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Background: Plants belonging to the genus Viola and family Violaceae are well known in Ayurvedic and Unani medicine for their pharmaceutical importance. Viola, commonly known as Banafsha, has been traditionally used as an anti-malarial. The goal of this study was to determine the anti-Plasmodial activity of the cyclotide-rich crude methanol/water extract of leaves from Viola canescens Wall and to analyze its constituents by mass spectrometry (MS). Materials and Methods: Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) involving quadrupole time-of-flight (Q-ToF) and matrix-assisted laser desorption/ionization (MALDI)-time-of-flight-mass spectrometry (ToF-MS) were applied to investigate the cyclotides rich in methanol/water extract. The intact molecular masses were observed in the range of 2,800–3,400 Daltons, suggesting the presence of peptides. Since various head-to-tail cyclized and intramolecularly disulfide-bonded peptides known as cyclotides have been identified in the Violaceae family, we wanted to verify whether cyclotides are present in our extract. So, the intact masses inferred from the observed spectra were interrogated with Cybase ( www.cybase.org.au ), which is a database on plant cyclotides. Results: We observed promising anti-Plasmodial activity (IC50 44 µg/ml) in the cyclotide-rich methanol/water extract prepared from the leaves of the Himalayan V. canescens Wall. The output obtained from Cybase confirmed the presence of about 20 different cyclotides in our extracts. However, no sequence information could be obtained from Cybase for 14 intact molecular masses, which were inferred from the observed LC-ESI-MS data. Hence, these could correspond to novel peptide/cyclotide sequences, which might be characteristic of Himalayan V. canescens. Conclusion: This is the first report on the anti-Plasmodial activity of the cyclotide-enriched methanol/water crude extract of the leaves of V. canescens.

The antibodies targeting invasive proteins of Plasmodium falciparum (Pf) merozoites is a clever strategy against malaria parasite. The recent finding that Plasmodium merozoites surface enolase is a target for growth neutralizing antibodies has generated interest in identifying its re-ceptor (s) on erythrocytes. In the present study, several biochemical experiments were undertaken involving recombinant Pf enolase and antibody against it to search for its cognate receptor. The binding of rPfeno to erythrocytes was selectively sensitive to trypsin but resistant to neuramini-dase. Failure of yeast enolase binding to human red blood cells under similar conditions indicat-ed high specificity of parasite Pfeno. The mass spectrometric and immunological analyses of pro-teins obtained in pull downs and co-immunoprecipitation samples led to identification of band 3 as an interactor/receptor for Plasmodium enolase. Structural characterization of sequences of band 3 - rPfeno interacting regions revealed C-terminal exocytic regions of band 3 to be binding to Pfeno. Similarly, band 3 binding regions of rPfeno were also identified. Identification of receptor-ligand (band 3: Pfeno) pair paves the way for antimalarial anti-Pf enolase-based vaccine, anti-Pf enolase antibodies as drug and also for developing novel small molecule-based invasion inhibi-tory therapeutics including peptidomimetics that could disrupt the band 3: Pfeno protein-protein interactions.

A series of 22 different 3,5-diarylidenetetrahydro-2H-pyran-4(3H)-ones (DATPs) were synthesized, characterized, and screened for their in vitro antiplasmodial activities against chloroquine (CQ)-sensitive Pf3D7, CQ-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains of Plasmodium falciparum. DATP 19 (3,5-bis(4-hydroxy-3,5-dimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) was found to be the most potent (IC

Twenty-five (Ia-Iu, IIa-IIb, IIIa, and IVa) diarylidene-N-methyl-4-piperidones (DANMPs) were synthesized and characterized via UV, FT-IR, NMR and MS while Id was characterized also by single-crystal XRD. Twenty-one compounds were shortlisted after initial in vitro anti-plasmodial activity screening at 100 µM and 10 µM, were evaluated for their IC50s against chloroquine-sensitive Pf3D7, chloroquine-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains. The four most promising compounds were Ie (IC50s µM 0.35MRA, 1.39INDO, 1.923D7), If (IC50s µM 1.07MRA, 1.36INDO, 3.393D7), Ir (IC50s µM 0.74MRA, 2.45INDO, 1.443D7), and In (IC50s µM 1.27MRA, 1.8INDO, 1.73D7). Resistance indices as low as 0.2 to 0.5 for these potent compounds and

