scholarly journals Artemisinin-independent inhibitory activity of Artemisia sp. infusions against different Plasmodium stages including relapse-causing hypnozoites

2021 ◽  
Vol 5 (3) ◽  
pp. e202101237
Author(s):  
Kutub Ashraf ◽  
Shahin Tajeri ◽  
Christophe-Sébastien Arnold ◽  
Nadia Amanzougaghene ◽  
Jean-François Franetich ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Inhibitory Activity ◽  
Parasite Species ◽  
Artemisia Annua ◽  
Combination Therapies ◽  
Lead Compounds ◽  
Low Concentrations ◽  
Inhibitory Activities

Artemisinin-based combination therapies (ACT) are the frontline treatments against malaria worldwide. Recently the use of traditional infusions from Artemisia annua (from which artemisinin is obtained) or Artemisia afra (lacking artemisinin) has been controversially advocated. Such unregulated plant-based remedies are strongly discouraged as they might constitute sub-optimal therapies and promote drug resistance. Here, we conducted the first comparative study of the anti-malarial effects of both plant infusions in vitro against the asexual erythrocytic stages of Plasmodium falciparum and the pre-erythrocytic (i.e., liver) stages of various Plasmodium species. Low concentrations of either infusion accounted for significant inhibitory activities across every parasite species and stage studied. We show that these antiplasmodial effects were essentially artemisinin-independent and were additionally monitored by observations of the parasite apicoplast and mitochondrion. In particular, the infusions significantly incapacitated sporozoites, and for Plasmodium vivax and P. cynomolgi, disrupted the hypnozoites. This provides the first indication that compounds other than 8-aminoquinolines could be effective antimalarials against relapsing parasites. These observations advocate for further screening to uncover urgently needed novel antimalarial lead compounds.

scholarly journals Artemisinin-independent inhibitory activity of Artemisia sp. infusions against different Plasmodium stages including relapse-causing hypnozoites

2021 ◽  
Author(s):  
Kutub Ashraf ◽  
Shahin Tajeri ◽  
Christophe-Sébastien Arnold ◽  
Nadia Amanzougaghene ◽  
Jean-François Franetich ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Inhibitory Activity ◽  
Parasite Species ◽  
Artemisia Annua ◽  
Plasmodium Species ◽  
Combination Therapies ◽  
Lead Compounds ◽  
Low Concentrations ◽  
Inhibitory Activities

Artemisinin-based combination therapies (ACT) are the frontline treatments against malaria worldwide. Recently the use of traditional infusions from Artemisia annua (from which artemisinin is obtained) or A. afra (lacking artemisinin) has been controversially advocated. Such unregulated plant-based remedies are strongly discouraged as they might constitute sub-optimal therapies and promote drug resistance. Here, we conducted the first comparative study of the anti-malarial effects of both plant infusions in vitro against the asexual erythrocytic stages of P. falciparum and the pre-erythrocytic (i. e., liver) stages of various Plasmodium species. Low concentrations of either infusion accounted for significant inhibitory activities across every parasite species and stage studied. We show that these antiplasmodial effects were essentially artemisinin-independent and were additionally monitored by observations of the parasite apicoplast and mitochondrion. In particular, the infusions significantly incapacitated sporozoites, and for P. vivax and P. cynomolgi, disrupted the hypnozoites. This provides the first indication that compounds other than 8- aminoquinolines could be effective antimalarials against relapsing parasites. These observations advocate for further screening to uncover urgently needed novel antimalarial lead compounds.

scholarly journals Assessment of the Drug Susceptibility of Plasmodium falciparum Clinical Isolates from Africa by Using a Plasmodium Lactate Dehydrogenase Immunodetection Assay and an Inhibitory Maximum Effect Model for Precise Measurement of the 50-Percent Inhibitory Concentration

2006 ◽  
Vol 50 (10) ◽  
pp. 3343-3349 ◽  
Author(s):  
Halima Kaddouri ◽  
Serge Nakache ◽  
Sandrine Houzé ◽  
France Mentré ◽  
Jacques Le Bras
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Lactate Dehydrogenase ◽  
Active Metabolite ◽  
Inhibitory Concentration ◽  
Drug Susceptibility ◽  
Maximum Effect ◽  
Malaria Parasites ◽  
Effect Model

