Antibiotic hypersensitivity in MRSA induced by special protein aggregates

Extraction, purification, structural characteristics, bioactivity and potential applications of polysaccharides from Semen Coicis: A review

Semen Coicis (S. Coicis) has been regarded as a valuable source of traditional herbal medicine in China for thousands of years. S. Coicis polysaccharides (SCPs) are one of the most important bioactive ingredients of S. Coicis, which have attracted worldwide attention, because of their great marketing potential and development prospects. Hot water extraction is currently the most commonly used method to isolate SCPs. The structural characteristics of SCPs have been extensively investigated through various advanced modern analytical techniques to dissect the structure-activity relationships. SCPs are mainly composed of diverse monosaccharides, from which Rha and Ara are the most prevalent glycosyl groups. In addition, the structures of SCPs are found to be closely related to their multiple biological activities, including antioxidant activity, immunomodulatory function, antitumor activity, hypoglycemic effect, intestinal microbiota regulatory activity, anti-inflammatory activity, among others. In view of this, this review aimed to provide systematic and current information on the isolation, structural characteristics, and bioactivities of SCPs to support their future applications as therapeutic agents and functional foods.

A fabricated hydrogel of hyaluronic acid/curcumin shows super-activity to heal the bacterial infected wound

High risk of acute morbidities and even mortality from expanding the antibiotics resistant infectious wounds force indefinite efforts for development of high performance wound-healing materials. Herein, we design a procedure to fabricate a hyaluronic acid (HA)-based hydrogel to conjugate curcumin (Gel-H.P.Cur). The highlight of this work is to provide a favorite condition for capturing curcumin while protecting its structure and intensifying its activities because of the synchronization with HA. Accordingly, HA as a major component of dermis with a critical role in establishing skin health, could fortify the wound healing property as well as antibacterial activity of the hydrogel. Gel-H.P.Cur showed antibacterial properties against Pseudomonas aeruginosa (P. aeruginosa), which were examined by bactericidal efficiency, disk diffusion, anti-biofilm, and pyocyanin production assays. The effects of Gel-H.P.Cur on the inhibition of quorum sensing (QS) regulatory genes that contribute to expanding bacteria in the injured place was also significant. In addition, Gel-H.P.Cur showed high potential to heal the cutaneous wounds on the mouse excisional wound model with repairing histopathological damages rapidly and without scar. Taken together, the results strongly support Gel-H.P.Cur as a multipotent biomaterial for medical applications regarding the treatment of chronic, infected, and dehiscent wounds.

The anti-platelet drug ticlopidine inhibits FapC fibrillation and biofilm production: Highlighting its antibiotic activity

Multidrug resistance of bacteria and persistent infections related to biofilms, as well as the low availability of new antibacterial drugs, make it urgent to develop new antibiotics. Here, we evaluate the antibacterial and anti-biofilm properties of ticlopidine (TP), an anti-platelet aggregation drug, TP showed antibacterial activity against both gram-positive (MRSA) and gram-negative (E. coli, and P. aeruginosa) bacteria over a long treatment period. TP significantly reduced the survival of gram-negative bacteria in human blood though impact on gram-positives was more limited. TP may cause death in MRSA by inhibiting staphyloxanthin pigment synthesis, leading to oxidative stress, while scanning electron microscopy imaging indicate a loss of membrane integrity, damage, and consequent death due to lysis in gram-negative bacteria. TP showed good anti-biofilm activity against P. aeruginosa and MRSA, and a stronger biofilm degradation activity on P. aeruginosa compared to MRSA. Measuring fluorescence of the amyloid-reporter Thioflavin T (ThT) in biofilm implicated inhibition of amyloid formation as part of TP activity. This was confirmed by assays on the purified protein in P. aeruginosa, FapC, whose fibrillation kinetics was inhibited by TP. TP prolonged the lag phase of aggregation and reduced the subsequent growth rate and prolonging the lag phase to very long times provides ample opportunity to exert TP's antibacterial effect. We conclude that TP shows activity as an antibiotic against both gram-positive and gram-negative bacteria thanks to a broad range of activities, targeting bacterial metabolic processes, cellular structures and the biofilm matrix.

