Abstract
This work describes an untargeted analytical approach for the screening, identification, and characterization of the trans-epithelial transport of green tea (Camellia sinensis) catechin extracts with in vitro inhibitory effect against the SARS-CoV-2 papain-like protease (PLpro) activity. After specific catechin extraction, a chromatographic separation obtained six fractions were carried out. The fractions were assessed in vitro against the PLpro target. Fraction 5 showed the highest inhibitory activity against the SARS-CoV-2 PLpro (IC50 of 0.125 μg mL−1). The untargeted characterization revealed that (−)-epicatechin-3-gallate (ECG) was the most abundant compound in the fraction and the primary molecule absorbed by differentiated Caco-2 cells. Results indicated that fraction 5 was approximately 10 times more active than ECG (IC50 value equal to 11.62 ± 0.47 μg mL−1) to inhibit the PLpro target. Overall, our findings highlight the synergistic effects of the various components of the crude extract compared to isolated ECG.
Highlights
IntroductionThe pandemic emergency prompted the scientific community to pursue efforts for developing pharmacological therapies through the screening of some old drugs capable of working against SARS-CoV-2 and vaccines for counteracting this new disease threat [3,4]
COVID-19 is a viral disease caused by SARS-CoV-2, a new strain of single-stranded RNA viruses of the Coronavirus (CoV) family, which is responsible for the current pandemic outbreak [1,2].The pandemic emergency prompted the scientific community to pursue efforts for developing pharmacological therapies through the screening of some old drugs capable of working against SARS-CoV-2 and vaccines for counteracting this new disease threat [3,4]
A potential mechanism underlying the antiviral effect seems to be related to the ability of flavonoids to inhibit the SARS-CoV-2 proteins that are considered to be the best drug targets, i.e., the main protease Mpro or 3-Chymotrypsinlike protease (3CLpro), papain-like protease (PLpro) [14], the spike protein (S), and the RNA-dependent RNA polymerase (RdRp) [15]
Summary
The pandemic emergency prompted the scientific community to pursue efforts for developing pharmacological therapies through the screening of some old drugs capable of working against SARS-CoV-2 and vaccines for counteracting this new disease threat [3,4] In this context, identifying natural compounds able to prevent infection represents an efficient and complementary strategy. A class of phenolic compounds, primarily present in food products, such as cocoa, red wine, fruits, vegetables, and tea leaves, are already well known for their interesting health-promoting activities, including anti-inflammatory and antioxidant antibacterial, anticancer, and neuroprotective ones [9] In this field, green tea (C. sinensis) is one of the wealthiest catechin sources that contains (−)-epicatechin (EC), (−)-epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin-3-gallate (EGCG) as its major catechin components. Together with this mechanism of action, the inactivation of the virus and the inhibition of the replication were considered [17,18,19]
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