Research progress on antiviral constituents in traditional Chinese medicines and their mechanisms of action

CONTEXT

Viruses have the characteristics of rapid transmission and high mortality. At present, western medicines still lack an ideal antiviral. As natural products, many traditional Chinese medicines (TCM) have certain inhibitory effects on viruses, which has become the hotspot of medical research in recent years.

OBJECTIVE

The antiviral active ingredients and mechanisms of TCM against viral diseases was studied in combination with the pathogenesis of viral diseases and antiviral effects.

MATERIALS AND METHODS

English and Chinese literature from 1999 to 2021 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2020 (CP), and CNKI (Chinese). Traditional Chinese medicines (TCM), active ingredients, antiviral, mechanism of action, and anti-inflammatory effect were used as the key words.

RESULTS

The antiviral activity of TCM is clarified to put forward a strategy for discovering active compounds against viruses, and provide reference for screening antivirus drugs from TCM. TCM can not only directly kill viruses and inhibit the proliferation of viruses in cells, but also prevent viruses from infecting cells and causing cytophilia. It can also regulate the human immune system, enhance human immunity, and play an indirect antiviral role.

DISCUSSION AND CONCLUSION

Based on the experimental study and antiviral mechanism of TCM, this paper can provide analytical evidence that supports the effectiveness of TCM in treating virus infections, as well as their mechanisms against viruses. It could be helpful to provide reference for the research and development of innovative TCMs with multiple components, multiple targets and low toxicity.

A Natural Plant Source-Tea Polyphenols, a Potential Drug for Improving Immunity and Combating Virus

The coronavirus disease 2019 (COVID-19) is still in a global epidemic, which has profoundly affected people’s lives. Tea polyphenols (TP) has been reported to enhance the immunity of the body to COVID-19 and other viral infectious diseases. The inhibitory effect of TP on COVID-19 may be achieved through a series of mechanisms, including the inhibition of multiple viral targets, the blocking of cellular receptors, and the activation of transcription factors. Emerging evidence shows gastrointestinal tract is closely related to respiratory tract, therefore, the relationship between the state of the gut–lung axis microflora and immune homeostasis of the host needs further research. This article summarized that TP can improve the disorder of flora, reduce the occurrence of cytokine storm, improve immunity, and prevent COVID-19 infection. TP may be regarded as a potential and valuable source for the design of new antiviral drugs with high efficiency and low toxicity.

Evaluation of botanicals as potential COVID-19 symptoms terminator

Information about the coronavirus disease 2019 (COVID-19) pandemic is still evolving since its appearance in December 2019 and has affected the whole world. Particularly, a search for an effective and safe treatment for COVID-19 continues. Botanical mixtures contain secondary metabolites (such as flavonoids, phenolics, alkaloids, essential oils etc.) with many therapeutic effects. In this study, the use of herbal treatments against COVID-19 was evaluated. Medical synthetic drugs focus mainly on respiratory symptoms, however herbal therapy with plant extracts may be useful to relieve overall symptoms of COVID-19 due to the variety of bioactive ingredients. Since COVID-19 is a virus that affects the respiratory tract, the antiviral effects of botanicals/plants against respiratory viruses have been examined through clinical studies. Data about COVID-19 patients revealed that the virus not only affects the respiratory system but different organs including the gastrointestinal (GI) system. As GI symptoms seriously affect quality of life, herbal options that might eliminate these problems were also evaluated. Finally, computer modeling studies of plants and their active compounds on COVID-19 were included. In summary, herbal therapies were identified as potential options for both antiviral effects and control of COVID-19 symptoms. Further data will be needed to enlighten all aspects of COVID-19 pathogenesis, before determining the effects of plants on severe acute respiratory syndrome coronavirus 2.

