Plant extracts and betulin from Ligaria cuneifolia inhibit P-glycoprotein function in leukemia cells.

Overexpression of P-glycoprotein (P-gp), which is linked to multidrug resistance (MDR), is one of the underlying obstacles to the success of chemotherapy as it reduces the efficacy of anticancer drugs and the side effects of these increase as a result of any increased dose to achieve the therapeutic effect. To identify agents with P-gp inhibitory properties, ethanol extracts from 80 plants were screened for their ability to increase intracellular doxorubicin-associated fluorescence, and the extract of Ligaria cuneifolia was found to be the most effective. Its bioassay-guided isolation yielded the pentacyclic triterpene betulin as active agent. This efficiently inhibited P-gp mediated efflux, as demonstrated by the enhancement of the intracellular accumulation of doxorubicin and rhodamine 123 from 1.56 µM in the P-gp overexpressing MDR leukemia cell, Lucena 1. Betulin was also able to render Lucena 1 sensitive to Dox from 0.39 µM. The docking studies revealed that betulin tightly binds to a key region of the TMDs, with a binding mode overlapping one main site of doxorubicin and, more interestingly, emulating the same contacts as tariquidar, as revealed by the per-residue energetic analysis from molecular dynamics simulations. MTT assay using peripheral blood mononuclear cells and hemolysis assay showed that betulin is devoid of toxicity. These findings provide important evidence that betulin may be a safe and promising entity to be further investigated to develop agents able to overcome P-gp-mediated MDR, resulting in a more effective and less toxic chemotherapy.

Cytotoxic Activity of Germacrane-Type Sesquiterpene Lactones from Dimerostemma aspilioides.

The need for effective candidates as cytotoxic drugs that at the same time challenge cancer multidrug resistance encouraged a search for these in plants of central Argentina. Bioassay-guided fractionation of the cytotoxic extract from Dimerostemma aspilioides led to the isolation of the germacranolide tomenphantin A (1), along with three new analogues (2-4). These efficiently inhibited the proliferation of the leukemia cell lines K562 and CCRF-CEM and their resistant variants, Lucena 1 and CEM/ADR5000, respectively, with IC50 values ranging from 0.40 to 7.7 µM. The structures and relative configurations of compounds 1-4 were elucidated by analysis of the spectroscopic data, in particular NMR spectroscopy. The most active among these was compound 1 (IC50 = 0.40-5.1 µM), and, therefore, this was selected as a model for a mechanistic study, which revealed that its antiproliferative effect was mediated by cell cycle arrest in the G2/M phase followed by apoptosis. The activity of compound 1 was selective, given the absence of cytotoxicity toward peripheral blood mononuclear cells. The results show the potential of these compounds, and in particular of compound 1, as leads for the development of drug candidates to fight sensitive and resistant leukemia cells.

Antifeedant effect of polygodial and drimenol derivatives against Spodoptera frugiperda and Epilachna paenulata and quantitative structure-activity analysis.

BACKGROUND: The antifeedant activity of 18 sesquiterpenoids of the drimane family (polygodial, drimenol and derivatives) was investigated. RESULTS: Polygodial, drimanic and nordrimanic derivatives were found to exert antifeedant effects against two insect species, Spodoptera frugiperda and Epilachna paenulata, which are pests of agronomic interest, indicating that they have potential as biopesticide agents. Among the 18 compounds tested, the epoxynordrimane compound (11) and isonordrimenone (4) showed the highest activity [50% effective concentration (EC50 ) = 23.28 and 25.63 nmol cm-2 , respectively, against S. frugiperda, and 50.50 and 59.00 nmol/cm2 , respectively, against E. paenulata]. CONCLUSION: The results suggest that drimanic compounds have potential as new agents against S. frugiperda and E. paenulata. A quantitative structure-activity relationship (QSAR) analysis of the whole series, supported by electronic studies, suggested that drimanic compounds have structural features necessary for increasing antifeedant activity, namely a C-9 carbonyl group and an epoxide at C-8 and C-9. © 2018 Society of Chemical Industry.

