Larvicidal activity of some Euphorbiaceae plant extracts against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

Mosquito-Borne Diseases and Their Control Strategies: An Overview Focused on Green Synthesized Plant-Based Metallic Nanoparticles

Mosquitoes act as vectors of pathogens that cause most life-threatening diseases, such as malaria, Dengue, Chikungunya, Yellow fever, Zika, West Nile, Lymphatic filariasis, etc. To reduce the transmission of these mosquito-borne diseases in humans, several chemical, biological, mechanical, and pharmaceutical methods of control are used. However, these different strategies are facing important and timely challenges that include the rapid spread of highly invasive mosquitoes worldwide, the development of resistance in several mosquito species, and the recent outbreaks of novel arthropod-borne viruses (e.g., Dengue, Rift Valley fever, tick-borne encephalitis, West Nile, yellow fever, etc.). Therefore, the development of novel and effective methods of control is urgently needed to manage mosquito vectors. Adapting the principles of nanobiotechnology to mosquito vector control is one of the current approaches. As a single-step, eco-friendly, and biodegradable method that does not require the use of toxic chemicals, the green synthesis of nanoparticles using active toxic agents from plant extracts available since ancient times exhibits antagonistic responses and broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on the different mosquito control strategies in general, and on repellent and mosquitocidal plant-mediated synthesis of nanoparticles in particular, has been reviewed. By doing so, this review may open new doors for research on mosquito-borne diseases.

An insight into the potent medicinal plant Phyllanthus amarus Schum. and Thonn

Phyllanthus amarus Schum. and Thonn., a globally distributed herb is known for its several therapeutic potentials. P. amarus has a long history of use in the traditional system of medicine for over 2000 years owing to its wide array of secondary metabolites that confer significant medicinal attributes. Research on various aspects including ethnobotany, phytochemistry to bioactivity, or pharmacological studies has been conducted over the past several decades on this potent herb. P. amarus extracts have shown a broad range of pharmacological activities like hepatoprotective, antioxidant, antiviral, antimicrobial, antidiabetic, anti-inflammatory, anticancer, antimalarial, nephroprotective, diuretic, and several other properties. The present review compiles and covers literature and research of several groups across past decades to date and focuses on how the therapeutic significance of this plant can be further explored for future research either as herbal formulations, alternative medicine, or in the pharmaceutical industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13237-022-00409-z.

Exploitation of cantaloupe peels for bacterial cellulose production and functionalization with green synthesized Copper oxide nanoparticles for diverse biological applications

The promising features of most bacterial celluloses (BC) promote the continuous mining for a cost-effective production approach toward wide and sustainable applications. Herein, cantaloupe peels (CP) were successfully implemented for sustainable BC production. Results indicated that the enzymatically hydrolyzed CP supported the maximum BC production of approximately 3.49 g/L when used as a sole fermentation media. The produced BC was fabricated with polyvinyl alcohol (PVA) and chitosan (Ch), and loaded with green synthesized copper oxide nanoparticles (CuO-NPs) to improve its biological activity. The novel composite showed an antimicrobial activity against several human pathogens such as Staphylococcus aureus, Streptococcus mutans, Salmonella typhimurium, Escherichia coli, and Pseudomonas fluorescens. Furthermore, the new composite revealed a significant in vitro anticancer activity against colon (Caco-2), hepatocellular (HepG-2), and breast (MDA) cancer cells, with low IC₅₀ of 0.48, 0.27, and 0.33 mg/mL for the three cell lines, respectively. On the other hand, the new composite was remarkably safe for human skin fibroblast (HSF) with IC₅₀ of 1.08 mg/mL. Interestingly, the composite membranes exhibited lethal effects against all stages of larval instar and pupal stage compared with the control. In this study, we first report the diverse potential applications of BC/PVA/Ch/CuO-NPs composites based on green synthesized CuO-NPs and sustainably produced BC membrane.

Biochemical characterization and phytotoxic activity of protein extract from Euphorbia tirucalli L

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia tirucalli L., a tropical and subtropical plant, also known by the popular name avelós, has been used in folk medicine against many diseases as rheumatism, asthma, toothache, and cancer. Studies have shown that natural compounds contained in this plant species may be associated with these functions. However, little is known about its potential toxicity.

AIM OF THE STUDY

Several proteins conduct biological functions, in particular, proteinases, play a crucial role in many mechanisms of living beings, including plants, animals and microorganisms. However, when poorly regulated, they can generate consequences, such as the non-production of certain substances, or even the abnormal multiplication of cells, which leads to tumors. On the other hand, by regulating these enzymes, proteinase inhibitors act by reducing the activity of proteinases, thus preventing their malfunction. The objective of this work was to evaluate the toxicity of the protein extract of E. tirucalli and to purify a protease inhibitor that may be associated with the biological medicinal functions of the plant.

MATERIALS AND METHODS

The cytotoxic and mutagenic properties of the protein extract produced from the stem of avelós was investigated using the Ames test. The protein extract was also submitted to a protease inhibitor purification process using the gel filtration chromatography technique and the purified protein was biochemically characterized.

RESULTS

A protease inhibitor, called tirustatin, was isolated 1.84-fold by Biogel P100. The calculated molecular mass of the isolated protein is 25.97 kDa. The inhibitor was stable at pH 3-10, with pronounced activity at pH 6. Thermostability was observed even at elevated temperature (100 °C) with inhibitory activity increased by 1.14-fold compared to inhibitor activity at room temperature. Incubation at basic pH values for up to 60 min caused little reduction (0.25-fold) in the papain inhibitory activity of tirustatin. The stoichiometry of the papain-tirustatin interaction was 1.5: 1 and 28.8 pM of the inhibitor effected 50% inhibition. With an equilibrium dissociation constant of 8.74 x 10-8M for the papain enzyme, it is possible to evaluate the isolated protein as a non-competitive inhibitor. In addition, the protein extract of E. tirucalli even at the maximum concentration used (20 μg/mL), did not show a cytotoxic and mutagenic profile in a bacterial model.

CONCLUSION

The results presented in this work provide data that reinforce the idea of the potential use of proteins produced in E. tirucalli as pharmacological and biotechnological agents that can be exploited for the development of efficient drugs.

