Integrated Evaluation of Urtica dioica Extract Assessing Physiochemical Analysis with Antioxidant, Antiviral, and Immunomodulatory Effects Against SARS-CoV-2

Abstract

Background: A major challenge in antiviral development is the identification of novel virus-host interactions while ensuring therapeutic efficacy and safety. These challenges have renewed interest in phytochemicals derived from medicinal plants as alternative antiviral agents. Objectives: In this study, we investigated the antioxidant, antiviral, and immunomodulatory properties of a Mediterranean Urtica dioica extract (UdE) against SARS-CoV-2 using chemical, biochemical, and in vitro approaches. Methods: The physicochemical properties of UdE were characterized using microtiter assays and HPLC analysis. Cytocompatibility was evaluated in HEK293T, Vero E6, Caco-2, and Calu-3 cell lines while antioxidant activity was assessed using both chemical and cell-based assays. Antiviral activity was evaluated by assessing inhibition of SARS-CoV-2 receptor binding domain (RBD)-ACE2 interaction using ELISA, inhibition of SARS-CoV-2 main protease (Mpro) activity via FRET assay and inhibition of viral entry using SARS-CoV-2 S1 pseudovirus neutralization assay. Results: UdE (100 & micro;g/mL) inhibited RBD-ACE2 binding by 94% and suppressed Mpro activity by 74%, while reducing moderate but significant inhibition of pseudovirus entry (33.6%) at 300 & micro;g/mL dose level in ACE2 expressing HEK293T cells. Immunomodulatory analysis revealed significant suppression of IL-1 beta and IL-6 production, accompanied by increased TNF-alpha and IL-8 levels. Conclusions: Collectively, these findings highlight that UdE exhibits multi-target in vitro antioxidant, antiviral, and immunomodulatory activity against SARS-CoV-2; therefore, UdE represents a promising bioactive extract for the management of SARS-CoV-2 infection.