Molecular modelling, docking and network analysis of phytochemicals from Haritaki churna: role of protein cross-talks for their action

Phytochemicals are bioactive agents present in medicinal plants with therapeutic values. Phytochemicals isolated from plants target multiple cellular processes. In the current work, we have used fractionation techniques to identify 13 bioactive polyphenols in ayurvedic medicine Haritaki Churna. Employing the advanced spectroscopic and fractionation, structure of bioactive polyphenols was determined. Blasting the phytochemical structure allow us to identify a total of 469 protein targets from Drug bank and Binding DB. Phytochemicals with their protein targets from Drug bank was used to create a phytochemical-protein network comprising of 394 nodes and 1023 edges. It highlights the extensive cross-talk between protein target corresponding to different phytochemicals. Analysis of protein targets from Binding data bank gives a network comprised of 143 nodes and 275 edges. Taking the data together from Drug bank and binding data, seven most prominent drug targets (HSP90AA1, c-Src kinase, EGFR, Akt1, EGFR, AR, and ESR-α) were found to be target of the phytochemicals. Molecular modelling and docking experiment indicate that phytochemicals are fitting nicely into active site of the target proteins. The binding energy of the phytochemicals were better than the inhibitors of these protein targets. The strength and stability of the protein ligand complexes were further confirmed using molecular dynamic simulation studies. Further, the ADMET profiles of phytochemicals extracted from HCAE suggests that they can be potential drug targets. The phytochemical cross-talk was further proven by choosing c-Src as a model. HCAE down regulated c-Src and its downstream protein targets such as Akt1, cyclin D1 and vimentin. Hence, network analysis followed by molecular docking, molecular dynamics simulation and in-vitro studies clearly highlight the role of protein network and subsequent selection of drug candidate based on network pharmacology.Communicated by Ramaswamy H. Sarma.

Role Transformation of HSPA8 to Heme-peroxidase After Binding Hemin to Catalyze Heme Polymerization

Hemin, a byproduct of hemoglobin degradation, inflicts oxidative insult to cells. Following its accumulation, several proteins are recruited for heme detoxification with heme oxygenase playing the key role. Chaperones play a protective role primarily by preventing protein degradation and unfolding. They also are known to have miscellaneous secondary roles during similar situations. To discover a secondary role of chaperones during heme stress we studied the role of the chaperone HSPA8 in the detoxification of hemin. In-silico studies indicated that HSPA8 has a well-defined biophoric environment to bind hemin. Through optical difference spectroscopy, we found that HSPA8 binds hemin through its N-terminal domain with a Kd value of 5.9 ± 0.04 µM and transforms into a hemoprotein. The hemoprotein was tested for exhibiting peroxidase activity using guaiacol as substrate. The complex formed reacts with H2O2 and exhibits classical peroxidase activity with an ability to oxidize aromatic and halide substrates. HSPA8 is dose-dependently catalyzing heme polymerization through its N-terminal domain. The IR results reveal that the polymer formed exhibits structural similarities to β-hematin suggesting its covalent nature. The polymerization mechanism was tested through optical spectroscopy, spin-trap, and activity inhibition experiments. The results suggest that the polymerization occurs through a peroxidase-H2O2 system involving a one-electron transfer mechanism, and the formation of free radical and radical-radical interaction. It highlights a possible role of the HSPA8-hemin complex in exhibiting cytoprotective function during pathological conditions like malaria, sickle cell disease, etc.

Hemin competitively inhibits HSPA8 ATPase activity mitigating its foldase function

Hemolysis in red blood cells followed by hemoglobin degradation results in high hemin levels in the systemic circulation. Such a level of hemin is disastrous for cells and tissues and is considerably responsible for the pathologies of diseases like severe malaria. Hemin's hydrophobic chemical nature and structure allow it to bind several proteins leading to their functional modification. Such modifications in physiologically relevant proteins can have a high impact on various cellular processes. HSPA8 is a chaperone that has a protective role in oxidative stress by aiding protein refolding. Through ATPase activity assays we found that hemin can competitively inhibit ATP hydrolysis by the chaperone HSPA8. Hemin as such does not affect the structural integrity of the protein which is inferred from CD spectroscopy and Gel filtration but it hinders the ATP-dependent foldase function of the chaperone. HSPA8 was not able to cause the refolding of the model protein lysozyme in the presence of hemin. The loss in HSPA8 function was due to competition between hemin and ATP as the chaperone was able to regain the foldase function when the concentration of ATP was gradually increased with hemin present at the inhibitory concentration. In-silico studies to establish the competition for the specific binding site revealed that ATP was unable to replace hemin from the ATP binding pocket of HSPA8 and was forced to form a non-specific and unstable complex. In-vitro isothermal calorimetry revealed that the affinity of ATP for binding to HSPA8 was reduced 22 folds in the presence of hemin. The prevention of HSPA8's cytoprotective function by hemin can be a major factor contributing to the overall cellular damage during hemin accumulation in the case of severe malaria and other hemolytic diseases.

Tandem (4 + 3)-Annulation of Aziridines: Stereoselective Access to Fused Azepinoindoles

A stereoselective tandem (4 + 3)-coupling of aziridines with 4-alkylidene indole malonates has been disclosed under Cu-catalysis involving a base-promoted annulation. The methodology serves as a potential approach toward the facile construction of fused azepinoindoles with good yields and diastereoselectivities. Late-stage natural product and drug modification as well as preliminary investigations for the enantioselective (4 + 3)-annulation are important practical features.

Plasmodium falciparum FIKK 9.1 kinase modeling to screen and identify potent antimalarial agents from chemical library

The Plasmodium FIKK kinases are diverged from human kinases structurally. They harbour conserved ATP-binding domains that are non-homologous to other existing kinases. FIKK9.1 kinase is considered as an essential protein for parasite survival. It is localized in major organelles present in parasite and trafficked throughout the infected RBC. It is speculated that FIKK9.1 may phosphorylate several substrates in the parasite's proteome and contribute to parasite survival. Therefore, FIKK9.1 is an attractive target that may lead to a novel class of antimalarials. To identify specific FIKK9.1 kinase inhibitors, we virtually screened organic structural scaffolds from a library of 623 entries. The top hits were identified based on conformations and molecular interactions with the ATP biophore. The hits were also validated under in vitro conditions. In this study, we identified seven top hit organic compounds that may arrest the growth of parasites by inhibiting FIKK9.1 kinase. Evaluation of top hit compounds in antimalarial activity assay identifies that the highly substituted 1,3-selenazolidin-2-imine 1 and thiophene 2 are inhibiting parasite growth with an IC50 of 3.2 ± 0.27 μg/ml and 3.13 ± 0.16 μg/ml, respectively. These functionalized heterocyclic compounds 1 and 2 kills the malaria parasite with an IC50 of 2.68 ± 0.02 μg/ml and 3.08 ± 0.14 μg/ml, respectively. Isothermal titration calorimetry analysis indicate that ATP is binding to the FIKK9.1 kinase. The dissociation constant (Kd) is measured to be 27.8 ± 2.07 μM with a stoichiometry of n = 1. The heterocyclic scaffolds 1 and 2 were abolishing the binding of ATP into the binding pocket. They in-turn reduce the ability of FIKK9.1 kinase to phosphorylate its substrate. Our study found that compounds 1 and 2 are potent inhibitor of FIKK9.1 kinase and the inhibition of FIKK9.1 kinase using small molecules disturbs the parasite life cycle and leads to the death of parasites. This provides new insight in development of novel antimalarials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03677-x.

