Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria
Abstract
Purpose: In the present study, six flavonoids
(5,7-dimethoxyflavanone-4'-O-β-D-glucopyranoside,
5,7dimethoxyflavanone-4'-O-[2''-O-(5'''-O-trans-cinnamoyl)-β-D-apiofuranosyl]-β-D-glucopyranoside,
naringenin-7-O-β-D-glucopyranoside,
5,7,3'-trihydroxy-flavanone-4'-O-β-D-glucopyranoside, rutin, and
nicotiflorin) isolated from Galium fissurense , Viscum album ssp.
album and Cirsium hypoleucum were screened against extended-spectrum
β-lactamase producing multidrug-resistant
(trimetoprimesulphametoxazole, sulbactam-ampicillin,
clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime,
tobramicin, gentamicin, ofloxacin, ciprofloxacin) bacteria Klebsiella
pneumoniae (ESβLs). Methods: We performed susceptibility
testing according to the Clinical and Laboratory Standards Institute
(CLSI, formerly NCCLS) and used an inhibition endpoint for
determination of the minimum inhibition concentrations (MICs).
Results: All the flavonoids showed in vitro antimicrobial activity
against all the isolated strains of K. pneumoniae similar to the
control antibacterial (ofloxacin) at the concentrations of 32 -64
µg ml-l; another control, ampicillin, had no activity. Since,
ESβL-producing strains are known to be resistant to all
β-lactam antibiotics, our results fall notably within the
concentration range for antimicrobial activity. Conclusion: To the
best of our knowledge, this is the first report of the study of the
activity of these flavonoids against (ESβL)-producing K.
pneumoniae and may throw light to the low-toxicity of flavonoids, and
their potentials for developing therapies for infections caused by
ESβL-producing bacteria in the future. Further work is under
investigation to identify their precise antibacterial mechanism