Mechanism Underlying the Reversal of Drug Resistance in P-Glycoprotein-Expressing Leukemia Cells by Pinoresinol and the Study of a Derivative.

P-glycoprotein (P-gp) is a membrane protein associated with multidrug resistance (MDR) due to its key role in mediating the traffic of chemotherapeutic drugs outside cancer cells, leading to a cellular response that hinders efforts toward successful therapy. With the aim of finding agents that circumvent the MDR phenotype mediated by P-gp, 15 compounds isolated from native and naturalized plants of Argentina were screened. Among these, the non-cytotoxic lignan (±) pinoresinol successfully restored sensitivity to doxorubicin from 7 µM in the P-gp overexpressed human myelogenous leukemia cells, Lucena 1. This resistance-reversing effect was confirmed by competitively increasing the intracellular doxorubicin accumulation and by significantly inhibiting the efflux of doxorubicin and, to a lesser extent, that of rhodamine 123. The activity obtained was similar to that observed with verapamil. No such results were observed in the sensitive parental K562 cell line. To gain deeper insight into the mode of action of pinoresinol, its effect on P-gp function and expression was examined. The docking simulations indicated that the lignan bound to P-gp at the apex of the V-shaped transmembrane cavity, involving transmembrane helices 4, 5, and 6, and partially overlapped the binding region of tariquidar, which was used as a positive control. These results would shed some light on the nature of its interaction with P-gp at molecular level and merit further mechanistic and kinetic studies. In addition, it showed a maximum 29% activation of ATP hydrolysis and antagonized verapamil-stimulated ATPase activity with an IC50 of 20.9 µM. On the other hand, pinoresinol decreased the presence of P-gp in the cell surface. Derivatives of pinoresinol with improved activity were identified by docking studies. The most promising one, the non-cytotoxic 1-acetoxypinoresinol, caused a reversion of doxorubicin resistance from 0.11 µM and thus higher activity than the lead compound. It also caused a significant increase in doxorubicin accumulation. Results were similar to those observed with verapamil. The results obtained positioned these compounds as potential candidates for effective agents to overcome P-gp-mediated MDR, leading to better outcomes for leukemia chemotherapy.

Phytotoxic phenylpropanoids isolated from Ophryosporus charua (Griseb.) Hieron.

Bioguided isolation of the EtOH extract from the medicinal native plant, Ophryosporus charua, against Raphanus sativus, yielded three phenylpropanoids, charuol A [(Z)-4-((1S,2R)-3-acetoxy-1,2-dihydroxypropyl)phenyl) 2-methylbut-2-enoate], charuepoxide [(Z)-4-((2S,3R)-3-(acetoxymethyl oxiran-2-yl)phenyl) 2-methylbut-2-enoate] and charuol B [(Z)-4-((1R,2R)-3-acetoxy-1,2-dihydroxypropyl)phenyl) 2-methylbut-2-enoate]. Their structures and absolute configuration were established by extensive spectroscopic analyses. The effective concentrations for 50% inhibition of germination (ECg50) and root (ECr50) and shoot (ECs50) elongations were determined for these compounds against P. miliaceum (monocot) and Raphanus sativus (dicot). Charuol A was the most active in the inhibition of germination of P. miliaceum (ECg50 = 0.97 mM), followed by charuol B and charuepoxide, although charuol B was the most effective in regulating the root growth of P. miliaceum seedlings, with an ECr50 of 1.0 mM. Charuol A inhibited the germination of R. sativus, while its seedling development was also affected by all three compounds with different effectiveness. Charuol A was also highly effective in the 0.09-0.30 mM range against other test species such as Lactuca sativa, Eruca sativa, Allium ampeloprasum and Secale cereale.

Insecticidal Properties of a Highly Potent Wax Isolated from Dolichandra cynanchoides Cham.