Extraction, phytochemical characterization and anti-cancer mechanism of Haritaki churna: An ayurvedic formulation

Haritaki churna (HC), a single herb ayurvedic formulations is known to be prescribed for various gastro-intestinal disorders in Ayurveda. Haritaki churna aqueous extract (HCAE) has anti-cancer activity against different types of cancer cells with an IC50 in the range of 50-97 μg/ml. Bioavailability of Haritaki Churna is very high in digestive track and treatment of colorectal cancer cells HCT-116, DLD1, HT-29 with HCAE reduces its cellular viability with anti-cancer IC50 70μg/ml. HCAE consumption is safe for human as it didn't affect the cellular viability of primary human PBMCs or non-cancerogenic HEK-293 cells. Haritaki churna was found to be stable in biological gastric fluids and bioactive agents are not losing their anti-cancer activity under such harsh conditions. The HPLC Chromatogram of HCAE is giving 13 major peaks and 11 minor peaks. Exploiting LC-MS, IR and NMR spectroscopic techniques, a total of 13 compounds were identified from HCAE namely Shikimic acid, Chebulic acid, gallic acid, 5-hydroxymethylfurfural, Protocatechuic acid, 4-O-galloyl-shikimic Acid, 5-O-galloyl-shikimic Acid, Methylgallate, corilagin, 1, 2, 6, Tri-O-galloyl β-D-glucose, chebulagic acid, chebulinic acid, and Ellagic acid. Reconstitution and subtraction of phytochemicals from the mixture indicate that Ellagic acid significantly contribute into anti-cancer effect of HCAE. Cancer cells treated with ellagic acid from HCAE were incapable of completing their cell-cycle and halted the cell-cycle at DNA synthesis S-Phase, as demonstrated by decreased cyclin A2 expression levels with increasing ellagic acid concentration. Halting of cells at S-phase causes induction of apoptosis in cancer cells. Cancer cells exhibiting DNA fragmentation, changes in expression of several apoptotic proteins such as Bcl2, cytochrome-c and formation of cleaved products of caspase 3 and PARP-1 suggests ellagic acid induces cell death via mitochondrial pathway of apoptosis.

Clinical efficacy of the virtual fracture clinic: analysis of 17,269 referrals by type of injury

INTRODUCTION

Numerous studies have deemed the virtual fracture clinic (VFC) model to be both cost and clinically effective. However, very few of these studies have analysed the type of injuries seen in the VFC. The objectives of this study were to assess the clinical effectiveness of the VFC and analyse the types of injuries that lead to patients re-presenting in the face-to-face fracture clinic after being discharged virtually.

METHODS

This is a retrospective study analysing 17,269 patients referred to the VFC between September 2017 and February 2020. Data regarding the type of presenting injury were collected to understand which injuries required further management after being discharged virtually. Patient clinic letters provided data regarding the purpose and outcomes of VFC referrals as well as face-to-face appointments. Theatre lists were cross-referenced to extract data regarding surgical management.

RESULTS

In total, 57.37% (9,908) patients were discharged virtually. Of these patients, 92.52% were discharged successfully and 7.48% re-presented to the fracture clinic: 98.11% were managed conservatively and 1.88% required surgery. The highest number of failed discharges were for distal radius fractures (109, 14.69%). Face-to-face follow-up in fracture clinic was requested for 37.06% (6,400) of patients; 4.98% of them required surgical intervention. Some 5.56% (961) of referrals were removed from our analysis: 807 were inappropriate referrals and 154 were deemed suitable for multidisciplinary team discussion. The trust has saved an average of £702,205 annually since introduction of the VFC.

CONCLUSIONS

The VFC model delivers as promised in terms of clinical efficacy and cost management. Injury types showing higher numbers of unsuccessful discharges could benefit from having modified management pathways.

Isolation and characterization of Newcastle disease virus from biological fluids using column chromatography

Newcastle disease virus (NDV), belonging to the species avian orthoavulavirus 1, genus Orthoavulavirus, and family Paramyxoviridae, is responsible for Newcastle disease in poultry and other avian species. It has shown significant potential as an oncolytic virus and as a vector for vaccine delivery. NDV from infected biological serum is usually isolated or purified using density gradient ultracentrifugation. However, it has many disadvantages, including the fact that it is time consuming and can process only a limited quantity of sample at one time. In our study, native agarose gel electrophoresis and dynamic light scattering (DLS) analysis showed that NDV carried a net negative surface charge. Thus, we purified the virus using a HiTrap Q Sepharose Fast Flow anion exchange column with salt elution. Hemagglutination assay and plaque assay showed that the procedure yielded high-purity NDV particles with a recovery of more than 80%, and the process was fast and simple. The purity of the virus was confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. The hydrodynamic volume and 'dry state' diameter of the purified NDV were analyzed using dynamic light scattering and transmission electron microscopy and were to be in the range of 200-300 nm. The viruses did not exhibit any deviation from their known physical properties. The genome of the virus was also detected by amplifying a 423-bp region using reverse transcription-polymerase chain reaction. Our study confirmed that NDV could be effectively purified using an anion exchange column. In addition, the procedure could be easily upscaled or downscaled based on the experimental requirements.

Delivery of Small Molecules by Syndiotactic Peptides for Breast Cancer Therapy

The utilization of peptide-based drug delivery systems has been suboptimal due to their poor proteolytic susceptibility, poor cell permeability, and limited tumor homing capabilities. Earlier attempts in using d-enantiomers in peptide sequences increased proteolytic stability but have compromised the overall penetration capability. We designed a series of peptides (STRAPs) with a syndiotactic polypeptide backbone that can potentially form a spatial array of cationic groups, an important feature that facilitates cellular uptake. The peptides penetrate cell membranes through a combination of active and passive modes. Furthermore, the cellular uptake of the peptides was unaffected by the presence of or treatment with bovine serum and human plasma. The designed peptides successfully delivered methotrexate, an anticancer drug, to the in vitro and in vivo models of breast cancer, with the best performing peptide STRAP-4-MTX conjugate having an EC50 value of 1.34 μM. Peptide drug delivery in mouse xenograft models showed a greater reduction of primary tumor and metastasis of breast cancer, in comparison to methotrexate of the same dose. The in vivo biodistribution assay of the STRAP-4 peptide suggests that the peptide accumulates at the tumor site after 2 h of treatment, and in the absence of tumors, the peptide gets metabolized and excreted from the system.

