Photocatalytic reduction and anti-bacterial activity of biosynthesized silver nanoparticles against multi drug resistant Staphylococcus saprophyticus BDUMS 5 (MN310601)

Morinda citrifolia L.: A Comprehensive Review on Phytochemistry, Pharmacological Effects, and Antioxidant Potential

Morinda citrifolia L. (M. citrifolia), commonly referred to as noni, a Polynesian medicinal plant with over 2000 years of traditional use, has garnered global interest for its rich repertoire of antioxidant phytochemicals, including flavonoids (kaempferol, rutin), iridoids (aucubin, asperulosidic acid, deacetylasperulosidic acid, asperuloside), polysaccharides (nonioside A), and coumarins (scopoletin). This comprehensive review synthesizes recent advances (2018-2023) on noni's bioactive constituents, pharmacological properties, and molecular mechanisms, with a focus on its antioxidant potential. Systematic analyses reveal that noni-derived compounds exhibit potent free radical scavenging capacity (e.g., 2,2-Diphenyl-1-picrylhydrazyl/2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid) (DPPH/ABTS) inhibition), upregulate endogenous antioxidant enzymes (Superoxide Dismutase (SOD), Catalase (CAT), Glutathione Peroxidase (GPx)), and modulate key pathways such as Nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) and Nuclear Factor kappa-B (NF-κB). Notably, polysaccharides and iridoids demonstrate dual antioxidant and anti-inflammatory effects via gut microbiota regulation. This highlights the plant's potential for innovation in the medical and pharmaceutical fields. However, it is also recognized that further research is needed to clarify its mechanisms of action and ensure its safety for widespread application. We emphasize the need for mechanistic studies to bridge traditional knowledge with modern applications, particularly in developing antioxidant-rich nutraceuticals and sustainable livestock feed additives. This review underscores noni's role as a multi-target antioxidant agent and provides a roadmap for future research to optimize its health benefits.

Anti-quorum Sensing and Anti-biofilm Effect of Nocardiopsis synnemataformans RMN 4 (MN061002) Compound 2,6-Di-tert-butyl, 1,4-Benzoquinone Against Biofilm-Producing Bacteria

In this study, the anti-biofilm compound of 2,6-Di-tert-butyl, 1,4-benzoquinone was purified from Nocardiopsis synnemataformans (N. synnemataformans) RMN 4 (MN061002). To confirm the compound, various spectroscopy analyses were done including ultraviolet (UV) spectrometer, Fourier transform infrared spectroscopy (FTIR), analytical high-performance liquid chromatography (HPLC), preparative HPLC, gas chromatography-mass spectroscopy (GC-MS), liquid chromatography-mass spectroscopy (LC-MS), and 2D nuclear magnetic resonance (NMR). Furthermore, the purified compound was shown 94% inhibition against biofilm-producing Proteus mirabilis (P. mirabilis) (MN396686) at 70 µg/mL concentrations. Furthermore, the metabolic activity, exopolysaccharide damage, and hydrophobicity degradation results of identified compound exhibited excellent inhibition at 100 µg/mL concentration. Furthermore, the confocal laser scanning electron microscope (CLSM) and scanning electron microscope (SEM) results were shown with intracellular damages and architectural changes in bacteria. Consecutively, the in vivo toxicity effect of the compound against Artemia franciscana (A. franciscana) was shown to have a low mortality rate at 100 µg/mL. Finally, the molecular docking interaction between the quorum sensing (QS) genes and identified compound clearly suggested that the identified compound 2,6-Di-tert-butyl, 1,4-benzoquinone has anti-quorum sensing and anti-biofilm activities against P. mirabilis (MN396686).