Bioassay-guided fractionation of an ethanolic extract of the aerial parts of Dolichandra cynanchoides Cham. (Bignoniaceae) led to the isolation of a natural wax with anti-insect activity against Spodoptera frugiperda (Noctuidae) and Epilachna paenulata (Coleptera). The compound was identified spectroscopically as an ester of a C27 fatty acid and a C25 alcohol, pentacosyl heptacosanoate (1). The effective doses of 1 for 50% feeding inhibition (ED50) of S. frugiperda and E. paenulata were 0.82 and 8.53 µg/cm², respectively, in a choice test, while azadirachtin showed ED50 of 0.10 and 0.59 µg/cm², respectively. In a no-choice test, both insects refused to feed on leaves treated with 1 at doses of 0.1 µg/cm² or greater inhibiting larval growth and dramatically reducing survival. The lethal doses 50 (LD50) of 1 were 0.39 and 0.68 µg/cm² for S. frugiperda and E. paenulata, respectively. These results indicate that 1 has potential for development as botanical insecticides. Similar esters might be obtainable in large quantities as many edible crops produce wax esters that are discarded during food processing. Research on these materials could lead to the detection of similar waxes with insecticidal activity.

Insecticidal effect of Cryptocarya alba essential oil on the housefly, Musca domestica L / Efecto insecticida del aceite esencial de Cryptocarya alba en la mosca doméstica, Musca domestica L

The composition of the essential oil (EO) from Cryptocarya alba obtained by hydro distillation of fresh leaves was analyzed using gas chromatography (GC) and gas chromatography/mass spectrosmetry (GC/MS). The insecticidal effect of the oil on the house fly Musca domestica was evaluated by placing flies in a sealed glass jar containing a piece of EO-treated cotton yarn. The dose necessary to kill 50 percent of flies (LC50) in 0.5 and 1 h was determined at 26 +/- 1 °C. The essential oil from Cryptocarya alba showed significant insecticidal properties [33.56 (7.06-159.50) mg/dm3 (0.5 h) and 15.07 (5.29-42.91) mg/dm3 (1 h)]. According to GC and GC/MS analysis a total of 38 compounds were identified. The composition of the Cryptocarya alba essential oil reported in this study is different to that reported in other publications with 4-terpineol (17.48 percent) ; 4- (3,3-dimethyl-but-1-ynyl) -4-hydroxy-2,6,6-trimethylcyclohex-2-enone (12.84 percent); 1,8-cineole (7.90 percent); p-cymene (7.11 percent) and sabinene (6.80 percent), accounting for 52.13 percent of the EO. The EO from Cryptocarya alba appears promising as a natural insecticide against houseflies.

La composición del aceite esencial (AE), obtenido por hidrodestilación de hojas frescas de Cryptocarya alba se analizó mediante cromatografía de gases (CG) y cromatografía de gases/espectrometría de masas (CG/EM). La actividad insecticida del aceite contra la mosca doméstica, Musca domestica se evaluó colocando las moscas en un frasco de vidrio sellado con un trozo de hilo de algodón tratado con diferentes cantidades de AE. La dosis necesaria para matar el 50 por ciento de las moscas (LC50) en 0,5 y 1 hora se determinó a 26 +/- 1 oC. El aceite esencial de Cryptocarya alba mostró un buen efecto insecticida [33,56 (7,06-159,50) mg/dm3 (0,5 h) and 15,07 (5,29-42,91) mg/dm3 (1 h)]. La composición del aceite esencial de Cryptocarya alba encontrada en este trabajo es diferente al informado en otras publicaciones, con 4-terpineol (17,48 por ciento); 4-(3,3-dimetil-but-1-inil)-4-hidroxi-2,6,6-trimetilciclohex-2-enona (12.84 por ciento); 1,8-cineole (7,90 por ciento); p-cimeno (7,11 por ciento) y sabineno (6,80 por ciento), lo que representa el 52.13 por ciento del AE. El AE de Cryptocarya alba parece prometedor como un insecticida natural contra la mosca doméstica.

