Propolis has a very complex composition, with antibacterial, anti-inflammatory and other properties. To determine the composition of ethanol extracts of Brazilian green propolis (EEP-B) and their protective effect on mouse aortic endothelial cells (MAECs), the chemical composition of EEP-B was analysed by UPLC/Q-TOF-MS/MS, and the protective effect of EEP-B on the proliferation of lipopolysaccharide (LPS)-induced MAECs was determined by Cell Counting Kit-8 (CCK-8) assays. The protein levels of inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin- 6 (IL-6) were measured by enzyme-linked immunosorbent assay (ELISA), and ICAM-1, VCAM-1 and MCP-1 expressions were analysed by western blotting. The results showed that a total of 24 compounds belonging to cinnamic acids and flavonoids, including 3,5-diisopentenyl-4-hydroxycinnamic acid (artepillin C), kaempferide, 3-isoprenyl p-coumaric acid, pinocembrin and 4′-methoxy pinobanksin, were identified in EEP-B. Among them, a new component, suggested to be 5-isoprenyl caffeic acid p-coumaric acid ester, was reported for the first time. The LPS-induced levels of TNF-α, IL-6, ICAM-1, VCAM-1 and MCP-1 were downregulated in response to 5, 10 and 20 μg/mL EEP-B. This study revealed that EEP-B could reduce LPS-induced inflammatory reactions, improve cell survival, and protect MAECs by regulating ICAM-1, VCAM-1 and MCP-1 expression. These findings could provide a theoretical basis for MAEC treatment using EEP-B.

The chemical compositions of ethanol extracts of propolis from China (EEP-C) and the United States (EEP-A) and their antifungal activity against Penicillium notatum were determined. The result showed that a total of 49 compounds were detected by UPLC-Q-TOF-MS, 30 of which were present in samples from two regions. The major compounds of EEP-C and EEP-A were similar, including pinocembrin, pinobanksin-3-O-acetate, galanin, chrysin, pinobanksin, and pinobanksin-methyl ether, and both of them showed antifungal activity against P. notatum with same minimum inhibitory concentration (MIC) value of 0.8 mg·mL⁻¹. In the presence of propolis, the mycelial growth was inhibited, the hyphae became shriveled and wrinkled, the extracellular conductivities were increased, and the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) were decreased. In addition, iTRAQ-based quantitative proteomic analysis of P. notatum in response to propolis revealed that a total of 341 proteins were differentially expressed, of which 88 (25.8%) were upregulated and 253 (74.2%) were downregulated. Meanwhile, the differentially expressed proteins (DEPs) involved in energy production and conversion, carbohydrate transport and metabolism, and the sterol biosynthetic pathway were identified. This study revealed that propolis could affect respiration, interfere with energy metabolism, and influence steroid biosynthesis to inhibit the growth of P. notatum.

Antibiotics are omnipresent in the environment due to their widespread use, and they have wide-ranging negative impacts on organisms. Virus resistance differs substantially between domesticated Apis mellifera and wild Apis cerana, although both are commonly raised in China. Here, we investigated whether antibiotics can increase the sensitivity of honey bees to viral infection using the Israeli acute paralysis virus (IAPV) and tetracycline as representative virus and antibiotic. Although IAPV multiplied to lower levels in A. cerana than A. mellifera, resulting in decreased mortality (P < 0.01), there was no significant difference in immune responses to viral infection between the two species. Adult worker bees (A. cerana and A. mellifera) were treated with or without tetracycline to demonstrate the prominent role of gut microbiota against viral infection, and found Lactobacillus played a vital antiviral role in A. cerana. In A. cerana but not A. mellifera, tetracycline treatment reduced clearly bee survival and increased susceptibility to IAPV infection (P < 0.01). Our findings revealed that long-term antibiotic treatment in A. mellifera had altered the native gut microbiome and promoted the sensitivity to viral infection. We highlight the effects of antibiotics exposure on resistance to microbial and viral infection.