Antiparasitic Efficacy of Crude Plant Extracts and Compounds Purified from Plants against the Fish Monogenean Neobenedenia girellae

Neobenedenia girellae is a pathogenic ectoparasite of many marine fishes, and it causes major epidemics in marine aquaculture. In this study, the efficacy of ethanol extracts of huangqi Astragalus membranaceus (known as milkvetch in North America), guanzhong Dryopteris setosa (known as beaded wood fern in North America), gancao Glycyrrhiza uralensis (known as Chinese licorice in North America), danshen Salvia miltiorrhiza (known as red sage in North America), and pomegranate Punica granatum, as well as seven phytochemicals (10-gingerol, curcumin, cynatratoside-C, emodin, kuwanon-G, kuwanon-O, and sophoraflavanone-G), against adult N. girellae was investigated. In vitro results indicated that pomegranate extract killed all adult N. girellae at a 62.5-mg/L concentration with an 8-h exposure, but gancao extract did not cause 100% mortality until a 1,000-mg/L concentration was used. Additionally, all adult N. girellae died after an 8-h exposure to cynatratoside-C, kuwanon-G, kuwanon-O, or sophoraflavanone-G at a concentration of 125 mg/L. Curcumin, emodin, and 10-gingerol at a concentration of 1,000 mg/L did not kill all parasites after an 8-h exposure. These findings demonstrate that plant extracts and active phytochemicals are potential sources of botanical drugs for controlling N. girellae infection in aquaculture.

Change in susceptibility response of Aedes aegypti (Diptera: Culicidae) to organophosphate insecticide and Copaifera oleoresin

The growth of resistance in vector mosquitoes to insecticides, especially the organophosphate Temephos can facilitate the transmission of various disease agents worldwide. Consequently, it arises a challenge to public health agencies, which is the urgency use of other possibilities as botanical insecticides. Such insecticides have specific properties against insects due to the plant's ability to synthesize products derived from its secondary metabolism. The diversity and complexity of active compounds of botanical insecticides can help reduce the selection of resistant individuals and consequently not change susceptibility. To corroborate this hypothesis, the aim of this study was to compare two populations of Aedes aegypti treated with Temephos and Copaifera oleoresin. Thus, Ae. aegypti larvae were exposed from (F₁) up to tenth generation (F₁₀) with sublethal doses (±LC₂₅) of these products (Copaifera oleoresin: 40 mg/L and Temephos: 0.0030 mg/L). The triplicates and control groups were monitored every 48 hours and the surviving larvae were separated until the emergence of the adults. Each new population were then subjected to a series of concentrations (LC₅₀ and LC₉₅) of Temephos and Copaifera oleoresin to calculate the Resistance Ratio (RR) of each exposed generation. The population of Ae. aegypti exposed to Temephos had an increase in RR from 05 (considered low) to 13 (considered high). Those population exposed to Copaifera oleoresin, had no increasing in RR and continued susceptible to the oil in all generations. There was a significant difference in mortality between the generations exposed to the two products. The results presented here show that the change in the susceptibility status of Ae. aegypti population to Temephos was already expected. So, we believe that this work will be of great contribution to research related to mosquito control with plant products, and resistance to chemical insecticides.

Jatropha curcas, a Novel Crop for Developing the Marginal Lands

Jatropha curcas L. has more attention from researchers and policymakers as an inexpensive source for produce biofuel to reduce environmental pollution by fossil fuel in the next decades without competing for lands and freshwater currently used for food production. Jatropha is a perennial deciduous, succulent oilseed shrub, belonging to family Euphorbiaceae. It is native to Central and South America. It is a multipurpose shrub, each part of the plant can be used for various purposes, Jatropha produces flowers throughout the year and enables multiple harvests, while, in arid and semi-arid regions it is harvesting twice time per year.Jatropha is a drought-tolerant plant that could be growing under malnutrition conditions, and in different climatic conditions; therefore, it is proper plant for developing marginal lands and rural areas.Due to the growing demand for biofuel, jatropha cultivation has received more attention to providing seeds. While, there are various aspects of using jatropha include use as a traditional medicine for treating skin ailments, as a hedge for protecting other crops, to reduce soil degradation, combating desertification, and deforestation, also, jatropha cultivation protects the environment through using wastewater in irrigation and reduce sequester carbon dioxide.Conventional propagation of Jatropha propagated by seeds or stem cutting which is a more satisfactory technique to produce high-yielding seedlings, while, tissue culture method used in propagation but on small scale.Jatropha curcas L. contains mixtures of numerous active substances in all parts of the plant, which are used as biopesticides, larvicides, fungicide, and nematicide; also extracts are used as pesticides for whiteflies and termites.Jatropha crude oil is used for industrial purposes like manufacturing candles, soaps, varnishes, and as a lubricant; also press seedcake is used to produce biogas and organic fertilizers. Jatropha propagated by seeds or stem cutting which is more applicable techniques to produce high-yielding seedlings, also, tissue culture method used in propagation but on small scale for scientific work.

Extracts of Euphorbia nivulia Buch.-Ham. showed both phytotoxic and insecticidal capacities against Lemna minor L. and Oxycarenus hyalinipennis Costa

Many phytochemicals can affect the growth and development of plants and insects which can be used as biological control agents. In this study, different concentrations of crude, hexane, chloroform, butanol, and aqueous extracts of Euphorbia nivulia Buch.-Ham., an endemic plant of the Cholistan desert in South Punjab of Pakistan, were analysed for their chemical constituents. Their various concentrations were also tested for their phytotoxic and insecticidal potential against duckweed, Lemna minor L., and the dusky cotton bug, Oxycarenus hyalinipennis Costa. various polyphenols, i.e., quercetin, gallic acid, caffeic acid, syringic acid, coumaric acid, ferulic acid, and cinnamic acid were detected in different concentrations with different solvents during the phytochemical screening of E. nivulia. In the phytotoxicity test, except for 100 μg/mL of the butanol extract gave 4.5% growth regulation, no phytotoxic lethality could be found at 10 and 100 μg/mL of all the extracts. The highest concentration, 1000 μg/mL, of the chloroform, crude, and butanol extracts showed 100, 63.1, and 27.1% of growth inhibition in duckweed, respectively. In the insecticidal bioassay, the highest O. hyalinipennis mortalities (87 and 75%) were recorded at 15% concentration of the chloroform and butanol extracts of E. nivulia. In contrast, the lower concentrations of the E. nivulia extracts caused the lower mortalities. Altogether, these findings revealed that E. nivulia chloroform extracts showed significant phytotoxicity while all the extracts showed insecticidal potential. This potential can be, further, refined to be developed for bio-control agents.

