Synergistic Antibacterial Efficacy of Biogenic Synthesized Silver Nanoparticles using Ajuga bractosa with Standard Antibiotics: A Study Against Bacterial Pathogens

Updated Review of Metal Nanoparticles Fabricated by Green Chemistry Using Natural Extracts: Biosynthesis, Mechanisms, and Applications

Metallic nanoparticles have found wide applications due to their unique physical and chemical properties. Green biosynthesis using plants, microbes, and plant/microbial extracts provides an environmentally friendly approach for nanoparticle synthesis. This review discusses the mechanisms and factors governing the biosynthesis of metallic nanoparticles such as silver, gold, and zinc using various plant extracts and microorganisms, including bacteria, fungi, and algae. The phytochemicals and biomolecules responsible for reducing metal ions and stabilizing nanoparticles are discussed. Key process parameters like pH, temperature, and precursor concentration affecting particle size are highlighted. Characterization techniques for confirming the formation and properties of nanoparticles are also mentioned. Applications of biosynthesized nanoparticles in areas such as antibacterial delivery, cancer therapy, biosensors, and environmental remediation are reviewed. Challenges in scaling up production and regulating nanoparticle properties are addressed. Power Point 365 was used for creating graphics. Overall, green biosynthesis is an emerging field with opportunities for developing eco-friendly nanomanufacturing platforms using abundant natural resources. Further work on optimizing conditions, standardizing protocols, and exploring new biosources is needed to realize the full potential of this approach.

Green synthesised AuNps using Ajuga Bracteosa extract and AuNps-Free supernatant exhibited equivalent antibacterial and anticancerous efficacies

The current study is designed to synthesize gold nanoparticles using Ajuga bracteosa extract, which is a highly known medicinal herb found in the northern Himalayas. The synthesized gold nanoparticles were initially characterized by UV-Vis spectrophotometer, SEM, FTIR, pXRD, and, GC-MS. Antibacterial efficacy of A. bracteosa extract, AuNps, and AuNps-free supernatant activity was checked against highly pathogenic clinical isolates of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa via agar well diffusion method, assuming that supernatant might have active compounds. The Nps-free supernatant showed the maximum antibacterial activity against E. coli (20.8±0.3 mm), Staphylococcus aureus (16.5±0.5), and Pseudomonas aeruginosa (13±0.6). While green synthesized AuNps showed effective antibacterial activity (Escherichia coli (16.4±0.3mm), Staphylococcus aureus (15.05±0.5mm), and Pseudomonas aeruginosa (11.07±0.6mm)) which was high compared to A. bracteosa extract. Anticancer activity was assessed by MTT assay on U87 and HEK293 cell lines. Aj-AuNps have an antigrowth effect on both the cell lines however Aj-AuNps-free supernatant which was also evaluated along with the Aj-AuNps, showed high toxicity toward HEK293 cell line compared to U87. Further, the GC-MS analysis of supernatant showed the presence of resultant toxic compounds after the reduction of gold salt, which include Trichloromethane, Propanoic acid, 2-methyl-, methyl ester, Methyl isovalerate, Pentanoic acid, 2-hydroxy-4-methyl-, Benzene-propanoic acid, and alpha-hydroxy. Based on the observation small molecular weight ligands of Ajuga bracteosa were analyzed in-silico for their binding efficacy towards selected membrane proteins of our target pathogens. RMSD is also calculated for the best docked protein ligand pose. The results revealed that among all listed ligands, Ergosterol and Decacetylajugrin IV have high virtuous binding affinities towards the membrane proteins of targeted pathogens. The current findings revealed that the Aj-AuNps are good antibacterial as well as anticancerous agents while the Nps-free supernatant is also exceedingly effective against resistant pathogens and cancer cell lines.

Phytochemical-based nanodrugs going beyond the state-of-the-art in cancer management-Targeting cancer stem cells in the framework of predictive, preventive, personalized medicine

Cancer causes many deaths worldwide each year, especially due to tumor heterogeneity leading to disease progression and treatment failure. Targeted treatment of heterogeneous population of cells - cancer stem cells is still an issue in protecting affected individuals against associated multidrug resistance and disease progression. Nanotherapeutic agents have the potential to go beyond state-of-the-art approaches in overall cancer management. Specially assembled nanoparticles act as carriers for targeted drug delivery. Several nanodrugs have already been approved by the US Food and Drug Administration (FDA) for treating different cancer types. Phytochemicals isolated from plants demonstrate considerable potential for nanomedical applications in oncology thanks to their antioxidant, anti-inflammatory, anti-proliferative, and other health benefits. Phytochemical-based NPs can enhance anticancer therapeutic effects, improve cellular uptake of therapeutic agents, and mitigate the side effects of toxic anticancer treatments. Per evidence, phytochemical-based NPs can specifically target CSCs decreasing risks of tumor relapse and metastatic disease manifestation. Therefore, this review focuses on current outlook of phytochemical-based NPs and their potential targeting CSCs in cancer research studies and their consideration in the framework of predictive, preventive, and personalized medicine (3PM).

