Glycyrrhizin Use for Multi-Drug Resistant Pseudomonas aeruginosa: In Vitro and In Vivo Studies

Abstract

PURPOSE.Our purpose was to test glycyrrhizin (GLY) effects and ciprofloxacin interactions on multidrug resistant (MDR) isolates of Pseudomonas aeruginosa in vitro and in vivo in a mouse model of keratitis. METHODS.A Hardy-disk tested antibiotic sensitivity of isolates MDR9 (nonocular) and B1045 (ocular). GLY MIC (both isolates) and ciprofloxacin was determined spectrophotometrically. A live/dead assay using confocal microscopy and plate count, tested GLY effects on bacterial permeabilization/viability. Proteomics profiled bacterial efflux pumps (MDR9 vs. PAO1); RT-PCR comparatively tested GLY effects on their mRNA expression levels. The activity of efflux pumps was tested using ethidium bromide (EB); and scanning electron microscopy (SEM) visualized the effects of GLY treatment of bacteria. A combination of GLY and ciprofloxacin was tested in C57BL/6 mice (begun 18 hours after infection) and disease scored, photographed and MPO and plate counts done.RESULTS. MDR9 was resistant to 6/12 and B1045 to 7/12 antibiotics (both to ciprofloxacin). MIC GLY for MDR9 was 40 mg/mL and 15 mg/mL for B1045. Ciprofloxacin MIC (32 lg/ mL) was reduced 2-fold to 16 lg/mL when ciprofloxacin and GLY were combined. GLY altered bacterial membrane permeability and reduced viability. Proteomics revealed increased efflux pumps in MDR9 versus PAO1; GLY reduced their mRNA expression levels and EB suggested decreased activity. In C57BL/6 mice, treatment with GLY and ciprofloxacin versus ciprofloxacin, significantly reduced clinical scores, plate count, and MPO.CONCLUSIONS. GLY decreases MDR by: altering bacterial parameters, including viability and efflux pump activity. In vivo, it increases the effectiveness of ciprofloxacin, reducing ocular disease, plate count, and MPO activity.

In vitro anthelmintic activity of an aqueous extract of Glycyrrhiza glabra and of glycyrrhetinic acid against gastrointestinal nematodes of small ruminants

“…Glycyrrhetinic acid is considered the major active component of G. glabra root extract, which may contain about 2-25% glycyrrhetinic acid, both as such and as the glycosidic glycyrrhizinic acid saponin [23]. In humans, it is in fact known that after oral administration, glycyrrhizinic acid is hydrolysed to glycyrrhetinic acid mainly by the intestinal bacteria b-D-glucuronidase [20,40].…”

Effects of Glycyrrhizin on Multi-Drug Resistant Pseudomonas aeruginosa

“…GLY had a minimum inhibitory concentration (MIC) of 40 mg/mL for each of the clinical isolates as well as two lab strains (PAO1 and 19660) tested [8,19,20]. The MIC of multi-drug resistant strain MDR9, isolated from sputum also was 40 mg/mL, but MIC was reduced to 15 mg/mL for the ocular isolate B1045 [21], suggesting that GLY may not affect all MDR similarly.…”

“…Past studies from our laboratory, including a proteomic comparison of RS1 (a non-ocular, drug resistant clinical isolate) and PAO1 showed that the gene ampC, which is responsible for beta lactamase production, was detectable in RS1 but not PAO1 [20]. Additional studies showed GLY treatment had an effect on other intrinsic resistance mechanisms, namely increase in membrane permeability in MDR9 and significant reduction in expression of major resistance-nodulation-division (RND) efflux pump genes in both MDR9 and B1045 [21]. Combined with the finding that GLY reduces beta-lactamase in MDR9, but not B1045, the premise that GLY can alter multi-drug resistant mechanisms differentially between isolates appears supportable.…”

The potential of glycyrrhizin and licorice extract in combating COVID-19 and associated conditions

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