cells and amelanotic melanoma cells

An in vitro correlate of the binding in vivo of Plasmodium falciparum-infected erythrocytes to capillary and venular endothelium, using cultured human endothelial cells and amelanotic melanoma cells, was previously developed. The effects of different times in continuous culture on binding of erythrocytes infected with nine different isolates of P. falciparum is now reported. Four isolates, which bound at the time they were first tested, rapidly lost the ability to bind after 26-43 days in culture. One of these, the Cameroun isolate, tested 12 h after the blood was obtained from the patient, had the highest rate of binding of all isolates (680 infected erythrocytes per 100 melanoma cells). After 37 days in culture, only 18 infected erythrocytes per 100 melanoma cells bound. Three isolates first tested after 30-62 days in culture bound poorly. In contrast, two others, the Vietnam (VI) and Brazil (It), continued to bind during the period of study. The Brazil (It) isolate studied after 43 days in culture bound 505 infected erythrocytes per 100 melanoma cells; its clone ItG2G1 continued to bind equally well after 400 days in culture. The ultrastructural morphology of knobs on the binding and nonbinding infected erythrocytes were indistinguishable. Since evidence from other studies indicates that knobs are necessary for binding to endothelium, it is proposed that some parasites in continuous culture may not express the molecules responsible for binding, although the morphologic knobs are still present.     

Insecticidal and synergistic effects of Majorana hortensis essential oil and some of its major constituents

The essential oil from leaves of Majorana hortensis Moench (Lamiaceae) was isolated by hydrodistillation with a yield of 1.6% (wt/wt). The insecticidal activity of the oil was evaluated against fourth instars of Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) and adults of Aphis fabae L. (Hemiptera: Aphididae). The oil showed a remarkable toxic effect against S. littoralis in a topical application assay (LD₅₀ = 2.48 μg per larva) and in a residual film assay (LC₅₀ = 3.14 g/l). The oil of M. hortensis also exhibited a pronounced toxic effect against A. fabae adults with LC₅₀ values of 1.86 and 2.27 g/l in rapid dipping and residual film assays, respectively. Gas chromatography-mass spectrometry analyses of M. hortensis essential oils revealed the presence of 31 compounds and the main components were terpinen-4-ol (30.0%), γ-terpinene (11.3%), and trans -sabinene hydrate (10.8%). Repeated column chromatography of M. hortensis oil on silica gel led to the isolation of two major constituents, which were characterized based on ¹H-nuclear magnetic resonance and mass spectrometric data, as terpinen-4-ol and γ-terpinene. These two components were examined for their insecticidal and synergistic activities towards S. littoralis and A. fabae . Terpinen-4-ol and γ-terpinene exhibited a significant insecticidal activity against both insects, but γ-terpinene was more toxic than terpinen-4-ol. When tested in a binary mixture with the synthetic insecticides profenofos and methomyl, it was found that both compounds enhanced the insecticidal activity of these insecticides by two- to threefold. These results show that terpinen-4-ol and γ-terpinene have a synergistic effect on the insecticidal activities of synthetic insecticides profenofos and methomyl.     

Anti-inflammatory activity of linalool and linalyl acetate constituents of essential oils

Linalool and linalyl acetate are the principal components of many essential oils known to possess several biological activities, attributable to these monoterpene compounds. In this work, we evaluated individually the anti-inflammatory properties of (-) linalool, that is, the natural occurring enantiomer, and its racemate form, present in various amounts in distilled or extracted essential oils. Because in the linalool-containing essential oils, linalyl acetate, is frequently present, we also examined the anti-inflammatory action of this monoterpene ester. Carrageenin-induced edema in rats was used as a model of inflammation. The experimental data indicate that both the pure enantiomer and its racemate induced, after systemic administration, a reduction of edema. Moreover, the pure enantiomer, at a dose of 25 mg/kg, elicited a delayed and more prolonged effect, while the racemate form induced a significant reduction of the edema only one hour after carrageenin administration. At higher doses, no differences were observed between the (-) enantiomer and the racemate; a further increase in the dose of both forms did not result in an increased effect at any time of observation. The effects of equi-molar doses of linalyl acetate on local edema were less relevant and more delayed than that of the corresponding alcohol. These finding suggest a typical pro-drug behavior of linalyl acetate. The results obtained indicate that linalool and the corresponding acetate play a major role in the anti-inflammatory activity displayed by the essential oils containing them, and provide further evidence suggesting that linalool and linalyl acetate-producing species are potentially anti-inflammatory agents.     

