| 摘要: | 我們實驗室曾報告槲皮素 (quercetin) 能抑制phosphodiesterase (PDE)1~4，且對 PDE3 和 PDE4的抑制較具有選擇性，並具抗氣喘的作用。因此我們有興趣比較口服rutin (quercetin-3-O-rutinoside)、quercitrin (quercetin-3-O-α-L-rhamnoside)及isoquercitrin (quercetin-3-O-β-D-glucoside)，在活體及離體實驗是否有抗氣喘的作用。
在雌性的BALB/c小鼠因卵蛋白 (ovalbumin, OVA) 引起的過敏性氣喘 (allergic asthma)模式，rutin (30~100 μmol/kg, p.o.) 及quercitrin (100 μmol/kg, p.o.) 能劑量依存性且有意義地減少因methacholine (MCh, 25~50 mg/ml) 增加的enhanced pause (Penh) 值，以及減少肺泡灌洗液的總發炎細胞、巨噬細胞、淋巴球、嗜中性白血球和嗜伊紅性白血球，但 quercitrin無法有意義地抑制巨噬細胞的數目，是唯一的例外。它們也會有意義地降低肺泡灌洗液interleukin (IL)-2, IL-4, IL-5 和tumor necrosis factor (TNF)-α的釋放，也會降低血清及肺泡灌洗液的total和OVA-specific IgE的量，但可以劑量依存性且有意義地使血清的IgG2a含量增加，顯示有抗發炎作用。然而isoquercitrin即使投予劑量 (100 μmol/kg, p.o.)也無法降低肺泡灌洗液中的發炎細胞，也無法降低血清及肺泡灌洗液中的Total和OVA-specific IgE的量。
Rutin不會抑制PDE1~5 (IC50 > 100 μM)，而quercitrin抑制 PDE1~5活性的IC50分別為16.6、> 100、10.0、13.1及16.3 μM。而isoquercitrin抑制PDE1~5活性的IC50分別為>100、> 100、10.9、>100及13.7 μM。Rutin、quercitrin及isoquercitrin取代結合在敏感化天竺鼠全腦細胞顆粒high affinity rolipram binding sites (HARBS) 之 [3H]-rolipram的EC50值皆 > 300 μM，因此quercitrin之PDE4H/PDE4L比值大於23。並且進一步發現rutin、quercitrin及isoquercitrin (均300 μmol/kg, s.c.) 皆不會縮短由xylazine/ketamine所引起的麻醉時間，所以推測其副作用極低。
Quercitrin (100 μM)，但非rutin (100~300 μM) 及isoquercitrin (100 μM) ，會抑制累加OVA (10~100 μg/ml) 引起的敏感化離體天竺鼠氣管的收縮，顯示僅quercitrin (100 μM)能去抑制肥胖細胞的去顆粒化。
結論，rutin、quercitrin具有抗發炎的作用，並且副作用可能很低，因此深具有抗氣喘的潛力。
In our laboratory, we have previously reported that quercetin has inhibitory effects on phosphodiesterase (PDE) 1~4，in which quercetin more potently inhibits PDE3 and PDE4, and has antiasthmatic effect. Therefore we are interested in the anti-asthmatic effect of orally administered rutin (quercetin-3-O-rutinoside), quercitrin (quercetin-3-O-α-L-rhamnoside) and isoquercitrin (quercetin-3-O-β-D-glucoside) in vivo and in vitro.
In ovalbumin (OVA)-induced allergic asthma of female BALB/c mouse model, rutin (30~100 μmol/kg, p.o.) and quercitrin (100 μmol/kg, p.o.) can dose-dependently attenuated the enhanced pause (Penh) value induced by methacholine (MCh, 25~50 mg/ml), and significantly suppressed the total number of inflammatory cells, macrophages, lymphocytes, neutrophils, and eosinophils in the bronchoalveolar lavage fluid (BALF) of mice with the exception that quercitrin did not reduce the number of macrophages. They also significantly attenuated the release of interleukin (IL)-2, IL-4, IL-5 and tumor necrosis factor (TNF)-α in the BALF. Rutin and quercitrin also significantly reduced the total and OVA-specific IgE levels in the serum and in the BALF. On the other hand, they dose-dependently and significantly increased the levels of IgG2a in the serum, suggesting that they have anti-inflammatory effect. However, isoquercitrin (100 μmol/kg, p.o.) could attenuate neither the inflammatory cells in the BALF nor the total and OVA-specific IgE levels in the serum and the BALF.
Rutin had no inhibitory effects on PDE1~5 activities (IC50 > 100 ?嵱). Quercitrin inhibited PDE1~5 activities with respective IC50 values of 16.6, > 100, 10.0, 13.1 and 16.3 μM, and isoquercitrin inhibited PDE1~5 activities with respective IC50 values of >100, > 100, 10.9, >100 and 13.7 μM. Rutin, quercitrin and isoquercitrin displaced [3H]-rolipram from high affinity rolipram binding sites (HARBS) of particulates of whole brains isolated from sensitized guinea pigs, with an EC50 value (all > 300 μM). Therefore, the PDE4H/PDE4L ratio of quercitrin was > 23. Rutin, quercitrin and isoquercitrin (all 300 μmol/kg, s.c.) did not shorten the duration of anesthesia induced by xylazine/ketamine, suggesting that their adverse effects may be very low.
Quercitrin (100 μM), but not rutin (300 μM) and quercitrin (100 μM), significantly suppressed cumulative OVA (10~100 μg/ml)-induced contractions in isolated sensitized guinea pig trachealis, suggesting that quercitrin (100 μM) may prevent the degranulation of mast cells.
In conclusion, rutin and quercitrin had anti-inflammatory effects and may have little side effects. The above results suggest that rutin and quercitrin may have the potential for treating asthma. |
