Drug Resistance Reversal Potential of Isoliquiritigenin and Liquiritigenin Isolated fromGlycyrrhiza glabraAgainst Methicillin-ResistantStaphylococcus aureus(MRSA)

Abstract

Isoliquiritigenin (ISL) and liquiritigenin (LTG) are structurally related flavonoids found in a variety of plants. Discovery of novel antimicrobial combinations for combating methicillin-resistant Staphylococcus aureus (MRSA) infections is of vital importance in the post-antibiotic era. The present study was taken to explore the in vitro and in vivo combination effect of LTG and ISL with β-lactam antibiotics (penicillin, ampicillin and oxacillin) against mec A-containing strains of MRSA. Minimum inhibitory concentration (MIC) of both LTG and ISL exhibited significant anti-MRSA activity (50-100 µg/mL) against clinical isolates of MRSA. The result of in vitro combination study showed that ISL significantly reduced MIC of β-lactam antibiotics up to 16-folds [∑ fractional inhibitory concentration (FIC) 0.312-0.5], while LTG reduced up to 8-folds (∑FIC 0.372-0.5). Time kill kinetics at graded MIC combinations (ISL/LTG + β-lactam) indicated 3.27-9.79-fold and 2.59-3.48-fold reduction in the growth of clinical isolates of S. aureus respectively. In S. aureus-infected Swiss albino mice model, combination of ISL with oxacillin significantly (p < 0.05, p < 0.01, p < 0.001) lowered the systemic microbial burden in blood, liver, kidney, lung and spleen tissues in comparison with ISL, oxacillin alone as well as untreated control. Considering its synergistic antibacterial effect, we suggest both ISL and LTG as promising compounds for the development of novel antistaphylococcal combinations. Copyright © 2016 John Wiley & Sons, Ltd.

Comprehensive multivariate correlations between climatic effect, metabolite-profile, antioxidant capacity and antibacterial activity of Brazilian red propolis metabolites during seasonal study

“…Studies of Gaur et al . 71 have shown minimal inhibitory concentration of liquiritigenin (MIC 50 µg/mL) for four MRSA strains and isoliquiritigenin showed MIC of 50 µg/mL for three MRSA strains. In another study, liquiritigenin and isoliquiritigenin were able to inhibit growth of Mycobacterium tuberculosis at a concentration of 25 µg/mL 72 .…”

In vitro and in vivo activity of d-serine in combination with β-lactam antibiotics against methicillin-resistant Staphylococcus aureus

“…This highlights the need of development of novel treatments. Research institutes, including our laboratory, have been searching for novel targets 30 , potential alternatives to antibiotics 31 , as well as effective combinations of antibiotics with agents such as manuka honey, isoliquiritigenin, plant essential oils and plant extracts24., 30., 31., 32., 33., 34..…”

Natural Chalcones in Chinese Materia Medica: Licorice

“…On the basis of previous research studies, isoliquiritigenin had obvious inhibitory effect on methicillin-resistant Staphylococcus aureus and Ralstonia solanacearum [82,83]. Licochalcone A, as one of the vital antibacterial components in licorice, was resistant to both bacterial and fungal infections [118,119].…”