Having faced increased clinical treatment failures with dihydroartemisinin-piperaquine (DHA-PPQ), Cambodia swapped the first line artemisinin-based combination therapy (ACT) from DHA-PPQ to artesunate-mefloquine given that parasites resistant to piperaquine are susceptible to mefloquine. However, triple mutants have now emerged, suggesting that drug rotations may not be adequate to keep resistance at bay. There is, therefore, an urgent need for alternative treatment strategies to tackle resistance and prevent its spread. A proper understanding of all contributors to artemisinin resistance may help us identify novel strategies to keep artemisinins effective until new drugs become available for their replacement. This review highlights the role of the key players in artemisinin resistance, the current strategies to deal with it and suggests ways of protecting future antimalarial drugs from bowing to resistance as their predecessors did., Graphical abstract Image 1, Highlights • Molecular Mechanisms of Artemisinin action and Resistance. • Current Strategies for Combating ACT failures. • Profiles of the Antimalarial Drugs in Development. • Lessons learnt from ACT failures as guide for the development of future antimalarial drugs. • The ideal antimalarial Single Exposure Radical Cure and Prophylaxis (SERCaP).

We herein report unsymmetrical coupling of 2-methylquinolines under the blue LED light conditions using iridium-based photocatalyst. This methodology represents the direct synthetic method for the ...

C. pareira L. is a centuries-old traditional medicinal plant utilized to treat various diseases like asthma, diarrhea, fever, heart disorders, snakebite, vomiting, malaria, pneumonia, dog bite, inflammation and abdominal pain. Globally, based on traditional knowledge, different parts of this plant are being used individually or in combination in various forms to manage malaria. However, the scientific investigation for validating the most effective part of this plant against malaria parasite has not been done. Therefore, current study aimed to evaluate in vitro antiplasmodial activity of extracts/fractions (whole plant) and decoctions from different parts (roots, stem, leaves and whole plant) of C. pareira against different strains of Plasmodium falciparum followed by antiplasmodial activity guided isolation and quantification of isoquinoline alkaloids in extracts/fractions and decoctions. All extracts/fractions/decoctions and molecules isolated from active fractions were investigated for antiplasmodial activity. Results showed that the chloroform fraction of whole plant was the most promising with IC50 (µg/mL) of 0.79 (Pf3D7) and 2.26 (PfINDO) followed by root decoction having IC50 (µg/mL) 10.22 (Pf3D7) and 7.7 (PfINDO). Among three isolated molecules, two bisbenzylisoquinoline alkaloids namely curine (2) [IC50 (µM) 1.46 (Pf3D7) and 0.51 (PfINDO)], and O,O-dimethylcurine (1) [IC50 (µM) 0.92 (Pf3D7) and 2.6 (PfINDO)], were found to be the most potent against P. falciparum strains. The antiplasmodial activity of chloroform fraction was further validated by the developed UPLC-DAD method, which showed the highest quantities of curine (2) (~107 mg/g) and O,O-dimethylcurine (1) (~15 mg/g) in this fraction. This study showed that the root decoction was more effective than decoctions of each of the other parts of the plant and whole plant hydroalcoholic extract. Further, for the first time, this study validates the traditional use of C. pareira whole plant to manage malaria, providing further opportunity to explore the tremendous structural and chemical diversity of isoquinoline alkaloids for antimalarial drug development.

Malaria continues to be a killer disease even in the modern world. Indeed, vaccines and drugs have a lot to learn from the malaria parasite before they can be successful. Here, using a filter for glideosomal anchor protein PfGAP50, we have explored a plethora of small molecules to shortlist eight GAP50 binders with promising antiplasmodial activity (IC50 < 3 µM) that are also highly selective. Of these, Hayatinine, Curine, MMV689758 (Bedaquiline), MMV1634402 (Brilacidin), and MMV688271 with PfINDO IC50 ≤ 1 µM were found to stall merozoite invasion by inhibiting IMC formation besides increasing oxidant levels in trophozoites. Bedaquiline pre-treated and washed healthy RBCs showed prophylactic ability to prevent intraerythrocytic development of malaria parasite. Synergistic activities with ΣFIC values as low as 0.22 (Curine and Artemisinin) or 0.37 (Bedaquiline and Artemisinin) augur well for the development of drug combinations to combat malaria effectively. Interestingly, orally delivered Bedaquiline (50 mg/Kg b. wt.) showed substantial suppression of parasitemia in a mouse model of malaria.

