Antiviral Activity of Zinc Oxide Nanoparticles Mediated by Plumbago indica L. Extract Against Herpes Simplex Virus Type 1 (HSV-1)

Abstract

Introduction: Plumbago indica L. is considered a valuable source in the Plumbaginaceae family for various types of active compound such as alkaloids, phenolics and saponins. To promote the usage of P. indica in the bionanotechnology field, zinc oxide nanoparticles (ZnONPs) were biosynthesized by using its alcoholic extract. The inhibitory effects of ZnONPs and the plant extract were also evaluated against HSV-1.

Methods: ZnONPs were described by the following techniques, UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). The phenolic and flavonoid contents of P. indica extract, which are accountable for bioreduction, formation and stabilization of the nanoparticles, were analyzed by HPLC technique. The antiviral assessment was implemented on both agents by using Vero cell lines.

Results: DLS revealed that the average size of ZnONPs was 32.58 ± 7.98 nm and the zeta potential was -20.8 mV. The observation of TEM analysis revealed that the particle size of ZnONPs varied from 2.56 to 8.83 nm. The XRD analysis verified the existence of pure crystals of hexagonal shapes of nanoparticles of ZnO with a main average size of 35.28 nm that is approximating to the values of particle size acquired by SEM analysis (19.64 and 23.21 nm). The HPLC analysis of P. indica ethanolic extract showed that gallic acid, chlorogenic acid and rutin were the major compounds, with concentrations equal to 8203.99, 2965.95 and 1144.99 µg/g, respectively. Regarding the antiviral assessment, the synthesized uncalcinated ZnONPs were found to exhibit a promising activity against HSV-1, with CC₅₀ and IC₅₀ values equal to 43.96 ± 1.39 and 23.17 ± 2.29 µg/mL, respectively.

Conclusion: The green synthesized ZnONPs are considered promising adjuvants to enhance the efficacy of HSV-1 drugs.

Keywords: HPLC analysis; Plumbago indica L.; ZnO nanoparticles; antiviral activity and green synthesis.