NPC1161B, an 8-aminoquinoline analog, is metabolized in the mosquito and inhibits Plasmodium falciparum oocyst maturation

© 2019 by the authors. The goal of this study was to investigate the potential for a cannabidiol-rich cannabis extract (CRCE) to interact with the most common over-the-counter drug and the major known cause of drug-induced liver injury–acetaminophen (APAP)–in aged female CD-1 mice. Gavaging mice with 116 mg/kg of cannabidiol (CBD) [mouse equivalent dose (MED) of 10 mg/kg of CBD] in CRCE delivered with sesame oil for three consecutive days followed by intraperitoneally (i.p.) acetaminophen (APAP) administration (400 mg/kg) on day 4 resulted in overt toxicity with 37.5% mortality. No mortality was observed in mice treated with 290 mg/kg of CBD+APAP (MED of 25 mg/kg of CBD) or APAP alone. Following CRCE/APAP co-administration, microscopic examination revealed a sinusoidal obstruction syndrome-like liver injury–the severity of which correlated with the degree of alterations in physiological and clinical biochemistry end points. Mechanistically, glutathione depletion and oxidative stress were observed between the APAP-only and co-administration groups, but co-administration resulted in much greater activation of c-Jun N-terminal kinase (JNK). Strikingly, these effects were not observed in mice gavaged with 290 mg/kg CBD in CRCE followed by APAP administration. These findings highlight the potential for CBD/drug interactions, and reveal an interesting paradoxical effect of CBD/APAP-induced hepatotoxicity

Behavioural response of the malaria vector <it>Anopheles gambiae</it> to host plant volatiles and synthetic blends

Abstract Background Sugar feeding is critical for survival of malaria vectors and, although discriminative plant feeding previously has been shown to occur in Anopheles gambiae s.s., little is known about the cues mediating attraction to these plants. In this study, we investigated the role of olfaction in An. gambiae discriminative feeding behaviour. Methods Dual choice olfactometer assays were used to study odour discrimination by An. gambiae to three suspected host plants: Parthenium hysterophorus (Asteraceae), Bidens pilosa (Asteraceae) and Ricinus communis (Euphorbiaceae). Sugar content of the three plant species was determined by analysis of their trimethylsilyl derivatives by coupled gas chromatography–mass spectrometry (GC-MS) and confirmed with authentic standards. Volatiles from intact plants of the three species were collected on Super Q and analyzed by coupled GC-electroantennographic detection (GC-EAD) and GC-MS to identify electrophysiologically-active components whose identities were also confirmed with authentic standards. Active compounds and blends were formulated using dose–response olfactory bioassays. Responses of females were converted into preference indices and analyzed by chi-square tests. The amounts of common behaviourally-active components released by the three host plants were compared with one-way ANOVA. Results Overall, the sugar contents were similar in the two Asteraceae plants, P. hysterophorus and B. pilosa, but richer in R. communis. Odours released by P. hysterophorus were the most attractive, with those from B. pilosa being the least attractive to females in the olfactometer assays. Six EAD-active components identified were consistently detected by the antennae of adult females. The amounts of common antennally-active components released varied with the host plant, with the highest amounts released by P. hysterophorus. In dose–response assays, single compounds and blends of these components were attractive to females but to varying levels, with one of the blends recording a significantly attractive response from females when compared to volatiles released by either the most preferred plant, P. hysterophorus (χ2 = 5.23, df = 1, P P. hysterophorus. Conclusions Our results demonstrate that (a) a specific group of plant odours attract female An. gambiae (b) females use both qualitative and quantitative differences in volatile composition to associate and discriminate between different host plants, and (c) altering concentrations of individual EAD-active components in a blend provides a practical direction for developing effective plant-based lures for malaria vector management.</p

Host plant forensics and olfactory-based detection in Afro-tropical mosquito disease vectors

<div><p>The global spread of vector-borne diseases remains a worrying public health threat, raising the need for development of new combat strategies for vector control. Knowledge of vector ecology can be exploited in this regard, including plant feeding; a critical resource that mosquitoes of both sexes rely on for survival and other metabolic processes. However, the identity of plant species mosquitoes feed on in nature remains largely unknown. By testing the hypothesis about selectivity in plant feeding, we employed a DNA-based approach targeting trnH-psbA and matK genes and identified host plants of field-collected Afro-tropical mosquito vectors of dengue, Rift Valley fever and malaria being among the most important mosquito-borne diseases in East Africa. These included three plant species for <i>Aedes aegypti</i> (dengue), two for both <i>Aedes mcintoshi</i> and <i>Aedes ochraceus</i> (Rift Valley fever) and five for <i>Anopheles gambiae</i> (malaria). Since plant feeding is mediated by olfactory cues, we further sought to identify specific odor signatures that may modulate host plant location. Using coupled gas chromatography (GC)-electroantennographic detection, GC/mass spectrometry and electroantennogram analyses, we identified a total of 21 antennally-active components variably detected by <i>Ae</i>. <i>aegypti</i>, <i>Ae</i>. <i>mcintoshi</i> and <i>An</i>. <i>gambiae</i> from their respective host plants. Whereas <i>Ae</i>. <i>aegypti</i> predominantly detected benzenoids, <i>Ae</i>. <i>mcintoshi</i> detected mainly aldehydes while <i>An</i>. <i>gambiae</i> detected sesquiterpenes and alkenes. Interestingly, the monoterpenes β-myrcene and (<i>E</i>)-β-ocimene were consistently detected by all the mosquito species and present in all the identified host plants, suggesting that they may serve as signature cues in plant location. This study highlights the utility of molecular approaches in identifying specific vector-plant associations, which can be exploited in maximizing control strategies such as such as attractive toxic sugar bait and odor-bait technology.</p></div

Variable chemical profiles of plant species used by different mosquito species as host plants.