Malaria remains one of the most important pathogenic infectious diseases. Although Africa suffers the greatest brunt, a sizeable proportion of her population still relies on herbal medicines for reasons of cost as well as the belief etched in the minds of consumers that herbal medicines are safer and more efficacious than Modern medicines. Agbo-iba; a concoction of two or more than two plants is commonly used for the management of malaria in Nigeria.This study assessed the safety and efficacy of a hepta-herbal Agbo-iba (HHA) antimalarial decoction used for the management of malaria in Benin city, Nigeria.Assessment was done against malaria parasite in culture as well as in vivo in pre-clinical murine model of malaria.HHA (ICAlthough QPAs have strong in vitro antiplasmodial activity, their in vivo antimalarial activity is undermined by being substrates of Permeability glycoprotein (Pgp) efflux pump. Our study suggests that inhibitor(s) of Pgp in HHA could improve the bioavailability of QPAs in mice fed the herbal combo. Further, molecules from other HHA constituent plants may also contribute to the better potency observed for the polyherbal in vivo. These possibilities were validated by the curative antimalarial study at 100 mg/kg, where A.affinis was inactive but the HHA suppressed parasite growth by 44.45%.

Malaria continues to be a killer disease even in the modern world. Vaccines and drugs have a lot to learn from the malaria parasite before they can be successful. Here, using a filter for glideosomal anchor protein PfGAP50, we have explored a plethora of small molecules to shortlist eight GAP50 binders with promising antiplasmodial activity (IC50 < 3 µM) that are also highly selective. Of these, Hayatinin, Bedaquiline, MMV688271, Curine, and Brilacidin with PfINDO IC50 ≤ 1 µM were found to stall merozoites invasion by inhibiting IMC formation besides increasing ROS levels in trophozoites. Bedaquiline loaded healthy RBCs showed prophylactic ability to prevent intraerythrocytic development of malaria parasite. Synergistic activities with ΣFIC values as low as 0.22 (Curine and Artemisinin) or 0.37 (Bedaquiline and Artemisinin) augur well for the development of drug combinations to combat malaria effectively. Interestingly, orally delivered Bedaquiline (50 mg/Kg b. wt.) showed substantial suppression of parasitemia in the mouse model of malaria.

Aconitum heterophyllum Wall. ex Royle is a traditionally important medicinal plant having numerous therapeutic actions as documented in Ayurveda. This plant is traditionally known for combating worm infestation, fever, respiratory tract disease, vomiting, diarrhoea, diabetes, skin disorders, anaemia, and joint disorders. Further, it has been used alone and in combination with other plants to prepare various anti-malarial formulations. However, there is no report on the assessment of its anti-plasmodial activity, and the metabolite(s) responsible for this activity.The main aim of this study was to conduct phytochemical investigation of A. heterophyllum roots for the preparation of extract, fractions, and isolation of pure molecules to identify active fractions/molecules responsible for the anti-plasmodial activity, and development of UHPLC-DAD based analytical method which can be used for the quantification of marker compounds in the extracts and fractions.Hydroalcoholic extract (1:1 v/v) and fractions (n-hexane, chloroform, ethyl acetate, n-butanol, and water) were prepared from the dried powdered roots of A. heterophyllum. Fractions were further subjected to silica gel column chromatography to isolate pure specialized secondary metabolites from this plant. All extracts, fractions, and pure molecules were evaluated against the chloroquine resistant Pf INDO and chloroquine sensitive Pf3D7 strains in culture for calculating their ICPhytochemical investigation of A. heterophyllum root led to the isolation of six specialized metabolites viz. 2-O-cinnamoyl hetisine (1), atisinium (2), 4-oxabicyclo [3.2.2] nona-1(7),5,8-triene (3), atisinium cinnamate (4), aconitic acid (5), and atisinium formate (6). Compound 1 is a new hetisine type diterpenoid alkaloid, compounds 4 and 6 are new counter ionic forms observed with atisinium ion, and compound 3 is being reported for the first time from this genus. Chloroform fraction was found to be the most active with ICThis study provides the scientific rationale for the traditional use of this plant in treating malaria. Further, this study revealed that the anti-malarial potential of this plant might be due to the presence of diterpenoid alkaloids.

