Inhibition of human cytomegalovirus immediate-early gene expression and replication by the ethyl acetate (EtOAc) fraction of Elaeocarpus sylvestris in vitro

A review-plant medicine and its extraction components inhibit influenza virus

Influenza is a highly prevalent and highly contagious lung disease caused by influenza viruses. The main anti-influenza strategies are vaccination and antiviral drugs. Vaccination is an effective means of prevention, but the time lag in research and development makes it difficult to respond immediately to an outbreak. Approved drugs are mainly inhibitors of neuraminidase and M2 ion channels, but, due to the variability of influenza viruses, resistance to these drugs may emerge. Botanicals and their extracts have shown unique advantages in influenza treatment and are widely used in clinics across China. However, there are few reviews on the prevention and treatment of influenza with herbal medicines. We undertook a review of relevant literature in recent years to analyze the research progress of various botanicals and their extracts in the prevention and treatment of influenza. Our review provides theoretical support for the prevention and treatment of influenza by plant-based medicines, as well as new ideas for the development of novel low-toxicity and multi-target drugs.

Antiviral Activities of Ethyl Pheophorbides a and b Isolated from Aster pseudoglehnii against Influenza Viruses

Screening of the antiviral and virucidal activities of ethanol extracts from plants endemic to the Republic of Korea revealed the inhibitory activity of a 70% ethanol extract of the whole plant of A. pseudoglehnii (APE) against influenza virus infection. Two chlorophyll derivatives, ethyl pheophorbides a and b, isolated as active components of APE, exerted virucidal effects with no evident cytotoxicity. These compounds were effective only under conditions of direct incubation with the virus, and exerted no effects on the influenza A virus (IAV) surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). Interestingly, virucidal activities of ethyl pheophorbides a and b were observed against enveloped but not non-enveloped viruses, suggesting that these compounds act by affecting the integrity of the viral membrane and reducing infectivity.

Kaempferol Interferes with Varicella-Zoster Virus Replication in Human Foreskin Fibroblasts

Kaempferol, a natural flavonoid abundantly found in plants, is known to have pharmacological properties, such as anti-inflammatory and anti-cancer effects. In this study, we investigated the antiviral effects of kaempferol against a varicella-zoster virus (VZV) clinical isolate in vitro. We found that kaempferol significantly inhibited VZV replication without exhibiting cytotoxicity. Kaempferol exerted its antiviral effect at a similar stage of the VZV life cycle as acyclovir, which inhibits VZV DNA replication. Taken together, our results suggest that kaempferol inhibits VZV infection by blocking the DNA replication stage in the viral life cycle.

Anti-varicella zoster virus and related anti-inflammation effects of ethanolic extract of Elaeocarpus sylvestris

ETHNOPHARMACOLOGICAL RELEVANCE

Elaeocarpus sylvestris var. ellipticus (ES), a plant that grows in Taiwan, Japan, and Jeju Island in Korea. ES root bark, known as "sanduyoung," has long been used in traditional oriental medicine. ES is also traditionally used to treat anxiety, asthma, arthritis, stress, depression, palpitation, nerve pain, epilepsy, migraine, hypertension, liver diseases, diabetes, and malaria. However, lack of efficacy and mechanism studies on ES.

AIM OF THE STUDY

In the present study, we aim to investigate the VZV-antiviral efficacy, pain suppression, and the anti-inflammatory and antipyretic effects of ES.

METHODS

and methods: Inhibition of VZV was evaluated by hollow fiber assays. Analgesic and antipyretic experiments were conducted using ICR mice and SD Rats, and anti-inflammatory experiments were conducted using Raw264.7 cells.

RESULTS

To evaluate the efficacy of ESE against VZV, we conducted antiviral tests. ESE inhibited cell death by disrupting virus and gene expression related to invasion and replication. In addition, ESE suppressed the pain response as measured by writhing and formalin tests and suppressed LPS-induced inflammatory fever. Further, ESE inhibited the phosphorylation of IκB and NF-κB in LPS-induced Raw264.7 cells and expression of COX-2, iNOS, IL-1β, IL-6, and TNF-α.

CONCLUSION

E. sylvestris shows potential as a source of medicine. ESE had a direct effect on VZV and an inhibitory effect on the pain and inflammation caused by VZV infection.

Potent antiviral activity of the extract of Elaeocarpus sylvestris against influenza A virus in vitro and in vivo

BACKGROUND

Elaeocarpus sylvestris (Lour.) Poir. (Elaeocarpaceae) belongs to a genus of tropical and semitropical evergreen trees, which has known biological activities such as antiviral and immunomodulatory activities. However, its antiviral potential against influenza virus infection remains unknown.

PURPOSE

In this study, we investigated the antiviral activity of the 50% aqueous ethanolic extract of E. sylvestris (ESE) against influenza A virus (IAV) infection, which could lead to the development of novel phytomedicine to treat influenza virus infection.

METHODS

To investigate the in vitro antiviral activity of ESE and its main ingredients, 1,​2,​3,​4,​6-​penta-​O-​galloyl-β-d-glucose (PGG) and geraniin (GE), the levels of viral RNAs, proteins, and infectious viral particles in IAV-infected MDCK cells were analyzed. Molecular docking analysis was performed to determine the binding energy of PGG and GE for IAV proteins. To investigate in vivo antiviral activity, IAV-infected mice were treated intranasally or intragastrically with ESE, PGG, or GE.

RESULTS

ESE and its gallate main ingredients (PGG and GE) strongly inhibited the production of viral RNAs, viral proteins, and infectious viral particles in vitro. Also through the viral attachment on cells, polymerase activity, signaling pathway, we revealed the ESE, PGG, and GE inhibit multiple steps of IAV replication. Molecular docking analysis revealed that PGG and GE could interact with 12 key viral proteins (M1, NP, NS1 effector domain (ED), NS1 RNA-binding domain (RBD), HA pocket A, HA receptor-binding domain (RBD), NA, PA, PB1, PB2 C-terminal domain, PB2 middle domain, and PB2 cap-binding domain) of IAV proteins with stable binding energy. Furthermore, intranasal administration of ESE, PGG, or GE protected mice from IAV-induced mortality and morbidity. Importantly, oral administration of ESE suppressed IAV replication and the expression of inflammatory cytokines such as IFN-γ, TNF-α, and IL-6 in the lungs to a large extent.

CONCLUSION

ESE and its major components (PGG and PE) exhibited strong antiviral activity in multiple steps against IAV infection in silico, in vivo, and in vitro. Therefore, ESE could be used as a novel natural product derived therapeutic agent to treat influenza virus infection.

Antiviral Activities of Quercetin and Isoquercitrin Against Human Herpesviruses

We previously reported that the ethyl acetate (EtOAc) fraction of a 70% ethanol extract of Elaeocarpus sylvestris (ESE) inhibits varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) replication in vitro. PGG (1,2,3,4,6-penta-O-galloyl-ß-D-glucose) is a major chemical constituent of the EtOAc fraction of ESE that inhibits VZV but not HCMV replication. In this study, we comprehensively screened the chemical compounds identified in the EtOAc fraction of ESE for potential antiviral properties. Among the examined compounds, quercetin and isoquercitrin displayed potent antiviral activities against both VZV and HCMV with no significant cytotoxic effects. Both compounds strongly suppressed the expression of VZV and HCMV immediate–early (IE) genes. Our collective results indicated that, in addition to PGG, quercetin and isoquercitrin are bioactive compounds in the EtOAc fraction of ESE that effectively inhibit human herpesvirus replication.