Interactions of Chitosan-coated Green Synthesized Silver Nanoparticles using Mentha spicata and Standard Antibiotics against Bacterial Pathogens

BACKGROUND

Infectious diseases are caused by various multidrug-resistant pathogenic bacteria and in recent scenarios, nanoparticles have been used as innovative antimicrobial agents.

AIMS

This current research aimed to evaluate the bactericidal effect of chitosan-coated green synthesized silver nanoparticles using aqueous extract of Mentha spicata (MSaqu) against bacterial pathogens, i.e., Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, and Streptococcus pyogenes.

METHODS

Synthesis and characterization of silver nanoparticles (MSAgNPs) were carried out via atomic absorption spectrometer and Fourier-transform infrared spectroscopy. Agar well and agar disc diffusion methods were used to assess the antibacterial and synergistic effect of chitosanmediated biogenic silver nanoparticles and standard antibiotics. Three types of interactions, i.e., antagonistic (↓), synergistic (↑), and additive (¥) were observed.

RESULTS

Synergistic effect was recorded against Pseudomonas aeruginosa (8.5±0.25 mm↑), Serratia marcescens (19.0±1.0 mm↑), and Klebsiela pneumonia (8.5±0.25 mm↑), an additive effect was exhibited by Escherichia coli (9.0±0.0 mm¥), Streptococcus pyogenes (10.0±0.0 mm¥), and Staphylococcus aureus (7.5±0.25 mm↓) and they showed antagonistic effects when chitosan-coated silver nanoparticles (CLMSAgNPs) were applied compared to chitosan, MSaqu, and MSAgNPs. Interesting antibacterial results were recorded when chitosan-coated Mentha spicata extract and silver nanoparticles were applied along with antibiotics. The synergistic effects of chitosan-coated silver nanoparticles (CLMSAgNPs) + K were recorded against E. coli (14.5±0.25 mm). The synergistic effects of chitosan-coated silver nanoparticles (CLMSAgNPs) + AML were recorded against E. coli (5.5±0.0 mm), S. pyogenes (10.0±0.0 mm), K. pneumonia (5.5±0.0 mm), and S. aureus (4.0±0.0 mm). The synergistic effects of chitosan-coated silver nanoparticles (CLMSAgNPs) + NOR were recorded against E. coli (16.0±0.0 mm), P. aeruginosa (19.0±0.0 mm), S. marcescens (19.5±0.25 mm), S. pyogenes (11.5.0±0.25 mm), K. pneumonia (23.0±0.0 mm), and S. aureus (8.5±0.25 mm).

CONCLUSION

Current findings concluded that chitosan-coated biogenic silver nanoparticles have potential bactericidal effects against infectious pathogens and could be used as forthcoming antibacterial agents.

A Survey on Analytical Methods for the Characterization of Green Synthesized Nanomaterials

Nowadays, nanotechnologies are well established and the uses of a great variety of nanomaterials show exponential growth. The development of green synthesis procedures experienced a great development thanks to the contribution of researchers of diverse origins. The versatility of green chemistry allows producing a wide range of organic and inorganic nanomaterials with numerous promising applications. In all cases, it is of paramount importance to carefully characterize the resulting nanomaterials because their properties will determine their correct performance to accomplish the function to which they were synthesized or even their detrimental effects like nanotoxicological behavior. This review provides an overview of frequently employed characterization methods and their applications for green synthesized nanomaterials. However, while several different nanoscale materials and their associated green construction methodology are being developed, other important techniques would be extensively incorporated into this field soon. The aim is to encourage researchers in the field to employ a variety of these techniques for achieving an exhaustive characterization of new nanomaterials and for contributing to the development of validated green synthesis procedures.

