RESUMO
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the current pandemic, coronavirus disease 2019 (COVID-19), has taken a huge toll on human lives and the global economy. Therefore, effective treatments against this disease are urgently needed. Here, we established a fluorescence resonance energy transfer (FRET)-based high-throughput screening platform to screen compound libraries to identify drugs targeting the SARS-CoV-2 main protease (Mpro), in particular those which are FDA-approved, to be used immediately to treat patients with COVID-19. Mpro has been shown to be one of the most important drug targets among SARS-related coronaviruses as impairment of Mpro blocks processing of viral polyproteins which halts viral replication in host cells. Our findings indicate that the anti-malarial drug tafenoquine (TFQ) induces significant conformational change in SARS-CoV-2 Mpro and diminishes its protease activity. Specifically, TFQ reduces the -helical content of Mpro, which converts it into an inactive form. Moreover, TFQ greatly inhibits SARS-CoV-2 infection in cell culture system. Hence, the current study provides a mechanistic insight into the mode of action of TFQ against SARS-CoV-2 Mpro. Moreover, the low clinical toxicity of TFQ and its strong antiviral activity against SARS-CoV-2 should warrant further testing in clinical trials.
RESUMO
<p><b>OBJECTIVE</b>To observe the effect of salidroside on tic behavior and in vivo dopamine DA) and serotonin (5-HT) levels in Tourette syndrome (TS) model rats.</p><p><b>METHODS</b>Forty rats were randomly divided into the blank control group, the TS model group, the haloperidol-treated group (0.5 mg/kg x d(-1)), and the salidroside-treated group (50 mg/kg x d(-1)), 10 in each group. TS rat model was induced by imino-dipropio-nitrile (IDPN). Peritoneal injection of haloperidol and salidroside was started from the 4th day of modeling in the haloperidol-treated group and the salidroside-treated group respectively. Normal saline was peritoneally injected to rats in the blank control group and the TS model group respectively. Stereotyped behavior was scored, and changes of DA and 5-HT levels in blood and striatum were measured before modeling, after modeling, and after intervention.</p><p><b>RESULTS</b>Compared with the blank control group, the score of the tic behavior was elevated (P < 0.01) , levels of DA and 5-HT in plasma and striatum were reduced in the model group (P < 0.01, P < 0.05). Compared with the same group after modeling, the tic behavior score decreased and plasma DA levels increased in the two treated groups after intervention (P < 0.01). 5-HT content increased in the salidroside-treated group (P < 0.01). Compared with the model group after intervention, the tic behavior score was significantly reduced (P < 0.01), and DA levels in plasma and striatum were elevated (P < 0.01, P < 0.05) in the salidroside-treated group and the haloperidol-treated group. Compared with the haloperidol-treated group, the tic behavior score increased (P < 0.01), DA levels in plasma and striatum were lowered (P < 0.01, P < 0.05), the 5-HT level increased in plasma and striatum (P < 0.01, P < 0.05) in the salidroside-treated group.</p><p><b>CONCLUSIONS</b>In the salidroside-treated group, the tic behavior was significantly reduced, and DA levels in plasma and striatum were elevated. Its mechanism might be related to regulating activities of dopamine neurons in striatum.</p>