ABSTRACT The extension of drug resistance among malaria-causing Plasmodium falciparum parasites in Africa necessitates implementation of new combined therapeutic strategies. Drug susceptibility phenotyping requires precise measurements. Until recently, schizont maturation and isotopic in vitro assays were the only methods available, but their use was limited by technical constraints. This explains the revived interest in the development of replacement methods, such as the Plasmodium lactate dehydrogenase (pLDH) immunodetection assay. We evaluated a commercially controlled pLDH enzyme-linked immunosorbent assay (ELISA; the ELISA-Malaria antigen test; DiaMed AG, Cressier s/Morat, Switzerland) to assess drug susceptibility in a standard in vitro assay using fairly basic laboratory equipment to study the in vitro resistance of malaria parasites to major antimalarials. Five Plasmodium falciparum clones and 121 clinical African isolates collected during 2003 and 2004 were studied by the pLDH ELISA and the [8-3H]hypoxanthine isotopic assay as a reference with four antimalarials. Nonlinear regression with a maximum effect model was used to estimate the 50% inhibitory concentration (IC50) and its confidence intervals. The two methods were observed to have similar reproducibilities, but the pLDH ELISA demonstrated a higher sensitivity. The high correlation (r = 0.98) and the high phenotypic agreement (κ = 0.88) between the two methods allowed comparison by determination of the IC50s. Recently collected Plasmodium falciparum African isolates were tested by pLDH ELISA and showed drug resistance or decreased susceptibilities of 62% to chloroquine and 11.5% to the active metabolite of amodiaquine. No decreased susceptibility to lumefantrine or the active metabolite of artemisinin was detected. The availability of this simple and highly sensitive pLDH immunodetection assay will provide an easier method for drug susceptibility testing of malaria parasites.

scholarly journals Plasmodium falciparum Line-Dependent Association ofIn VitroGrowth-Inhibitory Activity and Risk of Malaria

2012 ◽  
Vol 80 (5) ◽  
pp. 1900-1908 ◽  
Author(s):  
Josea Rono ◽  
Anna Färnert ◽  
Daniel Olsson ◽  
Faith Osier ◽  
Ingegerd Rooth ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Inhibitory Activity ◽  
Content Type ◽  
Phenotypic Differences ◽  
Erythrocyte Invasion ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Control Study

ABSTRACTPlasmodium falciparum's ability to invade erythrocytes is essential for its survival within the human host. Immune mechanisms that impair this ability are therefore expected to contribute to immunity against the parasite. Plasma of humans who are naturally exposed to malaria has been shown to have growth-inhibitory activity (GIA)in vitro. However, the importance of GIA in relation to protection from malaria has been unclear. In a case-control study nested within a longitudinally followed population in Tanzania, plasma samples collected at baseline from 171 individuals (55 cases and 116 age-matched controls) were assayed for GIA using threeP. falciparumlines (3D7, K1, and W2mef) chosen based on their erythrocyte invasion phenotypes. Distribution of GIA differed between the lines, with most samples inhibiting the growth of 3D7 and K1 and enhancing the growth of W2mef. GIA to 3D7 was associated with a reduced risk of malaria within 40 weeks of follow-up (odds ratio, 0.45; 95% confidence interval [CI], 0.21 to 0.96;P= 0.04), whereas GIA to K1 and W2mef was not. These results show that GIA, as well as its association with protection from malaria, is dependent on theP. falciparumline and can be explained by differences in erythrocyte invasion phenotypes between parasite lines. Our study contributes knowledge on the biological importance of growth inhibition and the potential influence ofP. falciparumerythrocyte invasion phenotypic differences on its relationship to protective immunity against malaria.

scholarly journals Piperaquine resistant Cambodian Plasmodium falciparum clinical isolates: in vitro genotypic and phenotypic characterization

2020 ◽  
Author(s):  
Nonlawat Boonyalai ◽  
Brian A Vesely ◽  
Chatchadaporn Thamnurak ◽  
Chantida Praditpol ◽  
Watcharintorn Fagnark ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Copy Number ◽  
Drug Susceptibility ◽  
Antagonistic Activity ◽  
Drug Combinations ◽  
Chloroquine Resistance ◽  
Phenotypic Characterization ◽  
Field Isolates