Biosynthesis, characterization, and antifungal activity of plant-mediated silver nanoparticles using Cnidium monnieri fruit extract

The present study describes a novel method for green synthesis of silver nanoparticles using Cnidium monnieri (CM-AgNPs). Cnidium monnieri fruit is an excellent anti tinea drug that can be used externally to treat superficial fungal infections in the human body. The aqueous ethanolic extract of Cnidium monnieri fruit was prepared and employed in the synthesis of stable silver nanoparticles via biological reduction method. The synthesis conditions of CM-AgNPs was systematically optimized using Box-Behnken design. CM-AgNPs were well characterized by UV-spectroscopy and X-ray powder diffraction (XRD), and it was confirmed that the synthesized particles were AgNPs. The possible functional groups required for the reduction and stabilization of CM-AgNPs in the extract were identified through FTIR spectrum. The size of CM-AgNPs structure was confirmed to be approximately 44.6 nm in polydisperse spherical shape through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser dynamic light scattering (DLS). Further, the minimum inhibitory concentration 90% (MIC90) ratios values of Cm-AgNPs against Trichophyton rubrum (7 d), T. mentagrophytes (7 d) and Candida albicans (24 h) were 3.125, 3.125, and 0.78125 μg/mL, respectively, determined by the broth micro dilution method. Finally, the result was concluded that the synthesized AgNPs could be further evaluated in large scale as a potential human topical antifungal agent.

Morphological modification of silver nanoparticles against multi-drug resistant gram-negative bacteria and cytotoxicity effect in A549 lung cancer cells through in vitro approaches

In the present study, the individual cultures of Proteus mirabilis (P. mirabilis) and Klebsiella pneumoniae (K. pneumoniae) were treated with morphologically modified silver nanoparticles (Ag NPs) and were found to display zones of inhibition of ~ 8 mm, 16 mm, 20 mm, and 22 mm (P. mirabilis) and 6 mm, 14 mm, 20 mm, and 24 mm (K. pneumoniae) at concentrations of 25 µg/ml, 50 µg/mL, 75 µg/mL, and 100 µg/mL, respectively. In addition, turbidity tests were performed based on O. D. values, which exhibited 92% and 90% growth inhibitions at 100 µg/mL concentration for P. mirabilis and K. pneumoniae, respectively. Furthermore, the IC50 concentration of Ag NPs was established for A549 lung cancer cells and found to be at 500 µg/mL. Evidently, the morphological variation of Ag NPs treated A549 lung cancer cells was exhibited with differential morphology studied by phase-contrast microscopy. The results demonstrated that the synthesized Ag NPs was not only efficient against gram-positive bacteria but also against gram-negative bacteria and A549 cancer cells, suggesting that the potential of these biosynthesized Ag NPs is a future drug discovery source for inhibiting bacteria and cancer cells.

Magnetic covalent organic framework for the adsorption of silver nanoparticles and recycled as surface-enhanced Raman substrate and high-efficiency catalysts for 4-nitrophenol degradation

A magnetic covalent organic framework Fe₃O₄@BM was prepared with melamine and 4-4'-biphenyldialdehyde as monomers and used as adsorbent for Ag NP removal. Fe₃O₄@BM was characterized by zeta potential analysis, transform infrared spectrometry, X-ray diffraction, thermogravimetric analysis, contact angle, and N₂ adsorption-desorption. Fe₃O₄@BM possessed plentiful amino groups, positive potential, and rapid separation performance, making it a promising adsorbent for silver nanoparticles. The adsorption process followed the pseudo-second-order kinetic equation and Langmuir isotherm model. The maximum adsorption capacity of Ag NPs calculated by the Langmuir isotherm model was 544.9 mg/g. The adsorption product Fe₃O₄@BM@Ag could be recycled and efficiently catalyze the degradation of 4-nitrophenol within 6 min. Meanwhile, the recycled Fe₃O₄@BM@Ag could also be used as a surface-enhanced Raman substrate for DTNB detection, and the limit of detection of DTNB reached as low as 10^-7 mol/L. This work prepared a promising adsorbent Fe₃O₄@BM for Ag NP adsorption and provided a sustainable approach for the recycling of the adsorption product Fe₃O₄@BM@Ag.

