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Volume 31
Issue 14
10.3390/molecules31142428
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This is an early access version, the complete PDF, HTML, and XML versions will be available soon.
Article

Green Synthesis Characterization and Evaluation of Senna italica and Vepris reflexa Extracts and Silver Nanoparticles Against SARS-CoV-2 PLpro Enzyme

by
Rebotile M. Machika
1,
Joshua O. Olowoyo
2,
Malohle D. Tswaledi
3 and
Kokoette Bassey
1,*
1
Department of Pharmaceutical Sciences, School of Pharmacy, Sefako Makgatho Health Sciences University, P.O. Box 218, Pretoria 0208, South Africa
2
Department of Health Sciences, Marie College of Health and Human Services, Florida Gulf Coast University, 10501 FGCU Blvd, Fort Myers, FL 33965, USA
3
Department of Biochemistry and Biotechnology, School of Science and Technology, Sefako Makgatho Health Sciences University, P.O. Box 218, Pretoria 0208, South Africa
*
Author to whom correspondence should be addressed.
Molecules 2026, 31(14), 2428; https://doi.org/10.3390/molecules31142428
Submission received: 10 March 2026 / Revised: 19 May 2026 / Accepted: 5 June 2026 / Published: 10 July 2026
(This article belongs to the Special Issue Bioactive Compounds in Plants: Extraction and Application)
Versions Notes

Abstract

This study investigated the antiviral potential of silver nanoparticles (AgNPs) synthesized from Senna italica and Vepris reflexa plant extracts, rich in saponins and flavonoids. The aim was to explore the synthesis of AgNPs through green chemistry, followed by assessing their inhibitory activity against SARS-CoV-2 papain-like protease (PLpro) and evaluating cytotoxicity. The synthesized AgNPs were predominantly spherical in shape, with an average particle size in the nanoscale range (12–55 nm), as conformed by the transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. A dose-dependent inhibition of SARS-CoV-2 PLpro was observed, with IC50 values ranging from 0.12 to 0.48 mg/mL for different formulations. Cytotoxicity tests on Vero-76 cells revealed a high viability (>75%) at concentrations below 0.5 mg/mL for all AgNP samples. The findings suggest that the plant-derived AgNPs exhibit significant antiviral activity and minimal cytotoxicity, supporting their potential for further development as therapeutic agents.
Keywords: silver nanoparticles; Vepris reflexa; Senna italica; SARS-CoV-2 PLpro; phytochemicals; cytotoxicity; antiviral assay silver nanoparticles; Vepris reflexa; Senna italica; SARS-CoV-2 PLpro; phytochemicals; cytotoxicity; antiviral assay

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MDPI and ACS Style

Machika, R.M.; Olowoyo, J.O.; Tswaledi, M.D.; Bassey, K. Green Synthesis Characterization and Evaluation of Senna italica and Vepris reflexa Extracts and Silver Nanoparticles Against SARS-CoV-2 PLpro Enzyme. Molecules 2026, 31, 2428. https://doi.org/10.3390/molecules31142428

AMA Style

Machika RM, Olowoyo JO, Tswaledi MD, Bassey K. Green Synthesis Characterization and Evaluation of Senna italica and Vepris reflexa Extracts and Silver Nanoparticles Against SARS-CoV-2 PLpro Enzyme. Molecules. 2026; 31(14):2428. https://doi.org/10.3390/molecules31142428

Chicago/Turabian Style

Machika, Rebotile M., Joshua O. Olowoyo, Malohle D. Tswaledi, and Kokoette Bassey. 2026. "Green Synthesis Characterization and Evaluation of Senna italica and Vepris reflexa Extracts and Silver Nanoparticles Against SARS-CoV-2 PLpro Enzyme" Molecules 31, no. 14: 2428. https://doi.org/10.3390/molecules31142428

APA Style

Machika, R. M., Olowoyo, J. O., Tswaledi, M. D., & Bassey, K. (2026). Green Synthesis Characterization and Evaluation of Senna italica and Vepris reflexa Extracts and Silver Nanoparticles Against SARS-CoV-2 PLpro Enzyme. Molecules, 31(14), 2428. https://doi.org/10.3390/molecules31142428

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