Lignans are widely produced by various plant species; they are a class of natural products that share structural similarity. They usually contain a core scaffold that is formed by two or more phenylpropanoid units. Lignans possess diverse pharmacological properties, including their antiviral activities that have been reported in recent years. This review discusses the distribution of lignans in nature according to their structural classification, and it provides a comprehensive summary of their antiviral activities. Among them, two types of antiviral lignans—podophyllotoxin and bicyclol, which are used to treat venereal warts and chronic hepatitis B (CHB) in clinical, serve as examples of using lignans for antivirals—are discussed in some detail. Prospects of lignans in antiviral drug discovery are also discussed.

The global pandemic caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), named coronavirus disease 2019, has infected more than 8.9 million people worldwide. This calls for urgent effective therapeutic measures. RNA‐dependent RNA polymerase (RdRp) activity in viral transcription and replication has been recognized as an attractive target to design novel antiviral strategies. Although SARS‐CoV‐2 shares less genetic similarity with SARS‐CoV (~79%) and Middle East respiratory syndrome coronavirus (~50%), the respective RdRps of the three coronaviruses are highly conserved, suggesting that RdRp is a good broad‐spectrum antiviral target for coronaviruses. In this review, we discuss the antiviral potential of RdRp inhibitors (mainly nucleoside analogs) with an aim to provide a comprehensive account of drug discovery on SARS‐CoV‐2.

The hemagglutinin (HA) and neuraminidase (NA) of influenza A virus possess antagonistic activities on interaction with sialic acid (SA), which is the receptor for virus attachment. HA binds SA through its receptor-binding sites, while NA is a receptor-destroying enzyme by removing SAs. The function of HA during virus entry has been extensively investigated, however, examination of NA has long been focused to its role in the exit of progeny virus from infected cells, and the role of NA in the entry process is still under-appreciated. This review summarizes the current understanding of the roles of HA and NA in relation to each other during virus entry.

The leaves of Ficus carica Linn. (FC) have been widely used for medicine purposes since ancient times, and its decoction is consumed as tea. Many scientific papers have been published in the literature and the researchers across the world are still exploring the health benefits of FC leaves. In this review, we have collected the literature published since 2010 in the databases: Pubmed, Scopus, Web of Science, SciFinder, Google Scholar, Baidu Scholar and local classic herbal literature. The summary of the chemical constituents in FC leaves, biological activities, toxicity studies, and clinical studies carried out on FC leaves is provided in this review. In addition, the molecular mechanisms of the active constituents in FC leaves are also comprehended. FC leaves are reported to 126 constituents out of which the polyphenolic compounds are predominant. Many scientific studies have proven the antidiabetic, antioxidant, anti-inflammatory, anticancer, anticholinesterase, antimicrobial, hepatoprotective, and renoprotective activities. Many studies have carried out to provide the insights on molecular pathways involved in the biological activities of FC leaves. The toxicity studies have suggested that FC leaves exhibit toxicity only at very high doses. We believe this review serve as a comprehensive resource for those who are interested to understand the scientific evidence that support the medicinal values of FC leaves and also the research gaps to further improve the commercial value and health benefits of FC leaves.

The recent 2014–2016 West African Ebola virus epidemic underscores the need for the development of novel anti-Ebola therapeutics, due to the high mortality rates of Ebola virus infections and the lack of FDA-approved vaccine or therapy that is available for the prevention and treatment. Traditional Chinese medicines (TCMs) represent a huge reservoir of bioactive chemicals and many TCMs have been shown to have antiviral activities. 373 extracts from 128 TCMs were evaluated using a high throughput assay to screen for inhibitors of Ebola virus cell entry. Extract of Rhodiola rosea displayed specific and potent inhibition against cell entry of both Ebola virus and Marburg virus. In addition, twenty commercial compounds that were isolated from Rhodiola rosea were evaluated using the pseudotyped Ebola virus entry assay, and it was found that ellagic acid and gallic acid, which are two structurally related compounds, are the most effective ones. The activity of the extract and the two pure compounds were validated using infectious Ebola virus. The time-of-addition experiments suggest that, mechanistically, the Rhodiola rosea extract and the effective compounds act at an early step in the infection cycle following initial cell attachment, but prior to viral/cell membrane fusion. Our findings provide evidence that Rhodiola rosea has potent anti-filovirus properties that may be developed as a novel anti-Ebola treatment.