Drug screening and development from the affinity of S protein of new coronavirus with ACE2.

Recently, various studies have shown that angiotensin-converting enzyme 2 (ACE2) acts as the "doorknob" that can be bound by the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which conduces to its entrance to the host cells, and plays an important role in corona virus disease 2019 (COVID-19). This paper aims to collect and sorts out the existing drugs, which exert the ability to block the binding of S protein and ACE2 so as to provide directions for the later drug development. By reviewing the existing literature, we expound the pathogenesis of SARS-CoV-2 from the perspective of S protein and ACE2 binding, and summarize the drugs and compounds that can interfere with the interaction of spike protein and ACE2 receptor from different ways. We summarized five kinds of substances, including peptide P6, griffithsin, hr2p analogs, EK1, vaccine, monoclonal antibody, cholesterol-depleting agents, and extracts from traditional Chinese medicine. They can fight SARS-CoV-2 by specifically binding to ACE2 receptor, S protein, or blocking membrane fusion between the host and virus. ACE2 is the key point for SARS-CoV-2 to enter the cells, and it is also the focus of drug intervention. Our drug summary on this pathomechanism is expected to provide ideas for the drug research on SARS-CoV-2 and help to develop anti-coronavirus drugs of broad spectrum for future epidemics.

Optimization of technology for dietary fiber extraction from Maixiansan by response surface methodology.

BACKGROUND: Our study aims to determine whether response surface methodology can optimize the extraction of dietary fiber from Maixiansan. METHODS: A Box-Behnken design was employed to optimize the extraction parameters, including α-amylase concentration (X1: 0.3 - 0.5%), enzymolysis time (X2: 30 - 60 min) and NaOH content (X3: 1.0 - 5.0%), of dietary fiber from Maixiansan using an enzyme-alkali extraction technique. RESULTS: The optimal technological conditions were as follows: α-amylase concentration: 0.4%; enzymolysis time: 45 min; NaOH content: 4.0%. Under these conditions, the extraction yield reached 57.14%, which was well consistent with the predicted models with a coefficient of determination (R2) of 0.9818. An evaluation of the anti-inflammatory activity indicated that Maixiansan was able to significantly inhibit dextran sodium sulfate-induced ulcerative colitis in rats by increasing the concentration of short-chain fatty acids (acetate, propionate and butyrate), among which the butyrate content was significantly higher in the Maixiansan group than in the other groups. CONCLUSION: Our experiments showed that response surface methodology can optimize the extraction of dietary fiber from Maixiansan. Maixiansan could be explored as an anti-ulcerative colitis agent.