MycoVarP: Mycobacterium Variant and Drug Resistance Prediction Pipeline for Whole-Genome Sequence Data Analysis

Whole-genome sequencing (WGS) provides a comprehensive tool to analyze the bacterial genomes for genotype–phenotype correlations, diversity of single-nucleotide variant (SNV), and their evolution and transmission. Several online pipelines and standalone tools are available for WGS analysis of Mycobacterium tuberculosis (Mtb) complex (MTBC). While they facilitate the processing of WGS data with minimal user expertise, they are either too general, providing little insights into bacterium-specific issues such as gene variations, INDEL/synonymous/PE-PPE (IDP family), and drug resistance from sample data, or are limited to specific objectives, such as drug resistance. It is understood that drug resistance and lineage-specific issues require an elaborate prioritization of identified variants to choose the best target for subsequent therapeutic intervention. Mycobacterium variant pipeline (MycoVarP) addresses these specific issues with a flexible battery of user-defined and default filters. It provides an end-to-end solution for WGS analysis of Mtb variants from the raw reads and performs two quality checks, viz, before trimming and after alignments of reads to the reference genome. MycoVarP maps the annotated variants to the drug-susceptible (DS) database and removes the false-positive variants, provides lineage identification, and predicts potential drug resistance. We have re-analyzed the WGS data reported by Advani et al. (2019) using MycoVarP and identified some additional variants not reported so far. We conclude that MycoVarP will help in identifying nonsynonymous, true-positive, drug resistance–associated variants more effectively and comprehensively, including those within the IDP of the PE-PPE/PGRS family, than possible from the currently available pipelines.

Ultrahigh nanostructured drug payloads from degradable mesoporous silicon aerocrystals

Porous silicon has found increased attention as a drug delivery system due to its unique features such as high drug payloads, surface area and biodegradation. In this study supercritical fluid (SCF) assisted drying of ultrahigh porosity (>90%) silicon particles and flakes was shown to result in much higher mesopore volumes (~4.66 cm³/g) and surface areas (~680 m²/g) than with air-drying. The loading and physical state of the model drug (S)-(+)-Ibuprofen in SCF dried matrices was quantified and assessed using thermogravimetric analysis, differential scanning calorimetry, UV-Vis spectrophotometry, gravimetric analysis, gas adsorption and electron microscopy. Internal drug payloads of up to 72% were achieved which was substantially higher than values published for both conventionally dried porous silicon (17-51%) and other mesoporous materials (7-45%). In-vitro degradability kinetics of SCF-dried matrices in simulated media was also found to be faster than air-dried controls. The in-vitro release studies provided improved but sustained drug dissolution at both pH 2.0 and pH 7.4.

CD36 Ectodomain Detects Apoptosis in Mammalian Cells

The cells that undergo apoptosis show phosphatidylserine (PS) on the cell membrane. The fluorescently labeled hCD36_ecto is staining and detecting apoptotic cells in a flow-based assay with several advantages over Annexin V. The human CD36 ectodomain (hCD36_ecto) is stable for a range of temperatures and experimental conditions and doesn't require Ca²⁺ for detecting apoptosis and specific towards PS compared to other lipids. The blocking with unlabeled hCD36_ecto reduces the staining of Annexin V-FITC for apoptotic cells, whereas R63A does not affect the binding of Annexin V- FITC to apoptotic cells. It indicates the role of CD36-PS interaction in detecting apoptotic cells. Dual-staining with hCD36_ecto-FITC/PI is universally detecting apoptosis in different nucleated cells or eryptosis in non-nucleated RBCs. Hence, our study highlights the utility of CD36 as a probe to detect apoptosis in mammalian cells. It might be a robust, economical reagent for the scientific community to facilitate their research.

Hemozoin is a potential threat in cerebral malaria pathology through the induction of RBC-EC cytoadherence

Cerebral malaria is an outcome of multifaceted and complicated condition. Cytoadherence is one critical factor in cerebral malaria pathology as high order cytoadherence complexes result in vascular congestion and cell apoptosis. Morphological abnormalities in uninfected RBCs can be a contributing factor to aggravate cytoadherence. Malaria pigment hemozoin is a potential bioactive molecule and the role of this pigment in cerebral malaria pathology is not completely understood. To understand this, primarily we investigated the impact of hemozoin pigment on uninfected RBCs. Secondarily, we investigated the role of this pigment in formation of endothelial cells-RBCs (EC-RBC) cytoadherence complex. We first observed that a dose dependent hemozoin exposure to uninfected RBCs induced structural abnormalities. Differential counting of these abnormal RBCs indicated population of acanthocytes, spherocytes and microcytes. The formation of abnormal RBCs was observed with phosphatidylserine externalization. Lipid peroxidation, reduced glutathione and reactive oxygen species (ROS) levels indicated an increase in hemozoin exposure mediated oxidative stress. Our in-vitro cytoadherence assay indicated formation of endothelial EC-RBC cytoadherence complex. The dose dependent hemozoin exposure to uninfected RBCs resulted in oxidative stress mediated high order cytoadherence complex formation. This effect was reversed in presence of antioxidant molecules. The inhibitory effect of antioxidant molecules indicates that oxidative stress can be a regulatory factor to control cerebral malaria pathology. Being the first report to highlight the impact of malaria pigment hemozoin on uninfected RBCs, this study brings attention to the role of abnormal RBCs in worsening of cerebral malaria pathology.

The risk of malignancy in patients with secukinumab-treated psoriasis, psoriatic arthritis and ankylosing spondylitis: analysis of clinical trial and postmarketing surveillance data with up to five years of follow-up

BACKGROUND

Data on the use of biologic therapy and malignancy risk are inconsistent due to limited long-term robust studies.

OBJECTIVES

To assess the malignancy risk in patients with secukinumab-treated psoriasis, psoriatic arthritis (PsA) and ankylosing spondylitis (AS).

METHODS

This integrated safety analysis from both the secukinumab clinical trial programme and postmarketing safety surveillance data included any patient receiving at least one approved dose of secukinumab with a maximum of 5 years of follow-up. Safety analyses evaluated the rate of malignancy using exposure-adjusted incidence rates [EAIR; incidence rates per 100 patient treatment-years (PTY)]. Standardized incidence ratios (SIRs) were reported using the Surveillance, Epidemiology, and End Results Program (SEER) database as a reference population. Crude incidence of malignancy was also reported using postmarketing surveillance data.