Plant Natural Products for the Control of Aedes aegypti: The Main Vector of Important Arboviruses

The mosquito species Aedes aegypti is one of the main vectors of arboviruses, including dengue, Zika and chikungunya. Considering the deficiency or absence of vaccines to prevent these diseases, vector control remains an important strategy. The use of plant natural product-based insecticides constitutes an alternative to chemical insecticides as they are degraded more easily and are less harmful to the environment, not to mention their lower toxicity to non-target insects. This review details plant species and their secondary metabolites that have demonstrated insecticidal properties (ovicidal, larvicidal, pupicidal, adulticidal, repellent and ovipositional effects) against the mosquito, together with their mechanisms of action. In particular, essential oils and some of their chemical constituents such as terpenoids and phenylpropanoids offer distinct advantages. Thiophenes, amides and alkaloids also possess high larvicidal and adulticidal activities, adding to the wealth of plant natural products with potential in vector control applications.

Effects of the essential oil from Cymbopogon citratus on mortality and morphology of the tick Haemaphysalis longicornis (Acari: Ixodidae)

Haemaphysalis longicornis is one of the most prevalent tick species across eastern Asia, Australia, and New Zealand, and has been implicated as a vector of several pathogenic agents. This study evaluated the in vitro acaricidal efficacy of Cymbopogon citratus (lemongrass) essential oil on unfed H. longicornis using the adult and nymph immersion test, and the larval packet test. Six concentrations with three replications each of 10, 20, 30, 40, 50 and 60 mg/mL (adults and nymphs) were used, and 2.5, 5, 10, 20, 40 and 80 mg/mL (larvae), with control group (50% ethanol). The adult and nymph mortality rates were 98 and 100% at 50 mg/mL, and 95 and 100% at 60 mg/mL, respectively, whereas the larval mortality rate was 94 and 96% at 40 and 80 mg/mL, respectively. Mortality of adult, nymph and larva increased significantly in a dose-dependent manner. The LC₅₀ for adult, nymph, and larva, were 29.21 (95% confidence interval 25.90-32.58), 28.18 (23.78-32.25), and 28.06 (25.57-30.90) mg/mL, respectively. Scanning electron microscopy and light microscopy revealed a disjointed sensilla base from the sockets, cuticular cracks, blocked aeropyles, and shrinking of the midgut. These results showed that C. citratus essential oil could be a good eco-friendly alternative control strategy against ectoparasites like ticks due to its high acaricidal efficacy.

Potential of medicinal plants to treat dengue

Dengue is a major public health challenge worldwide, particularly in tropical areas. Nearly 390 million infections and 22,000 deaths occur every year. At present, there are no specific therapeutics available to treat dengue; however, possible treatment procedures are explained in the traditional medical systems (TMSs), such as Sri Lankan TMS, Indian Ayurvedic, Unani, and Siddha TMS. In these TMSs, medicinal plants have been used in several ways against dengue, such as virocides, larvicides, and mosquito repellents. Therefore, medicinal plants inherit biologically active compounds/lead compounds that are yet to be identified chemically and physiologically. Herein, we discuss the possible applications of crude plant extracts and isolated phytochemicals from medicinal plants such as quercetin, sulfated galactomannans, flavonoids, and glabranine in controlling dengue. Moreover, medicinal plant-based therapeutics can be safer, cost-effective, and non-toxic. Therefore, this paper reviews the medicinal plants that are used in TMSs to manage dengue, the phytochemicals they contain, and mode of action of these phytochemicals such as virocides, larvicides, and mosquito repellents.

Evaluation of bioactivity of aqueous extracts of Bougainvillea spectabilis, Saraca asoca, and Chenopodium album against immature forms of Aedes aegypti

Background

Increasing rate of vector transmission of dengue has led to the exponential rise in the mortality and morbidity scales in the past five years. There are various natural and synthetic chemical agents available commercially as potent larvicides, but they are either highly toxic, difficult to obtain, have a high manufacturing cost, or show cross-resistance, hence do not suffice as ideal larvicides. The objective was to screen aqueous extracts of Bougainvillea spectabilis (B. spectabilis), Saraca asoca (S.asoca), and Chenopodium album (C. album) for larvicidal activity against Aedes aegypti (A. aegypti).

Methods

The larvae were exposed to increasing concentrations of aqueous extracts of B. spectabilis, S. asoca, and C. album under controlled laboratory environment. The mortality was checked after 24 hours, results were statistically analyzed, and LC50 and LC90 were determined.

Results

B. spectabilis and S. asoca were found effective as larvicides against A. aegypti with LC50 values of 0.22% and 0.26%, respectively.

Conclusion

The aqueous extracts of B . spectabilis and S. asoca are efficient larvicides against A . aegypti and can be used as effective, accessible, and eco-friendly control options for management of A. aegypti, the vector of dengue/chikungunya.

Larvicidal and Enzymatic Inhibition Effects of Annona muricata Seed Extract and Main Constituent Annonacin against Aedes aegypti and Aedes albopictus (Diptera: Culicidae)

The mosquitoes Aedes aegypti and Aedes albopictus are vectors of arboviruses that cause dengue, zika and chikungunya. Bioactive compounds from plants are environmentally sustainable alternatives to control these vectors and thus the arboviruses transmitted by them. The present study evaluated the larvicidal activity of an acetogenin-rich fraction (ACERF) and its main constituent annonacin obtained from Annona muricata seeds on Ae. aegypti and Ae. albopictus. The larvicidal assays were performed using different concentrations to calculate the LC50 and LC90 values observed 24 h after exposure to the treatment. Annonacin was more active against Ae. aegypti (LC50 2.65 μg·mL-1) in comparison with Ae. albopictus (LC50 8.34 μg·mL-1). In contrast, the acetogenin-rich fraction was more active against Ae. albopictus (LC50 3.41 μg·mL-1) than Ae. aegypti (LC50 12.41 μg·mL-1). ACERF and annonacin treated larvae of Ae. aegypti and Ae. albopictus showed significant differences in the inhibition of their metabolic enzymes when compared to untreated larvae. The results demonstrate the relevant larvicidal action of the acetogenin-rich fraction and annonacin showing the potential to develop new products for the control of Ae. aegypti and Ae. albopictus.