Green synthesis of silver nanoparticles from Mahonia fortunei extracts and characterization of its inhibitory effect on Chinese cabbage soft rot pathogen

The pathogenic bacterium Pectobacterium carotovorum causes soft rot in cabbage and significantly reduces plant yield. In this study, we employed Mhonia fortunei extracts to synthesis silver nanoparticles (Mf-AgNPs) and investigated their functions against P. carotovorum. The results showed that the surface plasmon resonance (SPR) peak of AgNP was 412 nm under optimal synthesis conditions. Furthermore, the results of Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS) and High-resolution transmission electron microscopy (HR-TEM) revealed that the Mf-AgNPs had a spherical structure with an average diameter of 13.19 nm and the content of Ag0 ions accounted for 82.68% of the total elemental content. The X-Ray diffraction (XRD) results confirmed that AgNPs had a face-centered cubic (FCC) crystal structure, while Fourier transform infrared spectroscopy (FTIR) results indicated the presence of various biomolecules as reducing and stabilizing agents on the AgNP surface. Antibacterial activity was first evaluated by an inhibitory zone test, which revealed that 500 μg ml⁻¹ of AgNPs had antibacterial activity against P. carotovorum and four model bacteria including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, respectively with an antibacterial function comparable to 1 mM AgNO₃ solution. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for P. carotovorum were 8 μg ml⁻¹, respectively. Furthermore, AgNPs at 8 μg ml⁻¹ completely inhibited the growth of P. carotovorum, decreased their tolerance to 0.25 mM H₂O₂ as well as considerably reduced colony formation after 1 h of treatment and thereafter. Treatment with Mf-AgNPs resulted in bacterial cell membrane destruction and biofilm formation inhibition, respectively. With an FIC (fractional inhibitory concentration) index of 0.174, AgNP and zhongshengmycin showed a significant synergistic effect. The infection of P. carotovorum to cabbage explants was significantly inhibited in vitro by a combination of 2 μg ml⁻¹ Mf-AgNP and 5 μg ml⁻¹ zhongshengmycin. In conclusion, the synthesized Mf-AgNP exhibited significant antibacterial activity against P. carotovorum.

Multifunctional Silver Nanoparticles Based on Chitosan: Antibacterial, Antibiofilm, Antifungal, Antioxidant, and Wound-Healing Activities

The purpose of this study is to create chitosan-stabilized silver nanoparticles (Chi/Ag-NPs) and determine whether they were cytotoxic and also to determine their characteristic antibacterial, antibiofilm, and wound healing activities. Recently, the development of an efficient and environmentally friendly method for synthesizing metal nanoparticles based on polysaccharides has attracted a lot of interest in the field of nanotechnology. Colloidal Chi/Ag-NPs are prepared by chemical reduction of silver ions in the presence of Chi, giving Chi/Ag-NPs. Physiochemical properties are determined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analyses. TEM pictures indicate that the generated Chi/Ag-NPs are nearly spherical in shape with a thin chitosan covering around the Ag core and had sizes in the range of 9–65 nm. In vitro antibacterial activity was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa by a resazurin-mediated microtiter plate assay. The highest activity was observed with the lowest concentration of Chi/Ag-NPs, which was 12.5 µg/mL for both bacterial strains. Additionally, Chi/Ag-NPs showed promising antifungal features against Candida albicans, Aspergillus fumigatus, Aspergillus terreus, and Aspergillus niger, where inhibition zones were 22, 29, 20, and 17 mm, respectively. Likewise, Chi/Ag-NPs revealed potential antioxidant activity is 92, 90, and 75% at concentrations of 4000, 2000, and 1000 µg/mL, where the IC₅₀ of Chi/Ag-NPs was 261 µg/mL. Wound healing results illustrated that fibroblasts advanced toward the opening to close the scratch wound by roughly 50.5% after a 24-h exposure to Chi/Ag-NPs, greatly accelerating the wound healing process. In conclusion, a nanocomposite based on AgNPs and chitosan was successfully prepared and exhibited antibacterial, antibiofilm, antifungal, antioxidant, and wound healing activities that can be used in the medical field.

