Cytotoxic, anti-coronavirus, and antioxidant activity of Hypericum triquetrifolium: Potential therapeutic applications

Background: Hypericum triquetrifolium (HT) is an herbal medicine that has promising pharmacological properties and is traditionally used to treat multiple diseases. Aim: This study examined the chemical composition, antioxidant, anti-inflammatory, and antiviral properties of HT, focusing on its impact on the cytopathic effect of human coronavirus-229E (HCoV-229E). Methods: The phytochemical content and in vitro bioactivity of the aqueous extract of HT collected from Al Marj, Libya, were documented. Common antioxidants were quantified, and the antioxidant activity of the extract was assessed using standard methods. The anti-inflammatory effect of albumin denaturation was evaluated. In this study, we determined the cytotoxicity on Medical Research Council-5 cells and antiviral activity by measuring the extract’s ability to inhibit the cytopathic effect of HCoV-229E on MRC-5 cells. Results: The phytochemical analysis confirmed the presence of phenols, flavonoids, proanthocyanidin, anthocyanidin, and catechin, and a high total phenolic content. The extract possessed strong free radical scavenging activity. In addition, the HT extract significantly inhibited heat-induced albumin denaturation, demonstrating its anti-inflammatory effect. The extract significantly inhibited the cytopathic effect of HCoV-229E on MRC-5 cells, indicating for the first time the antiviral effect of HT. Conclusion: To the best of our knowledge, this study is the first to demonstrate that HT extract has low cytotoxicity and potential antiviral activity against a surrogate human coronavirus. Although these results are promising, they are based on in vitro testing with HCoV-229E, and further studies, including in vivo and clinical investigations, are necessary to assess the relevance of HCoV-2 to severe acute respiratory syndrome-CoV-2 and other human coronaviruses.