RESULTS

Safety data from 49 clinical trials with secukinumab-treated patients were included: 10 685 patients with psoriasis, 2523 with PsA and 1311 with AS. Across indications over a 5-year period, the EAIR of malignancy was 0·85 per 100 PTY [95% confidence interval (CI) 0·74-0·98] in secukinumab-treated patients, corresponding to 204 patients per 23 908 PTY. Overall, the observed vs. expected number of malignancies from secukinumab clinical trial data were comparable, as indicated by an SIR of 0·99 (95% CI 0·82-1·19) across indications. The estimated crude cumulative incidence reporting rate per 100 PTY for malignancy was 0·27 in the postmarketing surveillance data across indications with a cumulative exposure of 285 811 PTY.

CONCLUSIONS

In this large safety analysis, the risk of malignancy was low for up to 5 years of secukinumab treatment. These data support the long-term use of secukinumab in these indications.

Plasmodium falciparum FIKK9.1 is a monomeric serine-threonine protein kinase with features to exploit as a drug target

FIKK-9.1 is essential for parasite survival, but its structural and biochemical characterization will enable us to understand its role in the parasite life cycle. The recombinant FIKK9.1 kinase is monomeric with a native molecular weight of 60 ± 1.6 kDa. Structural characterization of FIKK9.1 kinase reveals that it consists of two domains: N-terminal FHA like domain and C-terminal kinase domain. The C-terminal domain has a well-defined pocket, but it displayed RMSD deviation of 1.38-3.2 Å from host kinases. ITC analysis indicates that ATP binds to the protein with a K_d of 45.6 ± 2.4 µM. Mutational studies confirm the role of Val-244, Met-245, Lys-320, 324, and Glu-366 for ATP binding. Co-localization studies revealed FIKK9.1 in the parasite cytosol with a component trafficked to the apicoplast and also to IRBC. FIKK9.1 has 23 pockets to serve as potential docking sites for substrates. Correlation analysis of peptides from the combinatorial library concluded that peptide P277 (MFDFHYTLGPMWGTL) was fitting nicely into the binding pocket. The peptide P277 picked up candidates from parasite and key players from RBC cytoskeleton. Interestingly, FIKK9.1 is phosphorylating spectrin, ankyrin, and band-3 from RBC cytoskeleton. Our study highlights the structural and biochemical features of FIKK9.1 to exploit it as a drug target.

Potentials of PKC in Cancer Progression and Anticancer Drug Development

PKC is a family of serine-threonine kinases which play crucial roles in the regulation of important signal transduction pathways in mammalian cell-biology. These enzymes are themselves regulated by various molecules that can serve as ligands to the regulatory domains and translocate PKC to membrane for activity. The role of PKC in the modulation of both proliferative and apoptotic signaling in cancer has become a subject of immense interest after it was discovered that PKC regulates a myriad of enzymes and transcription factors involved in carcinogenic signaling. Therefore, PKC has served as an attractive target for the development of newer generation of anti-cancer drugs. The following review discusses the potential of PKC to be regarded as a target for anti-cancer therapy. We also review all the molecules that have been discovered so far to be regulators/activators/inhibitors of PKC and also how far these molecules can be considered as potential candidates for anti-cancer drug development based on PKC.

Insulin signalling in RBC is responsible for growth stimulation of malaria parasite in diabetes patients

A cross-talk between diabetes and malaria within-host is well established. Diabetes is associated with modulation of the immune system, impairment of the healing process and to disturb the host metabolism to contribute towards propagation of parasite infection. Glucose metabolism in host is maintained by insulin and RBC has 2000 insulin receptor present on plasma membrane. These receptors are robust to relay down-stream signaling in RBCs but role of intracellular signaling in parasite growth is not been explored. The malaria parasite treated with insulin (100 ng/ml) is giving stimulation in parasite growth. The effect is lasting for several generations resulting into high parasitemia. Insulin signaling is phosphorylating protein in infected RBCs and level is high in parasite RBCs compared to uninfected RBCs. It is phosphorylating Spectrin-(α/β), Band-4.2, Ankyrin and the other proteins of RBC cytoskeleton. It in-turn induces enhanced glucose uptake inside infected RBCs. There is a high level of infection of normal RBCs by merozoites. In summary, insulin and glucose metabolism plays a crucial role in parasite propagation, disease severity and need consideration while treating patients.

Therapeutic Potentials of Scavenger Receptor CD36 Mediated Innate Immune Responses Against Infectious and Non-Infectious Diseases

CD36 is a multifunctional glycoprotein, expressed in different types of cells and known to play a significant role in the pathophysiology of the host. The structural studies revealed that the scavenger receptor consists of short cytosolic domains, two transmembrane domains, and a large ectodomain. The ectodomain serves as a receptor for a diverse number of endogenous and exogenous ligands. The CD36-specific ligands are involved in regulating the immune response during infectious and non-infectious diseases in the host. The role of CD36 in regulating the innate immune response during Pneumonia, Tuberculosis, Malaria, Leishmaniasis, HIV, and Sepsis in a ligand- mediated fashion. Apart from infectious diseases, it is also considered to be involved in metabolic disorders such as Atherosclerosis, Alzheimer's, cancer, and Diabetes. The ligand binding to scavenger receptor modulates the CD36 down-stream innate immune response, and it can be exploited to design suitable immuno-modulators. Hence, the current review focused on the role of the CD36 in innate immune response and therapeutic potentials of novel heterocyclic compounds as CD36 ligands during infectious and non-infectious diseases.

Conformationally constrained peptides for drug delivery

Peptides have shown great potential in acting as template for developing versatile carrier platforms in nanomedicine, aimed at selective delivery of drugs to only pathological tissues saving its normal neighbors. Cell-penetrating peptides (CPPs) are short oligomeric peptides capable of translocating across the cell membrane while simultaneously employing multiple mechanisms of entry. Most CPPs exist as disordered structures in solution and may adopt a helical conformation on interaction with cell membrane, vital to their penetrative capability. Herein, we report a series of cationic helical amphipathic peptides (CHAPs), which are topologically constrained to be helical. The peptides were tested against cervical and breast cancer cells for their cell penetration and drug delivery potential. The cellular uptake of CHAP peptides is independent of temperature and energy availability. The activity of the peptides is biocompatible in bovine serum. CHAPs delivered functional methotrexate (MTX) inside the cell as CHAP-MTX conjugates. CHAP-MTX conjugates were more toxic to cancer cells than MTX alone. However, the CHAP-MTX conjugates were less toxic to HEK-293 cells compared with the cancer cells suggesting higher affinity towards cancer cells.

Severe malaria: Biology, clinical manifestation, pathogenesis and consequences

Every year, millions of people are infected with malaria, resulting in significant economic losses to the developing and developed nations. The malaria parasite pursues a complicated life cycle in an invertebrate, mosquito and vertebrate host with several distinct stages. In the human host, it invades the liver and red blood cells to complete its life cycle. It is surprising that not only these two organs are under pressure and exhibit functional abnormalities; a large number of clinical studies also support the notion that malaria parasite propagation in the host affects several other organs and modulates functional outcomes of individual cells. Moreover, patients recovered from severe malaria may suffer throughout their life from impairments in organ function such as loss of eyesight, kidney failure, and much more. Thus, malaria infection leads to several pathological outcomes involving different organs and individual cells in the host. The sole purpose of the present article was to give an overview of pathological outcomes during severe malaria along with their molecular mechanisms. A large proportion of deaths associated with disease is contributed by the pathological effect in host due to parasite propagation and toxicity of antimalarials or combination of both. Hence, there is a need, not only to develop antiparasitic agents but also to discover lead molecules to take care of pathophysiological effects in the host. This may help a beginner to get involved with the topic and initiate research work towards improving adjuvant therapy or avoiding serious complications.

