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Biofilm contributes hugely to the persistence of typhoid fever in human population and quorum sensing (QS) is an integral mechanism involved in biofilms. Interruption of the QS network has therefore been put forward as one of the important anti-virulence strategies. Methanol extract of Psidium guajava leaves has been confirmed to possess antibacterial and anti-biofilm activities against Salmonella Typhi. This study therefore aimed at investigating the interactions of phytocompounds previously identified in the extract with selected QS proteins of S. Typhi in silico. Appropriate formats of compounds were retrieved and translated using online web servers. Quantitative estimate of drug-likeness, as well as absorption, distribution, metabolism, excretion and toxicity profiles of the compounds, were assessed on ADMETlab 2.0. Three-dimensional structures of two QS proteins of S. Typhi were obtained from Protein Data Bank while others were modelled on SWISS-MODEL. Selected compounds (ligands) were docked with the four proteins via AutoDock 1.5.6 and analyzed on Discovery studio. Eight, out of the seventy-two, phyto-compounds of methanol extract of P. guajava possess desirable drug-likeness (QED > 0.67). Three of them have toxic characteristics and thus, were removed from further consideration. Molecular docking revealed that, of the 5 ligands docked against the proteins, only Benzeneethanamine, 4-methoxy- and Cyclopentadecanone, 2-hydroxy- had affinities for the proteins of interest. The affinity of Cyclopenftadecanone,2-hydroxy- for each of the proteins is higher than that of Benzeneethanamine,4-methoxy- with hydrogen bonds contributing significantly to the interactions. Benzeneethanamine, 4-methoxy- and Cyclopentadecanone,2-hydroxy- from Psidium guajava leaves possess inhibitory properties against QS proteins of S. Typhi.

Background The study was designed to screen aqueous extract of Bilghia sapida leaves for its phytochemical constituents, in vivo antiplasmodial activity and biochemical changes in Plasmodium berghei (NK65)-infected female mice. Phytochemical screening was done using standard methods. In the acute toxicity test, three groups of mice received 1000, 2000 and 3000 mg/Kg/day of the extract respectively, and were observed for signs of toxicity, especially mortality for 24 h. Forty-eight mice were assigned into six groups of eight animals each. The uninfected group A (control) was administered distilled water, while groups B, C, D, E and F were inoculated intraperitoneally with about 107 parasitized erythrocytes and received distilled water, chloroquine (5 mg/Kg/day), 125, 250 and 500 mg/Kg/day of extract, respectively. The antiplasmodial activity was evaluated using Peter’s 4 days suppressive test. Haematological indices, selected biochemical parameters and liver histology were evaluated. Results Screening revealed the presence of six phytochemicals in the aqueous extract of B. sapida leaves. Median lethal dose of the extract is > 5,000 mg/Kg/day. The aqueous extract of the leaves significantly (P < 0.05) reduced the level of parasitaemia dose-dependently with chemosuppression of 74.09% at 500 mg/Kg/day. The extract significantly (P < 0.05) prevented P. berghei infection-associated reduction in red blood cell indices. The significant (P < 0.05) P. berghei-induced alterations in liver function indices were improved in extract-treated mice. There were no visible lesions in the livers of animals that received 125 mg/Kg/day of extract. Conclusion The aqueous extract of B. sapida leaves has in vivo antiplasmodial activity and justifies its folkloric use in malarial treatment.

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