Investigation of the antibacterial activities of methanolic and water extracts of Gongronema latifolium, Psidium guajava and Aspilia africana

Paul Ekene Chidebelu,Kenechukwu Francis Ojinna,Chinyere Blessing Chigor,Vincent Nnamdigadi Chigor

doi:10.4314/br.v19i2.7

Abstract

The epidemiological consequences of co-infections by enteric, wound, opportunistic, and drug-resistant pathogens, underscore the need for alternative and multi-target therapeutic approaches. Phytochemical properties of some plants are widely known but their potential utility as cheaper multi-target therapeutic options, have rarely been investigated. In the current work, Gongronema latifolium, Psidium guajava, and Aspilia africana extracts were studied for their potential utility as multi-target therapeutic alternatives. The plants were screened for phytochemical constituents. Based on the CLSI disc diffusion assay, the sensitivities of Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Pseudomonas aeruginosa to the plants’ extracts were tested. The minimum inhibitory concentration of the extracts against susceptible bacteria was determined by CLSI broth microdilution protocols. The major families of plant bioactive compounds were detected, with alkaloids, terpenoids, and flavonoids common to the three plants investigated. The plant extracts showed variable activity against the test bacteria (activity index, AI range = 0.43 – 2.59), while the highest activity based on the MIC was recorded for P. guajava (MIC range = 25- 100mg/ml). These results provide the basis of the plants’ therapeutic uses in folk medicine. Their activity index suggests the need for further investigation of their phytochemical components for potential medicinal application. The P. guajava methanolic extract with consistent activity across the test bacteria suggests its potentials in the formulation of multi-target antibiotic therapies

Highlights

The enteric bacteria including Enterococcus faecalis, Escherichia coli, and Klebsiella pneumoniae constitute important components of the human intestinal microbiota, which ecological niches in the gastrointestinal tract (GIT) are not often detrimental to the host (Koboziev et al, 2014)
Alkaloids, and flavonoids are common to all the plants investigated, only P. guajava and A. africana are positive for tannins
While only G. latifolium and A. africana were positive for saponins, only P. guajava was positive for glycosides

Summary

Introduction

The enteric bacteria including Enterococcus faecalis, Escherichia coli, and Klebsiella pneumoniae constitute important components of the human intestinal microbiota, which ecological niches in the gastrointestinal tract (GIT) are not often detrimental to the host (Koboziev et al, 2014). There has been an upward trend in the prevalence of immunosuppressive conditions (Thibault et al, 2016; Arem and Loftfield, 2017; Magliano et al, 2019.) This was further complicated with the increased emergence of antibioticresistant bacterial strains, and this ugly trend has remained unmitigated with improved therapeutic approaches (Ventola, 2015). Gongrenema latifolium is an edible herbaceous shrub commonly used in many parts of Nigeria as vegetable and drug for management of certain health conditions and has been described as a good candidate for production of anti-diabetic drugs based on the presence of minerals and essential oils, and other phytochemical components, which were identified as mediators of the plant’s hypoglycemic activity according to an in vivo study (Chime et al, 2014). Modulation of specific gene expressions resulting in hypoglycemia was evident after in vivo administration of the plant's aqueous leaf extracts in rats (Ajiboye et al, 2019)

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Discussion

Conclusion