Aconitum heterophyllum is a traditionally important medicinal plant having numerous therapeutic actions as documented in Ayurveda. This plant has been used alone as well as in combination with other plants for the preparation of different anti-malarial formulations. However, there is no report on the assessment of its anti-plasmodial activity, and the compound responsible for this activity. The main aim of this study was to conduct phytochemical investigation of A. heterophyllum roots for the preparation of extract, fractions and isolation of pure molecules to identify active fractions/molecules responsible for the anti-plasmodial activity, and development of UHPLC-DAD based analytical method which can be used for the quantification of marker compounds in the extracts and fractions. Hydro-alcoholic extract (1:1 v/v) and fractions (n-hexane, chloroform, ethyl acetate, n-butanol and water) were prepared from the dried powdered roots of A. heterophyllum. Fractions were further subjected to silica gel-based column chromatography to isolate pure specialized secondary metabolites from this plant. All extracts, fractions and pure molecules were evaluated against the chloroquine resistant Pf INDO and chloroquine sensitive Pf3D7 strains in culture for calculating their IC50 values. UHPLC-DAD based analytical method was also developed for the first time for the quantification and quality assessment of this commercially important Himalayan medicinal plant. Phytochemical investigation of A. heterophyllum root led to the isolation of six specialized metabolites named as 2-O-cinnamoyl hetisine (1), atisinium (2), 4-oxabicyclo [3.2.2] nona-1(7),5,8-triene (3), atisinium cinnamate (4), aconitic acid (5), and atisinium formate (6). Compound 1 is a new hetisine type diterpenoid alkaloid, compounds 4 and 6 are new counter ionic forms observed with atisinium ion, and compound 3 is being reported for the first time from this genus. Chloroform fraction was found to be the most active with IC50 (µg/mL) 1.01 (Pf INDO) and 1.32 (Pf3D7). The isolated molecule 2-O-cinnamoyl hetisine (1), a new diterpenoid alkaloid isolated from chloroform fraction, showed promising antiplasmodial activities with IC50 (µM) 1.92 (Pf INDO) and 10.8 (Pf 3D7). Activity of chloroform fraction was further validated by the developed UHPLC-DAD based method as the quantity of 2-O-cinnamoyl hetisine (1) was higher in the chloroform fraction (≅200 µg/mL) than in all other fractions (< 7µg/mL). Atisinium (2) and 2-O-cinnamoyl hetisine (1) were found to be the main marker compounds of this plant based on quantity and antiplasmodial activity, respectively. This study provides the scientific rational for the traditional use of this plant in treating malaria. Further, this study revealed that anti-malarial potential of this plant might be due to the presence of diterpenoid alkaloids.

Background: Malaria remains a common life-threatening infectious disease across the globe due to the development of resistance by Plasmodium parasite against most antimalarial drugs. The situation demands new and effective drug candidates against Plasmodium. Objectives: The objective of this study is to design, synthesize and test novel quinoline based molecules against the malaria parasite. Methods: C2 and C8 modified quinoline analogs obtained via C-H bond functionalization approach were synthesized and evaluated for inhibition of growth of P. falciparum grown in human red blood cells using SYBR Green microtiter plate based screening. Computational molecular docking studies were carried out with top fourteen molecules using Autodoc software. Results: The biological evaluation results revealed good activity of quinoline-8-acrylate 3f (IC50 14.2 µM), and the 2-quinoline-α-hydroxypropionates 4b (IC50 6.5 µM), 4j (IC50 5.5 µM) and 4g (IC50 9.5 µM), against chloroquine sensitive Pf3D7 strain. Top fourteen molecules were screened also against chloroquine resistant Pf INDO strain and the observed resistant indices were found to lie between 1 and 7.58. Computational molecular docking studies indicated a unique mode of binding of these quinolines to Falcipain-2 and heme moiety, indicating these to be the probable targets of their antiplasmodial action. Conclusion: An important finding of our work is the fact that unlike Chloroquine which shows a resistance Index of 15, the resistance indices for the most promising molecules studied by us were about one indicating equal potency against drug sensitive and resistant strains of the malaria parasite.

