Anticytotoxin Effects of Amentoflavone to Pneumolysin

Abstract

Pneumolysin (PLY) is a devastating bacterial protein toxin of Streptococcus pneumoniae that punctures the cytomembrane, leading to pathological reactions, such as cell disruption and inflammation. Drugs capable of closely impacting the toxin are considered advantageous in the treatment of bacterial infections. Amentoflavone (AMF) is a chemical substance extracted from traditional Chinese herbs. Previous studies have demonstrated that AMF has multiple pharmacological effects and mentioned without attenuating pneumolysin-mediated cytotoxicity. This work focuses on the influence of AMF on inhibitory hemolytic mechanisms. AMF interacts with the toxin at Ser254, Glu277, Arg359, and effectively weakens the oligomerization of wild-type PLY and provides considerable protection against pneumolysin-mediated human alveolar epithelial (A549) cell damage. The results of our study demonstrate that AMF could be a candidate against pneumolysin-related injury. Key words Streptococcus pneumoniae; pneumolysin; amentoflavone; oligomerizationAntibiotic abuse is a growing problem worldwide, referenced a recent WHO report as supposing that the problem is so severe and may lead to 1 million early deaths annually by 2050. Furthermore, antibiotics are used more frequently in livestock breeding industry for the purpose of reducing costs and pursuing profits. The outcome of this is bacteria are developing greater resistance to antibiotics. To curb the drug-resistance and improve the cure rate, government should strengthen the supervision of the application of existing antibiotics and novel agents must be developed, at the same time. As thus, advancements in the research of anti-virulence strategies demonstrate its importance as a potential drug target.

Amentoflavone Attenuates Clostridium perfringens Gas Gangrene by Targeting Alpha-Toxin and Perfringolysin O

“…The finding that amentoflavone targets PFO activity was expected since PFO is also a member of the CDC family. Here, our data support the inhibitory effect of amentoflavone on CDC family toxins (Zhao et al, 2017;Shen et al, 2018).…”

“…To date, there have been numerous studies on the development and use of natural compounds against bacterial infection via targeting toxins and other virulence factors (Qiu et al, 2012;Zhang et al, 2014;Wang et al, 2015). Zhao et al reported the anticytotoxin effects of amentoflavone on pneumolysin, a devastating bacterial protein toxin of Streptococcus pneumoniae and a member of the CDC family (Alouf, 2000;Zhao et al, 2017). Besides, study of Shen et al showed that amentoflavone effectively inhibited suilysin-mediated hemolysis, a member of the CDC family toxin from Streptococcus suis (Shen et al, 2018).…”

“…Hemolytic activity assays were performed according to previous study (Zhao et al, 2017). Briefly, purchased CPA or purified PFO in 975 ml of phosphate-buffered saline (PBS) buffer (pH = 7.4) was preincubated with a sequence of concentrations of amentoflavone (1, 2, or 4 mg/ml) at 37°C for 30 min in tubes.…”

“…Samples were supplied with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) loading buffer (b-mercaptoethanol free) and heated at 55°C for 5 min. Western blot assays were performed as described previously (Zhao et al, 2017). A rabbit polyclonal to PFO (1:4,000 dilution, Abcam, Cambridge, USA) were used as primary antibody and a goat anti-rabbit (1:2,000 dilution) were used as secondary antibody.…”

Amentoflavone Ameliorates Streptococcus suis-Induced Infection In Vitro and In Vivo

“…Amentoflavone has been shown to have antioxidant (21), anticancer (22), anti-inflammatory (21), antibacterial (23), antiviral (24), and antiradiation (25) activities. In addition, we recently found that amentoflavone exhibits strong antagonizing effects against pneumolysin by interacting with the toxin and reducing the oligomerization of wild-type PLY, suggesting that amentoflavone is an effective antivirulence agent (26). In this study, we investigated the antivirulence and anti-inflammatory activities of amentoflavone and investigated its mechanism of action on S. suis-induced infection.…”