Potency and Cytotoxicity of a Novel Gallium-Containing Mesoporous Bioactive Glass/Chitosan Composite Scaffold as Hemostatic Agents

Chitosan-based hemostats are promising candidates for immediate hemorrhage control. However, they have some disadvantages and require further improvement to achieve the desired hemostatic efficiency. Here, a series of 1% Ga2O3-containing mesoporous bioactive glass-chitosan composite scaffolds (Ga-MBG/CHT) were constructed by the lyophilization process and the effect of various concentrations of Ga-MBG (10, 30, and 50 wt %) on the hemostatic function of the CHT scaffold was assessed as compared to that of Celox Rapid gauze (CXR), a current commercially available chitosan-coated hemostatic gauze. The prepared scaffolds exhibited \u3e79% porosity and showed increased water uptake compared to that in CXR. The results of coagulation studies showed that pure CHT and composite scaffolds exhibited increased hemostatic performance with respect to CXR. Furthermore, the composite scaffold with the highest Ga-MBG content (50 wt %) had increased capability to enhancing thrombus generation, blood clotting, and platelet adhesion and aggregation than that of the scaffold made of pure CHT. The antibacterial efficacy and biocompatibility of the prepared scaffolds were also assessed by a time-killing assay and an Alamar Blue assay, respectively. Our results show that the antibacterial effect of 50% Ga-MBG/CHT was more pronounced than that of CHT and CXR. The cell viability results also demonstrated that Ga-MBG/CHT composite scaffolds had good biocompatibility, which facilitates the spreading and proliferation of human dermal fibroblast cells even with 50 wt % Ga-MBG loading. These results suggest that Ga-MBG/CHT scaffolds could be a promising hemostatic candidate for improving hemostasis in critical situations

Antioxidant activity of Ardisia Crispa (Mata pelanduk)

The leaf and fruit crude extracts of hexane, chloroform, methanol and water of Ardisia crispa were screened for their antioxidant activity using DPPH radical scavenging, ferric reducing power, and metal chelating antioxidant assay. The methanol crude extract of fruits showed higher antioxidant activity (90.16 ± 0.01%) than the methanol crude extract of leaves (82.24 ± 0.02%) in the DPPH radical scavenging assay. In the ferric reducing power assay methanol fruit extract showed the highest absorbance indicating high antioxidant activities than leaf extract. In the metal chelating antioxidant assay fruit methanol extract gave 40% antioxidant activities than the leaf. Thin Layer Chromatography of the fruit methanol crude extract showed that it contained phenolic compounds when it was detected with folin reagent. HPLC analysis revealed that the fruit methanol extract contained gallic acid. This indicated that the high antioxidant activities of the fruits were due to the presence of gallic acid in the fruits of Ardisia crispa

Hybrid peptides derived from natural antimicrobial peptides, indolicidin and ranalexin, exhibit potent antimicrobial activities against Streptococcus pneumoniae in vitro and in vivo / Hassan Mahmood Kzar Jindal

Streptococcus pneumoniae is one of the leading causes of morbidity and mortality in both children and adults. This pathogen is responsible for invasive and noninvasive diseases. Moreover, pneumococcus is the most leading cause of community-acquired pneumonia (CAP), meningitis, and bacteremia worldwide. According to WHO, this bacterial pathogen is responsible for 1.6 million deaths each year. Like other gram-positive bacteria, S. pneumoniae is increasingly difficult to treat due to the inappropriate use of antibiotics. At present, S. pneumoniae has developed resistance to conventional drugs including novel antibiotics such as vancomycin. Therefore, finding a new class of antibacterial agents to overcome this serious issue is a top priority worldwide. One of the promising alternatives to today’s antibiotics is antimicrobial peptides (AMPs). AMPs are produced by almost all living organisms as the first line of defense in their innate immune system against microbial infection. In this study, novel synthetic peptides were designed based on two natural templates indolicidin and ranalexin. Out of thirteen newly designed peptides, five hybrid peptides (RN7-IN10, RN7-IN9, RN7-IN8, RN7-IN7, and RN7-IN6) showed the strongest in vitro antibacterial activity against thirty pneumococcal clinical isolates. These four hybrid peptides also showed broad spectrum antibacterial activity against S. aureus, methicillin-resistant S. aureus (MRSA), and E. coli. Moreover, the killing kinetics of peptides demonstrated that the hybrid peptides were able to eliminate pneumococci within 150 min of treatment which is faster than the standard drugs erythromycin and ceftriaxone. The hybrid peptides produced synergism when combined with each other and with standard antibiotics erythromycin and ceftriaxone. In vitro toxicity assessment revealed that none of the designed peptides displayed and toxic effects against human erythrocytes, WRL-68, and NL-20 cell lines at their MIC levels. In silico molecular docking showed that all five hybrid peptides revealed strong binding affinity toward three pneumococcal virulence factors autolysin, pneumolysin, and iv pneumococcal surface protein A (PspA). Mechanism of action of peptides exhibited that the hybrid peptides kill pneumococci by attacking and damaging the integrity of their cellular membranes. Moreover, DNA binding assay showed that at 62.5 μg/ml all hybrid peptides were able to bind effectively to genomic DNA and to prevent it from migrating through the agarose gel, these results suggesting that hybrid peptides could possess another mechanism of action besides their ability to disrupt the cell membrane. Two hybrid peptides RN7-IN10 and RN7-IN8 were selected to test their in vivo therapeutic efficacy. At 20 mg/kg, the peptides were able to protect 30% and 50% of the mice from lethal systemic infection by resistant pneumococcal strain. The combination of both peptides at 10 mg/kg for each was able to protect 60% of the mice. Interestingly, a combination of RN7-IN8 (20 mg/kg) and ceftriaxone (20 mg/kg) were able to provide 100% protection to mice infected with a virulent strain of S. pneumoniae. Infections caused by antibiotic-resistant S. pneumoniae remain a serious threat to human life. The present study demonstrated that AMPs represent a promising new class of antibacterials either as standalone or in combination with traditional antibiotics

