Abstract:
The emerging significance of natural antimicrobial agents creates an imperative need to identify novel
plant sources with antimicrobial activities. The objective of the present study was to evaluate antibacterial,
antifungal and β-lactamase enzyme inhibitory activities of ethanolic and methanolic extracts of Ravi,
Rawana and Oshadha finger millet varieties. Flours of whole grains of the finger millet varieties were
extracted with absolute ethanol and methanol separately. Antibacterial activities against six antibioticsensitive and four antibiotic-resistant pathogenic bacterial strains were evaluated using the resazurin
reduction assay. Antifungal activities against six antimicrobial-sensitive pathogenic fungal strains were
evaluated using the agar tube dilution method. β-Lactamase enzyme inhibitory activity was evaluated using
a standard method. Both ethanolic and methanolic extracts of the three finger millet varieties showed dosedependent inhibitory activities against the tested antibiotic-sensitive and antibiotic-resistant bacterial
strains while exhibiting high inhibitions against Gram-positive antibiotic-sensitive bacterial strains when
compared to Gram-negative antibiotic-sensitive bacterial strains. The findings revealed the antibacterial
potential of both ethanolic and methanolic extracts of the three finger millet varieties against antibioticsensitive Staphylococcus aureus (ATCC® 6538™) and Bacillus subtilis (ATCC® 23857™) strains and the
minimum inhibitory concentrations of the extracts against S. aureus and B. subtilis were found to be 2.1
and 1.8 mg/ml, respectively. However, none of the extracts can be considered as significantly active against
the tested antibiotic-sensitive and antibiotic-resistant bacterial strains when compared to the standard
drugs. In addition, none of the extracts can be considered as active against the tested fungal strains at the
tested concentrations. Nevertheless, all extracts showed more activities against the tested bacterial strains
when compared to the tested fungal strains. Since all extracts showed less than 40% β-lactamase inhibitory
activities even at 2 mg/ml concentration, they do not qualify as promising sources of β-lactamase inhibitors
at the tested concentration
