Effect of a Total Extract and Saponins from Astragalus glycyphyllos L. on Human Coronavirus Replication In Vitro

Abstract

Members of the family Coronaviridae cause diseases in mammals, birds, and wildlife (bats), some of which may be transmissible to humans or specific to humans. In the human population, they can cause a wide range of diseases, mainly affecting the respiratory and digestive systems. In the scientific databases, there are huge numbers of research articles about the antiviral, antifungal, antibacterial, antiviral, and anthelmintic activities of medicinal herbs and crops with different ethnobotanical backgrounds. The subject of our research is the antiviral effect of isolated saponins, a purified saponin mixture, and a methanol extract of Astragalus glycyphyllos L. In the studies conducted for the cytotoxic effect of the substances, CC₅₀ (cytotoxic concentration 50) and MTC (maximum tolerable concentration) were determined by the colorimetric method (MTT assay). The virus was cultured in the MDBK cell line. As a result of the experiments carried out on the influence of substances on viral replication (using MTT-based colorimetric assay for detection of human Coronavirus replication inhibition), it was found that the extract and the purified saponin mixture inhibited 100% viral replication. The calculated selective indices are about 13 and 18, respectively. The obtained results make them promising for a preparation with anti-Coronavirus action.

Keywords: Astragalus glycyphyllos L.; antiviral activity; human coronavirus 229E; saponin.

Figure 1

The main investigated metabolites: (a) structure of the analytical marker (17(R),20(R)-3β,6α,16β-trihydroxycycloartanyl-23-carboxylic acid 16-lactone 3-O-β-D-glucopyranoside (S1); (b) Astrachrysoside A (S9); and (c) structure of 3-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-xylopyranosyl]-24-O-α-L-arabinopyranosyl-3β,6α,16β,24,25-pentahydroxy-20R,24R-cycloartane (S3).

Figure 1

The main investigated metabolites: (a) structure of the analytical marker (17(R),20(R)-3β,6α,16β-trihydroxycycloartanyl-23-carboxylic acid 16-lactone 3-O-β-D-glucopyranoside (S1); (b) Astrachrysoside A (S9); and (c) structure of 3-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-xylopyranosyl]-24-O-α-L-arabinopyranosyl-3β,6α,16β,24,25-pentahydroxy-20R,24R-cycloartane (S3).

Figure 2

Cultivation of human Coronavirus 229E in cell culture: (a) cell control–uninfected cells; (b) manifested cytopathic effect on the second day after virus inoculation; (c) manifested cytopathic effect on the fourth day after virus inoculation.

Figure 3

Antiviral activity according to MTT-based colorimetric assay for detection of virus replication inhibition: (a) DEAG added simultaneously with the inoculation of cell monolayer () and one and a half hours after the inoculation of cell monolayer () with HCoV 229E; (b) PSM added simultaneously with the inoculation of cell monolayer () and one and a half hours after the inoculation of cell monolayer () with HCoV 229E.