Herein, we have synthesized a series of lipophilic, halogenated-arylvinyl-1,2,4-trioxanes 8a–g (28 compounds) and assessed for their in vitro anti-plasmodial activity in Plasmodium falciparum culture using SYBRgreen-I fluorescence assay against chloroquine-resistant Pf INDO and artemisinin-resistant Pf Cam 3.1R539T (MRA-1240) strains. Alongside, the cell cytotoxic potential of 8a–g has also been determined against the HEK293 cell line in vitro. Out of twenty-eight halogenated-arylvinyl-1,2,4-trioxanes; ten analogues (8a2, 8a4, 8b2, 8b4, 8d4, 8e1, 8e2, 8e4, 8f2, and 8g4) have shown potent in vitro antiplasmodial activity with IC50 1M17 ) have demonstrated the strong virtual interaction.

A series of indolo[3,2-b]quinoline-C11-carboxamides were synthesized by incorporation of aminoalkyl side chains into the core of indolo[3,2-b]quinoline-C11-carboxylic acid. Their in vitro antiplasmodial evaluation against Plasmodium falciparum led to the identification of a 2-(piperidin-1-yl)ethanamine-linked analogue {2-bromo-N-[2-(piperidin-1-yl)ethyl]-10H-indolo[3,2-b]quinoline-11-carboxamide (3 g)} (IC50 =1.3 μm) as the most promising compound exhibiting good selectivity indices against mammalian cell lines. The kill kinetics on erythrocytic-stage parasites revealed that 3 g caused complete killing of only the trophozoite-stage parasites. Mechanistic studies showed that 3 g targets the food vacuole of the parasite and inhibits hemoglobin uptake, β-hematin formation, and the basic endocytic processes of the parasite. Analogue 3 g was found to be orally bioavailable, and its curative antimalarial studies at 50 mg per kg p.o. against a Plasmodium berghei (ANKA)-infected mouse model revealed that mice treated with 3 g showed 27-35 % suppression of parasitemia with an increase in life span relative to untreated, control mice. Thus, the present work demonstrated a proof of concept for the oral efficacy of indolo[3,2-b]quinoline-C11-carboxamides.

Here, a facile and efficient protocol for the synthesis of 3-hydroxyquinolin-8-yl propanoates via Rh(III)-catalyzed C(8)-H activation of 2-substituted quinolines has been developed. The reaction proceeds via C(8)-H activation, functionalization with acrylates, followed by intramolecular migration of the oxygen atom from quinoline N-oxides to the acrylate moiety. In this approach, N-oxide plays a dual role of a traceless directing group as well as a source of an oxygen atom for hydroxylation. This catalytic method involves simultaneous formation of new C-C and C-O bonds and is applicable only for C2-substituted quinolines. A catalytically competent five-membered rhodacycle has been characterized, thus revealing a key intermediate in the catalytic cycle. In silico docking studies against Falcipan-2 have revealed that 3a, 3b, 3g, and 3m have better scores. In vitro evaluation of selected compounds against CQ-sensitive pf3D7 and CQ-resistant pfINDO strains provided evidence that 3d (IC50 13.3 μM) and 3g (IC50 9.5 μM) had good promise against Plasmodium falciparum in the in vitro culture. Compound 3g was found to be the most potent on the basis of both in vitro antiplasmodial activity [IC50 9.5 μM ( Pf3D7) and 11.9 μM ( PfINDO), resistance index 1.25] and in silico studies.

Diarylidenecyclohexanone (DAC) derivatives (Ia-i, IIa-c and IIIa-b) were synthesized, characterized and screened for their in vitro antiplasmodial activities against erythrocytic stages of chloroquine (CQ) sensitive and resistant strains of P. falciparum by using SYBR green I fluorescence assay. SAR studies of DAC derivatives showed antiplasmodial activity in the order of 3-NO2 (Ib, IC50 0.95 µM) > 3-chloro (Id, IC50 3 µM) > 4-chloro (Ie, IC50 8.5 µM) > 2-chloro (Ic, IC50 13 µM). Further Ib and Id exhibited nearly equal potencies against CQ-resistant strains P. falciparum Dd2, {IC50 1 µM (Ib) and 2.7 µM (Id)} and PfINDO {IC50 1.1 µM (Ib) and 2.5 µM (Id)}. Drug exposure followed by drug withdrawal-based stage-specific kill kinetic studies showed that Ib is shizonticidal within 3 h while the earliest killing actions against Trophozoites and Rings were seen at >3 h and >6 h, respectively. Combination studies of the most potent leads viz. Ib and Id showed strong to moderate synergistic effects with Artemisinin (ƩFIC50: 0.34 to 0.63) whereas no interaction (ƩFIC50: 0.65 to 2.36) was observed with Chloroquine. The DACs showed significant in silico binding affinity with β-haematin and P. falciparum lactate dehydrogenase (PfLDH) suggesting these to be the targets of their antiplasmodial action. High compliance with Lipinski rule of 5 and high selectivity index of Ib (105.3) and Id (8.3) against HeLa cell line indicated that Diarylidenecyclohexanones could serve as structural templates towards lead optimization of compounds for discovery of novel, potent, safe and affordable drugs against malaria.

