Antiviral effect and mode of action of methanolic extract ofVerbascum thapsusL. on pseudorabies virus (strain RC/79)

Abstract

The methanolic extract of Verbascum thapsus was evaluated for its antiviral activity against the pseudorabies virus strain RC/79 (PrV), and also for its cytotoxic activity on Vero cells. The extract showed CC₅₀ values of 1100 µg mL⁻¹ and 1426 µg mL⁻¹ by NRU and MTT assays, respectively. The 50% inhibitory concentration of the extract for PrV plaque formation was determined at 35 µg mL⁻¹, and selectivity indices were 31.4 (NRU) and 40.7 (MTT). When cells were pre-treated with the extract prior to virus infection, the inhibition in plaque formation was 70%. PrV was highly inhibited when it was incubated with plant extract or when the extract was added during the adsorption phase (99%). However, no inhibitory effect was observed when the extract was added to the cells after the adsorption period. Thus, these results suggest that the methanolic extract of Verbascum thapsus may contain bioactive compound(s) that affect PrV mostly in the adsorption phase.

Evaluation of toxicity and antioxidative effects of Tussilago farfara and Verbascum thapsus water extracts in zebrafish and in bronchial epithelial cells

“…The result described from our study warrants further investigation in order to identify toxic compounds and to further elucidate their potential toxicity in humans. The cytotoxic effects of V. thapsus have been reported [7,29,30]. The water extract of the crude plant produced toxic effects in three human liver tumor cell lines at a concentration of 2000 µg/mL, which is much higher than the concentration used in our experiments (0.36 µg/mL).…”

“…Flower and leaf extracts of V. thapsus, commonly known as mullein, exhibit demulcent properties and are used in the treatment of various respiratory and gastrointestinal problems [6]. Various extracts of V. thapsus have antibacterial, antiviral and antifungal activities [6,7]. The antioxidant activities of extracts prepared from different parts of V. thapsus were reported in previous studies [8][9][10].…”

Health‐promoting and disease‐mitigating potential of Verbascum thapsus L. (common mullein): A review

“…In vitro antiviral activity of aerial part methanolic extract versus herpes simplex virus type 1 (HSV-1) and influenza virus-A revealed that extract exhibited comparatively potent anti-influenza virus activity (IC 50 < 6.25 mg/ml) than HSV-1 virus (Rajbhandari et al, 2009). Escobar et al (2012) studied the antiviral activity of methanolic extract of V. thapsus plant against the pseudorabies virus strain RC/79 (PrV). The extract exerted dose-mediated prevention of the Vero cells' growth and the cytotoxic concentration was 1.1-1.4 mg/ml.…”

“…The extract exerted dose‐mediated prevention of the Vero cells' growth and the cytotoxic concentration was 1.1–1.4 mg/ml. Moreover, pre‐treatment of extract prior to infection exhibited a noteworthy decrease in contamination of PrV, 90% at 4°C and 98% at 37°C (Escobar et al, 2012).…”

Plant-Based Support of Respiratory Health during Viral Outbreaks

“…136 The plant is a good source of monoterpene iridoids such as aucubin (Figure 2, 8) and phenylpropanoids such as verbascoside. 137 Preclinical data showed moderate antiinflammatory 138 and antiviral 139 activities of mullein bioactives, with the underlying effects of verbascoside to induce interferon-γ production and promote T helper-type effector switching in a mouse-adapted influenza H1N1 virus model. 140 No clinical studies were performed in humans to support these claims.…”