Table 2 Natural compounds and their antiviral mechanisms

Astragaloside IV

Inhibits ROS production; inhibits NLRP3 inflammasome and Caspase-1 activation; reduces IL-1β and IL-18 secretion; inhibits TGF-β1/Smad pathway

The specific mechanisms, dose dependency, safety, and synergistic effects with conventional antiviral therapies require further basic research and clinical validation

[73,74,75]

Houttuynia Cordata Flavonoids

–

Inhibits influenza virus and Toll-like receptor signaling; regulates gut microbiota, reduces pathogenic Enterobacteriaceae and pro-inflammatory cytokines

Shows better efficacy when used in combination with polysaccharides; its effectiveness as a standalone treatment may be limited and requires more research to determine optimal usage

[78,79,80,81,82]

Houttuynia Cordata Polysaccharides

–

Regulates gut microbiota, reduces pathogenic Enterobacteriaceae and pro-inflammatory cytokines

Its effectiveness is less pronounced when used alone compared to when combined with flavonoids, and its exact mechanisms are not fully understood

Theaflavin-3′-Gallate

Inhibits influenza virus replication; inhibits TLR4/MAPK/p38 signaling pathway

Limited direct evidence for use in viral pneumonia; more experimental and clinical studies are needed to validate its efficacy

[85, 86]

Berberine

Inhibits influenza virus replication; inhibits TLR7 signaling pathway; inhibits NLRP3 inflammasome activation

May cause gastrointestinal side effects; long-term safety and efficacy need further evaluation

[89, 90]

Paeoniflorin

Alleviates acute lung injury; inhibits TGF-β1, Smad2, NF-κB, and p38MAPK expression

Research on its application in viral pneumonia is relatively limited; more targeted studies are needed

[92,93,94]

Patchouli Alcohol

Prevents viral membrane fusion with intracellular membranes; inhibits influenza virus replication; enhances host immune response

Lacks large-scale clinical trial data on its specific application in viral pneumonia

[96,97,98,99]

Emodin

Inhibits multiple viral infections; inhibits influenza virus replication; activates Nrf2 pathway, reduces ROS levels

Long-term toxicity and safety issues are not fully established; caution is advised in its use

[103, 104]

Resveratrol

Inhibits RSV-induced persistent airway inflammation; reduces inflammatory cells and NGF levels

High doses may cause adverse reactions like gastrointestinal discomfort; low bioavailability affects efficacy

[106]

Geniposide

Inhibits lung inflammation, activates Nrf2, inhibits NF-κB; inhibits nuclear export of influenza virus gene mRNAs, reduces M1 protein expression

Most research focuses on liver diseases; specific efficacy for viral pneumonia needs more study

[108,109,110,111,112]

Glycyrrhizic Acid

Increases nitric oxide production; alters viral lipid bilayer, binds to ACE2 receptor; inhibits HMGB1/TLR4 signaling pathway

May cause water and sodium retention and increased blood pressure, making it unsuitable for all patients

[114,115,116,117,118,119]

Baicalein

Inhibits SARS-CoV-2 replication; inhibits influenza virus replication, inhibits neuraminidase activity

Low bioavailability and poor oral absorption limit its clinical application

[123, 124]