Screening for extracts with insect antifeedant properties in native plants from central Argentina / Evaluación de la actividad antialimentaria de insectos en extractos de plantas nativas del centro de Argentina

Ethanol extracts obtained from aerial parts of 64 native plants from Central Argentina were tested for their insect antifeedant activity against Epilachna paenulata (Coleoptera: Coccinellidae) by choice test. Extracts derived from Achyrocline satureioides (Asteraceae), Baccharis coridifolia (Asteraceae), Baccharis flabellata (Asteraceae), Ruprechtia apetala (Polygonaceae) and Vernonanthura nudiflora (Asteraceae), showed more than 97 percent inhibition of the feeding of E. paenulata at 100 micrograms/cm2. These active extracts were further evaluated for their effectiveness against Spodoptera frugiperda (Lepidoptera: Noctuidae). All these extracts except for that derived from A. satureioides, negatively influenced the feeding behavior of S. frugiperda at 100 microrams/cm2...

Se evaluaron los extractos etanólicos obtenidos de las partes aéreas de 64 plantas de la región Central de Argentina, como antialimentarios de insectos mediante ensayos de elección, contra Epilachna paenulata (Coleoptera: Coccinellidae). Los extractos derivados de Achyrocline satureioides (Asteraceae), Baccharis coridifolia (Asteraceae), Baccharis flabellata (Asteraceae), Ruprechtia apetala (Polygonaceae) y Vernonanthura nudiflora (Asteraceae) mostraron mas de 97 por ciento de inhibición de la alimentación de E. paenulata a 100 microgramos/cm2. Estos extractos fueron posteriormente evaluados en su efectividad contra Spodoptera frugiperda (Lepidoptera: Noctuidae). Todos ellos, con excepción del extracto de A. satureioides, afectaron negativamente el comportamiento alimentario de S. frugiperda a 100 microgramos/cm2...

Phytotoxicity of secondary metabolites isolated from Flourensia oolepis S.F.Blake.

The aim of this study was to isolate the active principles of Flourensia oolepis S.F.Blake (Asteraceae), which completely inhibited the germination of Raphanus sativus seeds at 10 mg/ml. Flavanone pinocembrin and sesquiterpene ilicol, were isolated by bioassay-guided fractionation. They were active both against monocot and dicot seeds. Pinocembrin was the most active compound, with an IC50 (germination) value of 0.24, 3.40, 3.28, and 3.55 mM against Panicum miliaceum, Avena sativa, Lactuca sativa, and R. sativus, respectively; ilicol, however, exhibited IC50 (germination) values of 0.67, 2.73, 5.25, and 9.66 mM for the same species, respectively. Pinocembrin and ilicol inhibited root growth and showed IC50 (root growth) values of 0.199, 14.68, 8.05, 7.69 mM, and 1.22, 2.90, 7.35, 8.07 mM, against P. miliaceum, A. sativa, L. sativa, and R. sativus, respectively. Pinocembrin and ilicol reduced Allium cepa cell division without chromosome aberrations.

Antibacterial activity of the plant-derived compounds 23-methyl-6-O-desmethylauricepyrone and (Z,Z)-5-(trideca-4,7-dienyl)resorcinol and their synergy with antibiotics against methicillin-susceptible and -resistant Staphylococcus aureus.

The present study investigated the antibacterial activity of two plant-derived compounds, 23-methyl-6-O-desmethylauricepyrone (1) and (Z,Z)-5-(trideca-4,7-dienyl)resorcinol (2), and their synergistic effects with erythromycin and gentamicin against methicillin-susceptible (MSSA) and gentamicin- and methicillin-resistant Staphylococcus aureus (MRSA). Studies of the individual antibacterial activity of each plant-derived compound and synergy experiments were carried out, by the microdilution test in agar and by the checkerboard method, respectively. Compound 1 showed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 2 and 8 µg/mL, respectively, against both strains of S. aureus, while compound 2 exhibited anti-MSSA and anti-MRSA activity with MICs and MBCs of 4 and 8 and 2 and 8 µg/mL, respectively. Time-kill curves showed that, while compound 1 produced complete killing of both strains at 24 h from the beginning of the experiment, 2 produced the same effect in the first hour. Combinations of 1 with erythromycin or gentamicin showed a notable synergism against MSSA, which enabled the antibiotic concentration to decrease by up to 300 or 260 times, respectively. When the aminoglycoside was placed together with compound 2, only an additive effect was observed. The assayed compounds did not produce erythrocyte hemolysis or genotoxicity and they did not affect macrophage viability at the effective or higher concentrations. These results suggest that both compounds could be considered as promising antibacterial agents while compound 1 could be used in combinatory therapies with erythromycin and gentamicin.

