Comparative Antimicrobial Activities of a Consortium of <i>Vernonia amygdalina</i> and <i>Amaranthus hybridus</i> Extracts With Their CuO Nanoparticle Complexes

Abstract

<strong>Introduction: </strong>The synthesis of nanoparticles from plant extracts has gained much attention in recent times. This study aimed at screening a consortium of crude extracts of <em>Vernonia amygdalina </em>and <em>Amaranthus hybridus </em>for antimicrobial activities.<br /> <strong>Methods: </strong>The activities were compared with nanoparticles synthesized using the extracts. Powdered plant materials were separately suspended in distilled water and ethanol which were filtered to obtain crude extracts, while plant nanoparticles were synthesized by coupling with copper oxide (CuO). Crude extracts were screened for the presence of bioactive constituents. Antibacterial assay was carried out by agar well diffusion, while the poisoned plate technique was used to determine antifungal activity.<br /> <strong>Results: </strong>Plant extracts revealed the presence of alkaloids, steroids, saponins, and tannins. The aqueous crude extract produced higher activity than the ethanolic extract with the highest inhibition zone (29) against <em>Bacillus megaterium </em>at a concentration of 40 mg/mL. Antifungal activity also showed that the aqueous extract was better than the ethanolic one. The aqueous nanoparticle extract was higher in antimicrobial activities compared to its crude counterpart, exhibiting inhibition zones of 34 mm at 40 mg/mL and 31 mm at 60 mg/mL for antibacterial and antifungal assays, respectively.<br /> <strong>Conclusions: </strong>The results of this study indicate that aqueous extracts demonstrated higher antimicrobial activity than ethanolic ones, and the synthesis of nanoparticles using a consortium of 2 plants has the potential to enhance antimicrobial activity.