Synthesis, Characterization, Applications, and Toxicity of Green Synthesized Nanoparticles

Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1-100 nm which exhibit significantly different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment; and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

Cytotoxicity, Anti-diabetic, and hepato-protective potential of Ajuga bracteosa-conjugated silver nanoparticles in Balb/c mice

BACKGROUND

Ajuga bracteosa is a traditional herb used against various diseases.

OBJECTIVE

Current research aimed to investigate the anti-diabetic and hepato-protective effect of green synthesized silver nanoparticles (ABAgNPs) using Ajuga bracteosa aqueous extract (ABaqu).

METHODS

In vitro anti-diabetic and cytotoxic effects were carried out via α- glucosidase inhibition, brine shrimp lethality, and protein kinase inhibition assays. For in vivo screening of 200 mg/kg and 400 mg/kg of both ABAgNPs and ABaqu in alloxan-induced and CCl4-induced Swiss albino mice were used. Liver and kidney functional markers, hematology, and histopathological studies were carried out after 14 days of administration.

RESULTS

In vivo antidiabetic and anti-cancerous effects showed valuable anti-hyperglycemic and hepato-protective potential when mice were treated with ABaqu and ABAgNPs. A significant reduction in the blood glucose level was recorded when ABaqu and ABAgNPs were administrated orally compared to Glibenclamide treated group. Significant reduction in ALT, AST, ALP, urea, uric acid, and creatinine was recorded in ABaqu and ABAgNPs treated diabetic mice. The hepato-protective findings indicated that ALT, ALP, AST were elevated in CCl4-induced mice while declined in both ABAgNPs and ABaqu treated CCl4-induced mice. Histopathological examination revealed that ABAgNPs have hepato-protective activity.

CONCLUSION

It was concluded that ABAgNPs and ABaqu possessed strong anti-diabetic and hepato-protective phytoconstituents which could be used in the prevention of diseases.

Emerging Strategies to Combat β-Lactamase Producing ESKAPE Pathogens

Since the discovery of penicillin by Alexander Fleming in 1929 as a therapeutic agent against staphylococci, β-lactam antibiotics (BLAs) remained the most successful antibiotic classes against the majority of bacterial strains, reaching a percentage of 65% of all medical prescriptions. Unfortunately, the emergence and diversification of β-lactamases pose indefinite health issues, limiting the clinical effectiveness of all current BLAs. One solution is to develop β-lactamase inhibitors (BLIs) capable of restoring the activity of β-lactam drugs. In this review, we will briefly present the older and new BLAs classes, their mechanisms of action, and an update of the BLIs capable of restoring the activity of β-lactam drugs against ESKAPE (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens. Subsequently, we will discuss several promising alternative approaches such as bacteriophages, antimicrobial peptides, nanoparticles, CRISPR (clustered regularly interspaced short palindromic repeats) cas technology, or vaccination developed to limit antimicrobial resistance in this endless fight against Gram-negative pathogens.

Antibacterial, anti-efflux, anti-biofilm, anti-slime (exopolysaccharide) production and urease inhibitory efficacies of novel synthesized gold nanoparticles coated Anthemis atropatana extract against multidrug- resistant Klebsiella pneumoniae strains

In this study, the antibacterial, anti-efflux, anti-biofilm, anti-slime (exopolysaccharide) production and urease inhibitory efficacies of green synthesized gold nanoparticles (AuNPs) coated Anthemis atropatana extract against multidrug- resistant (MDR) Klebsiella pneumoniae strains were evaluated. The green synthesized AuNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), particle size distribution, zeta potential and Fourier-transform infrared spectroscopy (FTIR). Then, antibacterial, anti-slime (exopolysaccharide) production, anti-biofilm and anti-efflux activities of AuNPs were investigated using micro-dilation, Congored agar, microtiter plate and MIC of ethidium bromide methods, respectively. Subsequently, the expression of mrkA, wzm and acrB genes was evaluated using quantitative Real-Time PCR (qRT-PCR). The synthesized AuNPs exhibited antibacterial activity against MDR strains of K. pneumoniae (minimum inhibitory concentration (MIC) of 6.25-50 µg/ml), as well as showed significant anti-slime (exopolysaccharide) production, anti-biofilm and anti-efflux activities against MDR strains. AuNPs showed significant inhibition against jack-bean urease and down-regulated the expression of mrkA, wzm and acrB genes. Moreover, the in vitro cytotoxic activity confirmed by MTT assay on the HEK-293 normal cell line showed negligible cytotoxicity. Thus, the present study suggests the potential use of AuNPs in the development of novel therapeutics for the prevention of biofilm-associated K. pneumoniae infections.