Abstract
Cyperus rotundus L. has been used for pharmaceutical applications including antibacterial infections. Nevertheless, there is still no data regarding the mode of actions. This study aimed to determine the antibacterial activity and mode of actions of Cyperus rotundus extract (CRE) against ampicillin-resistant Staphylococcus aureus (ARSA) which poses a serious problem for hospitalized patients. The majority of chemical compounds of CRE were flavonoids and alkaloids. The minimum inhibitory concentrations (MICs) for ampicillin and CRE against all ARSA strains were 64 μg/ml and 0.5 mg/ml, respectively. Checkerboard assay revealed synergistic activity in the combination of ampicillin and CRE at the lowest fractional inhibitory concentration index (FICI) at 0.27. The killing curve assay had confirmed the synergistic and bactericidal activity of the combination against ARSA. Electron microscopic results showed that these ARSA cells treated with this combination caused peptidoglycan and cytoplasmic membrane (CM) damage and average cell areas significantly smaller than control. Also, this combination caused an increase in CM permeability of ARSA. CRE revealed the inhibitory activity against β-lactamase. It is normally known that some drugs are derived from flavonoids or alkaloids. So, this CRE proposes the potential to develop a novel adjunct phytopharmaceutical to ampicillin for the remedy of ARSA.
Highlights
Antibiotic resistance has become a serious problem threatening to public health and medical implications
The phytochemical compounds of crude extract (CRE) were positive for alkaloids, flavonoids, tannin, and polyphenols but negative for saponin and glycosides
The results indicated that the Total alkaloid content (TAC), Total flavonoid content (TFC), and Total polyphenol content (TPC) of CRE were 0.0000703 mg of RE/g, 0.077825 mg of QE/g, and 0.110772 mg of GAE/g dry weight of CRE, respectively (Table 1)
Summary
Antibiotic resistance has become a serious problem threatening to public health and medical implications. Recent studies demonstrated that β-lactamase inhibitors with β-lactam structures caused the induction of β-lactamase expression and hyperproduction of β-lactamase [1,2,3]. These currently most available β-lactamase inhibitors can lose their activities through the same mechanism as the β-lactam antibiotics [3]. Cyperus rotundus crude extract (CRE) contains bioactive compounds such as alkaloids, flavonoids, and polyphenols [4,5,6,7,8] which may be responsible for MRSA inhibition. Some elementary mode of actions, such as a cytoplasmic membrane (CM) permeabilization, enzyme assay, and transmission electron microscopy, were studied
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