Introduction to Antimicrobial Therapeutics Reviews: the bacterial cell wall as an antimicrobial target

Antibacterial activities of anthraquinones: structure-activity relationships and action mechanisms

With the increasing prevalence of untreatable infections caused by antibiotic-resistant bacteria, the discovery of new drugs from natural products has become a hot research topic. The antibacterial activity of anthraquinones widely distributed in traditional Chinese medicine has attracted much attention. Herein, the structure and activity relationships (SARs) of anthraquinones as bacteriostatic agents are reviewed and elucidated. The substituents of anthraquinone and its derivatives are closely related to their antibacterial activities. The stronger the polarity of anthraquinone substituents is, the more potent the antibacterial effects appear. The presence of hydroxyl groups is not necessary for the antibacterial activity of hydroxyanthraquinone derivatives. Substitution of di-isopentenyl groups can improve the antibacterial activity of anthraquinone derivatives. The rigid plane structure of anthraquinone lowers its water solubility and results in the reduced activity. Meanwhile, the antibacterial mechanisms of anthraquinone and its analogs are explored, mainly including biofilm formation inhibition, destruction of the cell wall, endotoxin inhibition, inhibition of nucleic acid and protein synthesis, and blockage of energy metabolism and other substances.

Safety and efficacy of PLGA(Ag-Fe3O4)-coated dental implants in inhibiting bacteria adherence and osteogenic inducement under a magnetic field

Introduction

The placement of dental implants is performed in a contaminated surgical field in the oral cavity, which may lead to implant failure. Bacterial adhesion and proliferation (Streptococcus mutans, Porphyromonas gingivalis) often lead to implant infections. Although Ag nanoparticles hold great promise for a broad spectrum of antibacterial activities, their runoff from dental implants compromises their antibacterial efficacy and potentially impairs osteoblast proliferation. Thus, this aspect remains a primary challenge and should be controlled.

Materials and methods

In this study, PLGA(Ag-Fe₃O₄) was modified on the implanted tooth surface and was characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The magnetic and antibacterial properties were also determined.

Results

Results showed that Ag successfully bonded with Fe₃O₄, and Ag-Fe₃O₄ not only exerted superparamagnetism but also exhibited antibacterial activity almost identical to silver nanoparticles (nano-Ag). The PLGA(Ag-Fe₃O₄) coating could significantly maintain the antibacterial activity and avoid bacterial adhesion to the implant. Compared with the blank control group, PLGA(Ag-Fe₃O₄) under magnetic field-coated samples had a significantly lower amount of colonized S. mutans (P<0.01). Osteoblast proliferation results showed that the coated samples did not exhibit cytotoxicity and could promote osteoblast proliferation as shown by MTT, alkaline phosphatase, and the nucleolar organizer region count.

Conclusion

We developed a novel Ag biologically compatible nanoparticle in this study without compromising the nano-Ag antibacterial activity, which provided continuous antibacterial action.

In silico target fishing for the potential bioactive components contained in Huanglian Jiedu Tang (HLJDD) and elucidating molecular mechanisms for the treatment of sepsis

The present study was designed to target fish for potential bioactive components contained in a Huang Lian Jie Du decoction (HLJDD) and identify the underlying mechanisms of action for the treatment of sepsis at the molecular level. he bioactive components database of HLJDD was constructed and the sepsis-associated targets were comprehensively investigated. The 3D structures of the PAFR and TXA2R proteins were established using the homology modelling (HM) method, and the molecular effects for sepsis treatment were analysed by comparing the bioactive components database and the sepsis targets using computational biology methods. The results of the screening were validated with biological testing against the human oral epidermal carcinoma cell line KB in vitro. We found that multiple bioactive compounds contained in the HLJDD interacted with multiple targets. We also predicted the promising compound leads for sepsis treatment, and the first 28 compounds were characterized. Several compounds, such as berberine, berberrubine and epiberberine, dose-dependently inhibited PGE2 production in human KB cells, and the effects were similar in the presence or absence of TPA. This study demonstrates a novel approach to identifying natural chemical compounds as new leads for the treatment of sepsis.