Extracellular methemoglobin promotes cyto-adherence of uninfected RBC to endothelial cells: Insight into cerebral malaria pathology

The endothelial cell barrier is tightly regulated, and disruption or the leaky behavior of the barrier leads to pathology. Disturbance of blood-brain barrier is observed during viral infection, cerebral malaria, and acute hemorrhagic encephalitis. Red blood cells (RBCs) bind to the endothelial cells (ECs) and their affinity towards ECs enhances in the presence of Plasmodium falciparum infection. ECs stimulated with methemoglobin (MetHb; 20 µM) for 1 hour exhibit high levels of cyto-adherence receptors CD36 and ICAM-1 on their cell surface compared with unstimulated cells. These ECs have acquired affinity towards uninfected RBCs in flow at arterial shear stress. SEM analysis indicates that EC-RBC cyto-adherence involved multiple attachment points. Initially, ECs bind single layer of RBCs and the number of RBCs increases over time to give high-order cyto-adherence with more than 30 RBCs adhered to each endothelial cell. The cyto-adherence complexes are stable to high shear stress and can withstand shear stress up to 450 dyne/cm ² . MetHb-treated ECs exhibited high reactive oxygen species level, and preincubation of ECs with antioxidant (NAC or mannitol) abolished the formation of EC-RBC cyto-adherence complexes. In addition, gallic acid (present in red wine) and green tea extract has inhibited the formation of EC-RBC cyto-adherence complex. A better understanding of gallic acid and tea polyphenol targeting pathological cyto-adherence may allow us to develop a better adjuvant therapy for cerebral malaria and other noninfectious diseases.

Syndiotactic peptides for targeted delivery

Lack of cell-type specificity and proteolytic susceptibility have long been the major bottlenecks for the development of peptide-based biomaterials for targeted drug delivery. Though a poly-l backbone provides the adaptability to re-conform the peptide structure to bind to a receptor, it also makes the peptide more susceptible to proteolytic cleavage. We have attempted to address this issue by designing a set of syndiotactic peptides de novo, with alternating l- and d-amino acids in succession. The designed peptides have higher rates of cellular uptake than the Tat (48-60) peptide in breast and cervical cancer cells. The uptake is independent of concentration, temperature and endocytosis (clathrin mediated). Importantly, the peptides are stable in both human plasma and bovine serum. The peptide-drug conjugates are much less toxic to the non-cancerous cells than cancer cells. The designed peptides are a step forward towards the development of targeted drug delivery vectors on peptide templates. STATEMENT OF SIGNIFICANCE: Present options in chemotherapy have multiple side effects arising from the lack of cell-type specificity, which makes them synonymous with "a Pyrrhic victory". Proteolytic susceptibility and non-specificity towards cancer cells has stunted the development of peptide-based biomaterials for targeted drug delivery. We have designed a set of peptides, addressing the above-mentioned roadblocks at an in vitro level. The peptides were designed on the template of a naturally existing peptide antibiotic from Bacillus brevis. The designed peptides have higher rates of cellular transduction than the model peptide (Tat), and is majorly membrane based. The peptides are stable in serum and selective towards cancer cells. Observations presented in this work can potentially take the discipline of de novo design of biomaterial conjugates forward.

Virtual Screening, Molecular Modelling and Biochemical Studies to Exploit PF14_0660 as a Target to Identify Novel Anti-malarials

Background:

Malaria Parasite relies heavily on signal transduction pathways to control growth, the progression of the life cycle and sustaining stress for its survival. Unlike kinases, Plasmodium's phosphatome is one of the smallest and least explored for identifying drug target for clinical intervention. PF14_0660 is a putative protein present on the chromosome 14 of Plasmodium falciparum genome.

Methods:

Multiple sequence alignment of PF14_0660 with other known protein phosphatase indicate the presence of phosphatase motif with specific residues essential for metal binding, catalysis and providing structural stability. PF14_0660 is a mixed α/β type of protein with several β -sheet and α-helix arranged to form βαβαβα sub-structure. The surface properties of PF14_0660 is conserved with another phosphate of this family, but it profoundly diverges from the host protein tyrosine phosphatase. PF14_0660 was cloned, over-expressed and protein is exhibiting phosphatase activity in a dose-dependent manner. Docking of Heterocyclic compounds from chemical libraries into the PF14_0660 active site found nice fitting of several candidate molecules.

Results:

Compound PPinh6, PPinh 7 and PPinh 5 are exhibiting antimalarial activity with an IC50 of 1.4 ± 0.2µM, 3.8 ± 0.3 µM and 9.4 ± 0.6&#181M respectively. Compound PPinh 6 and PPinh 7 are inhibiting intracellular PF14_0660 phosphatase activity and killing parasite through the generation of reactive oxygen species.

Conclusion:

Hence, a combination of molecular modelling, virtual screening and biochemical study allowed us to explore the potentials of PF14_0660 as a drug target to design anti-malarials.

Plasmodium falciparum PFI1625c offers an opportunity to design potent anti-malarials: Biochemical characterization and testing potentials in drug discovery

Putative PFI1625c was cloned, over-expressed and purified to homogeneity. It is a 56.2 kDa monomeric protease which preferentially catalyzes the degradation of gelatin with a K_m = 30μM. It is a slow acting enzyme with optimal pH 8.5 and temperature 37 °C, and activity is sensitive to metalloprotease inhibitor 1,10-phenanthroline. PFI1625c active site was probed with a series of heterocyclic compounds and three molecules namely, BNPC-Inh2, DDBM-Inh1 and BHPM-Inh1 from the series were inhibiting PFI1625c protease activity. These heterocyclic compounds were found to irreversible inhibiting PFI1625c protease activity. Parasite culture was treated with these inhibitors and PFI1625c isolated from culture was found to be inactive without affecting other gelatinases present in the parasite. These inhibitors were used to generate chemically knockout PFI1625c in the parasite. PFI1625c knockout parasite remained at ring stage and was unable to complete its erythrocytic schizogony. Also, these knockout parasites were incapable to multiply. More careful analysis indicate these parasites develop oxidative stress as evident by the increase in lipid peroxidation, protein-carbonyl and a decrease of GSH level. In summary, the current study has employed biochemical, computational and pharmacological approaches to explore the role of PFI1625c in the parasite, its utility as a potential drug target to develop anti-malarials.

