Antibacterial and photocatalytic potential of piperine-derived zinc oxide nanoparticles against multi-drug-resistant non-typhoidal Salmonella spp.
Authors: Unni Varsha , Abishad Padikkamannil , Mohan Bibin , Arya Pokkittath Radhakrishnan , Juliet Sanis , John Lijo , Vinod Valil Kunjukunju , Karthikeyan Asha , Kurkure Nitin Vasantrao , Barbuddhe Sukhadeo Baliram , Rawool Deepak Bhiwa , Vergis Jess 
Published: February 2025

Abstract

Background
Drug-resistant pathogens and industrial dye wastes have emerged as critical global public health concerns, posing significant risks to human and animal health, as well as to environmental sustainability. Green synthesized nano absorbents were found to be a viable strategy for treating drug-resistant pathogens and in wastewater. Hence, this study endeavored the synthesis of piperine-driven nano-zinc oxide (ZnONPs) and evaluated them for antibacterial, antibiofilm, and photocatalytic disinfection potential against multi-drug resistant (MDR) foodborne strains of non-typhoidal Salmonella (NTS). Besides, the dye degradation potential of ZnONPs when exposed to UV, sunlight, and LED lights and their antioxidant capacity were assessed.

Results
Initially, in silico analysis of piperine revealed drug-likeliness with minimal toxicity and strong interaction between piperine and OmpC motifs of Salmonella spp. UV spectroscopy of ZnONPs revealed a prominent absorption peak at 340 nm, while PXRD analysis confirmed the hexagonal wurtzite structure of ZnONPs by exhibiting peaks at 30°, 35.6°, 41.3°, 43.6°, 44.3°, 48°, 53°, 58°, and 59.2°, which corresponded to the lattice planes (102), (110), (103), (200), (112), (004), (104), (210), and (211). Additionally, the TEM images demonstrated predominantly spherical ZnONPs with hexagonal wurtzite crystalline SAED pattern. The minimum inhibitory concentration and minimum bactericidal concentration values (µg/mL) of the ZnONPs were found to be 62.50 and 125, respectively. The ZnONPs were observed to be safe with minimal hemolysis (less than 2%) in chicken RBCs, and no cytopathic effects were observed in the MTT assay using HEK cell lines. The NPs were found to be variably stable (high-end temperatures, proteases, cationic salts, and diverse pH), and were tested safe towards commensal gut lactobacilli. Additionally, in vitro time-kill kinetic assay indicated that the MDR-NTS strains were eliminated after co-incubating with ZnONPs for 6 h. The photocatalytic studies exhibited complete bacterial elimination under visible light at 4 h. Interestingly, the ZnONPs significantly inhibited the biofilm formation in the crystal violet staining assay by MDR-NTS strains (P < 0.001) at 24 and 48 h. Besides, a dose-dependent reducing power assay and 2,2′- azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) assay were exhibited. Moreover, ZnONPs significantly degraded methylene blue, crystal violet, and rhodamine-B under different light sources (sunlight, UV light, and LED).

Conclusions
This study revealed a sustainable one-pot method of synthesizing ZnONPs from piperine, which might be used as a viable antibacterial candidate with antioxidant, antibiofilm, and photocatalytic properties with eco-friendly implications and wastewater treatment.