Larvicidal activity of crude extracts from Larrea cuneifolia (Zygophyllaceae) and of its metabolite nordihydroguaiaretic acid against the vector Culex quinquefasciatus (Diptera: Culicidae)

INTRODUCTION: The aim of the present study was to analyze the larvicidal activity of different crude extracts of Larrea cuneifolia and its most abundant lignan, nordihydroguaiaretic acid (NDGA), against Culex quinquefasciatus. METHODS: Chloroform, methanol, and aqueous extracts from L. cuneifolia and NDGA were tested against larvae of Cx. quinquefasciatus under laboratory conditions. RESULTS: The chloroform extract showed the highest larvicidal effect, with an estimated LC50 of 0.062 mg/ml. NDGA also demonstrated significant larvicidal activity with an estimated LC50 of 0.092 mg/ml. CONCLUSIONS: These results indicate that the chloroform extract of L. cuneifolia and NDGA are promising insecticides of botanical origin that could be useful for controlling Cx. quinquefasciatus.

Evaluation of larvicidal activity and brine shrimp toxicity of rhizome extracts of Zingiber zerumbet (L.) Smith

Introduction In this study, we used dichloromethane (DCM) and methanol (MeOH) extracts of the Zingiber zerumbet rhizome to evaluate brine shrimp lethality and larvicidal activity on Aedes aegypti and Anopheles nuneztovari mosquitoes. Methods Bioassays were performed by exposing third-instar larvae of each mosquito species to the DCM or MeOH extracts. Results Probit analysis with DCM and MeOH extracts demonstrated efficient larvicidal activity against A. aegypti and A. nuneztovari larvae. Conclusions The DCM and MeOH extracts showed higher activity against A. nuneztovari larvae than against A. aegypti larvae, suggesting that the extracts have species-specific activity.

Larvicidal effects of endophytic and basidiomycete fungus extracts on Aedes and Anopheles larvae (Diptera, Culicidae)

Introduction In vitro bioassays were performed to access the larvicidal activity of crude extracts from the endophytic fungus Pestalotiopsis virgulata (Melanconiales, Amphisphaeriaceae) and the saprophytic fungus Pycnoporus sanguineus (Basidiomycetes, Polyporaceae) against the mosquitoes Aedes aegypti and Anopheles nuneztovari. Methods The extracts were tested at concentrations of 100, 200, 300, 400 and 500ppm. Ethyl acetate mycelia (EAM) extracts and liquid culture media (LCM) from Pe. virgulata and Py. sanguineus were tested against third instar larvae of Ae. aegypti and An. nuneztovari. Results The larvicidal activity of the EAM extracts from Pe. virgulata against Ae. aegypti had an LC50=101.8ppm, and the extract from the basidiomycete fungus Py. sanguineus had an LC50=156.8ppm against the Ae. aegypti larvae. The Pe. virgulata extract had an LC50=16.3ppm against the An. nuneztovari larvae, and the Py. sanguineus extract had an LC50=87.2ppm against these larvae. Conclusions These results highlight the larvicidal effect of EAM extracts from the endophyte Pe. virgulata against the two larval mosquitoes tested. Thus, Pe. virgulata and Py. sanguineus have the potential for the production of bioactive substances against larvae of these two tropical disease vectors, with An. nuneztovari being more susceptible to these extracts.

Bioactivity of plant extracts on the larval and pupal stages of Aedes aegypti (Diptera, Culicidea)

Introduction Aedes aegypti is responsible for the transmission of the dengue and yellow fever viruses. This study evaluated the effects of extracts from Cnidosculos phyllacanthus, Ricinus communis, and Coutarea hexandra on the developmental periods of A.aegypti larvae and pupae. Crude extracts of C. phyllacanthus and C. hexandra and oil from R. communis and C. phyllacanthus were used. Methods Bioassays of the larvicidal and pupicidal effects of these products at different concentrations and times of exposure were evaluated. The lethal and sublethal effects were determined using different concentrations in larvicidal tests. Mortality data were evaluated by Probit analysis to determine the LC50 and LC90 values. Results The vegetable oils from C. phyllacanthus and R. communis demonstrated greater efficiency for larval control with an LC50=0.28µl/mL and an LC90=1.48µl/mL and LC50=0.029µl/mL and a LC90=0.26µl/mL, respectively. In pupal tests toxic effects for all insects were verified after exposure to the products at significant LC50 and LC90 values for 24 and 48h. The effects of sublethal concentrations of C. phyllacanthus (oil) were more effective on the insects. Conclusions The vegetables oils from C. phyllacanthus and R. communis demonstrated greater potential from the control of different developmental periods in the life cycle of this insect.

In vitro antifungal activities of leaf extracts of Lippia alba (Verbenaceae) against clinically important yeast species

Introduction There are few studies reporting the antifungal activities of Lippia alba extracts. Methods A broth microdilution assay was used to evaluate the antifungal effects of Lippia alba extracts against seven yeast species of Candida and Cryptococcus. The butanol fraction was investigated by gas chromatography-mass spectrometry. Results The butanol fraction showed the highest activity against Candida glabrata. The fraction also acted synergistically with itraconazole and fluconazole against C. glabrata. The dominant compounds in the butanol fraction were 2,2,5-trimethyl-3,4-hexanedione, 3,5-dimethyl-4-octanone and hexadecane. Conclusions The butanol fraction may be a good candidate in the search for new drugs from natural products with antifungal activity.

