Plant extract helps create zinc oxide nanoparticles for medical uses

Jenn Hoskins
4th January, 2026

Plant extract helps create zinc oxide nanoparticles for medical uses

Catunaregam spinosa (Thunb.) Triveng.

Image adapted from: Baraili et al. / CC BY (Source)

Key Findings

  • Researchers in Nepal successfully created zinc oxide nanoparticles (ZnO-NPs) using Catunaregam spinosa leaf extract as a sustainable alternative to traditional methods
  • The synthesized ZnO-NPs demonstrated notable antibacterial activity against common bacterial strains like E. coli and S. aureus, inhibiting their growth
  • These ZnO-NPs also exhibited significant antioxidant properties, protecting cells from damage, with moderate toxicity observed against brine shrimp
The increasing resistance of bacteria to conventional antibiotics poses a significant threat to global health, demanding the exploration of new antimicrobial agents. Traditional methods of nanoparticle synthesis often involve harsh chemicals and can be environmentally damaging. Green synthesis offers a more sustainable approach, utilizing natural sources like plant extracts to create nanoparticles with potentially reduced toxicity and comparable efficacy[2]. Researchers at Tribhuvan University recently investigated the potential of zinc oxide nanoparticles (ZnO-NPs) created using the aqueous extract of Catunaregam spinosa (C. spinosa) leaves, assessing their antioxidant, antibacterial properties and toxicity[1]. The study aimed to determine if ZnO-NPs produced through this green synthesis method could effectively combat bacterial infections and act as antioxidants, while also evaluating their potential harmful effects. To confirm the successful creation of ZnO-NPs, the researchers employed several analytical techniques. X-ray Powder Diffraction (XRD) verified the crystalline structure of the nanoparticles, calculating an average size of 12.39 nanometers. Field Emission Scanning Electron Microscopy (FE-SEM) showed the particles were roughly spherical, and Energy Dispersive X-ray Analysis (EDX) confirmed their elemental composition. UV-vis spectroscopy revealed a strong light absorption peak at 366 nanometers, indicative of ZnO-NP formation, while Fourier Transform Infrared Spectroscopy (FTIR) identified the presence of bioactive compounds from the plant extract coating the nanoparticles, contributing to their stability. The synthesized ZnO-NPs demonstrated notable antibacterial activity against four common bacterial strains: Escherichia coli, Shigella sonnei, Klebsiella pneumoniae, and Staphylococcus aureus. Testing at a concentration of 50 μg/mL resulted in inhibition zones – areas where bacterial growth was prevented – ranging from 9 mm to 16 mm, with Klebsiella pneumoniae showing the greatest sensitivity. Further analysis determined the Minimum Inhibitory Concentration (MIC), the lowest concentration needed to halt bacterial growth, to be 6.25 mg/mL for both Klebsiella pneumoniae and Staphylococcus aureus. This antibacterial effect aligns with findings from previous research highlighting the efficacy of green-synthesized ZnO-NPs against foodborne pathogens[2]. Beyond their antibacterial properties, the ZnO-NPs also exhibited significant antioxidant activity, measured using the DPPH assay. Antioxidants protect cells from damage caused by unstable molecules called free radicals, and these nanoparticles effectively scavenged these radicals. This antioxidant capability is consistent with the antioxidant properties observed in other plant-mediated ZnO-NP syntheses[2]. However, it’s crucial to assess the potential toxicity of any new antimicrobial agent. The researchers evaluated the toxicity of the ZnO-NPs using Artemia salina, a small crustacean commonly used in toxicity testing. They determined an LC50 – the concentration lethal to 50% of the test population – of 55.20 μg/mL, indicating a dose-dependent toxic effect. While this demonstrates some toxicity, it is an important step in understanding the safety profile of these nanoparticles. Metal-based nanoparticles, including zinc oxide, are known to exhibit non-specific toxicity towards bacteria, making the development of resistance less likely and broadening their spectrum of activity[3]. The results of this study contribute to the growing body of evidence supporting the use of green-synthesized nanoparticles as potential therapeutic agents. The C. spinosa leaf extract proved to be a suitable source for creating ZnO-NPs with promising antibacterial and antioxidant characteristics. Further research is needed to fully understand their mechanism of action, optimize their efficacy, and assess their safety for potential biomedical applications. This work expands on previous investigations into the use of plant extracts for nanoparticle synthesis and their subsequent biological activity[2][4], suggesting a pathway towards more sustainable and effective antimicrobial solutions.

HerbsMedicineBiotech

References

Main Study

1) Green synthesis of zinc oxide nanoparticles using Catunaregam spinosa (Thunb.) triveng for biologicals applications

Published 31st December, 2025

https://doi.org/10.1371/journal.pone.0320475

Related Studies

2) Green Synthesis and Characterization of ZnO Nanoparticles Using Pelargonium odoratissimum (L.) Aqueous Leaf Extract and Their Antioxidant, Antibacterial and Anti-inflammatory Activities.

https://doi.org/10.3390/antiox11081444

3) Metal-Based Nanoparticles as Antimicrobial Agents: An Overview.

https://doi.org/10.3390/nano10020292

4) Sustainable development through the bio-fabrication of ecofriendly ZnO nanoparticles and its approaches to toxicology and environmental protection.

https://doi.org/10.1007/s13399-022-03445-6


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