<p>A) Representative profiles of headspace volatile organic compounds (VOCs) of different plant species as measured by coupled gas chromatography/mass spectrometry. The identities of the compounds labeled 1–73 representing VOCs from the five plant species, their retention times and Kovats indices are listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006185#pntd.0006185.s001" target="_blank">S1 Table</a> (additional information). B) Three-dimensional graphical representation of PCA which resolves the volatile profiles of the five plant species into three distinct clusters. PCA1 = 38%, PCA2 = 32% and PCA3 = 22%. C) Mean amounts of VOCs from the five plant species. Bars capped with different letters are significantly different. Circles and asterisk above the box plots represent outliers. Quantitative differences in the VOCs content of the five plants were detected using Univariate analysis of variance and Tukey HSD.</p

Heat map showing varying intensities of antennal responses to synthetic standards of identified compounds in three mosquito species.

<p>The heat maps are based on doses (4ng/μl) of each compound eliciting the highest antennal responses in the respective mosquito species. Green represent higher responses while red indicate lower responses. White asterisks denote significant differences between two mosquito species. Differences in antennal responses were detected using ANOVA and the means separated with Tukey post hoc test.</p

Variable success rates of two gene targets in amplifying and sequencing plant DNA in the crop of different mosquito species.

<p>Variable success rates of two gene targets in amplifying and sequencing plant DNA in the crop of different mosquito species.</p

Electroantennographic detection responses of three Afro-tropical mosquito species to different doses of commonly detected plant volatile organic compounds.

<p>Variability in EAG responses were corrected by subtracting the responses to blanks (5 μl dichloromethane and bioassay filter paper) from each sample and the antennal response values normalized to a standard stimulus set at 100% (2 ng/μl 1-octen-3-ol). Bars capped with different letters are significantly different between the three doses. The differences in dose response were detected using ANOVA followed by Tukey post hoc test.</p

NJ phylogenetic trees from two gene targets showing plant species identified as natural host plants of the Afro-tropical mosquito species.

<p>A) Plant species identified using trnH-psbA gene targets as host plants for <i>Aedes aegypti</i>, <i>Aedes mcintoshi</i>, <i>Aedes ochraceus</i> and <i>Anopheles gambiae</i>. B) Plant species identified using matK gene targets as host plants for <i>Anopheles gambiae</i>. Plant species names with prefix Aa from <i>Aedes aegypti</i>, Am from <i>Aedes mcintoshi</i>, Ao from <i>Aedes ochraceus</i> and Ag represent those that were identified from <i>Anopheles gambiae</i>, the numbers being sample ID. Plant species with prefix P1-4 represent the plant samples sequences to confirm the identity of the mosquito host plants while those with suffixes are outgroups from GenBank with extension being accession numbers.</p

Forward and reverse primer sequences for three gene targets used to identify natural host plants of dengue, Rift Valley fever and malaria mosquito disease vectors.

<p>Forward and reverse primer sequences for three gene targets used to identify natural host plants of dengue, Rift Valley fever and malaria mosquito disease vectors.</p

The Invasive American Weed Parthenium hysterophorus Can Negatively Impact Malaria Control in Africa.

The direct negative effects of invasive plant species on agriculture and biodiversity are well known, but their indirect effects on human health, and particularly their interactions with disease-transmitting vectors, remains poorly explored. This study sought to investigate the impact of the invasive Neotropical weed Parthenium hysterophorus and its toxins on the survival and energy reserves of the malaria vector Anopheles gambiae. In this study, we compared the fitness of An. gambiae fed on three differentially attractive mosquito host plants and their major toxins; the highly aggressive invasive Neotropical weed Parthenium hysterophorus (Asteraceae) in East Africa and two other adapted weeds, Ricinus communis (Euphorbiaceae) and Bidens pilosa (Asteraceae). Our results showed that female An. gambiae fitness varied with host plants as females survived better and accumulated substantial energy reserves when fed on P. hysterophorus and R. communis compared to B. pilosa. Females tolerated parthenin and 1-phenylhepta-1, 3, 5-triyne, the toxins produced by P. hysterophorus and B. pilosa, respectively, but not ricinine produced by R. communis. Given that invasive plants like P. hysterophorus can suppress or even replace less competitive species that might be less suitable host-plants for arthropod disease vectors, the spread of invasive plants could lead to higher disease transmission. Parthenium hysterophorus represents a possible indirect effect of invasive plants on human health, which underpins the need to include an additional health dimension in risk-analysis modelling for invasive plants