Antimicrobial Efficacy of Green Synthesized Nanosilver with Entrapped Cinnamaldehyde against Multi-Drug-Resistant Enteroaggregative Escherichia coli in Galleria mellonella

The use of Galleria mellonella in metal nanoparticle development: A systematic review

Research on metal nanoparticles is crucial for their application in diverse fields, requiring detailed assessments of their effects and potential. Galleria mellonella larvae have emerged as a valuable model for studying the impacts of metal nanoparticles, offering ethical and logistical advantages over traditional models. This systematic review synthesizes evidence on the application of Galleria mellonella in evaluating the toxicity, distribution, and therapeutic potential of metal nanoparticles. Adhering to PRISMA guidelines, a comprehensive database search (MEDLINE, Embase, Cochrane, Scopus, Google Scholar, Science Citation Index Expanded) was conducted using keywords related to Galleria mellonella and metal nanoparticles. The SYRCLE's risk of bias tool (adapted for G. mellonella) was used for risk of bias assessment. Out of 1696 initially identified studies, 31 met the inclusion criteria, encompassing research from 2011 to 2024. The included studies effectively demonstrate G. mellonella's capacity to model the toxicity of metal nanoparticles, their therapeutic potential in treating infections, and the impact on the innate immune response, bridging the gap between simpler in vitro assays and more complex mammalian models. Galleria mellonella stands out as a critical model for the early-stage development and evaluation of metal nanoparticles, particularly in assessing toxicity, therapeutic efficacy in infection treatment, and interaction with immune systems. This review underscores the larvae's role in metal nanoparticle research, advocating for its broader use to streamline development processes while minimizing ethical concerns.

Galleria mellonella (Greater Wax Moth) as a Reliable Animal Model to Study the Efficacy of Nanomaterials in Fighting Pathogens

The spread of multidrug-resistant microbes has made it necessary and urgent to develop new strategies to deal with the infections they cause. Some of these are based on nanotechnology, which has revolutionized many fields in medicine. Evaluating the safety and efficacy of these new antimicrobial strategies requires testing in animal models before being tested in clinical trials. In this context, Galleria mellonella could represent a valid alternative to traditional mammalian and non-mammalian animal models, due to its low cost, ease of handling, and valuable biological properties to investigate host-pathogen interactions. The purpose of this review is to provide an updated overview of the literature concerning the use of G. mellonella larvae as an animal model to evaluate safety and efficacy of nanoparticles and nanomaterials, particularly, of those that are used or are under investigation to combat microbial pathogens.

Synergistic Antibacterial Properties of Silver Nanoparticles and Its Reducing Agent from Cinnamon Bark Extract

Synthesis of silver nanoparticles with antibacterial properties using a one-pot green approach that harnesses the natural reducing and capping properties of cinnamon (Cinnamomum verum) bark extract is presented in this work. Silver nitrate was the sole chemical reagent employed in this process, acting as the precursor salt. Gas Chromatography-Mass Spectroscopy (GC-MS), High-Performance Liquid Chromatography (HPLC) analysis, and some phytochemical tests demonstrated that cinnamaldehyde is the main component in the cinnamon bark extract. The resulting bio-reduced silver nanoparticles underwent comprehensive characterization by Ultraviolet-Vis (UV-Vis) and Fourier Transform InfraRed spectrophotometry (FTIR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy, and Scanning Electron Microscopy suggesting that cinnamaldehyde was chemically oxidated to produce silver nanoparticles. These cinnamon-extract-based silver nanoparticles (AgNPs-cinnamon) displayed diverse morphologies ranging from spherical to prismatic shapes, with sizes spanning between 2.94 and 65.1 nm. Subsequently, the antibacterial efficacy of these nanoparticles was investigated against Klebsiella, E. Coli, Pseudomonas, Staphylococcus aureus, and Acinetobacter strains. The results suggest the promising potential of silver nanoparticles obtained (AgNPs-cinnamon) as antimicrobial agents, offering a new avenue in the fight against bacterial infections.

Bioactive Compounds from Plant Origin as Natural Antimicrobial Agents for the Treatment of Wound Infections

The rising prevalence of drug-resistant bacteria underscores the need to search for innovative and nature-based solutions. One of the approaches may be the use of plants that constitute a rich source of miscellaneous compounds with a wide range of biological properties. This review explores the antimicrobial activity of seven bioactives and their possible molecular mechanisms of action. Special attention was focused on the antibacterial properties of berberine, catechin, chelerythrine, cinnamaldehyde, ellagic acid, proanthocyanidin, and sanguinarine against Staphylococcus aureus, Enterococcus spp., Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. The growing interest in novel therapeutic strategies based on new plant-derived formulations was confirmed by the growing number of articles. Natural products are one of the most promising and intensively examined agents to combat the consequences of the overuse and misuse of classical antibiotics.

