Identification of Plasmodium falciparum heat shock 90 inhibitors via molecular docking.

A virtual screen was performed to identify anti-malarial compounds targeting Plasmodium falciparum heat shock 90 protein by applying a series of drug-like and commercial availability filters to compounds in the ZINC database, resulting in a virtual library of more than 13 million candidates. The goal of the virtual screen was to identify novel compounds which could serve as a starting point for the development of antimalarials with a mode of action different from anything currently used in the clinic. The screen targeted the ATP binding pocket of the highly conserved Plasmodium heat shock 90 protein, as this protein is critical to the survival of the parasite and has several significant structural differences from the human homolog. The top twelve compounds from the virtual screen were tested in vitro, with all twelve showing no antiproliferative activity against the human fibroblast cell line and three compounds exhibiting single digit or better micromolar antiproliferative activity against the chloroquine-sensitive P. falciparum 3D7 strain.

Antimalarial activity of 2,6-dibenzylidenecyclohexanone derivatives.

Malaria remains one of the deadliest infectious diseases worldwide and continues to infect hundreds of millions of individuals each year. Here we report the discovery and derivatization of a series of 2,6-dibenzylidenecyclohexanones targeting the chloroquine-sensitive 3D7 strain of Plasmodium falciparum . While the initial lead compound displayed significant toxicity in a human cell proliferation assay, we were able to identify a derivative with no detectable toxicity and sub-micromolar potency.

Antimalarial activity of tetrahydro-ß-carbolines targeting the ATP binding pocket of the Plasmodium falciparum heat shock 90 protein.

A series of tetrahydro-ß-carboline derivatives of a lead compound known to target the heat shock 90 protein of Plasmodium falciparum were synthesized and assayed for both potency against the parasite and toxicity against a human cell line. Using a rationalized structure based design strategy, a new lead compound with a potency two orders of magnitude greater than the original lead compound was found. Additional modeling of this new lead compound suggests multiple avenues to further increase potency against this target, potentially paving the path for a therapeutic with a mode of action different than any current clinical treatment.

Evaluation of 1,1-cyclopropylidene as a thioether isostere in the 4-thio-thienopyrimidine (TTP) series of antimalarials.

The 4-(heteroarylthio)thieno[2,3-d]pyrimidine (TTP) series of antimalarials, represented by 1 and 17, potently inhibit proliferation of the 3D7 strain of P. falciparum (EC50 70-100 nM), but suffer from oxidative metabolism. The 1,1-cyclopropylidene isosteres 6 and 16 were designed to obviate this drawback. They were prepared by a short route that features a combined Peterson methylenation / cyclopropanation transformation of, e. g., ketone 7. Isosteres 6 and 16 possess significantly attenuated antimalarial potency relative to parents 1 and 17. This outcome can be rationalized based on the increased out-of-plane steric demands of the latter two. In support of this hypothesis, the relatively flat ketone 7 retains some of the potency of 1, even though it appears to be a comparatively inferior mimic with respect to electronics and bond lengths and angles. We also demonstrate crystallographically and computationally an apparent increase in the strength of the intramolecular sulfur hole interaction of 1 upon protonation.

Computational Screening of Approved Drugs for Inhibition of the Antibiotic Resistance Gene mecA in Methicillin-Resistant Staphylococcus aureus (MRSA) Strains.

Antibiotic resistance is a critical problem that results in a high morbidity and mortality rate. The process of discovering new chemotherapy and antibiotics is challenging, expensive, and time-consuming, with only a few getting approved for clinical use. Therefore, screening already-approved drugs to combat pathogens such as bacteria that cause serious infections in humans and animals is highly encouraged. In this work, we aim to identify approved antibiotics that can inhibit the mecA antibiotic resistance gene found in methicillin-resistant Staphylococcus aureus (MRSA) strains. The MecA protein sequence was utilized to perform a BLAST search against a drug database containing 4302 approved drugs. The results revealed that 50 medications, including known antibiotics for other bacterial strains, targeted the mecA antibiotic resistance gene. In addition, a structural similarity approach was employed to identify existing antibiotics for S. aureus, followed by molecular docking. The results of the docking experiment indicated that six drugs had a high binding affinity to the mecA antibiotic resistance gene. Furthermore, using the structural similarity strategy, it was discovered that afamelanotide, an approved drug with unclear antibiotic activity, had a strong binding affinity to the MRSA-MecA protein. These findings suggest that certain already-approved drugs have potential in chemotherapy against drug-resistant pathogenic bacteria, such as MRSA.

