Harnessing the antibacterial potentials of Allium sativum (garlic), Allium cepa (onions) and Zingiber officinale (ginger) extracts against multidrug-resistant bacterial strains

Josiah Bitrus Habu, Ponchang Apollos Wuyep and Micheal Gyang Sila

Advancement in Medicinal Plant Research
Published: December 4 2024
Volume 12, Issue 4
Pages 78-87

Abstract

The increasing resistance of bacterial pathogens to conventional antibiotics has heightened interest in exploring natural alternatives with potential antimicrobial properties. Plants such as Allium sativum (garlic), Allium cepa (onion), and Zingiber officinale (ginger) have long been recognized for their medicinal qualities, including antibacterial activity against a wide range of pathogens. These plants are rich in bioactive compounds, such as allicin in garlic, sulfur-containing compounds in onions, and gingerols in ginger, which contribute to their notable antimicrobial effects, making them valuable in combating virulent bacterial agents. This study aimed to evaluate the antibacterial activities of A. sativum (garlic), A. cepa (onion), and Z. officinale (ginger) against virulent bacterial agents. Antibacterial testing was conducted using clinical isolates of Escherichia coli, Staphylococcus aureus, and Salmonella typhi obtained from the National Veterinary Research Institute (NVRI), Vom, Plateau State. Plant materials were extracted using the maceration method with solvents of varying polarities: n-hexane, ethyl acetate, methanol, and water. Phytochemical screening was performed using standard methods. Antibacterial activity was assessed using the agar well diffusion method, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined via the broth dilution method using a 96-well microtiter plate with resazurin as a growth indicator. The extraction yield revealed the following: aqueous extract (A. cepa, highest yield: 54.50 g), methanol extract (A. cepa, highest yield: 104.40 g), ethyl acetate extract (Z. officinale, highest yield: 5.30 g), and hexane extract (A. cepa, highest yield: 21.00 g). Phytochemical screening identified secondary metabolites, including tannins, flavonoids, alkaloids, steroids, cardiac glycosides, carbohydrates, saponins, phenols, anthraquinones, and terpenoids. The bacterial strains were most susceptible to methanol and ethyl acetate extracts of A. cepa and Z. officinale, while they showed the least susceptibility to aqueous and hexane extracts of A. sativum and Z. officinale. S. aureus demonstrated the highest susceptibility across all extract concentrations (100–500 mg/mL), whereas E. coli and S. typhi exhibited variable susceptibility patterns. The minimum bactericidal concentration (MBC) for E. coli was 300 mg/mL for the aqueous extract of A. sativum. For S. typhi, the MBC was observed for aqueous and ethyl acetate extracts of A. sativum and the aqueous extract of A. cepa. All plant extracts demonstrated broad-spectrum antibacterial activity against the tested pathogenic bacteria. These findings confirm that the test plants contain valuable secondary metabolites with antibacterial potential, supporting their use in the treatment of bacterial infections.

Keywords: Antibacterial activities, virulent agents, antimicrobial resistance, phytochemistry.

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