Abstract
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.
Highlights
Propolis contains very complex chemical components, mainly flavonoids and polyphenols, which vary depending on the geographical location, plant species and season [1,2,3]
Chromatographic profiles and chemical compositions were determined by UPLC-quadrupole time-of-flight (Q-TOF)-MS, and are shown in Figure 1 and Table 1
A total of 28 constituents was identified in EEP-B. These components mainly belong to cinnamic acids, of which artepillin C was the most abundant component
Summary
Propolis contains very complex chemical components, mainly flavonoids and polyphenols, which vary depending on the geographical location, plant species and season [1,2,3]. The main plant sources of propolis are Populus spp. (Salicaceae) [4], Baccharis dracunculifolia [5], Dalbergia ecastaphyllum [6], Clusia (Clusiaceae) [7] and Azadirachta indica [8], resulting in the propolis composition being complex. Baccharis dracunculifolia is the plant source of Brazilian green propolis, which contains isopentenylated phenylpropanoids and their derivatives, caffeoylquinic acids and some terpenes [9,10,11]. Propolis has been demonstrated to have many pharmacological properties, including antimicrobial, antioxidant, anti-tumour, anti-inflammatory and immunomodulatory activities [14,15,16,17]. Propolis has an anti-inflammatory effect, which can prevent atherosclerosis, reduce blood lipids, affect angiogenesis, and play an important role in the prevention and treatment of cardiovascular diseases [18]
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