A dinitro-functionalized metal-organic framework featuring visual and fluorogenic sensing of H2S in living cells, human blood plasma and environmental samples

Here, we describe a new dinitro-functionalized Zr(iv) MOF (MOF = metal-organic framework) having a UiO-66 (UiO = University of Oslo) framework topology called UiO-66-(NO₂)₂ (1). It shows fluorescence turn-on behavior towards H₂S in simulated biological medium (HEPES buffer, pH = 7.4). By employing solvothermal conditions, 1 was successfully synthesized by reacting ZrCl₄, H₂BDC-(NO₂)₂ [H₂BDC-(NO₂)₂ = 2,5-dinitro-1,4-benzenedicarboxylic acid] ligand and benzoic acid with a molar ratio of 1 : 1 : 10 in DMF (DMF = N,N-dimethylformamide) at 130 °C for 24 h. The material was characterized by infrared spectroscopy, X-ray powder diffraction (XRPD) and thermogravimetric (TG) analyses. The compound not only displays highly sensitive fluorometric sensing of H₂S but also exhibits a visually detectable colorimetric change towards H₂S in daylight. Moreover, the high selectivity of 1' towards H₂S is retained even when several other biologically intrusive species co-exist in the sensing medium. The limit of detection (LOD) of the compound is 14.14 μM which lies in the range of the H₂S concentration found in biological systems. Fluorescence microscopy studies on J774A.1 cells revealed the efficacy of the probe for imaging H₂S in living cells. Moreover, this material can detect H₂S in human blood plasma (HBP) and monitor the sulfide concentration in real water samples. All these features clearly demonstrate that the material has huge potential for highly selective sensing of both extracellular and intracellular H₂S.

A dual functional MOF-based fluorescent sensor for intracellular phosphate and extracellular 4-nitrobenzaldehyde

A hydrazine-functionalized Zr(iv) MOF was used for the selective and sensitive detection of intracellular PO₄³⁻ ions and extracellular 4-nitrobenzaldehyde.

A phthalimide-functionalized UiO-66 metal–organic framework for the fluorogenic detection of hydrazine in live cells

A phthalimide-functionalized Zr(iv) UiO-66 MOF was utilized for fluorogenic detection of hydrazine in HEPES buffer and inside living cells.

Selective and Sensitive Sensing of Hydrogen Peroxide by a Boronic Acid Functionalized Metal-Organic Framework and Its Application in Live-Cell Imaging

A new boronic acid functionalized Zr(IV) metal-organic framework having the capability of sensing H₂O₂ in live cells is reported. The Zr-MOF bears a UiO-66 structure and contains 2-boronobenzene-1,4-dicarboxylic acid (BDC-B(OH)₂) as a framework linker. The activated Zr-UiO-66-B(OH)₂ compound (called 1') is highly selective for the fluorogenic detection of H₂O₂ in HEPES buffer at pH 7.4, even in the presence of interfering ROS (ROS = reactive oxygen species) and other biologically relevant analytes. The fluorescent probe was found to display extraordinary sensitivity for H₂O₂ (detection limit 0.015 μM) in HEPES buffer, which represents a lower value in comparison to those of the MOF probes documented so far for sensing H₂O₂ using other analytical methods. Taking advantage of its high selectivity and sensitivity for H₂O₂ in HEPES buffer, the probe was successfully employed for the imaging of intracellular H₂O₂. Imaging studies with MDAMB-231 cells revealed the emergence of bright blue fluorescence after loading with probe 1' and subsequent treatment with H₂O₂ solution.

Mapping of phosphatidylserine recognition region on CD36 ectodomain

CD36-PS interaction is an important affair to identify and remove dead/aged cells to control inflammation. CD36 ectodomain was cloned, over-expressed in bacterial expression system and purified to homogeneity. The dot-blot analysis shows that the CD36_ecto selectively binds PS vesicles blotted on the nitrocellulose membrane. PS binds strongly to CD36_ecto with a dissociation constant K_D of 53.7 ± 0.48 μM. The stoichiometry of interaction between CD36 and PS is 1:2. The hCD36_ecto-PS thermogram revealed that the hydrophobic and salt bridge interactions play crucial role in their interactions. PS docked nicely into the predicted pharmacophoric site with a binding energy of 5.1 kcal/mol. Analysis of CD36-PS molecular model showed that the residues R63, R96, N118, D270 and E418 were forming hydrogen bonds with PS. Molecular dynamics simulations indicate that R63 mutation has disrupted the integrity of biophoric constituents, directly affecting the hydrogen bonding from R96, N118 and D270. ITC thermogram analysis of mutant protein with PS vesicles indicate complete loss of binding with R63A and very low affinity of PS vesicles with D270A. Dot blot analysis further confirmed the ITC results. These finding may help to design suitable agents mimicking PS biophore with potentials in diagnostics of apoptotic cells and cardiovascular intervention.

Remarkably Efficient Blood-Brain Barrier Crossing Polyfluorene-Chitosan Nanoparticle Selectively Tweaks Amyloid Oligomer in Cerebrospinal Fluid and Aβ1-40

Amyloid oligomers have emerged as a key neurotoxin in Alzheimer's dementia. Amyloid aggregation inhibitors and modulators have therefore offered potential applications in therapeutics and diagnosis. However, crossing the blood-brain barrier (BBB) and finding the toxic aggregates among aggregates of different sizes and shapes remain a challenge. The ability of identifying early aggregates can provide a new approach to find inhibitors of the initial nucleation events correlating presenile dementia. In this study, we have prepared polyfluorene nanoparticles using chitosan as an additive, which enables it to cross BBB efficiently and employed as a highly efficient amyloid oligomer modulator. The polymer conjugate, polyfluorene-chitosan (PC), shows no toxicity in MTT assay and precludes self-aggregation of Aβ1-40 and human cerebrospinal fluid oligomers to final fibril formation. This modulation strategy is supported by thioflavin T assay, circular dichroism studies, atomic force microscope images, and Fourier transform infrared analysis. The polymer-protein interface exhibits the presence of co-aggregates and responded with a stable optical response. The simple synthesis to get desired sizes and shapes with necessary photophysical behavior, biocompatibility, and most prominently BBB permeability makes this polymer conjugate very unique and highly attractive for modulation of amyloid oligomers selectively as well as for developing next generation nanotheranostic materials toward presenile dementia.

Survival and prognostic factors for glioblastoma multiforme: Retrospective single-institutional study

INTRODUCTION

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults. The standard management has been maximum surgical resection followed by adjuvant radiotherapy with concurrent chemotherapy followed by adjuvant chemotherapy. Although the survival rate of patients with GBM has improved with recent advancements in treatment, the prognosis remains generally poor. The median survival rates are in the range of 9-12 months and 2-year survival rates are in the range of 8%-12%.

MATERIALS AND METHODS

A single-institution retrospective review of 61 patients of GBM from 2012 to 2014. Data regarding patient factors, disease factors, and treatment factors were collected and survival has been calculated.