Insecticidal effect of Schinus latifolius essential oil on the housefly, Musca domestica L / Efecto insecticida del aceite esencial de Schinus latifolius en mosca doméstica, Musca domestica

The composition of essential oil (EO) from Schinus latifolius obtained by hydro distillation of dry leaves was analyzed using gas chromatography (GC-FID) and gas chromatography/mass spectroscopy (GC/MS). The insecticidal effect of the oil on the house fly Musca domestica was evaluated by placing flies in a sealed glass jar containing a piece of EO-treated cotton yarn. The dose necessary to kill 50 percent of flies (LC50) in 0.5 and 1 h was determined at 26+/-1°C. The essential oil from Schinus latifolius showed significant insecticidal properties [LC50 = 31.98 mg/dm3 (0.5 h) and LC50 = 19.20 mg/dm3 (1 h)]. According to GC-FID and GC/MS analysis a total of 54 compounds were identified accounting for 99.45 percent of the EO, with limonene (50.23 percent); α-pinene (15.01percent); beta-pinene (11.81 percent); sabinene (4.71 percent) and α-thujene (2.18 percent) as the main components. The EO from Schinus latifolius appears promising as a natural insecticide against houseflies. The composition of the Schinus latifolius essential oil reported in this study is different to that reported in other publications. The most important characteristic is the high content of limonene (50.23 percent), which can be attributed to the time of year and the geographic location of the sampled plants.

La composición del aceite esencial (AE), obtenido por hidrodestilación de hojas secas de Schinus latifolius se analizó mediante cromatografía de gases (CG-FID) y cromatografía de gases / espectrometría de masas (CG/EM). La actividad insecticida del aceite contra la mosca doméstica, Musca domestica se evaluó colocando las moscas en un frasco de vidrio sellado con un trozo de hilo de algodón tratado con diferentes cantidades de AE. La dosis necesaria para matar el 50 por ciento de las moscas (LC50) en 0,5 y 1 hora se determinó a 26 +/- 1ºC. El aceite esencial de Schinus latifolius mostró un buen efecto insecticida [DL50 = 31,98 mg/dm3 (0,5 h) y DL50 = 19,20 mg/dm3 (1 h)]. De acuerdo con los análisis de GC-FID y CG/EM, un total de 54 compuestos fueron identificados lo que representa el 99.45 por ciento del AE, siendo limoneno (50.23 por ciento); α-pineno (15.01 por ciento); beta-pineno (11.81 por ciento); sabineno (4.71 por ciento) y α-tujeno (2.18 por ciento) los componentes principales del AE. El AE de Schinus latifolius parece prometedor como un insecticida natural contra la mosca doméstica. La composición del aceite esencial de Schinus latifolius encontrado en este trabajo es diferente al informado en otras publicaciones. La característica mas importante es el alto contenido de limoneno (50.23 por ciento), que podría atribuirse a la época del año y la ubicación geográfica de las plantas recolectadas.

Antibacterial activity of extracts from plants of central Argentina--isolation of an active principle from Achyrocline satureioides.

The great increase in bacterial infections is fueling interest in the search for antibacterial products of plant origin. Extracts obtained from 51 native and naturalized plants from central Argentina were therefore evaluated for their IN VITRO inhibitory activity on pathogenic bacteria with the aim of selecting the most active ones as new sources of effective antibiotics. The susceptibility of reference and clinical strains of Enterococcus faecalis, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus was determined. Extracts from Achyrocline satureioides, Flourensia oolepis, Lepechinia floribunda, and Lithrea molleoides were the most potent, with MIC and MBC values ranging from 0.006 to 2 and 0.012 to 10 mg/mL, respectively, on both gram-positive and negative bacteria. The antibacterial activity-guided isolation of A. satureioides ethanol extract showed 23-methyl-6-O-desmethylauricepyrone (1) to be the most active compound. This compound showed inhibitory effects against gram-positive bacteria with MIC and MBC values of 0.002 and 0.008 mg/mL, respectively, while on gram-negative strains, the MIC and MBC were 0.062-0.250 and 0.062-0.500 mg/mL, respectively. The strong antibacterial activity shown by the four plant extracts or the compound isolated from A. satureioides suggests that they could become part of the arsenal of antibacterial drugs currently used.