Saxifraga spinulosa-Derived Components Rapidly Inactivate Multiple Viruses Including SARS-CoV-2

Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and norovirus (NV) are highly contagious pathogens that threaten human health. Here we focused on the antiviral potential of the medicinal herb, Saxifragaspinulosa (SS). Water-soluble extracts of SS were prepared, and their virus-inactivating activity was evaluated against the human virus pathogens SARS-CoV-2 and IAV; we also examined virucidal activity against feline calicivirus and murine norovirus, which are surrogates for human NV. Among our findings, we found that SS-derived gallocatechin gallate compounds were capable of inactivating all viruses tested. Interestingly, a pyrogallol-enriched fraction (Fr 1C) inactivated all viruses more rapidly and effectively than did any of the component compounds used alone. We found that 25 µg/mL of Fr 1C inactivated >99.6% of SARS-CoV-2 within 10 s (reduction of ≥2.33 log₁₀ TCID₅₀/mL). Fr 1C resulted in the disruption of viral genomes and proteins as determined by gel electrophoresis, electron microscopy, and reverse transcription–PCR. Taken together, our results reveal the potential of Fr 1C for development as a novel antiviral disinfectant.

Effect of Tea Catechins on Influenza Infection and the Common Cold with a Focus on Epidemiological/Clinical Studies

Influenza and the common cold are acute infectious diseases of the respiratory tract. Influenza is a severe disease that is highly infectious and can progress to life-threating diseases such as pneumonia or encephalitis when aggravated. Due to the fact that influenza infections and common colds spread easily via droplets and contact, public prevention measures, such as hand washing and facial masks, are recommended for influenza prophylaxis. Experimental studies have reported that tea catechins inhibited influenza viral adsorption and suppressed replication and neuraminidase activity. They were also effective against some cold viruses. In addition, tea catechins enhance immunity against viral infection. Although the antiviral activity of tea catechins has been demonstrated, the clinical evidence to support their utility remains inconclusive. Since the late 1990s, several epidemiological studies have suggested that the regular consumption of green tea decreases influenza infection rates and some cold symptoms, and that gargling with tea catechin may protect against the development of influenza infection. This review briefly summarizes the effect of tea catechins on influenza infection and the common cold with a focus on epidemiological/clinical studies, and clarifies the need for further studies to confirm their clinical efficacy.

Pinus massoniana Bark Extract: Structure-Activity Relationship and Biomedical Potentials

Proanthocyanidins (PAs) belong to the condensed tannin subfamily of natural flavonoids. Recent studies have shown that the main bioactive compounds of Pinus massoniana bark extract (PMBE) are PAs, especially the proanthocyanidins B series, which play important roles in cell cycle arrest, apoptosis induction and migration inhibition of cancer cells in vivo and in vitro. PA-Bs are mixtures of oligomers and polymers composed of flavan-3-ol, and the relationship between their structure and corresponding biomedical potentials is summarized in this paper. The hydroxyl at certain positions or the linkage between different carbon atoms of different rings determines or affects their anti-oxidant and free radical scavenging bioactivities. The degree of polymerization and the water solubility of the reaction system also influence their biomedical potential. Taken together, PMBE has a promising future in clinical drug development as a candidate anticancer drug and as a food additive to prevent tumorigenesis. We hope this review will encourage interested researchers to conduct further preclinical and clinical studies to evaluate the anticancer activities of PMBE, its active constituents and their derivatives.

SUSCEPTIBILITY OF COMMERCIAL NEURAMINIDASE INHIBITORS AGAINST 2013 A/H7N9 INFLUENZA VIRUS: A DOCKING AND MOLECULAR DYNAMICS STUDY

The latest influenza A ( H 7 N 9) virus attracted a worldwide attention due to the first report of human infections and the continuing reported cases in China. In this work, homology modeling, docking and molecular dynamics simulations were combined to study the interactions between neuraminidase ( N 9_2013, from novel A/ H 7 N 9 virus) and agents zanamivir, oseltamivir, peramivir. It was found that N 9_2013 protein is structurally close to the template (PDB code: 1F8B), especially the active site. The binding properties of N 9_2013 protein were nearly identical to those of template. As a result, the three available drugs should be still efficacious for the new emerging A ( H 7 N 9) virus. However, the stabilities of docked complexes and binding affinities (Eint) were slightly reduced, in contrast to the corresponding inhibitor-template complexes, with the values of -82.27 (-84.30), -78.84 (-80.28) and -77.52 (-81.94) kcal mol-1, respectively. Besides, R292K mutation might induce the resistance of the novel virus to the commercial inhibitors. Thus, it arouses the need for continuous monitoring of antiviral drug susceptibilities.