Plant-based larvicidal agents: An overview from 2000 to 2018

Current review aims to systematically segregate, analyze and arrange the key findings of the scientific reports published on larvicidal plants including larvicidal formulations. The investigation was carried out by analyzing the published literature in various scientific databases, subsequently, the key findings of the selective scientific reports having larvicidal potency (LC₅₀) of extract or isolated oil<100 μg/mL were tabulated to provide the concise and crucial information. Special emphasis was given on reports in which LC₅₀ of extract or isolated oil was reported to be < 10 μg/mL, genus or species documented in multiple independent studies, advancement in larvicidal formulations and activity of isolated phytoconstituents. Extensive analysis of published literature revealed that the larvicidal potency of herbal resources varied from sub-microgram/ml to practically insignificant. Overall, this unprecedented summarized and arranged information can be utilized for design, development and optimization of herbal based formulation having potential larvicidal activity.

A new application of Trichoderma asperellum as an anopheline larvicide for eco friendly management in medical science

Microfungal applications are increasing daily in the medical science. Several species of Trichoderma are widely used in agricultural fields as biological control and plant growth promoting agents. The application of Trichoderma asperellum as an entomopathogenic fungus against the Anopheles mosquito, a vector of malaria, is a novel control approach. Controlling malaria with eco-friendly management practices is an urgent need. We isolated three T. asperellum from different natural sources using serial dilution and mosquito baiting techniques. The fungi were identified on the basis of phenotypical and molecular characteristics. The fungi were grown in different natural media to examine spore production ability and the fungal spore suspensions were applied to the anopheline larvae to determine their larvicidal activity in vitro. We investigated the efficacy of crude ME (methanolic extract) and different methanolic fractions (MFs) of the fungal extracts against anopheline larvae. Methanolic Fraction 8 (MF8) exhibited the strongest larvicidal activity. A GC-MS analysis of MF8 and a Chemolibrary search were performed to identify the active agents in the fungal extracts. Among the three isolates of T. asperellum, the TaspSKGN2 isolate showed the lowest LD50 (2.68 × 107 conidia/mL) and LT50 values (12.33 h). The crude ME exhibited LD50 values of 0.073 mg/mL and LT50 values of 11.33 h. MF8 showed LD50 values of 0.059 mg/mL and LT50 values of 8.57 h. In GC-MS study of MF8, 49 compounds were found. Among these, seven compounds (2,3-di hydro thiopene, p-cymene, alpha-pinene, hexadecanoic acid, 8-methyl quinoline, (Z,Z)-9,12-octa decadienoic acid, methyl ester, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-Pyran-4-one-) with high abundance were found to have insecticidal efficacy by a literature survey. We detected a reduction in the phenoloxidase content inside the cuticle and hemolymph of the anopheline larvae after a few hours of interaction with ME (0.073 mg/mL). Thus Trichoderma asperellum has new applications for the control of Anopheles spp. malaria vectors.

Crystal structure of a novel Kunitz type inhibitor, alocasin with anti-Aedes aegypti activity targeting midgut proteases

BACKGROUND

The pesticidal properties of many Kunitz-type inhibitors have been reported previously; however, the mechanism of action is not well established. In this study, the activity of alocasin against Aedes aegypti is demonstrated and the structure-activity relationship of this Kunitz-type inhibitor is explained through X-ray structure analyses.

RESULTS

Alocasin was purified from mature rhizomes of Alocasia as a single polypeptide chain of ∼ 20 kDa. The structure at 2.5 Å resolution revealed a Kunitz-type fold, but variation in the loop regions makes this structure unique; one loop with a single disulfide bridge is replaced by a long loop with two bridges. Alignment of homologous sequences revealed that this long loop contains a conserved Arg residue and modeling studies showed interaction with the catalytic Ser residue of trypsin-like enzymes. The anti-Aedes aegypti activity of alocasin is examined and discussed in detail. The in vitro activity of alocasin against midgut proteases of Aedes aegypti showed profound inhibition. Further, morphological changes in larvae upon treatment with alocasin revealed its activity against Ae. aegypti. Docking studies of alocasin with trypsin (5G1), a midgut protease involved in the development cycle and blood meal digestion, illustrated its insecticidal activity.

CONCLUSION

The three-dimensional structure of alocasin was determined and its structure-function relationship established for its anti Ae. aegypti activity. © 2018 Society of Chemical Industry.

Toxicity of squamocin on Aedes aegypti larvae, its predators and human cells

BACKGROUND

The mosquito Aedes aegypti transmits a virus that causes diverse human diseases, and control of the vector is an important strategy to avoid disease propagation. Plants in the family Annonaceae are recognised as sources of molecules with uses in the medical and agriculture fields. Molecules of secondary metabolites of Annonaceae plants exhibit insecticidal potential against insect pests and vectors, especially acetogenins, showing high toxicity at low doses, which has encouraged research into producing new insecticide molecules. Herein, we identify an acetogenin from Annona mucosa seeds (chemical analysis) and provide the results of toxicity tests against larvae of A. aegypti (target insect) and its predators Culex bigoti and Toxorhynchites theobaldi (non-target insects) and cytotoxicity to human leukocytes.

RESULTS

We identified squamocin (C₃₇ H₆₆ O₇ ), a fatty acid with a bis-tetrahydrofuran ring. In A. aegypti, this compound caused behavioural disturbance before larval death and high mortality at low concentrations (LC₅₀ = 0.01 µg mL^-1 and LC₉₀ = 0.11 µg mL^-1 ). However, in predators and human leukocytes, squamocin showed no toxicity effect, indicating the selectivity of this molecule for non-target organisms.

