Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Biyolojik Bilimler Bölümü, Türkiye
Tezin Onay Tarihi: 2015
Öğrenci: TÛBA ÇULCU
Danışman: ORHAN ADALI
Özet:Plants include many phenolic and polyphenolic compounds that are important in medicine, cosmetics and nutrition. Viscum album L. is a bi-perennial shrub and an evergreen semi-parasitic plant widely distributed in Europe. Epilobium hirsutum L., great willow-herb, grows in Eurasia, North Africa, Europe, Southern Australia and United States. Due to having a huge phenolic profiles, Viscum album L. and Epilobium hirsutum L. have many different biological functions including anti-tumor, anti-oxidant and anti-cancer. Thus, Viscum album L. and Epilobium hirsutum L. have been used traditionally for prevention and treatment of some diseases since the throughout the history of human. In mammals, excessive cholesterol is removed mainly through conversion to bile acids and cytochromes P450s initiate all quantitatively significant pathways of cholesterol metabolism and bile acid biosynthesis. The bile acid pathway is very important in maintaining normal cholesterol levels. There are two pathways namely the classical pathway and the acidic pathway involved in bile acid synthesis catalyzed by CYP7A1 and CYP27A1, respectively. These two pathways produce cholic acid (CA) and chenodeoxycholic acid (CDCA) roughly equal by CYP8B1 and CYP7B1. This study is the first about the possible potency of medicinal plants Viscum album L. and Epilobium hirsutum L. extracts and their major polyphenolic ingredients, o-coumaric acid and ellagic acid on rat liver cholesterol and bile acid metabolizing enzymes. In addition to molecular studies, bioactive compounds of Viscum album L. and Epilobium hirsutum L.extracts were identified using Liquid Chromatograph-Mass Spectrometry (LC-MS) technique. The water extracts of Viscum album L., Epilobium hirsutum L, o-coumaric acid and ellagic acid were injected intraperitoneally as 10 mg/kg, 37.5 mg/kg, 30 mg/kg and 20 mg/kg for 9 days, respectively. Then, in vivo effects of these plants and their major phenolic ingredients on rat liver cholesterol and bile acid metabolizing CYPs were analyzed by determining protein and mRNA expression levels using western blotting and qRT-PCR techniques, respectively. The results showed that Viscum album L. caused a 0.9 fold decrease in protein expression of CYP7A1 and CYP7B1, but 1.4 and 1.3 fold increases in protein expression of CYP27A1 and CYP8B1, respectively. Viscum album L. caused 9, 1.3 and 2.4 fold decrease in mRNA expression of CYP7A1, CYP27A1, CYP7B1, respectively, however, 4.2 fold increase in mRNA expression of CYP8B1. Injection of o-coumaric acid to ratsresulted 0.8 fold decrease in protein expression of CYP7A1, CYP27A1, CYP8B1 and CYP7B1. However, o-coumaric acid caused 1.8, 1.3, 2.3 and 2.3 fold increase in mRNA expression of CYP7A1, CYP27A1, CYP8B1 and CYP7B1, respectively. Epilobium hirsutum L. caused 0.6, 0.8 and 0.6 fold decrease in protein expression of CYP7A1, CYP8B1 and CYP7B1, respectively, whereas 1.3 fold increase in protein expression of CYP27A1. Epilobium hirsutum L. caused 2.1, 1.4 and 4.1 fold decrease in mRNA expression of CYP7A1, CYP27A1, CYP7B1, respectively, however, 2.3 fold increase in mRNA expression of CYP8B1. Injection of ellagic acid to rats resulted 0.7, 0.8 and 0.8 fold decrease in protein expression of CYP27A1, CYP8B1, CYP7B1, respectively, but one fold increase of protein expression of CYP7A1. Ellagic acid caused 2.6, 1.7, 1.8 and 2.3 fold increase in mRNA expression of CYP7A1, CYP27A1, CYP8B1 and CYP7B1, respectively. In addition, the CYP7A1 enzyme activity was determined by an Isocratic High-Performance Liquid Chromatography Assay using a calibration curve obtained by different cholesterol concentrations. According to these results, even though Viscum album L. and o-coumaric acid caused fold change in protein and mRNA expressions of bile acid metabolizing CYPs, serum cholesterol levels remained unchanged. Epilobium hirsutumL.and ellagic acid-treated animals showed a significant decrease in total cholesterol level compared to control animals. Therefore, bases on doses and time point that applied in this study, the medicinal plant Epilobium hirsutum L. and its polyphenolic compound, ellagic acid, may have regulatory effects on bile acid metabolizing enzymes. In conclusion, the synthesis of bile acids from cholesterol by CYP-catalyzed reactions may be altered due to the changes in CYP protein and mRNA expressions which may be resulted by the treatment of animals with Epilobium hirsutum L. and ellagic acid.