Natural Perylenequinone Compounds as Potent Inhibitors of Schistosoma mansoni Glutathione S-Transferase.

The existing treatment strategy for Schistosomiasis centers on praziquantel, a single drug, but its effectiveness is limited due to resistance and lack of preventive benefits. Thus, there is an urgent need for novel antischistosomal agents. Schistosoma glutathione S-transferase (GST) is an essential parasite enzyme, with a high potential for targeted drug discovery. In this study, we conducted a screening of compounds possessing antihelminth properties, focusing on their interaction with the Schistosoma mansoni glutathione S-transferase (SmGST) protein. We demonstrated the unique nature of SmGST in comparison to human GST. Evolutionary analysis indicated its close relationship with other parasitic worms, setting it apart from free-living worms such as C. elegans. Through an assessment of binding pockets and subsequent protein-ligand docking, we identified Scutiaquinone A and Scutiaquinone B, both naturally derived Perylenequinones, as robust binders to SmGST. These compounds have exhibited effectiveness against similar parasites and offer promising potential as antischistosomal agents.

Prevalence of Entamoeba gingivalis and Trichomonas tenax among patients with periodontal disease attending Dental Clinic, University College Hospital, Ibadan.

Background: Periodontal disease is often caused by bacterial plaque. However, there are indications that some infective agents, including parasites, may play important roles in the pathogenesis of the disease. Aim: This study aimed at assessing the prevalence of gingivitis and periodontitis, as well as the prevalence of Entamoeba gingivalis and Trichomonas tenax, in the oral biofilm of individuals with periodontal diseases using polymerase chain reaction. Materials and Methods: One hundred and six respondents with periodontal disease participated in the study. All study participants had a full-mouth examination, and dental plaque samples were collected with a sterile curette. Samples were transported to the laboratory in a cold chain and stored frozen till analyzed. DNA was extracted from the samples and amplified using EGO and ENTAM primers for Entamoeba and TGBK primers for T. tenax. Results: The mean age of respondents was 45 ± 16.3 years, with none using tobacco. The prevalence of gingivitis and periodontitis obtained from this study was 84.9% and 15.1%. The prevalence obtained for Entamoeba and T. tenax was 0.9% each; however, no participant had both parasites. The positive samples were from male participants with moderate gingivitis. Conclusion: Gingivitis was more prevalent than periodontitis, though with a high preponderance in females. E. gingivalis and T. tenax may not be of etiologic importance in periodontal disease as they occurred sparsely in the studied population.

Synthesis and Structure-Activity Relationship of Dual-Stage Antimalarial Pyrazolo[3,4-b]pyridines.

Malaria remains one of the most deadly infectious diseases, causing hundreds of thousands of deaths each year, primarily in young children and pregnant mothers. Here, we report the discovery and derivatization of a series of pyrazolo[3,4-b]pyridines targeting Plasmodium falciparum, the deadliest species of the malaria parasite. Hit compounds in this series display sub-micromolar in vitro activity against the intraerythrocytic stage of the parasite as well as little to no toxicity against the human fibroblast BJ and liver HepG2 cell lines. In addition, our hit compounds show good activity against the liver stage of the parasite but little activity against the gametocyte stage. Parasitological profiles, including rate of killing, docking, and molecular dynamics studies, suggest that our compounds may target the Qo binding site of cytochrome bc1.

Molecular identification, in vivo and in vitro activities of Calvatia gigantea (macro-fungus) as an antidiabetic agent.

