Sustainable synthesis of zinc oxide nanoparticles from Persicaria lapathifolia: versatile anticancer and antibacterial applications

Abstract

Colorectal cancer (CRC) is one of the most common cancers in the world and one of the leading causes of cancer mortality. In this study, zinc oxide nanoparticles (PlS-ZnO NPs) were synthesized eco-friendly using an aqueous extract from the stems of Persicaria lapathifolia and their anticancer and antibacterial activities were evaluated. The PlS-ZnO NPs were prepared by a simple sol-gel combustion method and investigated by different spectroscopic and microscopic techniques. The resulting nanoparticles were of polygonal and hexagonal morphology with the average size of 21.45 nm. The PlS-ZnO NPs exhibited high cytotoxicity against human colorectal cancer cell line (HCT-116) with IC50 value of 11.31 μg/mL. Cytomorphological studies showed that these nanoparticles killed cells through both apoptosis and necrosis. Apoptotic process was accompanied by enhancement of intracellular ROS and MMP. Moreover, the PlS-ZnO NPs exhibited excellent antibacterial activity towards different pathogenic bacteria like Bacillus subtilis, Bacillus megaterium, Vibrio cholerae and Proteus vulgaris and was found to be better than the positive control amoxicillin. These results indicate that the green synthesized PlS-ZnO NPs can be considered as a potential multifunctional agent for the treatment of colorectal cancer and bacterial infections. The environmentally friendly and cost-effective synthesis of PlS-ZnO nanoparticles (NPs) utilizing P. lapathifolia enhances the potential of this nanomaterial for medical applications. This sustainable approach not only reduces environmental impact but also aligns with the increasing demand for biocompatible materials in healthcare.

Keywords: Persicaria lapathifolia; ROS; antibacterial activity; apoptosis; colorectal cancer; green synthesis; zinc oxide nanoparticles.

FIGURE 1

(a) UV-visible spectrum of P. lapathifolia-synthesized ZnO nanoparticles alongside a visual representation of the reaction mixture. The observed color change from dark brown to pale yellow in the spectrum confirms the successful formation of ZnO phytocomplex. The precipitate after calcination turned into a white powder indicating the formation of Zinc oxide nanoparticles. (b) Tauc plot of synthesized ZnO NPs using P. lapathifolia stem extract.

FIGURE 2

FTIR spectrum of P. lapathifolia-synthesized ZnO nanoparticles.

FIGURE 3

XRD pattern of P. lapathifolia-synthesized ZnO nanoparticles.

FIGURE 4

Structure, elemental composition, and size of P. lapathifolia-synthesized ZnO nanoparticles: (a) FESEM micrograph, (b) EDX spectrum, and (c) Particle size distribution.

FIGURE 5

The cytotoxic effects of the phytogenic zinc oxide nanoparticles (PlS-ZnO NPs) were assessed against the human colorectal carcinoma (HCT-116) cell line and normal colon (CCD 841 CoN) cells using the MTT assay. The data presented represents the mean ± standard deviation (SD) of three independent experimental replicates. Statistical significance was determined through Tukey’s multiple comparisons test, where * indicates a significant difference at p = 0.018, and *** denotes high statistical significance at p < 0.001.

FIGURE 6

Fluorescence microscopic images of morphological alterations in HCT-116 treated with PlS-ZnO NPs: (a) control, (b) PlS-ZnO NPs (10 μg/mL), and (c) PlS-ZnO NPs (12.5 μg/mL).

FIGURE 7

Fluorescence microscopic images of ROS generation in HCT-116 cells treated with PlS-ZnO NPs: (a) control, (b) PlS-ZnO NPs (10 μg/mL, (c) PlS-ZnO NPs (12.5 μg/mL). and (d) Histogram represents the quantification of apoptotic cells in percentage.

FIGURE 8

Fluorescence microscopic images of alterations in MMP of HCT-116 treated with PlS- ZnO NPs analyzed using rhodamine 123 stain: (a) control, (b) PlS-ZnO NPs (10 μg/mL), (c) PlS-ZnO NPs (12.5 μg/mL) and (d) Histogram represents the quantification of MMP in percentage.

FIGURE 9

Morphological assessment of apoptosis and necrosis in HCT-116 cells treated with P. lapathifolia-synthesized ZnO nanoparticles. Bright-field microscopy images were captured following AO/EtBr staining. (a) Control, (b) PlS-ZnO NPs (10 μg/mL) and (c) PlS-ZnO NPs (12.5 μg/mL). (d) Quantitative analysis of apoptotic cells as a percentage of the total cell population.

FIGURE 10

Fluorescence microscopic images of HCT-116 treated with PlS-ZnO NPs analyzed using PI staining: (a) control, (b) PlS-ZnO NPs (10 μg/mL), (c) PlS-ZnO NPs (12.5 μg/mL), and (d) Histogram represents the quantification of apoptotic cells in percentage.

FIGURE 11

Zone of inhibition produced by PIS-ZnO NPs against selected bacterial pathogens. (a) Bacillus megaterium, (b) Bacillus subtilis, (c) Vibrio cholerae, and (d) Proteus vulgaris.

FIGURE 12

The growth kinetics of (a) Bacillus megaterium, (b) Proteus vulgaris, (c) Vibrio cholerae, and (d) Bacillus subtilis were evaluated in the presence and absence of PlS-ZnO NPs at a concentration of 150 μg/mL.