Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation.

BACKGROUND: Prunella vulgaris polysaccharide extracted by hot water and 30% ethanol precipitation (PVE30) was reported to possess potent antiviral effects against herpes simplex virus (HSV) infection. However, its anti-HSV mechanism has not yet been fully elucidated. PURPOSE: This study aimed to investigate the potential mechanisms of PVE30 against HSV infection. METHODS: Antiviral activity was evaluated by a plaque reduction assay, and the EC50 value was calculated. Immunofluorescence staining and heparin bead pull-down assays confirmed the interactions between PVE30 and viral glycoproteins. Real-time PCR was conducted to determine the mRNA levels of viral genes, including UL54, UL29, UL27, UL44, and US6, and the proinflammatory cytokines IL-6 and TNF-α. The protein expression of viral proteins (ICP27, ICP8, gB, gC, and gD), the activity of the TLR-NF-κB signalling pathway, and necroptotic-associated proteins were evaluated by Western blotting. The proportion of necroptotic cells was determined by flow cytometric analysis. RESULTS: The P. vulgaris polysaccharide PVE30 was shown to compete with heparan sulfate for interaction with HSV surface glycoprotein B and gC, thus strongly inhibiting HSV attachment to cells. In addition, PVE30 downregulated the expression of IE genes, which subsequently downregulated the expression of E and L viral gene products, and thus effectively restricted the yield of progeny virus. Further investigation confirmed that PVE30 inhibited TLR2 and TLR3 signalling, leading to the effective suppression of NF-κB activation and IL-6 and TNF-α expression levels, and blocked HSV-1-induced necroptosis by reducing HSV-1-induced phosphorylation of MLKL. CONCLUSION: Our results demonstrate that the P. vulgaris polysaccharide PVE30 is a potent anti-HSV agent that blocks TLR-mediated NF-κB activation.

Integrating multi-index determination coupled with hierarchical cluster analysis to evaluate the quality consistency of PVE30, an anti-HSV "glycoprotein" macromolecule of Prunellae Spica.

INTRODUCTION: Prunellae Spica (PS), derived from the dried fruit spikes of Prunella vulgaris L., is a traditional Chinese medicinal herb. Our previous studies found that PVE30, a water-extracting ethanol-precipitating "glycoprotein" macromolecule of PS, was a potential anti-herpes simplex virus (HSV) candidate. However, due to the complex structure and diverse bioactivity of the "glycoprotein", ensuring its quality consistency across different batches of PVE30 becomes particularly challenging. This poses a significant hurdle for new drug development based on PVE30. OBJECTIVE: Our study aimed to integrate multi-index determination coupled with hierarchical cluster analysis (HCA) to holistically profile the quality consistency of "glycoprotein" in PVE30. METHODS: High-performance gel permeation chromatography with refractive index detector (HPGPC-RID) was used to characterise the molecular weight (Mw) distribution, HPLC-PDA was used to quantitatively analyse the composed monosaccharides and amino acids, and UV-VIS was used to quantify the contents of polysaccharides and proteins. Qualitative and quantitative consistency was analysed for each single index in 16 batches of PVE30, and a 16 × 38 data matrix, coupled with HCA, was used to evaluate the holistic quality consistency of PVE30. RESULTS: The newly developed and validated methods were exclusive, linear, precise, accurate, and stable enough to quantify multi-indexes in PVE30. Single-index analysis revealed that 16 batches of PVE30 were qualitatively consistent in Mw distribution, polysaccharides and proteins, and the composition of composed monosaccharides and amino acids but quantitatively inconsistent in the relative contents of some "glycoprotein" macromolecules, as well as the composed monosaccharides/amino acids. HCA showed that the holistic quality of PVE30 was inconsistent, the inconsistency was uncorrelated with the regions where PS was commercially collected, and the contents of 17 amino acids and 2 monosaccharides contributed most to the holistic quality inconsistency. CONCLUSION: Multi-index determination coupled with HCA was successful in evaluating the quality consistency of PVE30, and the significant difference in quantitative indices was not caused by the origin of PS. The cultivating basis should be confirmed for PVE30-based new drug development.

Antiviral Potential of the Genus Panax: An updated review on their effects and underlying mechanism of action.

Viral infections are known as one of the major factors causing death. Ginseng is a medicinal plant that demonstrated a wide range of antiviral potential, and saponins are the major bioactive ingredients in the genus Panax with vast therapeutic potential. Studies focusing on the antiviral activity of the genus Panax plant-derived agents (extracts and saponins) and their mechanisms were identified and summarized, including contributions mainly from January 2016 until January 2022. P. ginseng, P. notoginseng, and P. quinquefolius were included in the review as valuable medicinal herbs against infections with 14 types of viruses. Reports from 9 extracts and 12 bioactive saponins were included, with 6 types of protopanaxadiol (PPD) ginsenosides and 6 types of protopanaxatriol (PPT) ginsenosides. The mechanisms mainly involved the inhibition of viral attachment and replication, the modulation of immune response by regulating signaling pathways, including the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) pathway, phosphoinositide-dependent kinase-1 (PDK1)/ protein kinase B (Akt) signaling pathway, c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) pathway, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. This review includes detailed information about the mentioned antiviral effects of the genus Panax extracts and saponins in vitro and in vivo, and in human clinical trials, which provides a scientific basis for ginseng as an adjunctive therapeutic drug or nutraceutical.

Medicinal plants and natural compounds against acyclovir-resistant HSV infections.

Herpes simplex virus (HSV), an alphaherpesvirus, is highly prevalent in the human population and is known to cause oral and genital herpes and various complications. Represented by acyclovir (ACV), nucleoside analogs have been the main clinical treatment against HSV infection thus far. However, due to prolonged and excessive use, HSV has developed ACV-resistant strains. Therefore, effective treatment against ACV-resistant HSV strains is urgently needed. In this review, we summarized the plant extracts and natural compounds that inhibited ACV-resistant HSV infection and their mechanism of action.

Polyphenolic-protein-polysaccharide conjugates from Spica of Prunella vulgaris: Chemical profile and anti-herpes simplex virus activities.

Previous studies showed that the water extract (PVW) from Spica of Prunella vulgaris Linn. (Labiatae) exerts anti-herpes simplex virus (HSV) activity. Evaluation the antiviral activity of the graded ethanol precipitations indicated that 30% ethanol precipitate (PVE30) was the active principle of water extract (PVW). Further activity-oriented separation of PVE30 through salting-out method revealed that the anti-HSV activity of P. vulgaris glycoconjugates (PVG) was more potent than PVE30 and PVW, 2-fold and 4-fold, respectively. UPLC-QTOF-MS/MS, FT-IR and NMR techniques identified PVG as a type of polyphenolic-protein-polysaccharides (PPPs) with an average molecular weight of 41.69 kDa. PVG was composed of dibenzylbutyrolactone lignan units, and rich in galacturonic acid, xylose, rhamnose, rhamnose, arabinose, glucose monosaccharide units, glutamic acid and aspartic acid. Further in vitro antiviral testing confirmed that PVG substantially and stably inhibited acyclovir (ACV) resistant HSV strains; its inhibitory action was even better than the positive control ACV. Overall, our findings support PVG as a potential drug resource for anti-HSV therapy.