Plant assisted synthesis of silver nanoparticles using Persicaria perfoliata (L.) for antioxidant, antibacterial, and anticancer properties

Abstract

Persicaria perfoliata (L.) is an herbaceous medicinal plant belonging to the Polygonaceae family. The plant is distributed in Nepal, India, Japan, China, Russia, and Korea. The present study involved the analysis of plant secondary metabolites, synthesis of silver nanoparticles (Ag NPs) using the plant, characterization, and exploration of antioxidant, antidiabetic, antibacterial, and cytotoxic activities. Among six different solvent extracts, the methanol extract displayed the highest total phenolic content (TPC) and total flavonoid content (TFC) of 68.61 ± 0.57 mg GAE/g and 40.69 ± 5.0 mg QE/g respectively. Ag NPs and hexane extract displayed the potential antioxidant activity of IC₅₀ 69.40 ± 0.13 and 144.50 ± 1.36 μg/mL in the DPPH assay. The α-amylase inhibition shown by an aqueous extract and the synthesized Ag NPs IC₅₀ of 1188.83 ± 33.52 and 1369.30 ± 46.86 μg/mL respectively. In antibacterial activity, the highest ZOI of 16 mm was displayed by Ag NPs against Klebsiella pneumoniae followed by a ZOI of 11 mm for methanol extract against Shigella sonnei. Similarly, the lowest MIC and MBC of 0.78125 and 1.5625 mg/mL were recorded for both Ag NPs and methanol extract against Staphylococcus aureus. Aqueous extract and Ag NPs did not display significant toxicity against brine shrimp nauplii. Ag NPs displayed an IC₅₀ of 251.86 ± 58.90 μg/mL against HeLa cell lines. Biosynthesized Ag NPs showed a distinct peak at 409 nm in UV-visible spectra. FTIR analysis revealed the involvement of different functional groups of the organic compounds present in plant extract as reducing, capping, and stabilizing agents in the synthesis of Ag NPs. XRD analysis confirmed the crystal structure of Ag NPs, whereas the average grain size of 44.28 nm was determined by FE-SEM analysis. EDX spectra established the elemental composition of Ag NPs. The present study shows the synthesized Ag NPs using plant extract impart the potential biological activities as compared to that of the crude extract.

Keywords: Antidiabetic; Antimicrobial; Antioxidant; Cytotoxicity; Green synthesis; Persicaria perfoliata; Silver nanoparticles.

Fig. 1

Showing the mechanism of DPPH activity.

Fig. 2

Standard curve of DPPH inhibition by quercetin.

Fig. 3

Percentage inhibition versus concentration curve for plant extracts and Ag NPs.

Fig. 4

(a) Correlation between TPC and antioxidant activity, and (b) correlation between TFC and antioxidant activity.

Fig. 5

Percentage inhibition versus concentration in α-amylase assay.

Fig. 6

ZOI shown by the plant extracts and silver nanoparticles against test organisms.

Fig. 7

Showing the colour change in a resazurin microtiter assay. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 8

MIC of methanol extract, aqueous extract, and Ag NPs against (a)Staphylococcus aureus and (b)Klebsiella pnemoniae shown in 96 well plates.

Fig. 9

Determination of MBC of an (a) aqueous extract, (b) methanol extract and (c) Ag NPs (d), and (e) positive control against KP: Klebsiella pneumoniae and SA: Staphylococcus aureus.

Fig. 10

Diagrammatic representation of the role of silver nanoparticles in the generation of ROS leading destruction of bacterial cells.

Fig. 11

UV visible spectra of synthesized silver nanoparticles and aqueous extract.

Fig. 12

FTIR spectra of plant extract and silver nanoparticles.

Fig. 13

XRD pattern of plant-assisted synthesized silver nanoparticles.

Fig. 14

FE-SEM images of the synthesized silver nanoparticles using P. perfoliata(a) 300 nm scale (b) measuring the length of Ag NPs (c) 5.00 μm scale, and (d) 1.00 μm scale.

Fig. 15

Size distribution of silver nanoparticles.

Fig. 16

EDX micrographic images (a) indicating elemental color mapping of carbon, nitrogen, oxygen, and silver elements (b) indicating elemental color mapping of carbon element (c) indicating elemental color mapping of nitrogen element (d) indicating elemental color mapping of oxygen element (e) indicating elemental color mapping of the silver element with the region of interest on the side. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 17

EDX spectrum of synthesized silver nanoparticle using P. perfoliata.

Fig. 18

(a) Percentage cytotoxicity versus concentration for MTT assay, and (b) Percentage mortality versus concentration graph for brine shrimp assay.

Fig. 19

Mechanism of anticancer activity shown by Ag NPs.