A comprehensive investigation of the medicinal efficacy of antimicrobial fusion peptides expressed in probiotic bacteria for the treatment of pan drug-resistant (PDR) infections

The present work aimed to examine the intracellular antibacterial efficacy of Recombinant Lactobacillus acidophilus/antimicrobial peptides (AMPs) Melittin and Alyteserin-1a, specifically targeting Gram-negative bacteria. The first assessment was to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Recombinant L. acidophilus/AMPs versus Gram-negative and Gram-positive bacteria. In addition, the researchers examined the in vitro viability and safety of AMPs generated by L. acidophilus. The experiments included exposing the AMPs to elevated temperatures, proteases, cationic salts at physiological levels, and specific pH settings. The safety aspect was evaluated using hemolytic analysis utilizing sheep erythrocytes; cytotoxicity assays employing cell lines, and experiments on beneficial gut lactobacilli. An experiment was done using a time-kill method to assess the intracellular antibacterial efficacy of Recombinant L. acidophilus/AMPs compared to pathogenic varieties in HEp-2 cells. Previous investigations have shown that the MBC levels of recombinant L. acidophilus/AMPs were consistently two to four times higher than the equivalent MIC values when evaluated versus Gram-negative bacteria. Furthermore, the stability of the Recombinant L. acidophilus/AMPs showed variability when exposed to elevated temperatures (70 and 90 ℃), treated with protease enzymes (proteinase K, lysozyme), exposed to higher concentrations of physiological salts (150 mM NaCl and 2 mM MgCl2), and varying pH levels (ranging from 4.0 to 9.0). The recombinant L. acidophilus/AMPs are non-hemolytic towards sheep erythrocytes, exhibit little cytotoxicity in RAW 264.7 and HEp-2 cells, and are considered safe when compared to beneficial gut lactobacilli. The research examined the intracellular bacteriostatic effects of recombinant L. acidophilus/AMPs on Gram-negative bacteria inside HEp-2 cells. Nevertheless, no notable bactericidal impact was seen on Gram-positive bacteria (P > 0.05). The research shows that recombinant L. acidophilus/AMPs, namely (L. acidophilus/melittin/Alyteserin-1a) as the focus of the investigation, effectively eliminate Gram-negative bacteria. Therefore, more investigation is necessary to elaborate on these discoveries.

In vitro and in vivo comparative analysis of antibacterial activity of green-synthesized silver nanoparticles

This study aims to compare antibacterial effects of green-synthesized silver nanoparticles (AgNPs) with silver nitrate (AgNO3 ). AgNPs were successfully synthesized using Eucalyptus camaldulensis leaf extract as a reducing and stabilizing agent. Minimum inhibitory concentrations (MIC) of AgNPs and AgNO3 against Staphylococcus aureus and Pseudomonas aeruginosa ranged between 4.8 and 6.75 µg mL-1 . Growth curves demonstrated that inhibition of P. aeruginosa occurred right after AgNPs were added and throughout the period of the study (72 h). Antibacterial effects of both AgNPs and AgNO3 could be abrogated by cysteine and 2-mercaptoethanol, thiol-containing compounds. Galleria mellonella model revealed relatively low toxic effects of both AgNPs and AgNO3 . At 20MIC of AgNPs (≈137.8 mg kg-1 ), more than 80% survival of G. mellonella was observed. Unexpectedly, silver-containing agents could not rescue larvae after S. aureus infection. Further ex vivo experiments in the presence of coelomic larval fluid demonstrated the reduction of antibacterial activity of both AgNPs and AgNO3 . It was speculated that anionic molecules present in the coelomic fluid might neutralize the action of Ag ions. Binding of AgNPs or AgNO3 to albumin, a major protein in human blood which transport several endogenous compounds was not detected, indicating that the silver-containing agents could be applied as an antimicrobial agent.

Galleria mellonella-A Model for the Study of aPDT-Prospects and Drawbacks

Galleria mellonella is a promising in vivo model insect used for microbiological, medical, and pharmacological research. It provides a platform for testing the biocompatibility of various compounds and the kinetics of survival after an infection followed by subsequent treatment, and for the evaluation of various parameters during treatment, including the host-pathogen interaction. There are some similarities in the development of pathologies with mammals. However, a limitation is the lack of adaptive immune response. Antimicrobial photodynamic therapy (aPDT) is an alternative approach for combating microbial infections, including biofilm-associated ones. aPDT is effective against Gram-positive and Gram-negative bacteria, viruses, fungi, and parasites, regardless of whether they are resistant to conventional treatment. The main idea of this comprehensive review was to collect information on the use of G. mellonella in aPDT. It provides a collection of references published in the last 10 years from this area of research, complemented by some practical experiences of the authors of this review. Additionally, the review summarizes in brief information on the G. mellonella model, its advantages and methods used in the processing of material from these larvae, as well as basic knowledge of the principles of aPDT.

Natural Substrates and Culture Conditions to Produce Pigments from Potential Microbes in Submerged Fermentation

Pigments from bacteria, fungi, yeast, cyanobacteria, and microalgae have been gaining more demand in the food, leather, and textile industries due to their natural origin and effective bioactive functions. Mass production of microbial pigments using inexpensive and ecofriendly agro-industrial residues is gaining more demand in the current research due to their low cost, natural origin, waste utilization, and high pigment stimulating characteristics. A wide range of natural substrates has been employed in submerged fermentation as carbon and nitrogen sources to enhance the pigment production from these microorganisms to obtain the required quantity of pigments. Submerged fermentation is proven to yield more pigment when added with agro-waste residues. Hence, in this review, aspects of potential pigmented microbes such as diversity, natural substrates that stimulate more pigment production from bacteria, fungi, yeast, and a few microalgae under submerged culture conditions, pigment identification, and ecological functions are detailed for the benefit of industrial personnel, researchers, and other entrepreneurs to explore pigmented microbes for multifaceted applications. In addition, some important aspects of microbial pigments are covered herein to disseminate the knowledge.