Effects of cotton plant (Gossypium herbaceum Linn.) extracts on some vancomycin and methicillin-resistant pathogenic bacteria

Abstract

Bacterial resistance to antibiotics is a serious global problem, hence attention is being turned to plants as alternative source of antimicrobial to combat the menace of antibiotic resistance among pathogenic microorganisms. This study explores the antibacterial properties of Gossypium herbaceum leaf extracts against a spectrum of antibiotic-resistant bacteria such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, sourced from clinical isolates at Don Bosco Catholic Laboratory and Obafemi Awolowo University Teaching Hospital in Nigeria. The research utilized cold extraction methods with methanol and n-hexane solvents to prepare the extracts, which were then analyzed for their phytochemical composition, revealing the presence of flavonoids, steroids, tannins, terpenoids, and glycosides. Antibacterial activity was assessed using the disc diffusion method, with the extracts showing varying zones of inhibition; n-hexane extracts produced zones between 21.35 mm and 4.10 mm, while methanol extracts showed zones between 18.75 mm and 5.05 mm at a concentration of 200mg/mL. Minimum inhibitory concentrations (MIC) were determined, with n-hexane extracts ranging from 25 mg/mL to 6.25 mg/mL and methanol extracts from 50 mg/mL to 6.25 mg/mL. Further analysis of the bioactive fractions was conducted through Fourier Transform Infrared Spectroscopy (FTIR), which identified six distinct bioactive compounds in the methanol extract, including alkenes, alcohols, amines, phenols, nitro compounds, and alkanes. Plasmid profiling indicated the presence of plasmids in clinically significant pathogens like P. aeruginosa and S. aureus, suggesting a potential mechanism for their antibiotic resistance. Overall, the study highlights the significant antibacterial activity of G. herbaceum extracts against resistant bacteria and suggests their potential as alternative antimicrobial agents in combating antibiotic resistance, which is a growing global health concern.