Document Details Document Type : Thesis  Document Title : Toxicological studies of some lichen acids on mouse-liver mitochonria دراسات سمية لبعض الأحماض الأشنية علي ميتوكوندريا كبد الفأر   Subject : Biological  Document Language : Arabic  Abstract : Three lichen acids, namely (+ )usnic acid (USN), vulpinic acid (VUL) and atra- norin (A TR) were isolated from three lichen species: Usnea a11iculata, Letharia vulpina and Parmelia tinctorzun , respectively. - The extraction, purification and chemical identification of these three lichen acids has been worked-out and the median lethal dose (ill 50) of U. a11iculata dry chloro- form extract (F)CE), dry ethanol extract (DEE) and pure (+)usnic acid (USN) to mice (s.c.) was determined. According to the classification of chemicals in relation to their relative toxicities both DCE and USN are considered to be among the highly toxic compounds. How- ever, no toxic effect was recorded for the DEE. The interesting common properties shared by the three lichen acids used in this study render them potentially active as membrane disruptors in biological systems. I These lichen products exhibited characteristic uncoupling activity to mouseliver mito- chondria similar to that produced by the classical uncoupler 2,4-dinitro-phenol (DNP). , They released respiratory control, hindered A TP synthesis, stimulated state~4 respiration (in the absence of ADP) and enhanced significantly ATPase activity. A TR was the only lichen acid with no effect on ATPase. The minimal concentrations requir- ed to cause complete uncoupling of oxidative phosphorylation were as follows: USN (1 microM), VUL (5 microM), ATR (5 microM) and DNP (50 microM). The uncoup- ling effect was dose-dependent in the three cases. In vivo studies using usnic acid-treated mice (injection s.c.) with a lethal dose (200 mg/kg) showed also significant uncoupling effects. It is postulated that the three lichen acids induce mitochondrial uncoupling by I acting on the inner mitochondrial membrane through their lipophilic properties and protonophoric activities.  Supervisor : Dr. Ahmed Nabil Abo Khatwa  Thesis Type : Master Thesis  Publishing Year : 1416 AH 1995 AD  Co-Supervisor : Prof. Ali Ahmed Alrobai  Added Date : Thursday, June 12, 2008  Researchers Researcher Name (Arabic) Researcher Name (English) Researcher Type Dr Grade Email دينا عبدالعزيز الجوهري Al-Jawhari, Dina Abdulaziz Researcher Master   Files File Name Type Description  24042.pdf pdf    24044.pdf pdf   Back To Researches Page