Exploring the antiviral activity of flavonoids from Strychnos variabilis leaves against SARS-CoV-2

Strychnos variabilis De Wild. is a small deciduous tree that is primarily distributed in and around Brazzaville and Kinshasa, located on both sides of the Congo River in Africa [1]. While the leaves have only trace amounts of indoline alkaloids (retuline series) [2] [3], our laboratory isolated numerous rare flavonoids, including flavonol glycosides, from the leaves over three decades ago [4] [5] [6]. Flavonoids are known for their antiviral activity, especially when in glycosidic form, which increases their solubility and effectiveness compared to their non- glycosidic forms [7] [8]. Therefore, our present study aims to investigate the potential antiviral activity of S. variabilis leaves against SARS-CoV-2. Our findings revealed that the total extract of S. variabilis exhibits significant antiviral activity with an IC₅₀ range of 12.5 to 6.25 µg/mL. Moreover, we tested two flavonoids, variabilosides C and D [5], which demonstrated even greater potency with an IC₅₀ range of 6.9 to 3.5 µM.

We suggest that the flavonoids present in S. variabilis leaves could provide a promising pathway for the development of a new herbal substrate used as an adjunctive therapeutic in the treatment of coronavirus disease. Further investigation into the pharmacological properties of these flavonoids is thus warranted to fully explore their potential as therapeutic agents against SARS-CoV-2.

 

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• References

• 1 Leeuwenberg AJ.M.. The Loganiaceae of Africa Vlll-Strychnos Ill. Meded. Landb. Hoogsch. Wageningen, Nederland 1969
• 2 Tits M., Angenot L.Pl.. Med. Phytother. 1980; 14: 213-217
• 3 Angenot L, Damas J., Tits M.. Use of compounds of the retuline series as compounds with pharmaceutical activity Brevet (PCT) WO8905301 1989
• 4 Brasseur T., Angenot L.. Phytochemistry 1986; 25: 563-564
• 5 Brasseur T., Angenot L.. Phytochemistry 1987; 26: 3331-3334
• 6 Brasseur T., Angenot L.. Phytochemistry 1988; 27: 1487-1490
• 7 Badshah S.L.. et al. Biomedicine and Pharmacotherapy 2021; 140: 111596
• 8 Solmier J., Fladerer J.P.. Phytochem. Rev 2021; 20: 773-795

Publication History

Article published online:
16 November 2023