Antiviral Activity of Plant-Based Preparations against SARS-CoV-2 and Herpes Simplex Virus Type 2 In Vitro: A Review of Experimental Findings.

We reviewed published data on the efficacy of plant-derived preparations, including the authors' original in vitro findings on the antiviral activity of aqueous and dry ethanol extracts against the RNA virus SARS-CoV-2 and the DNA virus herpes simplex virus type 2 (HSV-2). The study evaluates the activity of an aqueous extract prepared from fermented leaves of Epilobium angustifolium L., as well as dry ethanol extracts obtained from clove spice (Syzygium aromaticum L.), black and green tea (Camellia sinensis L.), leaves of Rhaponticum carthamoides, the basidiomycete fungus chaga (Inonotus obliquus (Ach. ex Pers.) Pil.), and four lichen species: Cetraria islandica L., Usnea L., Pseudevernia furfuracea L., and Cladonia stellaris Opiz. HPLC analysis of several dry ethanol extracts suggests that their antiviral activity may be attributed to polyphenolic compounds and ecdysteroids. These findings may serve as a basis both for the identification of individual bioactive plant-derived compounds and for the development of cost-effective therapeutic or prophylactic agents against COVID-19 and for reducing the recurrence rate of chronic genital herpes.