Antioxidant, cytotoxic and UVB-absorbing activity of Maytenus guyanensis Klotzch. (Celastraceae) bark extracts

Maytenus guyanensis Klotzch. is an Amazonian medicinal tree species known in Brazil by the common name chichuá and in Peru and Colombia by the name chuchuhuasi. It is used in traditional medicine as stimulant, tonic, and muscle relaxant, for the relief of arthritis, rheumatism, hemorrhoids, swollen kidney, skin eruptions, and skin cancer prevention, among others. Initially, different extraction solvents and methods were applied to dried, ground bark which made possible the preparation of extracts having both significant lethality to brine shrimp larvae (Artemia franciscana Leach) as well as antioxidant activity in vitro based on tests involving reactions with 2,2,-diphenyl-1-picrylhydrazyl (DPPH). Analysis of fractions from serial extractions with solvents of increasing polarity supports the notion that antioxidant activity is associated with compounds of intermediate polarity and cytotoxicity is associated with compounds of low to intermediate polarity. Variation of extraction time and conditions revealed that hot, continuous ethanol extraction provided good yields of bark extract in several hours. Hot extraction also provided ethanol extracts having greater lethality to brine shrimp and antioxidant activity (compared to the flavonoid rutin in semi-quantitative methods based on DPPH) than extracts obtained from maceration at room temperature. Freeze-dried ethanol extracts were prepared by: 1) maceration at room temperature and 2) hot extraction (eight hours) on several hundred gram scales and the latter extract was shown to have partial screening effects on UVB light. In this work, cytotoxic, antioxidant and potential sun-screening activity are shown for the first time in M. guyanensis.

Protein content and electrophoretic profile of fat body and ovary extracts from workers of Melipona quadrifasciata anthidioides (Hymenoptera, Meliponini)

Workers of Melipona quadrifasciata anthidioides (Lepeletier, 1836) develop their ovaries and lay eggs, therefore the production of vitellogenin is expected. In electrophoretic profiles only fat body extracts from nurse workers and ovary extracts from newly-emerged workers show protein with molecular mass similar to vitellogenin. However, an increase in the protein content was detected in forager fat body. This increase was attributed to storage of vitellogenin or other proteins in the previous phase and not discharged into the hemolymph or to an effect of the increased titre of juvenile hormone in this phase of worker life over the fat body functioning.

Schistosoma mansoni antigenic extracts obtained by different extraction procedures

Solubilization of Schistosoma mansoni antigens was obtained by agitation of adult worms in a 3M KCl solution. The protein contents of the KCl extrats varied from 0.35 to 0.96 mg/ml. Sera from 97 patients with hepatointestinal shistosomiasis and viable eggs in stools from a Brazilian endemic area were studied by immunoelectroomophoresis and Ouchterlony immunodiffusion methods with the KCl extract and with another antigen, obtained by homogenization of adult schistosomes in saline. The rate of positiveness of immunoprecipitation deterctions by immunoelectroomophoresis with the KCl extract was 53.5%. A correlation was verified between methods of detection and extration procedures, resulting in a better association of the extract obtained by agitation in 3M KCl and immunoelectroomophoresis.

Influence of several plant extracts on the oviposition behaviour of Aedes fluviatilis (Lutz) (Diptera: Culicidae) in the laboratory

Whole, ethanolic, hexanic, lyophilized extracts of several plants and anacardic acid tested in respect of their influence on the oviposition behavior of Aedes fluviatilis (Lutz) at 100, 10 and 1 ppm concentrations. Extracts of Allium stivum, Jatropha curcas, Mikania schenkii, Poinciana regia and Spatodea campanulata had a repulsive effect (α=0.05) on females at 100 ppm, those of Anacardium occidentale, Bidens segetum and Caesalpinia peltophoroides were also repelent at 10 ppm. Extracts of Coriandrum sativum (100, 10 and 1 ppm), Chara Zeylanica (10 ppm), Cupressus sempervirens (10 ppm), Foeniculum vulgare (10 ppm) and Spatodea campanulata (1 ppm) were attractive to the females; 13 (52.0%) of the extracts tested, did not influence the oviposition behavior.

