| 摘要: | 中華冬蟲夏草，也就是冬蟲夏草，它是一種中國傳統滋補的昂貴中草藥材，然而，當市面上出現了很多偽品或仿冒品時，人們也就開始尋找與冬蟲夏草有相同藥理活性的替代品，所以目前市面上常常使用北蟲草作為冬蟲夏草的天然替代品。但北蟲草仍然昂貴，故有釵h相對較便宜人工培養的北蟲草出現在市面上，因此本研究計畫評估人工培養的北蟲草子實體對mitomycin C (MMC) 所引發的毒性，是否具化學預防性的作用。
首先，本研究先評估人工培養的北蟲草子實體本身是否具有急毒性及基因毒性。在給予SD大白鼠2000 mg/kg人工培養的北蟲草子實體後，偵測第七天及第十四天的體重，與對照組間並無明顯差異，也無死亡狀況，因此認為人工培養的北蟲草子實體並不具急毒性。接著以微核實驗在螢光顯微鏡下計數1000個網狀細胞中有多少個是含有微核(micronuclei) 的網狀細胞，來評估人工培養的北蟲草子實體是否具基因毒性，結果不管是單一大劑量 (2000 mg/kg) 給予，或是低劑量 (125~1000 mg/kg)重 複給予七天，一樣不具基因毒性。
Mitomycin C (MMC) 是一種具細胞毒性的抗腫瘤藥物，在化學預防性評估方面當作誘導毒性之藥物，先餵食小鼠一週的125~1000 mg/kg人工培養的北蟲草子實體，在第七天給予腹腔注射0.5 mg/kg或1 mg/kg 的MMC，在腹腔注射MMC後的第24、48、72小時進行眼窩週邊血採樣來計數微核數量。實驗結果發現在處理MMC後的24小時，1000 mg/kg人工培養的北蟲草子實體，以及72小時後，500及1000 mg/kg人工培養的北蟲草子實體微核數目有減少的趨勢 (p<0.05)。且蟲草素也成劑量相關性減少MMC誘導的微核數目，表示人工培養的北蟲草子實體能降低MMC所誘導的微核數目與蟲草素有關。
彗星試驗為偵測DNA損傷的方法，經過實驗證實餵食1000 mg/kg人工培養的北蟲草子實體，可降低的MMC所誘導彗星影像拖尾的長度。在LDH試驗中，餵食1000 mg/kg人工培養的北蟲草子實體也可明顯降低MMC所誘導血清中的LDH濃度 (p<0.001)。綜合以上的實驗結果，本研究認為人工培養的北冬蟲夏草子實體對MMC所引發之毒性具有化學預防作用。
Cordyceps sinensis (CS) is an expensive tonic Chinese herbal medicine. However, people look for a similar pharmacological effects substitute of CS when many counterfeits and mimics of CS always found in markets, while Cordyceps militaris (CM) is a popularly using and cheaper natural of CS. The purpose of this study was evaluated the chemopreventive effects of cultured fruiting body of CM in mitomycin C-induced toxicity. We had started to evaluate the acute toxicity of cultured fruiting body of CM at SD rats and ICR mice.
A single maximum dose (2000 mg/kg) of CM were given by oral gavage (o.p.), we had measured the body weights of all animals after 7 and 14 days. Then we planed to evaluate the genotoxicity of cultured fruiting body of CM by the micronucleus test. We had sampled bone marrow of rats at 48 hours with 2000 mg/kg CM (o.p.), and collected the orbital peripheral blood of mice at 24, 48 and 72 hours with same treatment. The micronucleus test is an evaluated genotoxicity method by counting how many reticulocytes contained micronuclei (MN) in 1000 reticulocytes. And mitomycin C (MMC) is a famous anti-tumor cytotoxic drug. In our chemopreventive evaluations of cultured fruiting body of CM, we had designed to pre-treat six weeks age ICR mice with 125, 250, 500 and 1000 mg/kg CM (o.p.) for seven days, then given 0.5 mg/kg or 1 mg/kg MMC by intraperitoneal (i.p.) at the 7th day, than collected orbital peripheral blood of mice to counted the frequency of MN after 24, 48 and 72 hours treated mitomycin C.
The cultured fruiting body of CM were confirmed no acute toxicity or genotoxicity in this studies. In the chemopreventive evaluation, we found that CM decreased the frequency of MN at 24 hours (1000 mg/kg CM) and 72 hours (500, 1000 mg/kg) (p<0.05). Cordycepin, the well known active ingredient of CM, also reduce the mitomycin C-induced MN in a dose-dependent manner. In this study, our results suggest that CM can prevent mitomycin C-induced genotoxicity, and the active ingredient cordycepin may be involved in this chemopreventive effect.
In the COMET assay, which can detect the DNA damage, 1000 mg/kg CM also prevent 0.5 mg/kg MMC-induced COMET tail length. In LDH test, 1000 mg/kg CM can significant prevent 0.5 mg/kg MMC-induced cytotoxicity (p<0.001). From the above results, we had suggested that the cultured fruiting body of CM can against MMC-induced toxicity. |