CONCLUSION

We identified squamocin from A. mucosa seeds, which exhibited lethal action against A. aegypti and showed selectivity for non-target insects and low cytotoxicity to human cells. © 2016 Society of Chemical Industry.

Antiparasitic efficacy of curcumin from Curcuma longa against Ichthyophthirius multifiliis in grass carp

Ichthyophthirius multifiliis is a ciliated parasite that elicits great economic losses in aquaculture. In the present study, a polyphenol compound, curcumin, was obtained from the rhizome of Curcuma longa by bioassay-guided isolation based on the efficacy of anti-I. multifiliis theronts. Anti-I. multifiliis efficacy of curcumin was evaluated in vitro and in vivo. Curcumin resulted in 100% mortality of I. multifiliis theronts at a concentration of 1mg/L within 21.7±1.2min and killed all tomonts at 8mg/L within 31.0±1.0min. Curcumin at 4mg/L for 16h exposure can completely terminate the reproduction of tomonts. The pretreatment with curcumin at concentrations of 0.5, 0.25, and 0.125mg/L for 2h significantly reduced the infectivity of I. multifiliis theronts. Curcumin at 4mg/L completely cured the infected grass carp and protected naive fish from I. multifiliis infection after 10days exposure. The 4h median effective concentration (EC₅₀) of curcumin to I. multifiliis theronts and the 5h EC₅₀ of curcumin to I. multifiliis tomonts were 0.303mg/L and 2.891mg/L, respectively. The 96h median lethal concentration (LC₅₀) of curcumin to grass carp was 56.8mg/L, which was approximately 187.4 times EC₅₀ of curcumin to theronts and 19.6 times EC₅₀ of curcumin to tomonts. The results demonstrated that curcumin has the potential to be a safe and effective therapeutant for controlling ichthyophthiriasis in aquaculture.

Pterodon emarginatus oleoresin-based nanoemulsion as a promising tool for Culex quinquefasciatus (Diptera: Culicidae) control

BACKGROUND

Preparation of nanoformulations using natural products as bioactive substances is considered very promising for innovative larvicidal agents. On this context, oil in water nanoemulsions develop a main role, since they satisfactorily disperse poor-water soluble substances, such as herbal oils, in aqueous media. Pterodon emarginatus, popularly known as sucupira, has a promising bioactive oleoresin. However, to our knowledge, no previous studies were carried out to evaluate its potential against Culex quinquefasciatus, the main vector of the tropical neglected disease called lymphatic filariasis or elephantiasis. Thus, we aimed to investigate influence of different pairs of surfactants in nanoemulsion formation and investigate if a sucupira oleoresin-based nanoemulsion has promising larvicidal activity against this C. quinquefasciatus. We also evaluated morphological alteration, possible mechanism of insecticidal action and ecotoxicity of the nanoemulsion against a non-target organism.

RESULTS

Among the different pairs of surfactants that were tested, nanoemulsions obtained with polysorbate 80/sorbitan monooleate and polysorbate 80/sorbitan trioleate presented smallest mean droplet size just afterwards preparation, respectively 151.0 ± 2.252 and 160.7 ± 1.493 nm. They presented high negative zeta potential values, low polydispersity index (<0.300) and did not present great alteration in mean droplet size and polydispersity index after 1 day of preparation. Overall, nanoemulsion prepared with polysorbate 80/sorbitan monooleate was considered more stable and was chosen for biological assays. It presented low LC50 value against larvae (34.75; 7.31-51.86 mg/L) after 48 h of treatment and some morphological alteration was observed. The nanoemulsion did not inhibit acetylcholinesterase of C. quinquefasciatus larvae. It was not toxic to green algae Chlorella vulgaris at low concentration (25 mg/L).

CONCLUSIONS

Our results suggest that optimal nanoemulsions may be prepared with different surfactants using a low cost and low energy simple method. Moreover, this prototype proved to be effective against C. quinquefasciatus, being considered an ecofriendly novel nanoproduct that can be useful in integrated control programs of vector control.

S, M. V, S. R. S, P. M, V. R, Valiyaveettil S. Larvicidal, super hydrophobic and antibacterial properties of herbal nanoparticles from Acalypha indica for biomedical applications

Herbal nanoparticles usingAcalypha indicaleaves are investigated and found to possess superior larvicidal, water repellent and antimicrobial properties for biomedical applications.

Larvicidal and ovicidal activity of Terminalia chebula Retz. (Family: Combretaceae) medicinal plant extracts against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus

Insect-borne diseases remain to this day a major source of illness and death worldwide. The resistance to chemical insecticides among mosquito species has been considered as a setback in vector control. Mosquito control programs, botanical origin may have the potential to eliminate eggs and larvae. So, the larvicidal and ovicidal activities of crude benzene, hexane, ethyl acetate, chloroform and methanol extracts of Terminalia chebula were assayed for their toxicity against three important vector mosquitoes, viz., Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in the methanol extract of T. chebula against the larvae of A. stephensi, A. aegypti, and C. quinquefasciatus with the LC₅₀ values were 87.13, 93.24 and 111.98 ppm, respectively. Mean percent hatchability of the ovicidal activity was observed 48 h post treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. All the five solvent extracts showed moderate ovicidal activity; however, the maximum egg mortality (zero hatchability) was observed in the methanol extract of T. chebula at 200 and 250 ppm against A. stephensi, A. aegypti and C. quinquefasciatus showed 100% mortality at 300 ppm. No mortality was recorded in the control. The finding of the present investigation revealed that the leaf extract of Terminalia chebula possesses remarkable larvicidal and ovicidal activity against medically important vector mosquitoes and make this plant product promising as an alternative to synthetic insecticide in mosquito control programs.

Ipomoea batatas (Convolvulaceae)-mediated synthesis of silver nanoparticles for controlling mosquito vectors of Aedes albopictus, Anopheles stephensi, and Culex quinquefasciatus (Diptera:Culicidae)

We proposed an effective and eco-friendly control of dengue, malaria, and filariasis-causing vectors. We tested Ipomoea batatas leaves-mediated silver nanoparticles (AgNPs) against first to fourth instar larvae and adults of Aedes albopictus, Anopheles stephensi, and Culex quinquefasciatus at different concentrations. The synthesized AgNPs showed broad spectrum of larvicidal and adulticidal effects after 48 h of exposure. The characterization of synthesized AgNPs was done using various spectral and microscopy analyses. The maximum efficacy was observed in synthesized AgNPs against the adult of Ae. albopictus with the LC₅₀ and LC₉₀ values were 10.069 and 15.657 μg/mL, respectively, followed by others.

