• Bharathi S. Department of Zoology, Queen Mary’s College, Chennai-600004, Tamil Nadu
  • S. Kumaran Department of Microbiology, Sri Sankara Arts and Science College, Kanchipuram - 631561,Tamil Nadu
  • G. Suresh Department of Microbiology, Sri Sankara Arts and Science College, Kanchipuram-631561, Tamil Nadu
  • B. Ramesh Department of Biotechnology, Sri Sankara Arts and Science College, Kanchipuram-631561, Tamil Nadu
  • M.s. Nalina Sundari Department of Zoology, Queen Mary’s College, Chennai-600004, Tamil Nadu


Objective: In this study, the phytosynthesis of silver nanoparticles (AgNPs) using leaf extracts of Hygrophila auriculata (HA) and their biological activities was investigated.

Methods: The synthesis of AgNPs was done by using the green synthetic method and analyzed by UV-Visible spectroscopy, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and further characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The antibacterial activity of HA AgNPs was studied by agar well diffusion method and micro broth dilution method for determination of minimum inhibitory concentration (MIC). The antioxidant potentials of HA AgNPs were detected by Diphenyl-1-picryl hydrazyl radical scavenging assay (DPPH), Phosphomolybdenum assay, reducing power assay.

Results: The prepared HA AgNPs showed characteristic absorption peak at 420 nm in the UV-Vis spectrum. FTIR spectra had shown that the biomolecules present in leaf extract were responsible for the reduction and capping material of silver nanoparticles. XRD study showed the particles found to be crystalline in nature, with a face-centered cubic (fcc) structure. TEM and DLS results revealed that the AgNPs were mostly spherical with an average size ranging from ~15-115 nm with a mean diameter of 40.96 nm. The HA AgNPs showed good antibacterial activity and MIC against Staphylococcus aureus (ATCC 6538), Bacillus cereus (NCIM 2106), Pseudomonas aeruginosa (ATCC 9027) and Escherichia coli (ATCC 8739). In agar well diffusion method, the maximum zone of inhibition was found against Pseudomonas aeruginosa (ATCC 9027) with 18 mm and minimum zone of inhibition was found to be against Escherichia coli (ATCC 8739) with 13 mm. The MIC of the HA AgNp was found to be 5µg against all the test organisms. In addition, the Diphenyl-1-picryl hydrazyl radical scavenging assay (DPPH), Phosphomolybdenum assay, reducing power assay revealed they can be used as the potential scavenger against deleterious damages caused by the free radicals.

Conclusion: The present study explored that Hygrophila auriculata which are efficient producers of AgNPs and could act as safe and cost-effective with potential antibacterial and antioxidant activities. These findings encourage studying HA AgNP further for their potential biological applications.

Keywords: Phytosynthesis, Hygrophila auriculata, Silver nanoparticles, Antibacterial, Antioxidant


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