ABSTRACT
The epidemic of COVID-19 has brought great challenges to the global public health prevention and control system combined with clinical diagnosis and treatment system, and it makes the development of effective antiviral drugs an important task in current pharmaceutical research. Traditional Chinese medicine (TCM) has played an important role in the prevention and control of COVID-19. Due to its numerous chemical components and various structural types, TCM becomes a natural library for searching for lead compounds against SARS-CoV-2. In this study, a novel dual-target surface plasmon resonance (SPR) biosensor was developed for S protein receptor binding domain (SRBD) and angiotensin converting enzyme 2 (ACE2) which are two key proteins in the process of SARS-CoV-2 invading cells according to characteristics of synergistic effects of multiple components and comprehensive regulation of multiple targets of TCM. The SPR biosensor was applied to screen and identify active components from six TCMs, and daidzin from Puerariae Lobatae Radix was identified to bind with SRBD and ACE2. The affinity constant (KD) of daidzin and ACE2 was 5.18 μmol·L-1 through the SPR affinity assay. Competitive ELISA assay showed that daidzin could inhibit the binding of SRBD and ACE2, and the inhibition rate of daidzin (20 μmol·L-1) was 38.6%. Molecular docking experiments further confirmed that daidzin had the best binding near the binding region of SRBD-ACE2 complex. This study shows that the dual-target SPR screening system is accurate and efficient, and is particularly suitable for screening of complex drug systems and effective substances study of TCM. It provides a material basis for exploring the mechanism of TCM active constituents against SARS-CoV-2, and provides a source of lead compounds for the development of anti-SARS-CoV-2 drugs.