Transcriptome and proteome analyses provide insight into laticifer's defense of Euphorbia tirucalli against pests

The cytoplasm of laticifers, which are plant cells specialized for rubber production and defense against microbes and herbivores, is a latex. Although laticifers share common functions, the protein constituents of latexes are highly variable among plant species and even among organs. In this study, transcriptomic and proteomic analyses of Euphorbia tirucalli's (Euphorbiaceae) latex were conducted to determine the molecular basis of the laticifer's functions in this plant. The hybrid de novo assembly of Illumina mRNA-seq and expressed sequence tags obtained by Sanger's sequencing revealed 26,447 unigenes. A unigene similar to Arabidopsis embryo-specific protein 3 (AT5G62200), which is a PLAT domain-containing protein, and rubber elongation factor showed the highest expression levels. The proteome analysis, studied by liquid chromatography-mass spectrometry with the de novo assembled unigenes as the database, revealed 161 proteins in the latex, 107 of which were not detected in the stem. A gene ontology analysis indicated that the laticifer's proteome was enriched with proteins related to proteolysis, phosphatase, defense against various environmental stresses and lipid metabolisms. D-mannose-binding lectin, ricin (which lacked the N-terminal conserved ribosome-inactivating protein domain), chitinase and peroxidase were highly accumulated, as confirmed by two-dimensional polyacrylamide gel electrophoresis. Thus, the lectins and chitinase may be the major defensive proteins against pests, and the other defense-related proteins and transcripts detected in latex may work in coordination with them. Highly expressing unigenes with unknown functions are candidate novel defense- or rubber production-related genes.

Larvicidal efficacy and chemical constituents of O. gratissimum L. (Lamiaceae) essential oil against Aedes albopictus Skuse (Diptera: Culicidae)

The current study accentuates the use of botanicals as an alternative to the chemical compounds in vector control by estimating the mosquito larvicidal potential of Ocimum gratissimum L. leaf essential oil against the fourth instar larvae of Aedes albopictus Skuse (Diptera: Culicidae). The chemical composition of essential oil from leaves was evaluated using gas chromatography-mass spectrometry (GC/MS) analysis. GC/MS revealed that the essential oil of O. gratissimum contained 51 compounds. The major chemical constituents identified were 3-allyl-6-methoxyphenol (19.30%), 4-(5-ethenyl-1-azabicyclo (2, 2, 2) octan-2) (16.82%), 1-(2, 5-dimethoxyphenyl)-propanol (12.23%) and 1-(1-hydroxybutyl)-2, 5-dimethoxybenzene (5.53%). The essential oil showed pertinent larvicidal effect, and the LC50 value in 24 h was 26.10 ppm (LC90 = 82.83 ppm). Aromatic plants and their essential oils are very important sources of many compounds that are used for different applications, and they are more promising pesticides or insecticides for control of mosquito populations than synthetic ones. The results of the present investigation justify the larvicidal potential of leaf essential oil of O. gratissimum as a safer and more effective larvicide against A. albopictus.

Toxicological and hematological effect of Terminalia arjuna bark extract on a freshwater catfish, Heteropneustes fossilis

Increasing demand for eco-friendly botanical piscicides and pesticides as replacements for harmful synthetic chemicals has led to investigation of new sources of plant materials. Stem bark of Terminalia arjuna, which has been used as a popular folk medicine since ancient time, was examined for its piscicidal activity. This study aims to determine toxicity of ethanol extract of T. arjuna bark on fresh water stinging catfish (Heteropneustes fossilis), along with evaluation of changes in hematological parameters of the fishes exposed to a lethal concentration. The percent mortality of fishes varied significantly in response to concentrations of the extract and exposure times (between exposure time F = 36.57, p < 0.001; between concentrations F = 39.93, p < 0.001). The lethal concentrations (LC50) of ethanol extract were found to be 12.7, 8.94, 5.63 and 4.71 mg/l for 24, 48, 72 and 96 h, respectively. During acute toxicity test, blood samples of treatment fishes showed significant decreases in the red blood cells count, hematocrit content, hemoglobin concentration, mean corpuscular hemoglobin concentration and plasma protein level when compared to those of the control group, while there were significant increases in the mean corpuscular volume, mean corpuscular hemoglobin, white blood cells count and plasma glucose concentration. These results suggest that T. arjuna bark extract could be considered as a potent piscicide due to its toxic effect on fish, particularly fish hematology.

Evaluation of the Larvicidal Efficacy of Five Indigenous Weeds against an Indian Strain of Dengue Vector, Aedes aegypti L. (Diptera: Culicidae)

Background and Objectives. Aedes aegypti, dengue fever mosquito, is primarily associated with the transmission of dengue and chikungunya in tropical and subtropical regions of the world. The present investigations were carried out to assess the larvicidal efficiency of five indigenous weeds against Ae. aegypti. Methods. The 1,000 ppm hexane and ethanol extracts prepared from the leaves and stem of five plants (Achyranthes aspera, Cassia occidentalis, Catharanthus roseus, Lantana camara, and Xanthium strumarium) were screened for their larvicidal activity against early fourth instars of dengue vector. The extracts which could cause 80–100% mortality were further investigated for their efficacy. Results. The preliminary screening established the efficacy of hexane extracts as compared to the ethanol extracts. Further investigations revealed the highest larvicidal potential of A. aspera extracts exhibiting LC₅₀ value of 82.555 ppm and 68.133 ppm, respectively. Further, their leaf extracts showed 5–85.9% higher larvicidal activity and stem extracts exhibited 0.23- to 0.85-fold more efficiency than the other four extracts. Conclusion. The present investigations suggest the possible use of A. aspera as an ideal ecofriendly, larvicidal agent for the control of dengue vector, Ae. aegypti. Future studies are, however, required to explore and identify the bioactive component involved and its mode of action.