New Provisional Function of OmpA from Acinetobacter sp. Strain SA01 Based on Environmental Challenges

Acinetobacter OmpA is known as a multifaceted protein with multiple functions, including emulsifying properties. Bioemulsifiers are surface-active compounds that can disperse hydrophobic compounds in water and help increase the bioavailability of hydrophobic hydrocarbons to be used by degrading microorganisms.

An outer membrane protein A (OmpA) from Acinetobacter sp. strain SA01 was identified and characterized in-depth based on the structural and functional characteristics already known of its homologues. In silico structural studies showed that this protein can be a slow porin, binds to peptidoglycan, and exhibits emulsifying properties. Characterization of the recombinant SA01-OmpA, based on its emulsifying properties, represented its promising potentials in biotechnology. Also, the presence of SA01-OmpA in outer membrane vesicles (OMV) and biofilm showed that this protein, like its homologues in Acinetobacter baumannii, can be secreted into the extracellular environment through OMVs and play a role in the formation of biofilm. After ensuring the correct selection of the protein of interest, the role of oxidative stress induced by cell nutritional parameters (utilization of specific carbon sources) on the expression level of OmpA was carefully studied. For this purpose, the oxidative stress level of SA01 cell cultures in the presence of three nonrelevant carbon sources (sodium acetate, ethanol, and phenol) was examined under each condition. High expression of SA01-OmpA in ethanol- and phenol-fed cells with higher levels of oxidative stress than acetate suggested that oxidative stress could be a substantial factor in the regulation of SA01-OmpA expression. The significant association of SA01-OmpA expression with the levels of oxidative stress induced by cadmium and H₂O₂, with oxidative stress-inducing properties and lack of nutritional value, confirmed that the cells tend to harness their capacities with a possible increase in OmpA production. Collectively, this study suggests a homeostasis role for OmpA in Acinetobacter sp. SA01 under oxidative stress besides assuming many other roles hitherto attributed to this protein.

IMPORTANCEAcinetobacter OmpA is known as a multifaceted protein with multiple functions, including emulsifying properties. Bioemulsifiers are surface-active compounds that can disperse hydrophobic compounds in water and help increase the bioavailability of hydrophobic hydrocarbons to be used by degrading microorganisms. In this study, an OmpA from Acinetobacter sp. SA01 was identified and introduced as an emulsifier with a higher emulsifying capacity than Pseudomonas aeruginosa rhamnolipid. We also showed that the expression of this protein is not dependent on the nutritional requirements but is more influenced by the oxidative stress caused by stressors. This finding, along with the structural role of this protein as a slow porin or its role in OMV biogenesis and biofilm formation, suggests that this protein can play an important role in maintaining cellular homeostasis under oxidative stress conditions. Altogether, the present study provides a new perspective on the functional performance of Acinetobacter OmpA, which can be used both to optimize its production as an emulsifier and a target in the treatment of multidrug-resistant strains.

Nonwoven fabric supported, chitosan membrane anchored with curcumin/TiO2 complex: Scaffolds for MRSA infected wound skin reconstruction

Use of biomaterial scaffolds as drug carriers for infected wounds treatment is of wide scope. A series of curcumin/TiO₂ complex loaded chitosan scaffolds are fabricated for the same. Synthesized wound dressing material is screened for their morphology, water absorption capacity; in vitro drug release patterns, in vitro antibacterial studies against gram +ve and a gram -ve bacteria, cell viability for 3T3-L1 cell lines as well as in vivo MRSA infected wound healing capability. Formation of curcumin/TiO₂ complex was confirmed by X-ray diffraction studies, the anchoring pattern of them on the chitosan scaffold was analyzed by FESEM and EDS mapping. All membranes showed a better performance towards in vitro antibacterial and in vivo wound healing properties than the control ones in 14 days. The bacterial count on wound for a regular time period was measured and the scaffold with higher amount of curcumin in its complex is found to give the better performance, along with skin regeneration due to synergistic effect of curcumin and TiO₂.