Abstract Background High rates of dihydroartemisinin-piperaquine (DHA-PPQ) treatment failures have been documented for uncomplicated Plasmodium falciparum in Cambodia. The genetic markers plasmepsin 2 ( pfpm2 ), exonuclease ( pfexo ) and chloroquine resistance transporter ( pfcrt ) genes are associated with PPQ resistance and are used for monitoring the prevalence of drug resistance and guiding malaria drug treatment policy.Methods To examine the relative contribution of each marker to PPQ resistance, in vitro culture and the PPQ survival assay were performed on seventeen P. falciparum isolates from northern Cambodia, and the presence of E415G-Exo and pfcrt mutations (T93S, H97Y, F145I, I218F, M343L, C350R, and G353V) as well as pfpm2 copy number polymorphisms were determined. Parasites were then cloned by limiting dilution and the cloned parasites were tested for drug susceptibility. Isobolographic analysis of several drug combinations for standard clones and newly cloned P. falciparum Cambodian isolates was also determined.Results The characterization of culture-adapted isolates revealed that the presence of novel pfcrt mutations (T93S, H97Y, F145I, and I218F) with E415G-Exo mutation can confer PPQ-resistance, in the absence of pfpm2 amplification. In vitro testing of PPQ resistant parasites demonstrated a bimodal dose-response, the existence of a swollen digestive vacuole phenotype, and an increased susceptibility to quinine, chloroquine, mefloquine and lumefantrine. To further characterize drug sensitivity, parental parasites were cloned in which a clonal line, 14-B5, was identified as sensitive to artemisinin and piperaquine, but resistant to chloroquine. Assessment of the clone against a panel of drug combinations revealed antagonistic activity for six different drug combinations. However, mefloquine-proguanil and atovoquone-proguanil combinations revealed synergistic antimalarial activity.Conclusions Surveillance for PPQ resistance in regions relying on DHA-PPQ as the first-line treatment is dependent on the monitoring of molecular markers of drug resistance. P. falciparum harbouring novel pfcrt mutations with E415G-exo mutations displayed PPQ resistant phenotype. The presence of pfpm2 amplification was not required to render parasites PPQ resistant suggesting that the increase in pfpm2 copy number alone is not the sole modulator of PPQ resistance. Genetic background of circulating field isolates appear to play a role in drug susceptibility and biological responses induced by drug combinations. The use of latest field isolates may be necessary for assessment of relevant drug combinations against P. falciparum strains and when down-selecting novel drug candidates.

scholarly journals Molecular Surveillance of Drug Resistance of Plasmodium falciparum Isolates Imported from Angola in Henan Province, China

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Ruimin Zhou ◽  
Chengyun Yang ◽  
Suhua Li ◽  
Yuling Zhao ◽  
Ying Liu ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Antimalarial Drug ◽  
Henan Province ◽  
Nucleotide Polymorphisms ◽  
Combination Therapies ◽  
Antimalarial Drug Resistance ◽  
Single Nucleotide ◽  
Molecular Surveillance ◽  
Content Type

ABSTRACT Angola was the main origin country for the imported malaria in Henan Province, China. Antimalarial drug resistance has posed a threat to the control and elimination of malaria. Several molecular markers were confirmed to be associated with the antimalarial drug resistance, such as pfcrt, pfmdr1, pfdhfr, pfdhps, and K13. This study evaluated the drug resistance of the 180 imported Plasmodium falciparum isolates from Angola via nested PCR using Sanger sequencing. The prevalences of pfcrt C72V73M74N75K76, pfmdr1 N86Y184S1034N1042D1246, pfdhfr A16N51C59S108D139I164, and pfdhps S436A437A476K540A581 were 69.4%, 59.9%, 1.3% and 6.3%, respectively. Three nonsynonymous (A578S, M579I, and Q613E) and one synonymous (R471R) mutation of K13 were found, the prevalences of which were 2.5% and 1.3%, respectively. The single nucleotide polymorphisms (SNPs) in pfcrt, pfmdr1, pfdhfr, and pfdhps were generally shown as multiple mutations. The mutant prevalence of pfcrt reduced gradually, but pfdhfr and pfdhps still showed high mutant prevalence, while pfmdr1 was relatively low. The mutation of the K13 gene was rare. Molecular surveillance of artemisinin (ART) resistance will be used as a tool to evaluate the real-time efficacy of the artemisinin-based combination therapies (ACTs) and the ART resistance situation.

scholarly journals Evaluation of in vitro Anti-hyperglycemic Effect of Green Crab Hydrolysates Derived by Commercially Available Enzymes (P06-105-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Bouhee Kang ◽  
Angela Myracle ◽  
Denise Skonberg
Keyword(s):  
Inhibitory Activity ◽  
Unsaturated Fatty Acids ◽  
Carcinus Maenas ◽  
Primary Objective ◽  
Green Crab ◽  
Degree Of Hydrolysis ◽  
National Science Foundation Grant ◽  
Freeze Dried ◽  
Inhibitory Activities

