Synergistic Effects of Some Methoxyflavones Extracted from Rhizome of Kaempferia parviflora Combined with Gentamicin against Carbapenem-Resistant Strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii

Abstract

The present study aimed to investigate the antibacterial activity of ethanolic Kaempferia parviflora extracts and the combined effects of the plant’s specific compounds with gentamicin against clinical strains of carbapenem-resistant Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. The minimal inhibitory concentrations (MIC) of gentamicin and Kaempferia parviflora extracts against the tested bacterial strains were determined by using broth microdilution. The combined effects of Kaempferia parviflora extract and gentamicin were investigated by using a checkerboard assay and expressed as a fractional inhibitory concentration index (FICI). Crude ethanolic extract of Kaempferia parviflora showed the lowest median values of MIC towards the tested isolates (n = 10) of these tested bacteria at doses of 64 µg/mL, compared to those of other Kaempferia extracts. Among the isolated compounds, only three compounds, namely 3,5,7-trimethoxyflavone, 3,5,7,3′4′-pentamethoxyflavone, and 5,7,4′-trimethoxyflavone, were identified by NMR structural analysis. According to their FICIs, the synergistic effects of gentamicin combined with 3,5,7,3′4′-pentamethoxyflavone were approximately 90%, 90%, and 80% of tested carbapenem-resistant Klebsiella pneumoniae (CRKP), Pseudomonas aeruginosa (CRPA), and Acinetobacter baumannii (CRAB), respectively. The present study concluded that 3,5,7,3′4′-pentamethoxyflavone extracted from Kaempferia parviflora potentiated the antibacterial action of gentamicin to combat bacterial resistance against the tested bacteria.

Fabrication, Optimization, and Characterization of Antibacterial Electrospun Shellac Fibers Loaded with Kaempferia parviflora Extract

“…Both effects might very well accelerate wound healing. The methoxyflavones found in the ethanolic KP extract enhanced the antibacterial activity of gentamicin to combat bacterial resistance against P. aeruginosa , Klebsiella pneumoniae , and Acinetobacter baumannii strains resistant to carbapenems [ 57 ]. Therefore, KP extract should be combined with antibiotics to create electrospun shellac fibers for more efficient wound healing.…”

From Polymeric Nanoformulations to Polyphenols—Strategies for Enhancing the Efficacy and Drug Delivery of Gentamicin

“…A concrete conclusion regarding the mechanisms responsible for the synergic activity of natural products together with antibiotics cannot be obtained [161][162][163][164]. Some authors have suggested that synergic effects could be observed due to changes in the efflux system, damage to cell membranes, and the inhibition of protein synthesis.…”

“…Some authors have suggested that synergic effects could be observed due to changes in the efflux system, damage to cell membranes, and the inhibition of protein synthesis. Further research is needed to clearly understand the mechanisms [161,162,164]. A study using propolis revealed that the concentration of natural products is also crucial to the synergic activity [161].…”

Synergistic Inhibition of Synbiotic Cultures among Lactobacilli and Plant Extracts against Vaginal Discharge Causing Candida albicans

“…The standard checkerboard assays were performed as described previously to evaluate the combination effect of each tested lactic acid bacteria and the plant extracts against C. albicans ATCC10231 [29]. Fifty microliters of LM supernatant dissolved in MRS broth was serially diluted with MRS broth along the vertical axis of rows 1st-7th (top and bottom: the highest and lowest final concentrations were performed in titers at 1 and 7, respectively).…”

“…All experiments were performed in triplicate. The Fractional Inhibitory Concentration Index (FICI) value was used to assess whether synergism, indifference, or antagonism occurred following the combination effects of LM and PM employing the following formula [29]:…”