In vitro inhibition of coronavirus replications by the traditionally used medicinal herbal extracts, Cimicifuga rhizoma, Meliae cortex, Coptidis rhizoma, and Phellodendron cortex.
BACKGROUND
A search for new anti-coronaviral drugs to treat coronaviral infections was motivated by an outbreak of severe acute respiratory syndrome (SARS).


OBJECTIVE
In order to find drugs that treat coronavirus infections, including SARS, we screened traditional medicinal herbal extracts and evaluated their antiviral activities on coronavirus replication.


METHODS
We employed a plaque assay to evaluate the effect of 22 medicinal herbal extracts on virus replication. We determined the 50% effective concentration (EC50) of each extract that was necessary to inhibit the replication of mouse hepatitis virus A59 (MHV-A59); we also determined 50% cytotoxic concentrations (CC50) for each extract. Northern and Western blot analyzes were performed to investigate antiviral activity in MHV-infected DBT cells, including virus entry, viral RNA and protein expression, and virus release. Coronavirus specific inhibition was also demonstrated using porcine epidemic diarrhea virus (PEDV).


RESULTS
Cimicifuga rhizoma, Meliae cortex, Coptidis rhizoma, Phellodendron cortex and Sophora subprostrata radix decreased the MHV production and the intracellular viral RNA and protein expression with EC50 values ranging from 2.0 to 27.5 microg/ml. These extracts also significantly decreased PEDV production and less dramatically decreased vesicular stomatitis virus (VSV) production in vitro.


CONCLUSIONS
The extracts selected strongly inhibited MHV replication and could be potential candidates for new anti-coronavirus drugs.
Department of Microbiology, Ajou University School of Medicine, Suwon, South Korea.
Hye-Young
HY
Kim
Hyun-Soo
HS
Shin
Hyun
H
Park
Youn-Chul
YC
Kim
Yong Gab
YG
Yun
Sun
S
Park
Ho-Joon
HJ
Shin
Kyongmin
K
Kim
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D031885:Cimicifuga; D006801:Humans; D006517:Murine hepatitis virus / Q000187:drug effects* / Q000502:physiology; D032102:Phellodendron; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal; D014709:Vero Cells; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D010936:Plant Extracts