Viola betonicifolia-Mediated Biosynthesis of Silver Nanoparticles for Improved Biomedical Applications

We report the biosynthesis of silver (Ag) nanoparticles (NAPs) (LEVB-Ag NAPs) by an environmentally friendly green synthesis approach using the phytoconstituents of Viola betonicifolia leaf extract. The spectroscopic techniques were employed to characterize biosynthesized LEVB-Ag NAPs successfully. Biosynthesized LEVB-Ag NAPs were assessed for antibacterial and antimycotic activities against bacterium and mycological strains (H. pylori, S. epidermidis, C. tropicalis, and T. rubrum) using the serial dilution method. They were also evaluated for their biofilm inhibiting potential against both bacterial and fungi species. They were further assessed for the cytobiocompatible potential with two normal cell lines (293T and hMSC). The results demonstrate that the biosynthesized LEVB-Ag NAPs showed superior log₁₀ reduction in bacterial and fungal growth and presented more than 99.50% killing efficiency. Moreover, biosynthesized LEVB-Ag NAPs excellently inhibited the biofilm formation of bacterial (Gram-positive and Gram-negative) and mycological strains and presented more than 80% biofilm inhibiting percentage compared to both plant extract and CHE-Ag NAPs. They further presented good cytobiocompatibility in vitro with 293T and hMSC cells compared to CHE-Ag NAPs. Biosynthesized LEVB-Ag NAPs presented superior antibacterial, antimycotic, biofilm inhibition, and cytobiocompatible results that might be attributed to the synergistic effect of the NAPs’ physiochemical properties and the immobilized phytoconstituents from plant leaf extract on their surface. Hence, biosynthesized LEVB-Ag NAPs may be a promising contender for a variety of therapeutic applications.

Plant-Extract-Mediated Synthesis of Metal Nanoparticles

Metal nanoparticles (MNPs) have been widely used in several fields including catalysis, bioengineering, photoelectricity, antibacterial, anticancer, and medical imaging due to their unique physical and chemical properties. In the traditional synthesis method of MNPs, toxic chemicals are generally used as reducing agents and stabilizing agents, which is fussy to operate and extremely environment unfriendly. Based on this, the development of an environment-friendly synthesis method of MNPs has recently attracted great attention. The use of plant extracts as reductants and stabilizers to synthesize MNPs has the advantages of low cost, environmental friendliness, sustainability, and ease of operation. Besides, the as-synthesized MNPs are nontoxic, more stable, and more uniform in size than the counterparts prepared by the traditional method. Thus, green preparation methods have become a research hotspot in the field of MNPs synthesis. In this review, recent advances in green synthesis of MNPs using plant extracts as reductants and stabilizers have been systematically summarized. In addition, the insights into the potential applications and future development for MNPs prepared by using plant extracts have been provided.

Novel Multifunctional Silver Nanocomposite Serves as a Resistance-Reversal Agent to Synergistically Combat Carbapenem-Resistant Acinetobacter baumannii

In the face of the abundant production of various types of carbapenemases, the antibacterial efficiency of imipenem, seen as "the last line of defense", is weakening. Following, the incidence of carbapenem-resistant Acinetobacter baumannii (CRAB), which can generate antibiotic-resistant biofilms, is increasing. Based on the superior antimicrobial activity of silver nanoparticles against multifarious bacterial strains compared with common antibiotics, we constructed the IPM@AgNPs-PEG-NOTA nanocomposite (silver nanoparticles were coated with SH-PEG-NOTA as well as loaded by imipenem) whose core was a silver nanoparticle to address the current challenge, and IPM@AgNPs-PEG-NOTA was able to function as a novel smart pH-sensitive nanodrug system. Synergistic bactericidal effects of silver nanoparticles and imipenem as well as drug-resistance reversal via protection of the β-ring of carbapenem due to AgNPs-PEG-NOTA were observed; thus, this nanocomposite confers multiple advantages for efficient antibacterial activity. Additionally, IPM@AgNPs-PEG-NOTA not only offers immune regulation and accelerates tissue repair to improve therapeutic efficacy in vivo but also can prevent the interaction of pathogens and hosts. Compared with free imipenem or silver nanoparticles, this platform significantly enhanced antibacterial efficiency while increasing reactive oxygen species (ROS) production and membrane damage, as well as affecting cell wall formation and metabolic pathways. According to the results of crystal violet staining, LIVE/DEAD backlight bacterial viability staining, and real-time quantitative polymerase chain reaction (RT-qPCR), this silver nanocomposite downregulated the levels of ompA expression to prevent formation of biofilms. In summary, this research demonstrated that the IPM@AgNPs-PEG-NOTA nanocomposite is a promising antibacterial agent of security, pH sensitivity, and high efficiency in reversing resistance and synergistically combatting carbapenem-resistant A. baumannii. In the future, various embellishments and selected loads for silver nanoparticles will be the focus of research in the domains of medicine and nanotechnology.

