ABSTRACT
Histamine and leukotrienes (LTs), the chemical mediators released from mast cells, play an important role in type-I allergies such as hay fever. Echinacea purpurea (EP) has traditionally been used for herbal tea and has been reported to show biological functions. We evaluated the inhibitory activity of water extracts of EP petals, leaves, and stems against the chemical mediators released from mast cell lines. Petal and leaf extracts exhibited a significant inhibitory effect on histamine release from the stimulated cells, while the stem extract did not exert any effect. Activity of the petal extract was much stronger than that of the leaf extract. All the extracts significantly suppressed LTB4 production in the stimulated cells and displayed similar activities. The petal extract decreased Syk phosphorylation and Ca2+ influx associated with signal transduction in the stimulated cells. These results suggest that EP petal extract may have a relieving effect on allergic symptoms.
Subject(s)
Echinacea/chemistry , Inflammation Mediators/antagonists & inhibitors , Mast Cells/drug effects , Plant Extracts/pharmacology , Calcium/metabolism , Histamine Antagonists/pharmacology , Phosphorylation , Plant Leaves/chemistry , Plant Stems/chemistry , Signal Transduction/drug effects , Syk Kinase/metabolismABSTRACT
Oxidation of low-density lipoprotein (LDL) by reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been suggested to be involved in the onset of atherosclerosis. Oolong tea contains unique polyphenols including oolonghomobisflavan A (OFA). In this study, the effects of OFA on LDL oxidation by ROS and RNS were investigated in vitro. OFA suppressed formation of cholesterol ester hydroperoxides in LDL oxidized by peroxyl radical and peroxynitrite, and formation of thiobarbituric acid reactive substances in LDL oxidized by Cu2+. In addition, OFA inhibited fragmentation, carbonylation, and nitration of apolipoprotein B-100 (apo B-100) in the oxidized LDL, in which heparin-binding activity of apo B-100 was protected by OFA. Our results suggest that OFA exhibits antioxidant activity against both lipid peroxidation and oxidative modification of apo B-100 in LDL oxidized by ROS and RNS. Polyphenols in oolong tea may prevent atherosclerosis by reducing oxidative stress.