The distribution of agglutinins and lytic activity against Trypanosoma rangeli and erythrocytes in Rhodnius prolixus and Triatoma infestans tissue extracts and haemolymph

Haemolymph, heads, salivary glands, crops, midguts, hindguts, and Malpighian tubules from Rhodnius prolixus and Triatoma infestans were extracted in phosphate or Tris buffer saline with calcium, and tested for agglutination and lytic activities by microtitration against both vertebrateerythrocytes and cultured epimatigote forms of Trypanosoma rangeli. Haemagglutination activity against rabbit erythrocytes was found in the crop, midgut and hindgut extracts of T. infestans but only in the haemolymph of R. prolixus. Higher titres of parasite agglutinins were found in R. prolixus haemolymph than T. infestans, whilst the converse occurred for the tissue extracts. In addition, the extracts of T. infestans salivary glands, but not those of R. prolixus, showed a trypanolytic activity that was heat-inactivated and was not abolished by pre-incubation with any of the sugars or glycoproteins tested. T. infestans, which is refractory to infection by T. rangeli, thus appears to contain a much wider distribution of agglutinating and trypanolytic factors in its tissues than the more susceptible species, R. prolixus

Genotoxicity of plant extracts

Aqueous extracts of seven species used in Brazilian popular medicine (Achyrocline satureoides, Iodina rhombifolia, Desmodium incanum, Baccharis anomala, Tibouchina asperior, Luehea divaricata, Maytenus ilicifolia) were screened to the presence of mutagenic activity in the Ames test (Salmonella/microsome). Positive results were obtained for A. satureoides, B anomala and L. divaricata with microsomal activation. As shown elsewhere (Vargas et al., 1990) the metabolites of A. satureoides extract also show the capacity to induce prophage and/or SOS response in microscreen phage induction assay and SOS spot chromotest.

Screening of Asteraceae (Compositae) Plant Extracts for Larvicidal Activity against Aedes fluviatilis (Diptera: Culicidae)

Ethanol extracts of 83 plants species belonging to the Asteraceae (Compositae) family, collected in the State of Minas Gerais, Brazil, were tested for larvicidal activity against the mosquito Aedes fluviatilis - Diptera: Culicidae). The extract from Tagetes minuta was the most active with a LC90 of 1.5 mg/l and LC50 of 1.0 mg/l. This plant has been the object of several studies by other groups and its active components have already been identified as thiophene derivatives, a class of compounds present in many Asteraceae species. The extract of Eclipta paniculata was also significantly active, with a LC90 of 17.2 mg/l and LC50 of 3.3 mg/l and no previous studies on its larvicidal activity or chemical composition could be found in the literature. Extracts of Achryrocline satureoides, Gnaphalium spicatum, Senecio brasiliensis, Trixis vauthieri, Tagetes patula and Vernonia ammophila were less active, killing more than 50% of the larvae only at the higher dose tested (100 mg/l).

Antitumor and Antiviral Activity of Colombian Medicinal Plant Extracts

Extracts of nine species of plants traditionally used in Colombia for the treatment of a variety of diseases were tested in vitro for their potential antitumor (cytotoxicity) and antiherpetic activity. MTT (Tetrazolium blue) and Neutral Red colorimetric assays were used to evaluate the reduction of viability of cell cultures in presence and absence of the extracts. MTT was also used to evaluate the effects of the extracts on the lytic activity of herpes simplex virus type 2 (HSV-2). The 50% cytotoxic concentration (CC50) and the 50% inhibitory concentration of the viral effect (EC50) for each extract were calculated by linear regression analysis. Extracts from Annona muricata, A. cherimolia and Rollinia membranacea, known for their cytotoxicity were used as positive controls. Likewise, acyclovir and heparin were used as positive controls of antiherpetic activity. Methanolic extract from Annona sp. on HEp-2 cells presented a CC50 value at 72 hr of 49.6x103mg/ml. Neither of the other extracts examined showed a significant cytotoxicity. The aqueous extract from Beta vulgaris, the ethanol extract from Callisia grasilis and the methanol extract Annona sp. showed some antiherpetic activity with acceptable therapeutic indexes (the ratio of CC50 to EC50). These species are good candidates for further activity-monitored fractionation to identify active principles.

Cytotoxic and Antiviral Activities of Colombian Medicinal Plant Extracts of the Euphorbia genus

Forty-seven plant extracts of 10 species of the genus Euphorbia (Euphorbiaceae) used by Colombian traditional healers for the treatment of ulcers, cancers, tumors, warts, and other diseases, were tested in vitro for their potential antitumour (antiproliferative and cytotoxic) and antiherpetic activity. To evaluate the capacity of the extracts to inhibit the lytic activity of herpes simplex virus type 2 (HSV-2) and the reduction of viability of infected or uninfected cell cultures, the end-point titration technique (EPTT) and the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] colorimetric assay were used, respectively. The therapeutic index of the positive extracts for the antiviral activity was determined by calculating the ratio CC50 (50% cytotoxic concentration) over IC50 (50% inhibitory concentration of the viral effect). Five of the 47 extracts (11%) representing 3 out of 10 Euphorbia species (30%) exhibited antiherpetic action; the highest activity was found in the leaf/stem water-methanol extracts from E. cotinifolia and E. tirucalli. The therapeutic indexes of these two plant species were > 7.1; these extracts exhibited no cytotoxicity. Six extracts (13%) representing 4 plant species (40%) showed cytotoxic activity. The highest cytotoxicity was found in the dichloromethane extract obtained from E. cotinifolia leaves and the CC50 values for the most susceptible cell lines, HEp-2 and CHO, were 35.1 and 18.1 µg/ml, respectively.