Abstract:
On-going global pandemic COVID-19 has spread all over the world and has led to more than 1.97 million deaths till date. Natural compounds may be useful to protecting health in this perilous condition. Mechanism of shuttle entry of SARS-COV-2 virus is by interaction with viral spike protein with human angiotensin-converting enzyme-2
(ACE-2) receptor. To explore potential natural therapeutics, 213 important phytochemicals
of nine medicinal plants Aconitum heterophyllum, Cassia angustifolia, Cymbopogon
fl exuosus, Cymbopogon martinii, Nux vomica, Phyllanthus urinaria, Swertia chirayita, Justicia
adhatoda, Vetiveria zizanioides were selected for in-silico molecular docking against the
spike protein of SARS-COV-2 and compared with recently prescribed drug chloroquine,
ramdesivir, lopinavir and hydroxychloroquine. Results revealed that rhamnocitrin of P.
urinaria, 1,5-dihydroxy-3,8-dimethoxyxanthone of S. chirayita and laevojunenol of V. zizanioides
potentially binds with the receptor binding site of SARS-COV-2 spike glycoprotein
and more robustly destabilized the RBD-ACE-2 binding over chloroquine, ramdesivir,
lopinavir and hydroxychloroquine. It was also found that laevojunenol, rhamnocitrin,
and 1,5-dihydroxy-3,8-dimethoxyxanthone qualifi ed the criteria for drug-likeness as per
Lipinski rule. After attachment of the selected phytochemical with the spike protein the
affi nity of the later towards ACE-2 was minimized and the eff ect of 1,5-dihydroxy-3,8-
dimethoxyxanthone and laevojunenol was superior. Hence, rhamnocitrin of P. urinaria,
1,5-dihydroxy-3,8-dimethoxyxanthone of S. chirayita and laevojunenol of V. zizanioides,
are potential therapeutic molecules for SARS-COV-2, which upon binding with spike
protein changes the affi nity of the spike towards ACE-2 and therefore restrict the entry
of the virus into a human cell. Subsequent clinical validation is needed to confi rm these
phytochemicals as drugs to combat COVID-19.