Insecticidal properties of Peumus boldus Mol: essential oil on the house fly, Musca domestica L / Propiedades insecticidas del aceite esencial de Peumus boldus Mol: sobre la mosca doméstica, Musca domestica L

The composition of the essential oil (EO) obtained by hydro distillation from dry leaves of Peumus boldus was analyzed using gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS). The insecticidal activity of the oil against the house fly Musca domestica was evaluated by placing flies in a sealed glass jar containing a piece of EO-treated cotton yarn. The dose necessary to kill 50 percent of flies (LC50) in 1 h was determined at 26 +/-1°C. The essential oil from Peumus boldus showed potent insecticidal properties (LC50 = 6.26 mg/dm3). According to GC and GC/MS analysis, 1,8-cineol (36.72 percent); p-cymene (26.79 percent); ascaridol (6.25 percent); sabinene (5.10 percent); 4-terpineol (4.39 percent); beta-pinene (4.16 percent) and limonene (2.68 percent) were the principal components of the EO. The EO from Peumus boldus seems promising as a natural insecticide against houseflies. The peumus boldus essential oil reported in this paper is different to that reported in other publications. .The most important differences are the low content of ascaridol and the high content of both 1,8-cineol and p-cimene which can be attributed to the time of year and the geographic location of the samples plant.

La composición del aceite esencial (AE), obtenido por hidrodestilación de hojas secas de Peumus boldus se analizó mediante cromatografía de gases (CG) y cromatografía de gases / espectrometría de masas (CG / EM). La actividad insecticida del aceite contra la mosca doméstica, Musca domestica se evaluó colocando las moscas en un frasco de vidrio sellado con un trozo de hilo de algodón tratado con diferentes cantidades de AE. La dosis necesaria para matar el 50 por ciento de las moscas (LC50) en 1 hora se determinó a 26 +/- 1ºC. El aceite esencial de Peumus boldus mostró potentes propiedades insecticidas (LC50= 6.26 mg/dm3). De acuerdo con los análisis de GC y CG / EM, 1,8-cineol (36,72 por ciento), p-cimeno (26.79 por ciento); ascaridol (6,25 por ciento); sabineno (5.10 por ciento), 4-terpineol (4,39 por ciento), beta-pineno (4,16 por ciento) y limoneno (2,68 por ciento) fueron los componentes principales del AE. El AE de Peumus boldus parece prometedor como un insecticida natural contra moscas. La composición del aceite esencial de Peumus boldus encontrado en este trabajo es diferente a lo reportado en otras publicaciones. Las diferencias más importantes son el bajo contenido de ascaridol y el alto contenido de ambos 1,8-cineol y p-cimeno que puede atribuirse a la época del año y la ubicación geográfica de las plantas recolectadas.

Response of Epilachna paenulata to two flavonoids, pinocembrin and quercetin, in a comparative study.

We examined the effects of the flavonoids pinocembrin and quercetin on the feeding behavior, survival, and development of the Cucurbitaceae pest Epilachna paenulata (Coleoptera: Coccinellidae). In no-choice experiments, 48 hr-consumption of Cucurbita maxima Duch. leaves treated with pinocembrin at 1, 5, and 50 microg/cm(2) was less than one third of that for leaves treated with 0.1 microg/cm(2) of pinocembrin or untreated leaves. Larvae stopped feeding after 9 days of high doses of pinocembrin (5 and 50 microg/cm(2)), and larval weight and survival were negatively affected by pinocembrin at 1-50 microg/cm(2). Delayed mortality in comparison to food-deprived larvae suggests that the mechanism of action for pinocembrin is chronic intoxication, rather than simple starvation from antifeedant effects. In contrast, leaf consumption and larval weight were not significantly affected by quercetin (at 0.1, 1, 5, and 50 microg/cm(2)) while mortality rates were only slightly increased. The response of E. paenulata larvae in a choice-test to combinations of pinocembrin at antifeedant doses (5 and 50 microg/cm(2)) and quercetin at phagostimulant doses (0.01 and 0.1 microg/cm(2)) indicated that the feeding deterrent activity of the former completely overshadowed the stimulant activity of the latter. These results demonstrate the different responses of one insect species to two widely distributed plant flavonoids. Pinocembrin strongly affected survival of E. paenulata while quercetin had only a weak effect without major consequences on the insect life-cycle.

