Mechanisms of anti-asthmatic action of Luteolin in vivo and in vitro

• Main Authors: Jun-Hao Chen, 陳俊豪
• Other Authors: Wun-Chang Ko, Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/34546466291174359825

碩士 === 臺北醫學大學 === 藥學系 === 91 === Part I: Flavonoids are polyphenolic compounds occurring in nature, commonly presents in plants. They have anti-inflammatory and immuno-regulatory effects. Cyclic nucleotides play an important role in inflammatory cells. Their concentration is related to the relaxation of airway smooth muscle. Therefore we are interested in investigating the relationships between structure and inhibitory effect of flavonoids on various PDE isozymes separated from guinea-pig lungs and hearts. Isolated guinea-pig lungs and hearts were separately homogenized and centrifuged. The supernatant was chromatographed over a column of Q-sepharose, and eluted with various concentrations of NaCl. In the following order, PDE subtype 1, 5, 2, 4 from lungs, and 3 from hearts were separated. Acccording to the method described by Thompson and Appleman, the activities of PDE isozymes were determined in the presence of cAMP and [3H]-cAMP or cGMP and [3H]-cGMP as substrate. The results revealed that luteolin had effectively inhibitory actions on PDE1~5. Diosmetin, which OCH3 group substitutes the C-4 OH group of luteolin, enhanced inhibition on PDE2, but lost inhibition on PDE3 activity. Apigenin, lacking of C-3'' OH group from luteolin, lost inhibition both on PDE4 and 5. Chrysin lacking of both C-3'' and C-4'' OH groups from luteolin lost all inhibition on PDE1~5. Luteolin-7-glucoside glycosylated from luteolin attenuated inhibition on PDE2 and 4, lost inhibition on PDE1, 3, and 5. Quercetin hydroxylated from luteolin at position of C-3 enhanced inhibition on PDE4, but lost inhibition on PDE5. Myricetin, hydroxylated from luteolin at both position of C-3 and C-5'', enhanced inhibition on PDE4, but lost inhibition on PDE5. Eriodictyol saturated luteolin between C-2 and 3 attenuated inhibition on PDE3, but lost inhibition on other PDE isozymes. Hesperetin saturated from diosmetin between C-2 and 3 attenuated inhibition on PDE4, but lost inhibition on other PDE isozymes. Part II: Luteolin effectively but non-selectively inhibited PDE1~5. The aim of this present study is to investigate whether it has anti-asthmatic action. The present results revealed that luteolin inhibited ovalbumin (OVA)-induced airway hyperresponsiveness (AHR). Luteolin (3-30 mmol/kg, i.p.) dose-dependently attenuated the enhanced pause (Penh) value induced by aerosolized methacholine (MCh, 25~50 mg/ml) in sensitized mice after secondary allergen challenge. Luteolin at 30 mmol/kg even significantly inhibited MCh (12.5 mg/ml)-induced increase of Penh value. Mice administered luteolin (3-30 mmol/kg) did not significantly differ from those sensitized but not challenged with aerosolized OVA (non-treatment). Luteolin (3-30 mmol/kg, i.p.) also suppressed total inflammatory cells, neutrophils and eosinophils, but not lymphocytes. Luteolin at a dose of 30 mmol/kg even significantly reduced marcrophages. Luteolin (3-30 mmol/kg) significantly reduced the IL-2, IL-4, IFN-g and TNF-a production in bronchoalveolar lavage fluid (BALF). At a dose of 30 mmol/kg, luteolin even inhibited release of IL-5. Luteolin (3~30 mM) significantly attenuated OVA (10 mg/ml)-induced tracheal contractions in vitro. From Lineweaver-Burk analysis, luteolin (3~30 mM) competitively inhibited various PDE isozymes. In conclusion, luteolin non-selectively but competitively inhibited PDE1~5. At low doses of 3~30 mmol/kg (0.858~8.58 mg/kg), luteolin has both anti-inflammatory and bronchodilatory effects, and has a potential in the treatment of asthma.