Kaempferol inhibits SARS-CoV-2 invasion by impairing heptad repeats-mediated viral fusion.

BACKGROUND: The continuous evolution of SARS-CoV-2 has underscored the development of broad-spectrum prophylaxis. Antivirals targeting the membrane fusion process represent promising paradigms. Kaempferol (Kae), an ubiquitous plant flavonol, has been shown efficacy against various enveloped viruses. However, its potential in anti-SARS-CoV-2 invasion remains obscure. PURPOSE: To evaluate capabilities and mechanisms of Kae in preventing SARS-CoV-2 invasion. METHODS: To avoid interference of viral replication, virus-like particles (VLPs) constructed with luciferase reporter were applied. To investigate the antiviral potency of Kae, human induced pluripotent stem cells (hiPSC)-derived alveolar epithelial cells type II (AECII) and human ACE2 (hACE2) transgenic mice were utilized as in vitro and in vivo models, respectively. Using dual split protein (DSP) assays, inhibitory activities of Kae in viral fusion were determined in Alpha, Delta and Omicron variants of SARS-CoV-2, as well as in SARS-CoV and MERS-CoV. To further reveal molecular determinants of Kae in restricting viral fusion, synthetic peptides corresponding to the conserved heptad repeat (HR) 1 and 2, involved in viral fusion, and the mutant form of HR2 were explored by circular dichroism and native polyacrylamide gel electrophoresis. RESULTS: Kae inhibited SARS-CoV-2 invasion both in vitro and in vivo, which was mainly attributed to its suppressive effects on viral fusion, but not endocytosis, two pathways that mediate viral invasion. In accordance with the proposed model of anti-fusion prophylaxis, Kae functioned as a pan-inhibitor of viral fusion, including three emerged highly pathogenic coronaviruses, and the currently circulating Omicron BQ.1.1 and XBB.1 variants of SARS-CoV-2. Consistent with the typical target of viral fusion inhibitors, Kae interacted with HR regions of SARS-CoV-2 S2 subunits. Distinct from previous inhibitory fusion peptides which prevent the formation of six-helix bundle (6-HB) by competitively interacting with HRs, Kae deformed HR1 and directly reacted with lysine residues within HR2 region, the latter of which was considered critical for the preservation of stabilized S2 during SARS-CoV-2 invasion. CONCLUSIONS: Kae prevents SARS-CoV-2 infection by blocking membrane fusion and possesses a broad-spectrum anti-fusion ability. These findings provide valuable insights into potential benefits of Kae-containing botanical products as a complementary prophylaxis, especially during the waves of breakthrough infections and re-infections.

[The study of diabetes-related behavior status and affecting factors among urban and suburban residents in six provinces in China].

OBJECTIVE: To explore the status of diabetes-related behaviors and affecting factors among urban and suburban residents in China. METHODS: A sample of 18-60 years old residents from Zhejiang, Jiangsu, Shanxi, Henan, Yunnan and Qinghai provinces was investigated by using stratified cluster random sampling method from March to May in 2013, and 4 282 residents were recruited. The Questionnaire of Health Literacy of Diabetes Mellitus of the Public in China was used to conduct the survey. χ(2) test was used to compare the different risk behavior characteristics of diabetes. The results of the survey were standardized by the 6th national census data. Multiple regression analysis was used to understand the affecting factors to related behaviors. RESULTS: After data standardization, 14.3% sat more than 6 hours every day, 57.6% exercised less than 3 times every week, 21.3% had no regularly daily diet, 58.7% paid no attention to diet control, 15.7% and 7.8% residents preferred salty and oily diet, 51.4% had physical examination less than 1 time every year, 29.7% were smokers, and 9.2% often drank. Urban residents spent much more time on sitting (18.2%) than rural residents (8.4%) (P < 0.05), and the rates of lack of physical exercise(52.7%), irregular diet (17.2%), paying no attention to diet control (51.9%), smokers (23.6%) among urban residents were lower than rural residents (60.1%, 21.4%, 62.5% and 32.1% respectively) (P < 0.05). The rates of irregular diet (24.6%), paying no attention to diet control (63.5%), high-salt and high-fat diet (30.1%), smokers (57.7%), drinking (18.7%) among men were higher than those in females (15.5%, 52.1%, 23.2%, 2.2%, and 0.8% respectively) (P < 0.05); regions, genders, educational levels, occupations were related to relative behaviors of diabetes, residents in rural areas (t = 7.829, P < 0.01), males (t = -21.760, P < 0.01), lower education level (t = 0.771, P < 0.01), as well as institution personnel (t = -4.240, P < 0.01) had lower behavior scores, which meant they had more risk behaviors related to diabetes. CONCLUSION: There were diabetes-related risk behaviors among both urban and suburban residents in China, such as insufficient physical exercise, no diet control and regular medical examinations. These risk behaviors happened more in rural areas than in urban areas, men than women, older age group than lower age group.