Screening for acetylcholinesterase inhibitory activity in plant extracts from Argentina.

Plants are a potential source of bioactive compounds and offer a promising strategy for the treatment of neurological disorders such as Alzheimer's disease. The inhibitory effect of 73 native and naturalized plants collected from the central region of Argentina on acetylcholinesterase (AChE) was tested using microplate and TLC assays after solvent fractionation of complete ethanol extracts obtained from the plants. Organic fractions obtained from extracts of Achyrocline tomentosa (Asteraceae), Eupatorium viscidum (Asteraceae), Ruprechtia apetala (Polygonaceae) Trichocline reptans (Asteraceae) and Zanthoxylum coco (Rutaceae) presented strong inhibition of AChE (higher than 80%) at 1 mg/mL, with R. apetala and T. reptans being the most potent, showing complete inhibition of the enzyme. Their IC(50) values were 0.0779 and 0.1118 mg/mL, respectively. Aqueous fractions did not show any inhibitory activity on the enzyme. These results suggest that the most effective extracts deserve further investigation with the aim of obtaining new molecules for the treatment of neurodegenerative disorders.

Insecticidal activity of essential oils from native medicinal plants of Central Argentina against the house fly, Musca domestica (L.).

The insecticidal activity of nine essential oils (EOs) against the house fly (Musca domestica) was evaluated by placing flies in a screw-cap glass jar holding a piece of EO-treated cotton yarn. The dose necessary to kill 50% of flies (LC(50)) in 30 min was determined at 26 +/- 1 degrees C. The EOs showed LC(50) values ranging from 0.5 to 46.9 mg/dm(3). The EO from Minthostachys verticillata was the most potent insecticide (LC(50) = 0.5 mg/dm(3)) followed by EOs from Hedeoma multiflora (LC(50) = 1.3 mg/dm(3)) and Artemisia annua (LC(50) = 6.5 mg/dm(3)). The compositions of the nine EOs, obtained by hydrodistillation of medicinal herbs, were analyzed by gas chromatography/mass spectroscopy. These analyses showed that (4R)(+)-pulegone (69.70%), menthone (12.17%), and limonene (2.75%) were the principal components of M. verticillata EO. (4R)(+)-pulegone was also the main constituent (52.80%) of H. multiflora, while artemisia ketone (22.36%) and 1,8-cineole (16.67%) were the major constituents of A. annua EO. The terpene (4R)(+)-pulegone showed a lower toxicity (LC(50) = 1.7 mg/dm(3)) than M. verticillata or H. multiflora EOs. Dimethyl 2,2-dichlorovinyl phosphate, selected as a positive control, showed an LC(50) of 0.5 mg/dm(3). EOs from M. verticillata and H. multiflora show promise as natural insecticides against houseflies.

Efficacy of essential oils from edible plants as insecticides against the house fly, Musca domestica L.