Comparative genomic analysis of ten clinical Streptococcus pneumoniae collected from a Malaysian hospital reveal 31 new unique drug-resistant SNPs using whole genome sequencing

Abstract Background Streptococcus pneumoniae or pneumococcus is a leading cause of morbidity and mortality worldwide, specifically in relation to community-acquired pneumonia. Due to the overuse of antibiotics, S. pneumoniae has developed a high degree of resistance to a wide range of antibacterial drugs. Methods In this study, whole genome sequencing (WGS) was performed for 10 clinical strains of S. pneumoniae with different levels of sensitivity to standard antibiotics. The main objective was to investigate genetic changes associated with antibiotic resistance in S. pneumoniae. Results Our results showed that resistant isolates contain a higher number of non-synonymous single nucleotide polymorphisms (SNPs) as compared to susceptible isolates. We were able to identify SNPs that alter a single amino acid in many genes involved in virulence and capsular polysaccharide synthesis. In addition, 90 SNPs were only presented in the resistant isolates, and 31 SNPs were unique and had not been previously reported, suggesting that these unique SNPs could play a key role in altering the level of resistance to different antibiotics. Conclusion Whole genome sequencing is a powerful tool for comparing the full genome of multiple isolates, especially those closely related, and for analysing the variations found within antibiotic resistance genes that lead to differences in antibiotic sensitivity. We were able to identify specific mutations within virulence genes related to resistant isolates. These findings could provide insights into understanding the role of single nucleotide mutants in conferring drug resistance

Antibacterial Coating for Elimination of Pseudomonas aeruginosa and Escherichia coli

A polymer antibacterial surface has been successfully developed. The coating system used silane as binder and Ag particles as antibacterial agent. The silver was synthesized using precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) tests, energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) were carried out to evaluate the silver particles. Antibacterial properties of the coating system were tested against gram-negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli. Different amounts of Ag were used in the coating to optimize its usage. The Japanese International Standard, JISZ2801, was used for bacteria test and the surface developed complies with the standard being antibacterial

Elastomeric biocomposite of silver-containing mesoporous bioactive glass and poly(1,8-octanediol citrate): Physiochemistry and in vitro antibacterial capacity in tissue engineering applications

A novel series of silver-doped mesoporous bioactive glass/poly(1,8-octanediol citrate) (AgMBG/POC) elastomeric biocomposite scaffolds were successfully constructed by a salt-leaching technique for the first time and the effect of inclusion of different AgMBG contents (5, 10, and 20 wt%) on physicochemical and biological properties of pure POC elastomer was evaluated. Results indicated that AgMBG particles were uniformly dispersed in the POC matrix and increasing the AgMBG concentration into POC matrix up to 20 wt% enhanced thermal behaviour, mechanical properties and water uptake ability of the composite scaffolds compared to those from POC. The 20%AgMBG/POC additionally showed higher degradation rate in Tris(hydroxymethyl)-aminomethane–HCl (Tris–HCl) compared with pure POC and lost about 26% of its initial weight after soaking for 28 days. The AgMBG phase incorporation also significantly endowed the resulting composite scaffolds with efficient antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria while preserving their favorable biocompatibility with soft tissue cells (i.e., human dermal fibroblast cells). Taken together, our results suggest that the synergistic effect of both AgMBG and POC make these newly designed AgMBG/POC composite scaffold an attractive candidate for soft tissue engineering applications. © 2019 Elsevier B.V

Antimicrobial Activity of Novel Synthetic Peptides Derived from Indolicidin and Ranalexin against Streptococcus pneumoniae.

Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics in order to defeat multidrug-resistant bacteria such as Streptococcus pneumoniae. In this study, thirteen antimicrobial peptides were designed based on two natural peptides indolicidin and ranalexin. Our results revealed that four hybrid peptides RN7-IN10, RN7-IN9, RN7-IN8, and RN7-IN6 possess potent antibacterial activity against 30 pneumococcal clinical isolates (MIC 7.81-15.62µg/ml). These four hybrid peptides also showed broad spectrum antibacterial activity (7.81µg/ml) against S. aureus, methicillin resistant S. aureus (MRSA), and E. coli. Furthermore, the time killing assay results showed that the hybrid peptides were able to eliminate S. pneumoniae within less than one hour which is faster than the standard drugs erythromycin and ceftriaxone. The cytotoxic effects of peptides were tested against human erythrocytes, WRL-68 normal liver cell line, and NL-20 normal lung cell line. The results revealed that none of the thirteen peptides have cytotoxic or hemolytic effects at their MIC values. The in silico molecular docking study was carried out to investigate the binding properties of peptides with three pneumococcal virulent targets by Autodock Vina. RN7IN6 showed a strong affinity to target proteins; autolysin, pneumolysin, and pneumococcal surface protein A (PspA) based on rigid docking studies. Our results suggest that the hybrid peptides could be suitable candidates for antibacterial drug development

Genome map of clinical isolates compared to <i>P</i>. <i>aeruginosa</i> reference genome (NC_002516.2).

<p>All ten isolates were separated in rings. The inner most circle represents the reference genome and outer most circle with labels represent the CDS (in dark). The percentage similarity between each genome are represented in different colors. Map and underlying analysis were performed with the BLAST Ring Image Generator (BRIG) (<a href="http://sourceforge.net/projects/brig" target="_blank">http://sourceforge.net/projects/brig</a>).</p