Phytochemical constituents of fucoidan (Padina tetrastromatica) and its assisted AgNPs for enhanced antibacterial activity

Nano-functionalization and evaluation of antimicrobial activity of Tinospora cordifolia against the TolB protein of Pseudomonas aeruginosa - An antibacterial and computational study

Introduction

Antibacterial drug resistance, brought on by the overuse of antibiotics, is one of the biggest threats to human health. It is crucial to consider cutting-edge strategies, such as herbal remedies, to control multidrug-resistant (MDR) bacteria.

Methods

This study evaluated the phytochemical, antioxidant and antibacterial properties of the various Tinospora cordifolia extracts. Functionalization of the isolated active compound was done using gold (Au) and silver (Ag) nanoparticles (NPs). Further, to understand the interaction of the isolated class, Cordifolisides, with its target, various in-silico methods were used.

Results and Discussion

The plant was reported from the Charaideo district of Assam, whose methanolic stem extract showed the maximum activity towards the nosocomial pathogen Pseudomonas aeruginosa. Consequently, the active compound was isolated and characterized as belonging to the class Cordifoliside using NMR. The AuNPs and AgNPs functionalized isolates showed enhanced antimicrobial activity against P. aeruginosa compared to the unfunctionalized isolate. The most reactive compound, Cordifoliside C was determined using Density Functional Theory (DFT) analysis, whose interactions with the TolB protein were studied using molecular docking methods, which revealed good binding interactions of Cordifoliside C with the TolB protein.

Conclusion

This study offers enormous potential for drug design and might be used as a pipeline to address the urgent problem of multidrug-resistance in bacteria. Graphical Abstract.

Synergistic Antibacterial Effect from Silver Nanoparticles and Anticancer Activity Against Human Lung Cancer Cells

Microbially synthesized silver nanoparticles (AgNPs) with high stability and bioactivity have recently shown considerable promise in biomedical research and application. In this study, AgNPs prepared by Penicillium aculeatum Su1 exhibited effective antibacterial action by inhibiting bacterial growth and destroying cellular structure. Meanwhile, their assessed increased in fold area (IFA) through the Kirby-Bauer disc diffusion method proved that, the AgNPs showed synergistic antibacterial effect on different bacteria when combined with antibiotics, especially for drug-resistant P. aeruginosa (4.58∼6.36-fold) and B. subtilis (4.2-fold). Moreover, the CCK-8 assay and flow cytometric analysis were used to evaluate the cytotoxic effects of AgNPs on normal cells (HBE) and lung cancer cells (HTB-182), which confirmed that they presented higher biocompatibility towards HBE cells when compared with silver ions, but high cytotoxicity in a dosedependent manner with an IC50 values of 35.00 μg/mL towards HTB-182 cells by raising intracellular reactive oxygen species (ROS) levels, hindering cell proliferation, and ultimately leading to cell cycle arrest and cell apoptosis. These results demonstrate that, the biosynthesized AgNPs could be a potential candidate for future therapies of infection caused by drug-resistant bacteria, as well as lung squamous cell carcinoma.

An ocean of possibilities: a review of marine organisms as sources of nanoparticles for cancer care

Seas and oceans have been explored for the last 70 years in search of new compounds that can support the battle against cancer. Marine polysaccharides can act as nanomaterials for medical applications and marine-derived bioactive compounds can be applied for the biosynthesis of metallic and nonmetallic nanoparticles. Nanooncology can be used in numerous fields including diagnostics, serving as drug carriers or acting as drugs. This review focuses on marine-derived nanoparticles with potential oncological applications. It classifies organisms used for nanoparticle production, explains the production process, presents different types of nanoparticles with prospective applications in oncology, describes the molecular pathways responsible for numerous nanomedicine applications, tags areas of nanoparticle implementation in oncology and speculates about future directions.

Cytotoxicity of lycopene-mediated silver nanoparticles in the embryonic development of zebrafish-An animal study

Nano-silver (AgNP) has biological properties which are significant for consumer products, food technology, and medical applications (e.g., wound care products, implantable medical devices, in diagnosis, drug delivery, and imaging). Thus, the use of nano-silver is becoming more and more widespread in medicine. However, the effect of these AgNPs on zebrafish remains unclear. Whereas, lycopene, a fat-soluble carotenoid acts as a potent antioxidant has proved its major role in treating many oral health problems such as lichen planus, and periodontitis. Usage of these lycopene AgNPs would yield better results in wound healing. In this study, we investigated the cytotoxic effects of AgNPs on fibroblasts cells of humans. To investigate the toxic effects of the lycopene-mediated AgNPs on the zebrafish (Danio rerio) and to examine these effects on the embryonic development of the fetus of this species. In this study, zebrafish embryos were treated with AgNPs 0.5, 1, 2, 3, 4 or 5 L nanoparticles/ml for 24 to 96 h post fertilization. Our results showed that with the increasing concentration of nanoparticles, there was a very mild toxic effect. Less toxic effects were observed with 1μl. Our results show that exposure to silver nanoparticles is less toxic to embryonic zebrafish at lower concentrations. The results will contribute to the current understanding of the potential biotoxic effects of nanoparticles and will aid in the safety assessment and synthesis of silver oxide nanoparticles.