RESULTS

A total of 61 patients with GBM were analyzed. GBM is commonly seen in sixth decade of life. Male to female ratio is 2.6:1. The right side of the brain is commonly involved with right frontal lobe being the most common site. The median follow-up was 4.6 months. The median survival of our patients was 8 months. The 1-year and 2-year survival rates were 20% and 3.27%, respectively.

CONCLUSIONS

The overall survival and prognosis in patients with GBM remains poor despite of constant research and studies. Concurrent chemoradiotherapy followed by adjuvant chemotherapy with temozolomide should be used after maximal resection to improve the survival.

Evidence of PKC Binding and Translocation to Explain the Anticancer Mechanism of Chlorogenic Acid in Breast Cancer Cells

Chlorogenic acid (CGA) exhibits potentials towards liver, breast and skin cancer. Cancer cells stimulated with CGA exhibits differential expression of transcriptional factors and regulatory molecules but the molecular target of the molecule is not known. Superposition of biophoric elements of CGA with Curcumin gives maximum common substructure score of 0.90. Molecular modeling studies further suggest that CGA fits into the C1b domain of PKC with extensive interaction with residues lining binding site. It binds PKC in a concentration dependent manner with dissociation constant KD, 28.84±3.95 μM. PKC-CGA complex is stable with minimal distortion to the 3-D structure and maintains the hydrogen bonding between ligand and receptor during simulation period. Cells stimulated with CGA causes 12.1 ± 0.56% PKC translocation from the cytosol to the plasma membrane. It disturbs the cell cycle and arrest the cancer cell at the G1 phase with a reduction in S-phase. Chlorogenic acid exhibits killing of cancer cells in a dose-dependent manner with an IC50 of 75.88 ± 4.54μg/ml and 52.5 ± 4.72μg/ml towards MDAMB-231 and MCF-7 cells respectively. It induces apoptosis in cancer cells as evident by AO/EtBr staining and degradation of genomic DNA to give a laddering pattern. Apoptosis in cancer cells involves mitochondrial pathway as supported by a reduction in mitochondrial potentials and release of cyt-C into the cytosol. Hence, the current study has established PKC as an important signaling molecule to the observed anti-cancer effects of CGA and provides the impetus to design better CGA analogs for improved anti-cancer potential against the malignant tumor.

Extraordinary sensitivity for H2S and Fe(iii) sensing in aqueous medium by Al-MIL-53-N3 metal-organic framework: in vitro and in vivo applications of H2S sensing

An Al(iii) metal-organic framework (MOF) called Al-MIL-53-N₃ (1) was synthesized under solvothermal reaction conditions using Al(NO₃)₃·9H₂O and H₂BDC-N₃ (H₂BDC-N₃ = 2-azido-1,4-benzenedicarboxylic acid) ligand in a DMF/water (DMF = N,N-dimethylformamide) mixture. Phase purity was checked by performing X-ray powder diffraction, infrared spectroscopy and thermogravimetric analysis. Thermogravimetric analysis suggests that 1 is highly stable up to 300 °C under air atmosphere. The activated 1 (called 1') showed a very fast fluorescence response to H₂S (turn-on) and Fe(iii) ions (turn-off) in an aqueous medium with excellent sensitivity and selectivity even in the presence of other potentially intrusive analytes. In the presence of H₂S, the conversion of the azide moiety to amine is responsible for the fluorescence turn-on properties. On the other hand, the partial replacement of framework Al(iii) ions by Fe(iii) can be assigned for the selective detection behavior to Fe(iii) ions. The detection limits (90.47 nM for H₂S and 0.03 μM for Fe(iii) ions in water) of 1' are lower than those of the formerly reported MOF type of fluorescent sensors. The 1'-loaded J774A.1 macrophage cells are healthy and respond to intracellular H₂S to exhibit strong blue fluorescence, confirming its suitability to detect H₂S inside the cells. In addition, 1' can detect H₂S in human blood plasma (HBP) and sulfide ions in real water samples. These features make 1' a very promising candidate for the on-site sensing of Fe(iii) ions and the detection of intracellular and extracellular H₂S.

Integrating virtual screening and biochemical experimental approach to identify potential anti-cancer agents from drug databank

Chemical libraries constitute a reservoir of pharmacophoric molecules to identify potent anti-cancer agents. Virtual screening of heterocyclic compound library in conjugation with the agonist-competition assay, toxicity-carcinogenicity analysis, and string-based structural searches enabled us to identify several drugs as potential anti-cancer agents targeting protein kinase C (PKC) as a target. Molecular modeling study indicates that Cinnarizine fits well within the PKC C2 domain and exhibits extensive interaction with the protein residues. Molecular dynamics simulation of PKC-Cinnarizine complex at different temperatures (300, 325, 350, 375, and 400[Formula: see text]K) confirms that Cinnarizine fits nicely into the C2 domain and forms a stable complex. The drug Cinnarizine was found to bind PKC with a dissociation constant Kd of [Formula: see text]M. The breast cancer cells stimulated with Cinnarizine causes translocation of PKC-[Formula: see text] to the plasma membrane as revealed by immunoblotting and immunofluorescence studies. Cinnarizine also dose dependently reduced the viability of MDAMB-231 and MCF-7 breast cancer cells with an IC[Formula: see text] of [Formula: see text] and [Formula: see text]g/mL, respectively. It is due to the disturbance of cell cycle of breast cancer cells with reduction of S-phase and accumulation of cells in G1-phase. It disturbs mitochondrial membrane potentials to release cytochrome C into the cytosol and activates caspase-3 to induce apoptosis in cancer cells. The cell death was due to induction of apoptosis involving mitochondrial pathway. Hence, the current study has assigned an additional role to Cinnarizine as an activator of PKC and potentials of the approach to identify new molecules for anti-cancer therapy. Thus, in silico screening along with biochemical experimentation is a robust approach to assign additional roles to the drugs present in the databank for anti-cancer therapy.

Myocardial Perfusion Scans and Mortality in Asymptomatic Patients Awaiting Renal Transplantation

Cardiac risk assessment for asymptomatic patients awaiting renal transplantation is controversial. Patients awaiting renal transplantation in Southern Saskatchewan from 2005 to 2015 were retrospectively reviewed. Patients underwent cardiac risk stratification with stress myocardial perfusion scan. Baseline clinical characteristics, nuclear scan results, all-cause mortality, and cardiovascular events were analyzed. Abnormal scans were defined as studies with reversible defects, wall motion abnormalities, lung uptake, or transient ischemic dilation. Descriptive statistics and survival analysis were calculated. Charts from 285 consecutive patients with 608 nuclear scans were analyzed. Mean age was 55.2 ± 11.7 years and 34.7% were female. Forty-three (15.1%) patients were transplanted and 99 (40.9%) patients died while awaiting renal transplantation. One hundred fifty-three patients (63.2%) had at least one abnormal scan. The mean follow-up period was 5.47 ± 3.11 years. An abnormal scan was not associated with decreased survival and/or coronary events (hazard ratio: 0.94, P = .77; 95% confidence intervals: 0.62 to 1.43). Patients awaiting renal transplantation in Saskatchewan with abnormal myocardial perfusion scans were not at greater risk of death or coronary events.

