Allergic Immune-regulatory Effects of Adlay Bran and Isolation and Identification of Bioactive Components

Autor: Hong-Jhang Chen, 陳宏彰
Rok vydání: 2010
Druh dokumentu: 學位論文 ; thesis
Popis: 98
Allergy is an immune dysfunction, including atopic dermatitis, allergic rhinitis, asthma, etc. In Taiwan, the allergic disease is more and more prevalent. In addition to the usage of drugs to stop the allergic responses, taking advantage of dietary regimen is more important to regulate the immune system, to reduce the allergic symptom and avoid the waste of drugs. The inflammatory response is caused by allergic mediators such as histamine released and cytokine secretion by the mast cell, and the inflammatory response activated by macrophage. Therefore, we first investigated the anti-allergic and anti-inflammatory effects of ethanolic extracts of adlay on the RBL-2H3 cells and RAW 264.7 cells. Except the polished adlay, the ethanolic extracts from different parts of adlay can suppress the β-hexosaminodase released from RBL-2H3 cells stimulated with 1 μM A23187. The ethyl-acetate fraction from ethanolic extracts of adlay bran (ABE-EtOAc) presented more effective inhibition with an EC50 at 40.8 μg/mL. The 40~100% EtOAc/Hex sub-fractions of ABE-EtOAc can significantly inhibit the release of histamine with EC50 between 71~87 μg/mL Moreover, ABE-EtOAc suppressed IL-4, IL-6 and TNF-α secreted from RBL-2H3 cells indicated that the adlay bran can inhibit not only the cell degranulation but also the cytokine secretion. The alday contains anti-allergic compounds, such as palmitic acid, 4-hydroxybenzaldehyde, 6-methoxy-3H-benzoxazol, 4-hydroxyacetophenone, p-coumaric acid and quercetin, can reduce ROS production, inhibit the phosphorylation of Akt and ERK, and decrease the PKC protein expression. These combined effects influence the signaling transduction in RBL-2H3 cells, and showing the anti-allergic effect. The 40~100 % EtOAc/Hex sub-fractions of ABE-EtOAc at 50 μg/mL has no toxicity on the RAW 264.7 cells and inhibit the NO release. Furthermore, the result that ABE-EtOAc suppresses the IL-6 and TNF-α secretion in LPS (1 μg/mL)-stimulated RAW 264.7 cells in concentration dependent manner at 6~30 μg/mL. From above results demonstrates that the adlay bran has an anti-inflammatory effect. In the primary cells isolated from mice study, ABE-EtOAc suppressed the IL-6 and TNF-α secretion from peritoneal macrophages revealing the anti-inflammatory effects ex vivo. Furthermore, ABE-EtOAc can regulate the Th1/Th2 immune reaction via up-regulating IL-2 and down-regulating IL-4 and IL-5. Moreover, ABE-EtOAc reduced the anti-OVA IgE production, increased IFN-γ secretion and decreased IL-4 and IL-5 secretion in OVA immunized BALB/c mice. The ABE-EtOAc affects allergic reaction through balances of Th1/Th2 immune responses. To explore the anti-allergic components, the ABE-EtOAc-40~100% EtOAc/Hex fraction was isolated. There are 22 compounds were isolated from adlay bran. Among them, 15 compounds were first isolated from the adlay including 12 flavonoids, tangeretin (FL1), new flavonoids (FL2), formononetin (FL3), davidigenin (FL4), homoeriodictyol (FL5), 6'', 5, 7-trihydroxy-4''-methoxyflavonone (FL6), isoliquiritigenin (FL8), liquiritigenin (FL9), 3,5,6,7,8,3'',4''-heptamethoxyflavone (FL10), 5,7,4''-trihydroxy-3''-methoxyflavone (FL11), 3,5,7,3'',4''-pentamethoxyflavone (FL12)and 3,5,7,4''-tetramethoxyflavone (FL13), and two chromones, 5-hydroxy-7-methoxychromone (C1), 5,7-dihydroxychromone (C2) and a phenolic ester, ethyl ferulate (PE1). In conclusion, various flavonoids were found in the active fraction of adlay bran. They are suggested to correlate with the allergic response of mast cell in early phase and the inflammatory reaction of macrophage in late phase. Moreover, ABE-EtOAc can balance the Th1/Th2 immune responses. As a consequence the ethanolic extracts of adlay bran strengthen the modulation of immune system and alleviate allergic symptoms.
Databáze: Networked Digital Library of Theses & Dissertations
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