Green synthesis of plasmonic nanoparticles using Sargassum ilicifolium and application in photocatalytic degradation of cationic dyes

In the present work, a green synthetic method for the preparation of extremely stable silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using Sargassum ilicifolium has been demonstrated. Thus produced nanoparticles were characterized by UV-Visible (UV-Vis) spectroscopy, Fourier Transform InfraRed spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential analyses. The average size of Ag and Au NPs was 27.9 and 9.36 nm respectively from TEM, which was further substantiated by XRD data. Zeta potential values of -42.2 mV and -28.3 mV for Ag and Au NPs respectively suggested that the nanoparticles were negatively charged and highly stable. AgNPs showed desirable bactericidal activity towards Enterobacter species, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Proteus species. The photocatalytic behaviour of AgNPs was studied to degrade malachite green (MG) and methylene blue (MB) in aqueous medium. In MG, 82.9% degradation was achieved in 180 min of light exposure and the pseudo first order rate constant was 7.2 × 10-3 min-1. In MB, almost 100% of the dye was degraded in the same period and the pseudo first order rate constant calculated was 7.5 × 10-3 min-1. The bio-derived AgNPs are hence promising materials for treating effluent from dyeing industries and water purification.

Antimicrobial lead compounds from marine plants

Marine environment is a home to a very wide diversity of flora and fauna, which includes an array of genetically diverse coastline and under seawater plant species, animal species, microbial species, their habitats, ecosystems, and supporting ecological processes. The Earth is home to an estimated 10 million species, of which a large chunk belongs to marine environment. Marine plants are a store house of a variety of antimicrobial compounds like classes of marine flavonoids—flavones and flavonols, terpenoids, alkaloids, peptides, carbohydrates, fatty acids, polyketides, polysaccharides, phenolic compounds, and steroids. Lot of research today is directed toward marine species, which have proved to be a potent source of structurally widely diverse and yet highly bioactive secondary metabolites. Varied species of phylum Porifera, algae including diatoms, Chlorophyta, Euglenophyta, Dinoflagellata, Chrysophyta, cyanobacteria, Rhodophyta, and Phaeophyta, bacteria, fungi, and weeds have been exploited by mankind for their inherent indigenous biological antimicrobial compounds, produced under the extreme stressful underwater conditions of temperature, atmospheric pressure, light, and nutrition. The present study aims at presenting a brief review of bioactive marine compounds possessing antimicrobial potency.

Evaluation of the toxicities of silver and silver sulfide nanoparticles against Gram-positive and Gram-negative bacteria

In this study, the endogenous lipid signalling molecules, N-myristoylethanolamine, were explored as a capping agent to synthesise stable silver nanoparticles (AgNPs) and Ag sulphide NPs (Ag₂S NPs). Sulphidation of the AgNPs abolishes the surface plasmon resonance (SPR) maximum of AgNPs at 415 nm with concomitant changes in the SPR, indicating the formation of Ag₂S NPs. Transmission electron microscopy revealed that the AgNPs and Ag₂S NPs are spherical in shape with a size of 5-30 and 8-30 nm, respectively. AgNPs and Ag₂S NPs exhibit antimicrobial activity against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentrations (MIC) of 25 and 50 μM for AgNPs and Ag₂S NPs, respectively, were determined from resazurin microtitre plate assay. At or above MIC, both AgNPs and Ag₂S NPs decrease the cell viability through the mechanism of membrane damage and generation of excess reactive oxygen species.

Nanoengineered chlorin e6 conjugated with hydrogel for photodynamic therapy on cancer

The aim of the present study is to fabricate hydrogel as a photosensitizer (PS) for photodynamic therapy. Chlorin e6 (Ce6)-fucoidan/alginates@gellam gum (Ce6-Fu/AL@GG)-based hydrogel was fabricated and characterised in terms of morphology and functional groups. MTT assay was used to check toxicity and also performed scratch assay for wound healing property of Ce6-Fu/AL@GGH. Fourier transform infrared spectroscopy (FT-IR) confirmed the existence of physical interactions between polysaccharides. Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) analysis confirmed a decrease in the thermal stability of the fabricated hydrogel. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) images demonstrated porous matrixes representing homogeneous dispersion of nanoparticles in the hydrogel. Cytotoxicity tests revealed that a decrease in the cell viability occurred in PDT after 48 h treatment. Both Ce6 and laser irradiation induced the HT-29 apoptotic effect that was mediated by intracellular ROS generation and mitochondrial damage. The laser-treated hydrogel was effective in inhibiting HT-29 cell growth. Ce6-Fu/AL@GG hydrogel can be a promising platform for PDT on cancer treatment.

Marine Carbohydrate-Based Compounds with Medicinal Properties

The oceans harbor a great diversity of organisms, and have been recognized as an important source of new compounds with nutritional and therapeutic potential. Among these compounds, carbohydrate-based compounds are of particular interest because they exhibit numerous biological functions associated with their chemical diversity. This gives rise to new substances for the development of bioactive products. Many are the known applications of substances with glycosidic domains obtained from marine species. This review covers the structural properties and the current findings on the antioxidant, anti-inflammatory, anticoagulant, antitumor and antimicrobial activities of medium and high molecular-weight carbohydrates or glycosylated compounds extracted from various marine organisms.

Preparation, Characterization and Application of Polysaccharide-Based Metallic Nanoparticles: A Review

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction and stabilization of MNPs. Considerable research has been directed toward investigating polysaccharide-based metallic nanoparticles (PMNPs) through host⁻guest strategy. In this review, approaches of preparation, including top-down and bottom-up approaches, are presented and compared. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, dynamic light scattering, UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering are discussed in detail. Besides, the applications of PMNPs in the field of wound healing, targeted delivery, biosensing, catalysis and agents with antimicrobial, antiviral and anticancer capabilities are specifically highlighted. The controversial toxicological effects of PMNPs are also discussed. This review can provide significant insights into the utilization of polysaccharides as the hosts to synthesize MPNs and facilitate their further development in synthesis approaches, characterization techniques as well as potential applications.