Insecticidal activity of Jatropha curcas extracts against housefly, Musca domestica

The hexane and ether extracts of leaves, bark and roots of Jatropha curcas were screened for their toxicity against different developmental stages of housefly. The larvicidal, pupicidal and adulticidal activities were analysed at various concentrations (0.78-7.86 mg/cm(2)) of hexane and ether extracts. The lethal concentration values (LC50) of hexane extract of J. curcas leaves were 3.0 and 0.27 mg/cm(2) for adult and larval stages of housefly, respectively, after 48 h. Similarly, the ether extract of leaf showed the LC50 of 2.20 and 4.53 mg/cm(2) for adult and larval stages of housefly. Least toxicity was observed with hexane root extract of J. curcas with LC50 values of 14.18 and 14.26 mg/cm(2) for adult and larvae of housefly, respectively, after 48 h. The variation in LC50 against housefly pupae was found to be 8.88-13.10 mg/cm(2) at various J. curcas extract concentrations. The GC-MS analysis of J. curcas leaf extract revealed the presence of trans-phytol (60.81 %), squalene (28.58 %), phytol (2.52 %) and nonadecanone (1.06 %) as major components that could be attributed for insecticidal activity of J. curcas extracts.

Ovicidal and repellent activities of botanical extracts against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi (Diptera: Culicidae)

OBJECTIVE

To determine the ovicidal and repellent activities of methanol leaf extract of Ervatamia coronaria (E. coronaria) and Caesalpinia pulcherrima (C. pulcherrima) against Culex quinquefasciatus (Cx. quinquefasciatus), Aedes aegypti (Ae. aegypti) and Anopheles stephensi (An. stephensi).

METHODS

The ovicidal activity was determined against three mosquito species at various concentrations ranging from 50-450 ppm under the laboratory conditions. The hatch rates were assessed 48 h after treatment. The repellent efficacy was determined against three mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm(2) under the laboratory conditions.

RESULTS

The crude extract of E. coronaria exerted zero hatchability (100% mortality) at 250, 200 and 150 ppm for Cx. quinquefasciatus, Ae. aegypti and An. stephensi, respectively. The crude extract of C. pulcherrima exerted zero hatchability (100% mortality) at 375, 300 and 225 ppm for Cx. quinquefasciatus, Ae. aegypti and An. Stephensi, respectively. The methanol extract of E. coronaria found to be more repellenct than C. pulcherrima extract. A higher concentration of 5.0 mg/cm(2) provided 100% protection up to 150, 180 and 210 min against Cx. quinquefasciatus, Ae. aegypti and An. stephensi, respectively. The results clearly showed that repellent activity was dose dependent.

CONCLUSIONS

From the results it can be concluded the crude extracts of E. coronaria and C. pulcherrima are an excellent potential for controlling Cx. quinquefasciatus, Ae. aegypti and An. stephensi mosquitoes.

A protein extract and a cysteine protease inhibitor enriched fraction from Jatropha curcas seed cake have in vitro anti-Toxoplasma gondii activity

Toxoplasma gondii is a parasite of great medical and veterinary importance that has worldwide distribution and causes toxoplasmosis. There are few treatments available for toxoplasmosis and the search for plant extracts and compounds with anti-Toxoplasma activity is of utmost importance for the discovery of new active drugs. The objective of this study was to investigate the action of a protein extract and a protease inhibitor enriched fraction from J. curcas seed cake on developing tachyzoites of T. gondii-infected Vero cells. The protein extract (JcCE) was obtained after solubilization of the J. curcas seed cake with 100 mM sodium borate buffer, pH 10, centrifugation and dialysis of the resulting supernatant with the extracting buffer. JcCE was used for the in vitro assays of anti-Toxoplasma activity at 0.01, 0.1, 0.5, 1.5, 3.0 and 5.0 mg/ml concentration for 24 h. The results showed that JcCE reduced the percentage of infection and the number of intracellular parasites, but had no effect on the morphology of Vero cells up to 3.0 mg/mL. The cysteine protease inhibitor enriched fraction, which was obtained after chromatography of JcCE on Sephadex G-75 and presented a unique protein band following SDS-PAGE, reduced both the number of T. gondii infected cells and intracellular parasites. These results suggest that both JcCE and the cysteine protease inhibitor enriched fraction interfere with the intracellular growth of T. gondii.

Forest biorefinery: Potential of poplar phytochemicals as value-added co-products

The global forestry industry after experiencing a market downturn during the past decade has now aimed its vision towards the integrated biorefinery. New business models and strategies are constantly being explored to re-invent the global wood and pulp/paper industry through sustainable resource exploitation. The goal is to produce diversified, innovative and revenue generating product lines using on-site bioresources (wood and tree residues). The most popular product lines are generally produced from wood fibers (biofuels, pulp/paper, biomaterials, and bio/chemicals). However, the bark and other tree residues like foliage that constitute forest wastes, still remain largely an underexploited resource from which extractives and phytochemicals can be harnessed as by-products (biopharmaceuticals, food additives and nutraceuticals, biopesticides, cosmetics). Commercially, Populus (poplar) tree species including hybrid varieties are cultivated as a fast growing bioenergy crop, but can also be utilized to produce bio-based chemicals. This review identifies and underlines the potential of natural products (phytochemicals) from Populus species that could lead to new business ventures in biorefineries and contribute to the bioeconomy. In brief, this review highlights the importance of by-products/co-products in forest industries, methods that can be employed to extract and purify poplar phytochemicals, the potential pharmaceutical and other uses of >160 phytochemicals identified from poplar species - their chemical structures, properties and bioactivities, the challenges and limitations of utilizing poplar phytochemicals, and potential commercial opportunities. Finally, the overall discussion and conclusion are made considering the recent biotechnological advances in phytochemical research to indicate the areas for future commercial applications from poplar tree species.