Terminalia mantaly (H. Perrier) and Terminalia superba (Engl.Diels) are sources of treatment for various diseases, including malaria and/or related symptoms in parts of Southwestern Cameroon. However, there is limited information on the extent of the antiplasmodial potential of their extracts.The present study was designed to investigate the antiplasmodial potential of chromatographic sub fractions (SFs) from promising fractions of Terminalia mantaly (Tm) [TmsbSelected SFs were submitted to a second bio-guided fractionation using silica gel column chromatography. The partial phytochemical composition of potent antiplasmodial SFs was determined using gas chromatography coupled to mass spectrometry (GC-MS). The SYBR Green I-based fluorescence microtiter plate assay was used to monitor the growth of Plasmodium falciparum parasites in culture in the presence or absence of extracts. Microscopy and flow cytometry counting was used to assess the Plasmodium falciparum stage-specific inhibition and post-drug exposure growth suppression by highly potent extracts.Twenty-one of the 39 SFs afforded from TmsbThis study has identified highly potent antiplasmodial SFs from Terminalia mantaly with significant activity on the intraerythrocytic development of Plasmodium falciparum. These SFs qualify as promising sources of novel antiplasmodial lead compounds. Further purification and characterization studies are expected to unravel molecular targets in rings and merozoites.

The plant kingdom continues to hold great promise for the eradication of Malaria infection following the challenges of insecticide resistance by the vector mosquito, drug resistance by the parasite, and the development of a vaccine still being a mirage. Acalypha wilkesiana Muller Argoviensis, 1866 (family: Euphorbiaceae) leaves have the ethnopharmacological reputation for use as a remedy against dermal microbial infections in Nigeria. Here, we have studied the antiplasmodial potential of the extract of the leaves of this ornamental plant. Aqueous methanol crude extract (70%) and Prep reversed-phase high-performance liquid chromatography (RPHPLC) fractions were tested in vitro against blood stage Plasmodium falciparum 3D7 strain parasites for antiplasmodial activity using the SYBR Green assay. Results obtained were validated through Giemsa stained microscopic blood smeared slides. An IC50 of 100 μg/ml against mammalian HUH-7 cell lines and a HC50 of > 100 μg/ml against red blood cells indicate a high selectivity of this plant against Plasmodium. This is the first report of the antiplasmodial activity of this plant and a GC-MS fingerprinting of the same, opening the possibilities of identifying novel pharmacophores against the malaria parasite.

Malaria is a precarious disease and a serious illness that can become life threatening very fast and can be incurable if not treated on time. According to the World Health Organization, Malaria causes 150–250 million infections and an estimated more than a million deaths each year. Microscopic image capture followed by visual observation as per the manual is the gold standard method for diagnosis of malaria. However, due to subjectivity and the complexity of manual assessment, microscopic diagnosis of malaria is tiring, time consuming and subject to human error. In this study, we have developed a novel automatic high performance method with minimal human dependence for detection and quantitation of malaria infected Red Blood Cells (RBC). The parasites detection test to identify malaria was computed using digital image processing techniques. This automated quantitation procedure was done in three parts: Segmentation, Identification and Detection. The methods used for the quantitation were Six Sigma threshold for segmenting Region of Interest followed by modified Hough transform to identify and count RBCs, and Kapur’s threshold method to detect malaria parasite infected RBCs. The developed package using Microsoft ® VB.NET 2008 framework is executed on various Giemsa stained thin blood smears digitally acquired using a charge coupled device attached to a microscope. Following analysis performed on seven sets of thin blood smear images, the values of Precision, Recall and F -measures obtained were 96%, 97% and 97% respectively. This is the first attempt to use a combination of Six Sigma threshold, Chess-Board distance, Hough transform and Kapur’s threshold to find the RBCs by deriving information from the image itself. Further, Kapur’s entropy measure was successfully applied to distinguish parasitized from un-infected cells.

