Herbs And Phytochemicals: Study Shows That 3-Epi-Betulin From Daphniphyllum Glaucescens Inhibits SARS-CoV-2 Entry And Suppresses Inflammation!

Herbs And Phytochemicals: As the relentless march of SARS-CoV-2 variants prolongs the global COVID-19 pandemic, the quest for effective antiviral agents remains imperative. While vaccines and therapeutics primarily target viral proteins, the initial immune pathogenesis induced by SARS-CoV-2 involves inflammation. A recent groundbreaking Herbs And Phytochemicals study by researchers from China Medical University, National Taiwan University Hospital, National Taiwan University College of Medicine, National Yang Ming Chiao Tung University, and Chang Gung University unveils a potent natural compound – 3-epi-betulin, extracted from Daphniphyllum glaucescens. This compound showcases a dual prowess, inhibiting SARS-CoV-2 entry and suppressing virus-induced inflammation.


Daphniphyllum glaucescens

The Global Impact of SARS-CoV-2
SARS-CoV-2, identified in late 2019, swiftly escalated into a global pandemic, significantly impacting public health and the global economy. The virus's structural proteins, including the spike protein, play a pivotal role in inducing inflammation. The spike protein's receptor-binding domain (RBD) binds to angiotensin-converting enzyme 2 (ACE2), initiating virus entry. The virus's contagious nature leads to a spectrum of symptoms, ranging from mild to severe, with inflammation emerging as a key factor in the severity and progression of COVID-19.
 
The Dual Action of 3-Epi-Betulin
Traditional medicinal plants have long been explored for their potential in preventing and treating infectious diseases. In this context, 3-epi-betulin from Daphniphyllum glaucescens emerges as a dual-action compound with significant antiviral and anti-inflammatory properties. The study demonstrates that 3-epi-betulin effectively reduces proinflammatory cytokines induced by SARS-CoV-2, leading to decreased viral RNA accumulation and plaque formation.
 
Furthermore, 3-epi-betulin exhibits broad-spectrum inhibition of SARS-CoV-2 entry, including variants such as Alpha (B.1.1.7), Epsilon (B.1.429), Gamma (P1), Delta (B.1.617.2), and Omicron (BA.1). The compound's potency is highlighted by its EC50 of less than 20 μM in Calu-3 lung epithelial cells. Bioinformatic analysis elucidates the chemical interaction between 3-epi-betulin and the spike protein, identifying critical amino acid residues contributing to its inhibitory activity against virus entry.
 
Understanding SARS-CoV-2-Induced Inflammation
In the complex landscape of COVID-19, inflammation emerges as a pivotal player in disease severity. Elevated levels of proinflammatory cytokines and chemokines contribute to pulmonary inflammation and lung damage. The spike protein, particularly its receptor-binding domain, induces a proinflammatory state in macrophages, emphasizing its role in SARS-CoV-2-stimulated inflammation.
 
The study highlights CD147 as a potential receptor for SARS-CoV-2, mediating virus entry through endocytosis. The expression of CD147 on THP-1 cells sur passes ACE2, and its reduction correlates with decreased phosphorylated NFκB and proinflammatory cytokine IL-1β. This suggests the crucial role of spike protein interaction with receptors, including CD147, in SARS-CoV-2-induced inflammation. However, the precise molecular mechanisms warrant further investigation.
 
3-Epi-Betulin's Structural Insights and Variants Specificity
Comparative analysis with betulinic acid, a compound with reported anti-viral activity, reveals that 3-epi-betulin (compound 5) surpasses its inhibitory activity against SARS-CoV-2 entry. Structural analysis through iGEMDOCK indicates a higher affinity of 3-epi-betulin to the spike protein, attributed to an additional hydrogen bond interaction with residue Y453. This interaction, absent in betulinic acid, contributes to the compound's enhanced potential to disrupt the spike-ACE2 interaction.
 
While effective against various SARS-CoV-2 variants, 3-epi-betulin shows diminished potency against the Omicron variant. Molecular analysis attributes this to specific mutations (G496S, Q498R, and Y505H) in the receptor-binding site of the Omicron spike protein. These mutations potentially impact the stability of the spike protein and reduce the binding affinity of 3-epi-betulin, shedding light on the compound's variant specificity.
 
Clinical Presentation and Current Therapeutic Landscape
The clinical presentation of COVID-19 varies widely, from asymptomatic cases to fatal outcomes. Despite the rapid development of vaccines, long-term protective vaccines remain elusive. Antiviral agents, such as protease inhibitors (3CLpro and ritonavir) and polymerase inhibitors (remdesivir and molnupiravir), have shown efficacy in treating early-stage COVID-19. However, an imbalanced host-dependent response in COVID-19 patients leads to elevated levels of proinflammatory cytokines and chemokines, contributing to pulmonary inflammation and substantial lung damage.
 
Therefore, targeting pro-inflammatory molecules in the early phases of COVID-19 is crucial in preventing disease progression. The study reinforces the importance of finding compounds with dual antiviral and anti-inflammatory properties, and 3-epi-betulin emerges as a promising candidate in this context.
 
Structural Analysis and Molecular Mechanisms
The chemical structure of 3-epi-betulin shares similarities with betulinic acid, known for its anti-viral activity by inhibiting SARS-CoV-2 spike binding to ACE2 through computational screening. The study tested the inhibition activity of betulinic acid and 3-epi-betulin on the entry of SARS-CoV-2, revealing that 3-epi-betulin exhibited significantly higher inhibition activity. Structural analysis via iGEMDOCK indicated that while both compounds docked into similar positions on the spike protein, 3-epi-betulin formed an extra hydrogen bond with residue Y453 and exhibited lower binding energy than betulinic acid.
 
This additional interaction with Y453, located in the RBD domain of the spike protein, suggests that 3-epi-betulin has a higher potential to disrupt the spike-ACE2 interaction. Furthermore, 3-epi-betulin possesses unique functional groups absent in other compounds, contributing to its exclusive inhibitory potency against spike/ACE2-mediated virus entry in vitro.
 
The results provide valuable insights into the development of 3-epi-betulin as an adjuvant in current regimens against SARS-CoV-2.
 
Conclusion
The groundbreaking study on 3-epi-betulin from Daphniphyllum glaucescens sheds light on a natural compound with dual antiviral and anti-inflammatory properties. Its ability to reduce virus-induced inflammation and inhibit viral entry, especially against various SARS-CoV-2 variants, positions it as a promising candidate for further development as an antiviral agent.
 
As the global community navigates the complexities of the evolving COVID-19 pandemic, natural compounds like 3-epi-betulin offer hope in the quest for effective therapeutic strategies. The study underscores the need for continued research and clinical studies to harness the full potential of 3-epi-betulin and integrate it into current regimens against SARS-CoV-2. In the pursuit of a comprehensive approach to combatting COVID-19, 3-epi-betulin stands out as a dual-action warrior on the front lines of the battle against this formidable virus.
 
The study findings were published in the peer reviewed International Journal of Molecular Sciences.
https://www.mdpi.com/1422-0067/24/23/17040
 
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