RESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), a respiratory illness that poses a serious threat to global public health. In an essential step during infection, SARS-CoV-2 uses the receptor-binding domain (RBD) of the spike (S) protein to engage with angiotensin-converting enzyme 2 (ACE2) in host cells. Chinese herbal medicines and their active components exhibit antiviral activity, with luteolin being a flavonoid that can significantly inhibit SARS-CoV infection. However, whether it can block the interaction between the S-protein RBD of SARS-CoV-2 and ACE2 has not yet been elucidated. Here, we investigated the effects of luteolin on the binding of the S-protein RBD to ACE2. By employing a competitive binding assay in vitro, we found that luteolin significantly blocked the binding of S-protein RBD to ACE2 with IC50 values of 0.61 mM, which was confirmed by the neutralized infection with SARS-CoV-2 pseudovirus in vivo. A surface plasmon resonance-based competition assay revealed that luteolin significantly affects the binding of the S-protein RBD to the ACE2 receptor. Molecular docking was performed to predict the binding sites of luteolin to the S-protein RBD-ACE2 complex. The active binding sites were defined based on published literature, and we found that luteolin might interfere with the mixture at residues including LYS353, ASP30, and TYR83 in the cellular ACE2 receptor and GLY496, GLN498, TYR505, LEU455, GLN493, and GLU484 in the S-protein RBD. These residues may together form attractive charges and destroy the stable interaction of S-protein RBD-ACE2. Luteolin also inhibits SARS-CoV-2 spike protein-induced platelet spreading, thereby inhibiting the binding of the spike protein to ACE2. Our results are the first to provide evidence that luteolin is an anti-SARS-CoV-2 agent associated with interference between viral S-protein RBD-ACE2 interactions.
RESUMEN
PURPOSE: This study aimed to examine the levels of physical activity (PA) among children and adolescents in western China, and the influence of parents on their PA, in the era of coronavirus disease 2019 (COVID-19). METHODS: This cross-sectional study used a multistage questionnaire to evaluate 4800 children and adolescents of grades 4-12 (9-17 years old) from 48 primary and secondary schools across 16 districts and counties in western China. In addition to PA, questionnaires collected data on demography, family structure, and exercise habits. Data were assessed using the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and analyzed using chi-square tests, t-tests, Spearman's correlation, and logistic regression models in SPSS. RESULTS: In this study, a minority (42.1%, n = 1553) of children and adolescents met the daily exercise target (60 min) recommended by the World Health Organization (WHO). Moderate- to vigorous-intensity physical activity (MVPA) level of boys was significantly higher than that of girls. Regardless of sex, children with the highest MVPA levels were those in grades 4-6, and PA levels decreased with increasing age. Furthermore, for every hour of increase in the daily MVPA of parents, the MVPA also increased by 6.1-13.9 min in children and adolescents. Moreover, areas of higher economic development were associated with lower levels of MVPA. CONCLUSIONS: Overall, this study found a low level of MVPA in children and adolescents of western China; both family structure and parental activity have a significant influence on the children's PA levels. Besides, the impact of COVID-19 on PA levels has not been entirely negative.