Antimicrobial Activity against Antibiotic-resistant Pathogens and Antioxidant Activity and LCMS/MS Phytochemical Content Analysis of Selected Medicinal Plants
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Date
2024-02
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Abstract
Medicinal plants are a major source of numerous therapeutic agents, and the emergence of pathogenic
bacteria has rekindled interest in traditional medicine systems as an alternative approach to overcoming
resistance. The dried plant material of four medicinal plants, namely Terminalia arjuna (bark),
Terminalia bellirica (fruit), Aegle marmelos (leaves), and Bacopa monnieri (leaves), was powdered,
and aqueous extracts were prepared. The antimicrobial activity of the extracts was evaluated against
three clinically important strains: Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia
coli 385. As E. coli 385 was resistant to the broadest spectrum of antibiotics tested, it was classified
as (MDR multi-drug resistant). E. coli, Bacillus subtilis, Mycobacterium smegmatis (MTTC), and Vibrio
alginolyticus (ATCC) were also assessed using the agar well diffusion method for zones of inhibition and
minimum inhibitory/bactericidal concentration (MIC/MBC). Clinically important strains were found
to be sensitive to the aqueous extract of T. bellerica (19.51 ± 0.61 mm) with MICs ranging from 0.31
to 0.62 mg/ml. The MDR strain was also sensitive to Bellirica monnieri (16.10 ± 0.31 mm) aqueous
extract. To determine the potential for a wide range of applications, the antioxidant activities of the
extracts were evaluated using DPPH, ABTS, and FRAP assays. The T. arjuna plant extract exhibited the
highest radical scavenging activity with the lowest EC50 values for DPPH (1.15 ± 0.061 mg/ml) and ABTS
(1.02 ± 0.07 mg/ml). The plant extracts were characterized by UV-visible spectroscopy, Fourier-transform
infrared spectroscopy, and LC-MS/MS.