Zea mays leaf extract and fractions were investigated for antimalarial activity against Plasmodium berghei using a rodent malaria model and in vitro activity against chloroquine-sensitive (Pf 3D7) and -resistant (Pf INDO) strains of P. falciparum using the SYBR green assay method. Median lethal dose (LD50) and cytotoxic activities against HeLa and HEKS cells were also carried out. The most active fraction was analyzed by gas chromatography-mass spectrometry (GCMS). The leaf extract (170–510 mg.kg–1, p.o.), with LD50 of 1,732.05 mg.kg–1, demonstrated antimalarial activity against P. berghei infection in suppressive, prophylactive, and curative tests. The crude extract and the fractions also exerted prominent activity against both chloroquine-sensitive (Pf 3D7) and -resistant (Pf INDO) strains of P. falciparum, with the ethyl acetate fraction exerting the highest activity with IC50 value of 32.31 ± 2.56 μg.mL–1 (Pf 3D7) and 13.60 ± 0.57 μg.mL–1 (Pf INDO). The crude leaf extract and fractions were no...

A novel series of synthetic functionalized arylvinyl-1,2,4-trioxanes (8 a-p) has been prepared and assessed for their in vitro antiplasmodial activity against the chloroquine-resistant Pf INDO strain of Plasmodium falciparum by using a SYBR green-I fluorescence assay. Compounds 8 g (IC50 =0.051 μM; SI=589.41) and 8 m (IC50 =0.059 μM; SI=55.93) showed 11-fold and >9-fold more potent antiplasmodial activity, respectively, as compared to chloroquine (IC50 =0.546 μM; SI=36.63). Different in silico docking studies performed on many target proteins revealed that the most active arylvinyl-1,2,4-trioxanes (8 g and 8 m) showed dihydrofolate reductase (DHFR) binding affinities on a par with those of chloroquine and artesunate. The in vitro cytotoxic potentials of 8 a-p were also evaluated against human lung (A549) and liver (HepG2) cancer cell lines along with immortalized normal lung (BEAS-2B) and liver (LO2) cell lines. Following screening, five derivatives viz. 8 a, 8 h, 8 l, 8 m and 8 o (IC50 =1.65-31.7 μM; SI=1.08-10.96) were found to show potent cytotoxic activity against (A549) lung cancer cell lines, with selectivity superior to that of the reference compounds artemisinin (IC50 =100 μM), chloroquine (IC50 =100 μM) and artesunic acid (IC50 =9.85 μM; SI=0.76). In fact, the most active 4-naphthyl-substituted analogue 8 l (IC50 =1.65 μM; SI >10) exhibited >60 times more cytotoxicity than the standard reference, artemisinin, against A549 lung cancer cell lines. In silico docking studies of the most active anticancer compounds, 8 l and 8 m, against EGFR were found to validate the wet lab results. In summary, a new series of functionalized aryl-vinyl-1,2,4-trioxanes (8 a-p) has been shown to display dual potency as promising antiplasmodial and anticancer agents.

ispartof: FRONTIERS IN PHARMACOLOGY vol:10 ispartof: location:Switzerland status: published