Mushrooms are cherished as sources of food, nutrients and medicine. Inadequate data on the identity and medicinal properties of many wild Nigerian mushrooms has limited their utilization. This work was carried out to identify and authenticate a puffball mushroom using molecular tools and investigate its antidiabetic properties. Taxonomic guides were employed in morphological identifying the mushroom as Lycoperdon umbrinum, methanol extract of fruiting bodies was evaluated for antidiabetic activity using in vitro α-amylase assay and in vivo activity in the alloxan-induced diabetic rat model. The macro fungus was identified using Internal Transcribed Spacers (ITS) sequence analysis after which sequences generated were compared using the basic local alignment search tool (BLAST) at NCBI GenBank. In the acute in vivo test, the 400 mg/kg dose showed the best activity with percentage reduction in blood glucose 29.3%, compared with 5 mg/kg glibenclamide at 15%. The in vitro assay established that the extract possessed potent activity with IC50 of 0.46 µg/mL compared to its DCM, butanol fractions and acarbose (IC50 5.3 µg/mL, 5.6 µg/mL, 45 µg/mL) respectively. BLAST analysis revealed the mushroom (accession number, KRO78278.1) to show 98% identity to Calvatia gigantea. The study established the identity of this mushroom and confirmed its antidiabetic activity.

Comparative Functional Study of Thioester-containing Related Proteins in the Recently Sequenced Genome of Biomphalaria glabrata.

BACKGROUND: There is paucity of information on functional relationship and characterization of Biomphalaria glabrata thioester-containing proteins (BgTEP) to other well-annotated homologues. We performed functional characterization studies of BgTEP to homologues in Anopheles gambiae and in disparate invertebrates. METHODS: Genomic sequences of TEPs were retrieved after annotation of the B. glabrata genome. In addition, TEP sequences deposited in NCBI protein database were also retrieved and utilized for sequence analysis. BgTEP relatedness to its other homologues as well as functional domain and protein-protein interaction analysis was performed. RESULTS: Our analysis resulted in the identification of TEPs in a number of organisms including, B. glabrata, A. gambiae, and Chlamys farreri. In addition, we identified 19 TEP sequences spread across 10 animal species. The B. glabrata genome contains 14190 unannotated proteins after filtration with about 85% of its proteome annotated. The phylogenetics, functional domain and protein-protein interaction analyses suggest an immunological role for BgTEP in B. glabrata. CONCLUSION: The predicted role of thioester-containing proteins to be involved in immunological role in B. glabrata may have a strong effect on resistance to infection.

Identification and characterization of sodium and chloride-dependent gamma-aminobutyric acid (GABA) transporters from eukaryotic pathogens as a potential drug target.

We explored 285 completed eukaryotic pathogen genomes for GABA transporter proteins as effective chemotherapy targets. We identified 8 GABA proteins that spread across 4 phyla with 5 different pathogen species; Eimeria mitis Houghton, Neospora caninum Liverpool, S. mansoni, S. haematobium and Trichinella spiralis. Sub-cellular localization prediction revealed that these proteins are integral membrane and are mostly insoluble. It is found that about 81% of these proteins are non-crystallizable and 15% are crystallizable. Transmembrane helices predictions show that the GABA transporters have 10, 11, 12 and 14 TMHs with 15, 23, 31 and 11%, respectively. It is further observed that most of these GABA transporters are from several parasites`genomes.

Analysis of antibiotics resistant genes in different strains of Staphylococcus aureus.

The control of Staphylococcus aureus infection is being hampered by methicillin and other resistant strains. The identification of the unique antibiotic resistant genes from the genomes of various strains of S. aureus is of interest. We analyzed 11 S. aureus genomes sequences for Antibiotics Resistance Genes (ARGs) using CARD 2017 platform. We identified 32 ARGs across 11 S. aureus strains. Tet(38), norB, lmrB, mepA and mepR were present across genomes except for S. aureus strain UTSW MRSA 55. The mepA and mepR were found across 11 different genomes. However, FosB3, vgaALC, mphC and SAT-4 were found in UTSW MRSA 55, S.a. strain ISU935 and S.a. strain FDAARGOS_159. The prevalent mode of mechanism of antibiotics resistant was efflux pump complex or subunit conferring antibiotic resistance as well as protein(s). Analysis of norB, ImrB, norA, ImrB, tet (38), sav1866 and mecA have 12 to 14 TMHs. The results help in the understanding of Staphylococcus aureus pathogenesis in the context of antibiotic resistance.

