Ayurveda botanicals in COVID-19 management: An in silico multi-target approach

Abstract

The Coronavirus disease (COVID-19) caused by the virus SARS-CoV-2 has become a global pandemic in a very short time span. Currently, there is no specific treatment or vaccine to counter this highly contagious disease. There is an urgent need to find a specific cure for the disease and global efforts are directed at developing SARS-CoV-2 specific antivirals and immunomodulators. Ayurvedic Rasayana therapy has been traditionally used in India for its immunomodulatory and adaptogenic effects, and more recently has been included as therapeutic adjuvant for several maladies. Amongst several others, Withania somnifera (Ashwagandha), Tinospora cordifolia (Guduchi) and Asparagus racemosus (Shatavari) play an important role in Rasayana therapy. The objective of this study was to explore the immunomodulatory and anti SARS-CoV2 potential of phytoconstituents from Ashwagandha, Guduchi and Shatavari using network pharmacology and docking. The plant extracts were prepared as per ayurvedic procedures and a total of 31 phytoconstituents were identified using UHPLC-PDA and mass spectrometry studies. To assess the immunomodulatory potential of these phytoconstituents an in-silico network pharmacology model was constructed. The model predicts that the phytoconstituents possess the potential to modulate several targets in immune pathways potentially providing a protective role. To explore if these phytoconstituents also possess antiviral activity, docking was performed with the Spike protein, Main Protease and RNA dependent RNA polymerase of the virus. Interestingly, several phytoconstituents are predicted to possess good affinity for the three targets, suggesting their application for the termination of viral life cycle. Further, predictive tools indicate that there would not be adverse herb-drug pharmacokinetic-pharmacodynamic interactions with concomitantly administered drug therapy. We thus make a compelling case to evaluate the potential of these Rasayana botanicals as therapeutic adjuvants in the management of COVID-19 following rigorous experimental validation.

Fig 1

UHPLC−PDA chromatogram of reference compounds (RS) and samples with detection for (A) Withania somnifera at 227 nm comprising compounds WS (1−11) in the (A1) reference compounds (A2) WSHA (A3) WSW; where withanoside IV (WS1), withanoside VII (WS2), viscosalactone B (WS3), 27-hydroxywithanone (WS4), dihydrowithaferin A (WS5), withaferin A (WS6), withanoside V (WS7), 12-deoxywithastramonolide (WS8), withanolide A (WS9), withanone (WS10), and withanolide B (WS11).

Fig 2

UHPLC−PDA chromatogram of reference compounds (RS) and samples with detection for (B) Tinospora cordifolia at 210 nm for TC (1–6) in the (B1) reference compounds (B2) TCHA (B3) TCW where cordifolioside-A (TC1), 20-β-hydroxy ecdysone (TC2), tinosporaside (TC3), 8-hydroxy tinosporide (TC4), tinosporide (TC5), columbin (TC6).

Fig 3

UHPLC−PDA chromatogram of reference compounds (RS) and samples with detection for (C) Asparagus racemosus at 210 nm for AR-1in the (C1) reference compound AR1(C2) ARHA (C)3 ARW; where shatavarin-IV (AR1).

Fig 4. Mass spectrometer fingerprinting of Withania somnifera water extract (WSW).

Fig 5. Mass spectrometer fingerprinting of Withania somnifera hydro-alcoholic extract (WSHA).

Fig 6. Mass spectrometer fingerprinting of Tinospora cordifolia water extract (TCW).

Fig 7. Mass spectrometer fingerprinting of Tinospora cordifolia hydro-alcoholic extract (TCHA).

Fig 8. Mass spectrometer fingerprint of Asparagus racemosus water extract (ARW).

Fig 9. Mass spectrometer fingerprint of Asparagus racemosus hydro-alcoholic extract (ARHA).

Fig 10. Network of Rasayana botanicals associated with immune pathways.

Figure depicts potential mechanism of Rasayana botanicals to modulate several immune pathways through bioactive-target associations.

Fig 11. Analysis of bioactive-target associations in immune pathways.

(A) The figure depicts the involvement of AR, TC, and WS in pathways of human immune system. The represented association is number of connecting combinations between bioactives and their targets in a particular pathway. (B) The table lists all immune targets of AR, TC, and WS.

Fig 12

Interaction of (A and B) cyclohexyl-N-(3-pyridyl)acetamide (Z31792168), (C and D) Columbin and (E and F) Tinocordiside with M^pro: In the left panel the protein is shown in a surface representation colored by atom while the ligand is shown in stick representation. The right panel is a 2D interaction plot of the receptor with the inhibitors.

Fig 13

Interaction of (A and B) Remdesivir (C and D), Muzanzagenin and (E and F) Withanolide-B with RdRp. In the left panel the protein is shown in a surface representation colored by atom while the ligand is shown in stick representation. The right panel is a 2D interaction plot of the receptor with the inhibitors.

Fig 14

Interaction of (A and B) Withacoagin and (C and D) Withanolide-B with Spike protein: In the left panel the protein is shown in a surface representation colored by atom while the ligand is shown in stick representation. The right panel is a 2D interaction plot of the receptor with the inhibitors.

Fig 15. Predicted role of Ayurvedic Rasayana botanicals in the management of COVID-19.

Once the SARS-CoV-2 virus passes the respiratory tract, it enters the lung cells with the help of its Spike protein coupled with ACE-2 receptors (these are present almost all over the body enabling its spread to multiple organs and their failure in later stages of the disease). Rasayana botanical extract constituents (E), Withacoagin and Withanolide B may inhibit COVID-19 entry by disrupting interactions between viral spike protein and host ACE-2 receptor. Rasayana botanicals may inhibit viral replication through inhibition of coronavirus main protease (M^pro) and RNA-dependent RNA-polymerase (RdRp) Part A: The M^pro is can be inhibited by Columbin and Tinocordiside. RdRp can be inhibited by Muzanzagenin and Withanolide-B thereby inhibiting RNA synthesis of SARS-CoV-2. This may lead to its life cycle arrest. Part-(B): The patient related predisposition factors such as sex, age, diseases, individualization (PRF:SADI) and COVID-19 pathophysiology involved in the multiple organ failure and death. Part (C): the multi-targeted immunomodulatory and adaptogenic potential of Rasayana botanicals as predicted by network pharmacology approach. Part-(D) shows higher probability for the beneficial pharmacokinetic- pharmacodynamic herb-drug interactions 37 if co-prescribed with WHO Solidarity trial drugs and drugs for COVID-19 associated comorbidities. It is interesting to note that above mentioned phytoconstituents are predicted to have good docking score, ligand efficiency, oral bioavailability, and drug likeliness. This makes them potential molecules for rapid drug discovery and development based on multi-targeted and reverse pharmacology approach for COVID-19 management. However, these in silico predictions need in vitro–in vivo validation.