Lignans antiviral activity

Besides antitumor/anticancer activity, lignans are among the most potent antiviral compounds, although most of the lignans evaluated for antiviral potency belong to families of plants other than Taxaceae [3]. 

The mechanism of actions involves tubulin binding, reverse transcriptase inhibition, integrase inhibition and topoisomerase inhibition. Podophyllo-toxins bind to tubulin and are able to disrupt the cellular cytoskeleton and interfere with some vital virus processes. There is no relationship between the inhibition of reverse transcriptase (RT) and chemical structure in the case of lignans, because all the chemical antiviral structures are able to bind to the enzyme. As to the rest of the mechanism, there is not much information available. The effects of rabdosiin may be due to its topoisomerase inhibitory effects. Charlton concluded that the antiviral activity of lignans is not strong and that except for podophyllotoxin, which is used topically to treat various warts caused by HPV, none of them are of interest for commercial application. 

Asano, J. Chiba, K. Tada, M. Yoshi, T. Antiviral activity of Lignans and Their Glycosides from Justida procumbens. Phytochemistry. 1996, 42, 713-717. 

At least 40 lignans are known to have antitumor and antiviral activity and many are cytotoxic (Ayres and Loike, 1990 Davin et al., 1992 MacRae and Towers, 1984 Mac-Rae et al., 1989), although there are no common structural features to explain this activity. Podophyllotoxin (51) (Fig. 8.15), which has been isolated from a number of plant species, is a potent antineoplastic (i.e., tumor destructive) compound. Although too toxic for practical value, synthetically... 

Lignans from the mayapple Podophyllum peltatum) show potent antiviral activity in vivo (MacRae et al. 1989). 

Lignans show strong antitumor, antiviral and antibacterial activity, as well as influence upon expression of the tumor necrosis factor-alpha. 

Lignans are a well-known class of widespread natural phenolic compounds that exhibit great structural and biological diversity and are commonly found in vascular plants from various families [1]. They are present at different levels of abundance in all plant parts, including roots, rhizomes, hardwood, bark, stems, leaves, flowers, fruits and seeds [2]. Lignans are of considerable pharmacological and clinical interest and are used in the treatment of cancer and other diseases [3]. The extensive pharmaceutical use of lignans is due to their antitumor, antiviral and hepatoprotective properties as well as many other beneficial activities. 

Particular attention has been paid to the antibacterial, antiviral, antiinflammatory and antifertility effects of Wikstroemia indica that contains abrmdant active constituents, including flavonoids, biflavonoids, coumarins, lignans, volatile oils, polysaccharides, etc. [66]... 

Lignans have been described as the active principles in different antiviral and anticancer medicinal plants and crude extracts. However, few of them... 

In order to explain and confirm the biological activities claimed by the traditional medicine, and to search for new biologically active compounds we studied the antimicrobial, antioxidative, immunomodulatory, antiinflammatory, skin-regenerating and antiviral properties of Fraxinus ornus bark extract and its components. In a parallel detailed phytochemical investigation of the extract we isolated and determined the structures of many hydroxycoumarins, secoiridoid glucosides, caffeoyl esters of phenylethanoid glycosides, lignans and other phenolic compounds. 

Lignans are composed of two phenylpropanoid units joined together to form an 18-carbon skeleton, with various functional groups connected. They are always found in woody tissues and resins of plants. Several lignans show clinical activity, such as phytoestrogenic, cathartic, antineoplastic, antiviral, and liver protective activities. 

This chapter addresses the occurrence and distribution of a large class of phenylpropanoid metabolites, collectively known as lignans, and their increasing significance as physiologically and pharmacologically active substances e.g., as antiviral, antitumor, biocidal and other bioactive agents. 

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