Ethnopharmacological relevance Terminalia catappa L. (West Indian-Almond) is a medicinal plant used in traditional medicine for the treatment of infectious diseases. Moreover, various organic extracts prepared from this plant have been reported to exhibit antiplasmodial activity. Aim of the study The need for new antimalarials is still an urgency driven by the alarmingly high burden of malaria in endemic regions, with multitude of people dying annually. We have previously identified an endophytic fungus Aspergillus niger 58 harboured by T. catappa as having promising specialized secondary metabolites against the malaria parasites. In the present study, we report the antiplasmodial activity-guided chromatographic isolation of some metabolites secreted by this endophytic fungus. Materials and methods The SYBR Green I-based fluorescence microtiter plate assay was used to monitor the growth of Plasmodium falciparum parasites in culture in the presence and absence of inhibitors and results were validated by microscopic analysis of Giemsa-stained culture smears. Giemsa-stain microscopy was also used to study the cell cycle stage-specific action of selected fractions. Results The results revealed that the multidimensional purification of the crude extract (IC50: 4.03 μg/mL) provided RPHPLC F17 (IC50: 0.09 μg/mL) and RPHPLC F18 (IC50: 0.1 μg/mL) with activity against P. falciparum 3D7 (Pf3D7) strain. Moreover, both fractions at IC99 (0.5 μg/mL) exhibited multi-stages action by targeting all the three stages of the life cycle of blood-stage Pf3D7. Two compounds, flavasperone (1) and aurasperone A (2) were isolated, of which aurasperone A exhibited good potency against Pf3D7 (IC50: 4.17 μM) and P. falciparum INDO (PfINDO) (IC50: 3.08 μM). Conclusion Our study adds credence to the notion that endophytic extracts are potential storehouses for potent specialized secondary metabolites that can be harnessed to fight the malaria parasite and reduce the burden of this disease worldwide. An endophyte that can be cultured in laboratory with ability to secrete promising metabolites of medicinal value holds the promise of conserving Nature from the threat of annihilation of flora for medicinal purposes.

Alchornea laxiflora leaf extracts and their fractions used traditionally in the treatment of malaria by Nigerian tribal populations were investigated for antimalarial activity against Plasmodium berghei using a rodent malaria model and in vitro activity against chloroquine-sensitive (Pf 3D7) and -resistant (Pf INDO) strains of P. falciparum using the SYBR green assay method. Determination of median lethal dose and cytotoxic activities against HeLa and HEKS cells were carried out. The most active extract fraction was analyzed by gas chromatography-mass spectrometry (GC-MS). The leaf extract (200–600 mg.kg−1, p.o.) with LD50 of 2,236 mg.kg−1 were antimalarial against P. berghei infection in suppressive, prophylactive, and curative tests. The crude extract and the fractions exerted prominent activity against both chloroquine-sensitive (Pf 3D7) and -resistant (Pf INDO) strains of P. falciparum. The ethyl acetate fraction exerted the highest activity, with IC50 values of 9.92 ± 0.28 μg.mL−1 (Pf 3D7) an...

Today when the quest of new lead molecules to supply the development pipeline is driving the course of drug discovery, endophytic fungi with their outstanding biosynthetic potential seem to be highly promising avenues for natural product scientists. However, challenges such as the production of inadequate quantities of compounds, the attenuation or loss of ability of endophytes to produce the compound of interest when grown in culture and the inability of fungal endophytes to express their full biosynthetic potential in laboratory conditions have been the major constraints. These have led to the application of small chemical elicitors that induce epigenetic changes in fungi to activate their silent gene clusters optimizing the amount of metabolites of interest or inducing the synthesis of hitherto undescribed compounds. In this respect small molecular weight compounds which are known to function as inhibitors of histone deacetylase (HDAC), DNA methyltransferase (DNMT) and proteasome have proven their efficacy in enhancing or inducing the production of specialized metabolites by fungi. Moreover, organic solvents, metals and plants extracts are also acknowledged for their ability to cause shifts in fungal metabolism. We highlight the successful studies from the past two decades reporting the ability of structurally diverse small molecular weight compounds to elicit the production of previously undescribed metabolites from endophytic fungi grown in culture. This mini review argues in favor of chemical elicitation as an effective strategy to optimize the production of fungal metabolites and invigorate the pipeline of drug discovery with new chemical entities.

A convenient and eco-friendly synthesis of various fused N-heterocyclic compounds through catalyst and additive-free 1,3 dipolar cycloadditions of quinolinium imides with olefins, maleimides, and benzynes in excellent yields and diastereoselectivities is reported. The thermally controlled diastereoselective [3 + 2] cycloaddition reaction between quinolinium imides and olefins provided cis-isomers at low temperature and trans-isomers at high temperature. A reaction between quinolinium imides with substituted maleimides gave four-ring-fused N-heterocyclic compounds in high yields as a single diastereomer. The aryne precursors also provided four-ring-fused N,N′-heterocyclic compounds in high yields. The in vitro antiplasmodial activity of selected molecules revealed that this class of molecules possesses potential for ongoing studies against malaria.