Phytochemical screening and anti-oxidant activity of Sargassum wightii enhances the anti-bacterial activity against Pseudomonas aeruginosa

In this study, the phytochemical, phenolic, flavonoid and bioactive compounds were successfully screened from crude extract of Sargassum wightii by LC-MS analysis after NIST interpretation. Bacterial growth inhibition study result was shown with 24 mm zone inhibition at 200 µg/mL concentration against P. aeruginosa. The increased phenolic content was much closed to gallic acid and the range was observed at 250 μg/mL concentration. In addition, flavonoid contents of the algae extract was indicated more significant with rutin at 200 μg/mL. In result, both the phenolic and flavonoid contents of the extract were more correlated with gallic acid and rutin. Further, the total anti-oxidant and DPPH radical scavenging activities were shown increased activity at 200 μg/mL concentrations. Furthermore, the excellent anti-bacterial alteration result was observed at 200 μg/mL concentration by minimum inhibition concentration. Therefore, the result was revealed that the marine algae Sargassum wightii has excellent phytochemical and anti-oxidant activities, and it has improved anti-bacterial activity against P. aeruginosa.

Biosynthesized silver nanoparticles using Caulerpa taxifolia against A549 lung cancer cell line through cytotoxicity effect/morphological damage

The Caulerpa taxifolia is excellent marine green algae, which produced enormous bioactive compounds with more biological activities. Also, it is an excellent source for synthesis of Ag NPs with increased bioactivity against various infections. In our study, the marine algae marine algae Caulerpa taxifolia mediated Ag NPs was synthesized effectively. The synthesized Ag NPs was characterized well using UV-spectrometer and X-ray powder diffraction (XRD) and confirmed as synthesized particle was Ag NPs. The available structure of the Ag NPs was morphologically identified by scanning electron microscope (SEM), and exact minimum size, polydispersive spherical shape of the entire Ag NPs structure was confirmed by Transmission electron microscope (TEM). Further, the anti-cancer efficiency of biosynthesized Ag NPs against A549 lung cancer cells was found at 40 µg/mL concentration by cytotoxicity experiment. In addition, the phase contrast images of the result were supported the Ag NPs, which damaged the A549 morphologically clearly. Finally, florescence microscopic images were effectively proved the anti-cancerous effect against A549 lung cancer cells due to the condensed morphology of increased death cells. All the confirmed in-vitro results were clearly stated that the Caulerpa taxifolia mediated Ag NPs has superior anti-cancer agent against A549 lung cancer cells.

Anti-bacterial activity of chitosan loaded plant essential oil against multi drug resistant K. pneumoniae

The development of antibiotic resistant in K. pneumoniae is an emerging thread worldwide due to the poor antimicrobial drugs. To overcome this issue, researchers are focused on plant material and their essential oils to fight against multi drug resistant bacteria. In this context, the current study was concentrated in medicinal plant of guva leaves and their essential oils to combat multi drug resistant bacterial infections. The essential oils were successfully screened and confirmed by HRLC-MS analysis. The anti-bacterial ability of the compounds were loaded into the chitosan nanoparticles and proved by FT-IR analysis. In addition, the chitosan loaded essential oils morphology was compared with chitosan alone in SEM analysis and suggested that the material was loaded successfully. Further, the anti-bacterial ability of the chitosan loaded essential oils were primarily confirmed by agar well diffusion method. At the 100 µg/mL of lowest concentration of chitosan loaded essential oils, the multi-drug resistant K. pneumoniae was inhibited with 96% and confirmed by minimum inhibition concentration experiment. Hence, all the experiments were proved that the essential oils were successfully loaded into the chitosan nanoparticles, and it has more anti-bacterial activity against multi-drug resistant K. pneumoniae.