The compositions of 12 essential oils (EOs) obtained by hydrodistillation of edible fruits and herbs were analyzed by gas chromatography/mass spectroscopy (GC/MS). The insecticidal activity of each oil against the house fly Musca domestica was evaluated by placing flies in a glass jar with a screw cap that held a piece of EO-treated cotton yarn. The dose necessary to kill 50% of flies (LC(50)) in 30 min was determined at 26 +/- 1 degrees C. Twelve EOs and 17 individual terpenes were assayed against M. domestica, showing LC(50) values ranging from 3.9 to 85.2 and from 3.3 to >100 mg/dm(3), respectively. EO from Citrus sinensis was the most potent insecticide (LC(50 )= 3.9 mg/dm(3)), followed by EOs from C. aurantium (LC(50 )= 4.8 mg/dm(3)) and Eucalyptus cinerea (LC(50 )= 5.5 mg/dm(3)). According to GC/MS analysis, limonene (92.47%), linalool (1.43%), and b-myrcene (0.88%) were the principal components of C. sinensis EO. Limonene was also the principal constituent (94.07%) of C. aurantium, while 1,8-cineole (56.86%) was the major constituent of E. cinerea EO. 1,8-Cineole was most active against M. domestica (LC(50 )= 3.3 mg/dm(3)), while (4R)(+)-limonene, was moderately active (LC(50 )= 6.2 mg/dm(3)). Dimethyl 2,2-dichlorovinyl phosphate (DDVP) selected as a positive control, showed an LC(50) of 0.5 mg/dm(3). EOs from C. sinensis, C. aurantium, and E. cinerea show promise as natural insecticides against houseflies.

Antifeedant activity of ethanolic extract from Flourensia oolepis and isolation of pinocembrin as its active principle compound.

The ethanolic extract from Flourensia oolepis aerial parts showed strong antifeedant activity against the pest larvae, Epilachna paenulata, with an antifeedant index (AI%) of 99.1% at 100 microg/cm(2). Based on chromatographic fractionation of the extract, guided by bioassays on E. paenulata, the flavanone pinocembrin (1) was isolated as the most active principle. In a choice assay, compound 1 showed strong antifeedant activity against E. paenulata, Xanthogaleruca luteola and Spodoptera frugiperda with an AI% of 90, 94 and 91% (p<0.01) respectively, at 50 microg/cm(2). The dosages necessary for 50% feeding inhibition of the insects (ED(50)) were 7.98, 6.13 and 8.86 microg/cm(2), respectively. The feeding inhibitory activity of 1 against E. paenulata was compared with the activity of other structurally related flavonoids like naringenin, which was inactive up to 100 microg/cm(2), catechin which was nearly 6 times less active than 1, and quercetin which was equally active as 1. The effect of these on the feeding behavior of E. paenulata was also studied.

Screening of Argentinian plants for pesticide activity.

Aerial parts of 27 plant species native to Argentina were tested in anti-insect, germination inhibition and bactericide bio-assays. In antifeedant assays on Epilachna paenulata larvae, 11 species showed strong feeding deterrent effects (higher than 90% at 200 microg/cm(2)). Twelve plants strongly inhibited the germination of Avena sativa seeds, but only six inhibited Raphanus sativum germination at 10 mg/ml. Four plants showed complete growth inhibition of Escherichia coli at a concentration of 2 mg/ml.

In vitro pediculicidal and ovicidal activity of an extract and oil from fruits of Melia azedarach L.

BACKGROUND: Head louse infestation is difficult to control because of increasing lice resistance to synthetic pediculicidal drugs. OBJECTIVE: To test the activity of extract and oil obtained from fruits of Melia azedarach L. against the head louse Pediculus humanus capitis. METHODS: A filter paper diffusion bioassay was carried out in order to determine the pediculicidal and ovicidal activity of extract and oil from M azedarach L. fruits. RESULTS: Both vegetable products, tested either individually or in combinations, showed high levels of mortality on adult lice, with values ranging between 62.9% and 96.5%. The highest mortality rate was obtained with a combination of 20% ripe fruit extract with 10% ripe fruit oil. A formulation made with both extract and oil at 10% plus the addition of emulsifier and preserving agents showed 92.3% pediculicidal activity. The products were also successful in delaying or inhibiting nymph emergence, with the formulation being the most effective, with a complete inhibition of emergence. LIMITATIONS: Because adult lice are sensitive to starvation and therefore control mortalities are often higher than 20% in tests with field specimens, the results may not reflect the direct effect of the extract. CONCLUSIONS: These results demonstrate the possibility of using Melia products for controlling head lice, which are difficult to control because of their resistance to the currently used anti-louse agents.