Oxidative Stress-Mediated Antibacterial Activity of the Total Flavonoid Extracted from the Agrimonia pilosa Ledeb. in Methicillin-Resistant Staphylococcusaureus (MRSA).

Hang Zhang,Haibin Zhang,Liren He,Suquan Song,Han Cheng,Fuxin Chen,Xiaowei Bao,Chenghua He,Weidong Sun

doi:10.3390/vetsci9020071

Abstract

(1) Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a zoonotic pathogen that causes endocarditis, pneumonia, and skin diseases in humans and livestock. (2) Methods: The antibacterial effect of the total flavonoid against MRSA (ATCC43300) extracted from the Agrimonia pilosa Ledeb. (A. pilosa Ledeb) was evaluated by the microdilution method. The oxidative stresses in MRSA were evaluated by the levels of intracellular hydrogen peroxide (H2O2), reactive oxygen species (ROS), and oxidative stress-related genes. The DNA oxidative damage was tested by the 8-hydroxy-2′-deoxyguanosine (8-OHdG) and DNA gel electrophoresis. The differentially expressed proteins were determined by the method of SDS-PAGE and NanoLC-ESI-MS/MS, while the mRNAs of differential proteins were determined by Real-Time PCR. The changes of ultra-structures in MRSA were observed by Transmission Electron Microscope (TEM). (3) Results: The minimum inhibitory concentration (MIC) of the total flavonoid against MRSA was recorded as 62.5 μg/mL. After treatment with the total flavonoid, the levels of intracellular H2O2 and ROS were increased and the gene expressions against oxidative stress (SodA, katA, TrxB) were decreased (p < 0.01), while the gene expression for oxidative stress (PerR) was increased (p < 0.01). The level of intracellular 8-OHdG in MRSA was increased (p < 0.01) and the DNA was damaged. The results of TEM also showed that the total flavonoid could destroy the ultra-structures in the bacteria. (4) Conclusions: The total flavonoid extracted from the A. pilosa Ledeb can induce the oxidative stress that disturbed the energy metabolism and protein synthesis in MRSA.

Highlights

Staphylococcus aureus (S. aureus) is a zoonotic pathogen that can produce staphylococcal enterotoxin (SE) and lead to serious and sometimes fatal infections in humans [1]
The changes of ultra-structures in methicillin-resistant S. aureus (MRSA) were observed by Transmission Electron Microscope (TEM). (3) Results: The minimum inhibitory concentration (MIC) of the total flavonoid against MRSA was recorded as 62.5 μg/mL
This study aims to evaluate the antibacterial effects of the total flavonoid against MRSA extracted from A. pilosa Ledeb and to elucidate the oxidative stress-mediated antibacterial mechanism further

Summary

Introduction

Staphylococcus aureus (S. aureus) is a zoonotic pathogen that can produce staphylococcal enterotoxin (SE) and lead to serious and sometimes fatal infections in humans [1]. In 1960s, a methicillin-resistant S. aureus (MRSA) strain was first isolated and reported in England [4]. MRSA was isolated from the cows, milker’s nose [5], poultry farms (breeding hens, laying hens, broilers, and turkeys) [6], and pig’s nose [7]. MRSA infection in hospitals or communities has been reported in many countries [9]. The treatment of MRSA infection has become a thorny problem in clinic. Searching for an alternative to treat MRSA infection has become an important research focus. This medical plant extract is a promising alternative, which has many advantages including few side effects, low cost, and less susceptibility to bacterial resistance [10]

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Results