Efficacy of Lophira alata Leaf Extract and its Combination with Artesunate in Mice Prior Exposed to Plasmodium berghei.

Enhanced antimalarial activity of plant extracts used for treatment of malaria in endemic areas is attributed to partial immunity gained by prior infection. This suggests synergy between immunity and extract activity in treatment. Testing this hypothesis, rodent malaria was used to determine efficacy of Lophira alata leaf extracts in treating malaria in prior infected mice. One round of P. berghei infection and Pyrimethamine drug-cure was used to establish partial immunity in mice. Previously Exposed Mice (PEM) and Previously Unexposed Mice (PUM) mice challenged with P. berghei were used to determine influence of partial antimalarial immunity on efficacy of L. alata leaf extracts, administered alone or in combination with Artesunate (ART) in malaria treatment. There was a significant reduction in parasitemia in PEM when compared to PUM animals (P<0.001) irrespective of treatment regimen. Administration of L. alata combined with ART significantly reduced parasitemia (P<0.0032) and prolonged (P=0.0109) survival than when L. alata was administered alone in infected mice. These findings suggest that the action of L. alata in treating malaria infections in a murine model is enhanced by prior exposure to the malaria parasite. Thus the requirements of using plants in treating malaria in endemic populations may differ for those used in western systems, where trials are carried out with non-immune cohorts. Combining artemisinin derivatives and medicinal plants in malaria exposed populations may provide an alternative control measure in endemic regions and may justify the continued use of these plants by indigenous populations in treating malaria.

DNA barcoding of Clarias gariepinus, Coptodon zillii and Sarotherodon melanotheron from Southwestern Nigeria.

DNA barcoding has been adopted as a gold standard rapid, precise and unifying identification system for animal species and provides a database of genetic sequences that can be used as a tool for universal species identification. In this study, we employed mitochondrial genes 16S rRNA (16S) and cytochrome oxidase subunit I (COI) for the identification of some Nigerian freshwater catfish and Tilapia species. Approximately 655 bp were amplified from the 5' region of the mitochondrial cytochrome C oxidase subunit I (COI) gene whereas 570 bp were amplified for the 16S rRNA gene. Nucleotide divergences among sequences were estimated based on Kimura 2-parameter distances and the genetic relationships were assessed by constructing phylogenetic trees using the neighbour-joining (NJ) and maximum likelihood (ML) methods. Analyses of consensus barcode sequences for each species, and alignment of individual sequences from within a given species revealed highly consistent barcodes (99% similarity on average), which could be compared with deposited sequences in public databases. The nucleotide distance between species belonging to different genera based on COI ranged from 0.17% between Sarotherodonmelanotheron and Coptodon zillii to 0.49% between Clarias gariepinus and C. zillii, indicating that S. melanotheron and C. zillii are closely related. Based on the data obtained, the utility of COI gene was confirmed in accurate identification of three fish species from Southwest Nigeria.

Cytochrome c and c1 heme lyases are essential in Plasmodium berghei.

Malaria parasites possess a de novo heme synthetic pathway. Interestingly, this pathway is dispensable during the blood stages of development in mammalian hosts. The assembly of the two most important hemeproteins, cytochromes c and c1, is mediated by cytochrome heme lyase enzymes. Plasmodium spp. possess two cytochrome heme lyases encoded by separate genes. Given the redundancy of heme synthesis, we sought to determine if heme lyase function also exhibits redundancy. To answer this question, we performed gene knockout experiments. We found that the PBANKA_143950 and PBANKA_0602600 Plasmodium berghei genes encoding cytochrome c (Pbcchl) and cytochrome c1 (Pbcc1hl) heme lyases, respectively, can only be disrupted when a complementary gene is present. In contrast, four genes in the de novo heme synthesis pathway can be disrupted without complementation. This work provides evidence that Pbcchl and Pbcc1hl are both essential and thus may be antimalarial targets.