Biosynthesis of Silver Nanoparticles Using Plant Extract and its Anti-Plasmodial Property

Metallic nanoparticles have received great attention from chemists, physicists, biologists and engineers who wish to use them for the development of a new generation of nanodevices. In the present Communication, a completely “green” chemistry method for producing silver nanoparticles is introduced. The process is simple, environmentally benign, and quite efficient. Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and ecofriendly reducing and capping agents. In particular, silver nanoparticles are proved to have potential antibacterial, antifungal and antiplasmodial and antimicrobial properties. The present study was aimed to identify the antiplasmodial activity of green synthesised silver nanoparticles (AgNPs) using aqueous extract of plantEuphorbia hirtaagainstP.falciparum. Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant to generate extremely stable silver nanoparticles in water. The bio-reduced silver nanoparticles were appropriately characterized by UV–vis spectrum, Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The formation of the AgNPs synthesized from the XRD spectrum compared with the standard confirmed spectrum of silver particles formed in the present experiments were in the form of nanocrystals, as evidenced by the peaks at 2θ values of =28.01°, 32.41°, 46.44°, 55.05° and 57.75°. The scanning electron micrograph (SEM) showed structures of spherical, cubic shape, and the size range was found to be 30–60 nm. The EDX spectra showed the purity of the material and the complete chemical composition of the synthesized AgNPs. The parasitic inhibition was dose-dependent. The synthesized AgNPs showed considerable antiplasmodial activity than the crude methanol and aqueous leaf extract ofE.hirta. The maximum efficacy was

Properties for sourcing Nigerian larvicidal plants

Aedes aegypti is the primary vector of chikungunya, yellow and dengue fevers. Dengue fever is the major cause of child morbidity and hospitalisation in some Asian and African countries, while yellow fever is prevalent in Nigeria. The development of resistance to the available insecticides has necessitated the continued search for safer ones from plants. Eighteen plant extracts with ethnomedical claims of or demonstrated febrifuge, antimalarial, insecticidal and insect repellent biological activities were tested for activity against the fourth instar larvae of Aedes aegypti. About 61% of the eighteen extracts demonstrated high to moderate larvicidal activity. Extracts of Piper nigrum and Abrus precatorius seeds were the most active and the larvicidal constituent(s) of the latter should be determined.

Effect of mycosynthesized silver nanoparticles from filtrate of Trichoderma harzianum against larvae and pupa of dengue vector Aedes aegypti L

Mosquitoes transmit dreadful diseases, causing millions of deaths every year. Therefore, screening for larvicidal and pupicidal activity of microbial extracts attributes could lead to development of new and improved mosquito control methods that are economical and safe for nontarget organisms and are ecofriendly. Synthetic chemical insecticides occupy predominant position in control strategies. These hazardous chemicals exert unwarranted toxicity and lethal effects on nontarget organisms, develop physiological resistance in target, and cause adverse environmental effect. For vector control, fungal-mediated natural products have been a priority in this area at present. In the current study, effective larvicidal and pupicidal effect of mycosynthesized silver nanoparticles (Ag NPs) using an entomopathogenic fungi Trichoderma harzianum against developmental stages of the dengue vector Aedes aegypti was investigated. An attractive possibility of green nanotechnology is to use microorganisms in the synthesis of nanosilver especially Ag NPs. The mycosynthesized Ag NPs were characterized to find their unique properties through UV-visible spectrophotometer, X-ray diffraction analysis, Fourier transform infrared, and surface characteristics by scanning electron microscopy. To analyze the bioefficacy, different test concentrations for extracellular filtrate (0.2, 0.4, 0.6, 0.8, and 1.0 %) and Ag NPs (0.05, 0.10, 0.15, 0.20, and 0.25 %) were prepared to a final volume of 200 mL using deionized water; 20 larvae of each instars (I-IV) and pupa were exposed to each test concentration separately which included a set of control (distilled water) group with five replicates. Characterization of the synthesized Ag NPs were about 10-20 nm without aggregation. Susceptibility of larval instars to synthesized Ag NPs was higher than the extracellular filtrate of T. harzianum alone after 24-h exposure, where the highest mortality was recorded as 92 and 96 % for first and second instars and 100 % for third, fourth instars, and pupa. Lethal concentration 50 values of 0.079, 0.084, 0.087, 0.068, and 0.026 % were recorded for I-IV instars and pupa, respectively, when exposed to Ag NPs at 0.25 % concentration. Toxicity was exhibited against first (1.076 %), second (0.912 %), third (0.770 %), fourth (0.914 %) instars larvae, and pupa (0.387 %) with extracellular filtrate at a concentration of 1 % that was three- to fourfold higher compared to Ag NPs; no mortality was observed in the control. The present study is the first report on effective larvicidal and pupicidal activity of Ag NPs synthesized from an entomopathogenic fungi T. harzianum extracellular filtrate and could be an ideal ecofriendly, single-step, and inexpensive approach for the control of A. aegypti.

Eutirucallin, a RIP-2 type lectin from the latex of Euphorbia tirucalli L. presents proinflammatory properties

Lectins are carbohydrate-binding proteins that recognize and modulate physiological activities and have been used as a toll for detection and identification of biomolecules, and therapy of diseases. In this study we have isolated a lectin present in the latex of Euphorbia tirucalli, and named it Eutirucallin. The latex protein extract was subjected to ion exchange chromatography and showed two peaks with haemagglutinating activity. Polypeptides of 32 kDa protein extract strongly interacted with immobilized galactose (α-lactose > D-N-acetylgalactosamine). The Eutirucallin was obtained with a yield of 5.6% using the α-lactose column. The lectin domain has 32 kDa subunits and at least two of which are joined by disulfide bridges. The agglutinating capacity for human erythrocytes A(+), B(+) and O(+) is inhibited by D-galactose. The haemagglutinating activity of Eutirucallin was independent of Ca(2+) and maintained until the temperature of 55°C. Eutirucallin presented biological activities such as neutrophils recruitment and cytokine prodution by macrophages. The analysis of the trypsin-digested Eutirucallin by ms/ms in ESI-Q-TOFF resulted in nine peptides similar to type 2 ribosome-inactivating protein (type-2 RIP). It's partial sequence showed a similarity of 67.4 - 83.1% for the lectin domain of type-2 RIP [Ricin and Abrin (83.1%), Viscumin, Ebulin, Pulchellin, Cinnamomin, Volkensin and type-2 RIP Iris hollandica]. Our data suggest that Eutirucallin is a new member of type 2 ribosome-inactivating protein and presents biotechnological potential.