Abstract Objectives Invasive green crabs (Carcinus maenas) have become well established in the U.S. over the past 100 years. Despite containing nutritionally important proteins, unsaturated fatty acids, and minerals, green crabs are not consumed due to their small size. A variety of peptides derived from muscle foods are known to have health benefits, and we hypothesized that high quality green crab proteins and their derivatives might have potential as carbohydrase inhibitors. Therefore, the primary objective of this study was to obtain anti-hyperglycemic peptides via enzymatic hydrolysis to develop commercial value of this unutilized crustacean. Methods Mechanically separated crab meat was homogenized with water (1:1), then hydrolyzed with 1% of Alcalase (AL, pH 8), Protamex (PR, pH 7), Flavourzyme (FL, pH 7), or Papain (PA, pH 6) for 60 min. Enzymes were thermally inactivated and then the hydrolysates were centrifuged to obtain the supernatant, then freeze-dried. Samples were processed in triplicate and then evaluated for degree of hydrolysis (DH) and α-glucosidase and α-amylase inhibitory activities. Significant (p < 0.05) differences in DH and carbohydrase inhibitory activities among treatments were determined by one-way ANOVA. Results Crab mince treated with AL exhibited the highest DH (18.3%), followed by PR (17.1%), FL (16.5%), and PA (15.8%). The PR treatment showed the highest α-glucosidase inhibitory activity (IC50 3.6 mg/mL) compared to other enzyme treatments (IC50 19.3–46.3 mg/mL) and the Control (IC50 22.3 mg/mL). The α-amylase inhibitory activity of PR (IC50 24.4 mg/mL) was lower than its α-glucosidase inhibitory activity. FL showed the highest α-amylase inhibitory activity (IC50 23.5 mg/mL) followed by PR, PA (IC50 34.8 mg/mL), AL (IC50 35.4 mg/mL), and Control (IC50 36.5 mg/mL) samples. Conclusions Our findings indicate that Protamex treatment has potential to derive carbohydrase inhibitory peptides from green crab and these peptides could be utilized as a health promoting ingredient in food products. In order to investigate changes in bioactivity due to human digestion, the hydrolysates will be utilized in a simulated digestion model and their bioactivity will be further evaluated. Funding Sources This study is supported by a National Science Foundation grant to Maine EPSCoR at the University of Maine.

Acetylcholinesterase inhibitory activity and neuroprotection in vitro, molecular docking, and improved learning and memory functions of demethylcurcumin in scopolamine-induced amnesia ICR mice

2020 ◽  
Vol 11 (3) ◽  
pp. 2328-2338 ◽  
Author(s):  
Yuh-Hwa Liu ◽  
Chia-Jung Lee ◽  
Liang-Chieh Chen ◽  
Tai-Lin Lee ◽  
Ying-Ying Hsieh ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Learning And Memory ◽  
Inhibitory Activity ◽  
Proof Of Concept ◽  
Memory Functions ◽  
Icr Mice ◽  
Inhibitory Activities ◽  
Improved Learning ◽  
Concept Validation

Demethylcurcumin (DC) interventions improved learning and memory functions in scopolamine-induced amnesia ICR mice, providing the proof-of-concept validation of AChE inhibitory activities in vitro and molecular docking with AChE in silico.

scholarly journals Inhibitory Activities of Polyphenolic Extracts of Bangladeshi Vegetables against α-Amylase, α-Glucosidase, Pancreatic Lipase, Renin, and Angiotensin-Converting Enzyme

Foods ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 844
Author(s):  
Razia Sultana ◽  
Adeola M. Alashi ◽  
Khaleda Islam ◽  
Md Saifullah ◽  
C. Emdad Haque ◽  
...  
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Pancreatic Lipase ◽  
Lipase Activity ◽  
Inhibitory Activity ◽  
The Other ◽  
Converting Enzyme ◽  
Inhibitory Activities ◽  
Ash Gourd ◽  
Better Than

The aim of the study was to determine the in vitro enzyme inhibition activities of aqueous polyphenolic extracts of nine popular Bangladeshi vegetables, namely ash gourd, bitter gourd, brinjal, Indian spinach, kangkong, okra, ridge gourd, snake gourd, and stem amaranth. Polyphenolic glycosides were the major compounds present in the extracts. Inhibition of α-amylase (up to 100% at 1 mg/mL) was stronger than α-glucosidase inhibition (up to 70.78% at 10 mg/mL). The Indian spinach extract was the strongest inhibitor of pancreatic lipase activity (IC50 = 276.77 µg/mL), which was significantly better than that of orlistat (381.16 µg/mL), a drug. Ash gourd (76.51%), brinjal (72.48%), and snake gourd (66.82%) extracts were the most effective inhibitors of angiotensin-converting enzyme (ACE), an enzyme whose excessive activities have been associated with hypertension. Brinjal also had a significantly higher renin-inhibitory activity than the other vegetable extracts. We conclude that the vegetable extracts may have the ability to reduce enzyme activities that have been associated with hyperglycemia, hyperlipidemia, and hypertension.

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