Mofolusho O. Falade

In vitro antiplasmodial activity and toxicity assessment of some plants from Nigerian ethnomedicine

Context: The emergence and spread of Plasmodium falciparum-resistant parasites to nearly all available antimalarial drugs pose a threat to malaria control and necessitates the need to continue the search for new effective and affordable drugs. Ethnomedicine has been shown to be a potential source of antimalarial compounds or source of template for the synthesis of novel antimalarial molecules. Objective: The antiplasmodial activity and toxicity assessment of 30 plant extracts from eight medicinal plants identified in Nigerian ethnomedicine for the treatment of febrile illnesses were evaluated. Materials and methods: In vitro antimalarial activity was evaluated using Plasmodium falciparum NF54 (sensitive to all antimalarial drugs) and K1 (chloroquine/pyrimethamine resistant) strains in the [3H]-hypoxanthine incorporation assay. Toxicity was determined against mammalian L6 cells using Alamar blue assay. Results: The ethyl acetate extract of leaves of Ocimum gratissimum Linn. (Labiatae) and hexane extract of stem bark of Trema orientalis (L.) Blume (Ulmaceae) showed the highest antiplasmodial activity (IC50 1.8-1.93 µg/mL) against P. falciparum K1 strain but elicited low cytotoxicity (selective index >10). However, hexane, ethyl acetate or methanol extracts of leaves of Terminalia catappa Linn. (Combretaceae), Jatropha curcas Linn. (Euphorbiaceae), Vitex doniana Sweet. (Verbenaceae) and stem bark of Vitex doniana displayed antiplasmodial activity (IC50 2.3-16.9 µg/mL) with good selectivity (21–120) for malaria parasites. Discussion and conclusion: The antiplasmodial activity of Terminalia catappa and Vitex doniana against P. falciparum K1 is being reported for the first time in Nigerian ethnomedicine and these plants could be potential source of antimalarial agents.

In Vitro and In Vivo Antimalarial Activity of Ficus thonningii Blume (Moraceae) and Lophira alata Banks (Ochnaceae), Identified from the Ethnomedicine of the Nigerian Middle Belt

Drug resistance in Plasmodium falciparum requires that new drugs must be developed. Plants are a potential source for drug discovery and development. Two plants that used to treat febrile illnesses in Nigeria were tested for in vitro and in vivo antimalarial activity and cytotoxicity in cancer cell lines. Methanol, hexane, and ethyl acetate leaf extracts of Ficus thonningii and Lophira alata were active in in vitro assays against P. falciparum NF54 (sensitive) and K1 (multiresistant) strains. Hexane extracts of F. thonningii and L. alata were the most effective extracts in in vitro assays with IC50 of 2.7 ± 1.6 μg/mL and 2.5 ± 0.3 μg/mL for NF54 and 10.4 ± 1.6 μg/mL and 2.5 ± 2.1 μg/mL for K1 strain. All extracts were nontoxic in cytotoxicity assays against KB human cell line with IC50 of over 20 μg/mL, demonstrating selectivity against P. falciparum. In vivo analysis shows that hexane extracts of both plants reduced parasitaemia. At the maximum dose tested, L. alata had a 74.4% reduction of parasitaemia while F. thonningii had a reduction of 84.5%, both extracts prolonged animal survival in mice infected with P. berghei NK65 when compared with vehicle treated controls. The antiplasmodial activity observed justifies the use of both plants in treating febrile conditions.

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 Sarotherodon melanotheron 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.

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.

Survival potential, fecundity and fertility of Biomphalaria pfeifferi (Krauss, 1848) during acclimatization in the laboratory

Survival potential, fecundity and fertility of Biomphalaria pfeifferi were investigated during the process of acclimatization in the laboratory. Thirty adult snails (average size 5 × 13 mm) were used in Experiment A (control; laboratory-bred snails) and B (acclimatizing snails from the wild). Both experiments aimed at monitoring survival and reproductive potential of snails were performed at room temperature (21–29 °C) for five weeks. The mean pH, conductivity, total dissolved solid, dissolved oxygen, water and room temperature were 7.77, 228 ps/cm, 121, 0.5 mg/L, 25.0 and 29.0 °C, respectively. The mean and standard deviation of eggs per egg-mass was 19.86 ± 0.46 and 14.88 ± 5.01, the number of eggs per snail was 53.26 ± 10.34 and 38.51 ± 10.03, the amount of egg-mass per snail was 2.68 ± 0.04 and 2.48 ± 1.09 in Experiments A and B, respectively. Results of the experiment indicate a significant difference (p < 0.05) between fecundity, fertility and survival of B. pfeifferi in Experiments A and B. Experim...

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.

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.