Biotransformation of constituents of essential oils by germinating wheat seed

Wheat seeds, when exposed to essential oils, are able to metabolise certain monoterpenes. The actual amounts of the compounds and their derivatives in the endosperm and embryo of wheat seeds, after exposure to the monoterpenes were determined. Neral and geranial, which are the constituents of citral, are reduced and oxidised to the corresponding alcohols and acids. Similarly citronellal, pulegone and carvacrol are converted partly to the corresponding reduction and oxidation products. The aromatic compound vanillin is partly reduced to vanillyl alcohol or oxidised to vanillic acid. In all cases it seems that part of the compounds applied are degraded, as indicated by the inability to account for all the compounds, which were supplied to the germinated seeds. In most cases the derivatives of the essential oil applied were less toxic than the parent compound. The possible role of non-specific enzymes by which the compounds are oxidised or reduced is discussed.     

Gelsolin affects the migratory ability of human colon adenocarcinoma and melanoma cells

AimsFormation of different protrusive structures by migrating cells is driven by actin polymerization at the plasma membrane region. Gelsolin is an actin binding protein controlling the length of actin filaments by its severing and capping activity. The main goal of this study was to determine the effect of gelsolin expression on the migration of human colon adenocarcinoma LS180 and melanoma A375 cells.Main methodsColon adenocarcinoma cell line LS180 was stably transfected with plasmid containing human cytoplasmic gelsolin cDNA tagged to enhanced green fluorescence protein (EGFP). Melanoma A375 cells were transfected with siRNAs directed against gelsolin. Real-time PCR and Western blotting were used to determine the level of gelsolin. The ability of actin to inhibit DNase I activity was used to quantify monomeric and total actin level and calculate the state of actin polymerization. Fluorescence confocal microscopy was applied to observe gelsolin and vinculin distribution along with actin cytoskeleton organization.Key findingsIncreased level of gelsolin expression leads to its accumulation at the submembranous region of the cell accompanied by distinct changes in the state of actin polymerization and an increase in the migration of LS180 cells. In addition, LS180 cells overexpressing gelsolin form podosome-like structures as indicated by vinculin redistribution and its colocalization with gelsolin and actin. Downregulation of gelsolin expression in melanoma A375 cells significantly reduces their migratory potential.SignificanceOur experimental data indicate that alterations in the expression level of gelsolin and its subcellular distribution may be directly responsible for determining migration capacity of human cancer cells.     

MSH binding in bomirski amelanotic hamster melanoma cells is stimulated by L-tyrosine

Bomirski Ab amelanotic melanoma cells have recently been shown to undergo striking phenotypic changes when precursors of the melanogenic pathway, L-tyrosine and L-dopa, are added to the culture medium. The changes include increased tyrosinase activity andde novo synthesis of melanosomes and melanin. L-tyrosine and L-dopa appeared to elicit these responses through separate but overlapping regulatory pathways. Here we show an additional effect of L-tyrosine: stimulation of MSH binding capacity. Cells cultured for 24–48 hours in the presence of 200 M L-tyrosine display a 3–4 fold increase in their ability to bind¹²⁵l--MSH. L-dopa did not stimulate MSH binding under the same conditions. In control experiments neither L-tyrosine nor L-dopa had any effect on insulin binding. The amelanotic cells respond to MSH with increased dendrite formation, increased tyrosinase activity without melanin production, and decreased growth rate.     

广西小叶红叶藤挥发油化学成分及抗氧化性研究

采用气相色谱-质谱联用技术对小叶红叶藤挥发油的化学成分进行分析,并用DPPH·法、ABTS,+法和铁氰化钾还原法对其抗氧化能力进行研究.结果表明:从小叶红叶藤挥发油分离出221个色谱峰,共鉴定64个化合物,占挥发油总量的95.72％,主要成分为dl-薄荷酮(53.43％)、(E)-薄荷酮(14.20％)、5-甲基-2-...     

Antiproliferative effects of dibenzocyclooctadiene lignans isolated from Schisandra chinensis in human cancer cells

Dibenzocyclooctadiene lignans isolated from Schisandra chinensis showed antiproliferative effects in various human cancer cells. The methoxy groups at C-3, C-4, C-3', and C-4', the hydroxyl group at C-8', and the stereo-configuration of the biphenyl ring and the angeloyl group might have influence on these activities. Additional studies indicate that one of mechanism of action of an active compound schizantherin C in A549 human lung cancer cells was related to the inhibition of cell cycle progression in G0/G1 phase.