菟絲子品質評價及其奈米製劑之抗氧化、保肝活性研究

菟絲子為旋花科植物Cuscuta chinensis Lam.成熟種子是一種補益性的中草藥常被傳統中醫應用在藥膳與食療。先前研究文獻證明菟絲子具有抗癌、免疫調節，增加記憶，而其抗氧化及保肝作用未曾被探討過。因此，本研究利用體外抗氧化活性試驗及活性成分含量測定針對菟絲子之水、乙醇萃取物及其有機分層探討其抗氧化活性及其活性成分之間的相關性。而體內研究則利用中毒劑量acetaminophen誘發氧化壓力來造成急性肝炎來評估其保肝活性。本研究結果發現菟絲子乙醇萃取物比水萃取物更具有良好體外抗氧化活性，且與其活性成分含量呈正相關聯性。另外，本研究體內保肝動物試驗證實菟絲子乙醇萃取物可以有效地降低acetaminophen引起肝功能指數上升，並提升體內抗氧化酵素及減少脂質過氧化物質來達到良好保肝活性。可惜地是水萃取物卻無此活性，這樣的結果跟體外的抗氧化活性及含量分析互相吻合。再者，近年來因應中草藥資源有限而減少藥材使用量，中草藥劑型的開發有效地提高藥效和生物可用率，從而降低病人的用藥量，大大地節省藥物資源，奈米劑型是其中一種最有效方法。由於菟絲子乙醇萃取物具水難溶性特質，因此很適合開發成奈米劑型。本研究以奈米技術成功地製備菟絲子奈米製劑，並同時評估其保肝活性。實驗結果顯示，菟絲子奈米製劑只需乙醇萃取物的五分之一劑量便可呈現出相同的保肝活性。結論，本研究首次發現菟絲子具有抗氧化及保肝作用的新療效。也首次製備了菟絲子奈米新製劑，除可減少其使用劑量而達到相同活性以減少藥材使用量，降低成本，節省天然藥物資源，並使其能配合傳統醫藥之現代化及國際化。

關鍵字

菟絲子；抗氧化；保肝；奈米

並列摘要

The seed of Cuscuta chinensis Lam. (Convolvulaceae), a common traditional Chinese herb, has been used for centuries in the practice of medicated diet and dietetic therapy. Previous studies have indicated that C. chinensis possesses some pharmacological actvities. However, the antioxidant activity and hepatoprotective effect of C. chinensis have not yet been reported. The antioxidant activities were determined by several in vitro antioxidant activity assays, and also quantitated and characterized the flavonols in the different extracts and organic fractions from the seeds of C. chinensis. Moreover, as oxidative stress promotes the development of acetaminophen (APAP)-induced hepatotoxicity, I also evaluated and compared in vivo the hepatoprotective effects and antioxidant activities of the water (CH) and ethanol extract (CE) of C. chinensis on APAP-induced hepatotoxicity in rats. The results showed that the antioxidant activities of CE was more potent than CH, and a direct correlation between the flavonol content and the antioxidant activities from the extracts and fractions of C. chinensis was observed. In addition, the C. chinensis ethanol extract displayed a significant hepatoprotective effect by reducing levels of liver function index, increasing levels of antioxidant enzymes, and reducing lipid peroxidation. In contrast, CH did not exhibit any hepatoprotective effects that are seen in the CE. Furthermore, in recent years, the more efficient use of herbal medicine has helped to decrease the amount of herb material used and aid in coping with the resource restriction of traditional Chinese herb. Novel pharmaceutical technologies for drug preparation such as nanoparticle formulations are invented to increase drug efficacy, its bioavailability, and decrease the amount of material use. Due to the poor water solubility of CE, its absorption upon oral administration could be limited. Nanonization is one of the methods for drug size reduction which can improve the bioavailability of CE, as confirmed by these results. Indeed, an oral dose of C. chinensis nanoparticles that is 5 times as less as the CE was observed to exhibit similar hepatoprotective and antioxidant effects. In conclusion, the study report here for the first time novel therapeutic effects for C. chinensis, including its antioxidant and hepatoprotective activities. The study has also demonstrated for the first time that the use of C. chinensis nanoparticles can help decrease the dosage of CE while achieving the same level of effects. The nanonization of the drug which enhances the drug efficacy would translate to decreased cost and waste of herbal material. Accordingly, the study suggests modernization and potential international development in the application of herbal medicine.