Improving the frying performance of RBD palm olein oil using NaturFORT™ TRLG 101 liquid as on-top of TBHQ in deep-fat frying of potato chips

Improvement in the frying performance of palmolein oil with NaturFORT™ TRLG 101 (TRLG 101) liquid in addition to tert-butyl hydroquinone (TBHQ) has been evaluated. Four treatment groups (Negative control, 200 ppm TBHQ, 200 ppm TBHQ + 400 ppm TRLG 101 liquid and 200 ppm TBHQ + 750 ppm TRLG 101 liquid) were added to RBD (Refined, Bleached and Deodorized) palm olein oil which was used to produce potato chips. Frying trials were conducted for 120th frying cycles. The oil samples were analyzed for peroxide value, free fatty acid, p-anisidine value, oxidative stability index, %total polar compounds and Chroma (C*) values after every 20 frying cycles. Potato chips were analyzed for Chroma (C*) values after every 20 frying cycles. The results of oxidative stability index, total polar compounds and p-anisidine value showed that the addition of NaturFORT™ TRLG 101 liquid at 750 ppm had showed significantly better performance followed by the addition of NaturFORT™ TRLG 101 liquid at 400 ppm. Thus, the addition of NaturFORT™ TRLG 101 liquid as on top of TBHQ contributes to the improvement in the frying performance of palm olein oil with subject to their dosage and this could be a better solution for frying industries which would like to get extra frying cycles for their products without encountering the regulatory hurdles posed by the limitations of using such additives.

Synthesis and evaluation of oxindoles as promising inhibitors of the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1

Indoleamine 2,3-dioxygenase 1 (IDO1) is considered as an important therapeutic target for the treatment of cancer, chronic infections and other diseases that are associated with immune suppression. Recent developments in understanding the catalytic mechanism of the IDO1 enzyme revealed that conversion of l-tryptophan (l-Trp) to N-formylkynurenine proceeded through an epoxide intermediate state. Accordingly, we synthesized a series of 3-substituted oxindoles from l-Trp, tryptamine and isatin. Compounds with C3-substituted oxindole moieties showed moderate inhibitory activity against the purified human IDO1 enzyme. Their optimization led to the identification of potent compounds, 6, 22, 23 and 25 (IC₅₀ = 0.19 to 0.62 μM), which are competitive inhibitors of IDO1 with respect to l-Trp. These potent compounds also showed IDO1 inhibition potencies in the low-micromolar range (IC₅₀ = 0.33-0.49 μM) in MDA-MB-231 cells. The cytotoxicity of these potent compounds was trivial in different model cancer (MDA-MB-231, A549 and HeLa) cells and macrophage (J774A.1) cells. Stronger selectivity for the IDO1 enzyme (124 to 210-fold) over the tryptophan 2,3-dioxygenase (TDO) enzyme was also observed for these compounds. These results suggest that the oxindole moiety of the compounds could mimic the epoxide intermediate state of l-Trp. Therefore, the structural simplicity and low-micromolar inhibition potencies of these 3-substituted oxindoles make them quite attractive for further investigation of IDO1 function and immunotherapeutic applications.

Isolation and quantification of antimalarial N-alkylamides from flower-head derived in vitro callus cultures of Spilanthes paniculata

This is the pioneer work reporting on simple procedure for synchronized determination and quantification of two biologically active N-alkylamides, (2E,6Z,8E)-N-isobutyl-2,6,8-decatrienamide (spilanthol) and (2E,4Z)-N-isobutyl-2,4-undecadiene-8,10-diynamide (UDA), using in vitro callus cultures from flower-heads of Spilanthes paniculata. The extracts were purified using preparative thin layer chromatography (TLC) and finest separation of compounds was optimized using high performance liquid chromatography (HPLC). Eventually, N-alkylamides were validated by mass spectrometry. Linearity curve with its regression coefficients (R²) obtained for both these alkylamides was 0.99. While spilanthol was quantified using tentative standard dodeca-2(E),4(E)-dienoic acid due to the non-availability of commercial standard and the precision of a developed method was evaluated in terms of relative standard deviation by measuring inter- and intra-days variation 3.52% and 1.74%, respectively. Similarly, calibration curve was obtained for the compound UDA isolated from flower-head explants from field grown parental plant with its inter- and intra-day RSD values as 4.33% and 3.61%, respectively. With this protocol, a very high yield of 2.23 mg/g of spilanthol and 4.30 mg/g dry weight (DW) of UDA, was obtained, simultaneously, from callus cultures. Flower-heads from parent plants, used as control, showed negligible amount of spilanthol and quantity of UDA was marginally higher than that in callus cultures. The highly stable biotherapeutic spilanthol and UDA with m/z 222 and m/z 230, respectively, showed retardation of malaria parasite development through blockage at ring stage of erythrocytic schizogony and ultimately lead to parasite death. The effect on parasite was additive. This study signifies the utility of in vitro cell cultures for therapeutic compound production, throughout the year, at higher yield for down-stream applications.

Cloning, Overexpression, Purification and Immunolocal-ization of PFD0975w from the Malaria Parasite Plasmodium falciparum

Malaria is a parasitic disease, widespread along the tropical regions of the world. The disease has killed 4, 38,000 individuals in the year 2015 (WHO). The malaria parasite, Plasmodium falciparum, has evolved resistance to front-line antimalarials over the decade, necessitating the identification of new drug targets. Protein kinases are excellent drug targets since they participate in critical cell-signaling cascades. We have identified a putative RIO-like protein kinase, PFD0975w, from the Plasmodium kinome. It is believed to play a key role in ribosome biogenesis. We have cloned and over-expressed the protein in E. coli and purified it to homogeneity. The recombinant protein is of molecular weight 36.3±1.2 kDa. Purified recombinant PFD0975w is active in vitro and binds ATP. PFD0975w exhibits a unique localization pattern in each RBC stage. PFD0975w localizes within the parasite cytosol during ring stage and spread throughout the infected RBCs during trophozoite and schizont stages with the strongest expression signal during the trophozoite phase indicating the importance of the enzyme in parasite growth and survival. Interestingly, the localization pattern of the protein also responds to stress conditions such as starvation and antimalarial drug pressure. It exhibits punctuate pattern in the treated parasite during trophozoite and schizont stages compared to untreated parasites, indicating some role of the putative kinase in cellular stress handling. Our results indicate PFD0975w is a potential drug target in the malaria parasite and active recombinant PFD0975w can be exploited to identify, validate or design novel inhibitors.