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Nephropathy and tumour development caused by plant alkaloids aristolochic acid
Bárta, František ; Stiborová, Marie (advisor) ; Šácha, Pavel (referee)
Aristolochic acids (AA) are alkaloids contained in plant species of the family Aristolochiaceae. These plants are used since antiquity in traditional medicine to treatment of many varied diseases. There are known anti-inflammatory effects of these compounds, however these alkaloids exhibit mutagenic and carcinogenic properties. Despite of this fact, plant extracts AA are still used in traditional medicine, e.g. in China, India, Taiwan. Aristolochic acids are proven to be the cause of disease designated Aristolochic Acid Nephropathy (AAN, theretofore known as Chinese Herbs Nephropathy (CHN). This unusual nephropathy leads to a total renal failure. The late complication of this disease is the development of tumours in urothelial tissue of patients. AA can form persistent stable covalent DNA adducts. Formation of these DNA adducts lead to AT→TA transversion, the unique mutation in tumour suppressor gene p53 responsible for tumour formation. Balkan Endemic Nephropathy (BEN) is associated with AA, too. In this instance is supported also influence of another factors, e.g. mycotoxins (ochratoxin A). However, in all probability AA contribute to a development of this disease particularly. This hypothesis is supported by finding of AA-DNA adducts in tissues of patients suffering from AAN and BEN and that of...
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Study of metabolism carcinogenic and nephrotoxic natural compound aristolochic acid II
Martináková, Lenka ; Stiborová, Marie (advisor) ; Moserová, Michaela (referee)
Aristolochic acids (AA) have been considered as toxicants of plants which were found in plants of the family Aristolochiaceae. The most abundant acids in mentioned plants are aristolochic acid I (AAI) and aristolochic acid II (AAII). AA have been considered as causes kidney disease called Aristolochic acid nephropathy (AAN). AAN was initially discovered in patients of one Belgian clinic in Brussels specialized on treatment of patients leading to a decrease in their body weight. The first name of this disease was Chinese herb nephropathy (CHN). Later, it was discovered that one component of herbal preparation was changed by a mistake with the Aristolochiaceae plant. The second type of renal disease caused by AA was discovered in populations of countries along the Danube river, called as Balkan endemic nephropathy (BEN), which was probably caused by the contamination of grains with plants containing AA. These renal diseases (AAN and BEN) are often associated with development of upper urothelial cancer (UUC). AA (AAI + AAII) in organisms are subject to biotransformation leading to its reductive activation or oxidative detoxification. Both cytosolic enzymes [NAD(P)H:quinone oxidoreductase] and microsomal enzymes [cytochromes P450, NADPH:cytochrome P450 reductase] participate in their reduction. The...
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Plant alkaloids and their effects on enzymes metabolizing xenobiotics
Višněvská, Kateřina ; Stiborová, Marie (advisor) ; Černá, Věra (referee)
Sanguinarine and chelerythrine are quaternary benzo[c]phenanthridine alkaloids. The first step in sanguinarine metabolism is its reduction to dihydrosanguinarin. Antimicrobial and anti-inflammatory activities of these alkaloids are used in dentistry and as feed additives. Sanguinarine and chelerythrine induce apoptosis of cells. Fluorescence of these alkaloids and intercalation into DNA could be utilized to use the alkaloids as supravital DNA probe. Negative effect of sanguinarine and chelerythrine is their genotoxicity. Cytochrome P450 and peroxidase oxidize ellipticine to detoxication and activation metabolites. Ellipticine is a potent antineoplastic agent exhibiting the multimodal mechanism of its action. Ellipticine intercalates into DNA and inhibits topoisomerase II. Covalent DNA aducts are mediated by CYP or peroxidase oxidation of ellipticine. The anti-tumor activity of ellipticine and its derivatives is caused by a combination mechanism of cell cycle arrest and induction of the apoptotic pathway. Pharmacological efficiencies and geneotoxic side effects of ellipticine is dependent on levels and activities of cytochrome P450 or peroxidase in target tissues. Aristolactams are the major metabolites of biotransformation of aristolochic acid. Nitroreduction is the crucial step in formation of an...
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Nephropathy and tumour development caused by plant alkaloids aristolochic acid
Bárta, František ; Šácha, Pavel (referee) ; Stiborová, Marie (advisor)
Aristolochic acids (AA) are alkaloids contained in plant species of the family Aristolochiaceae. These plants are used since antiquity in traditional medicine to treatment of many varied diseases. There are known anti-inflammatory effects of these compounds, however these alkaloids exhibit mutagenic and carcinogenic properties. Despite of this fact, plant extracts AA are still used in traditional medicine, e.g. in China, India, Taiwan. Aristolochic acids are proven to be the cause of disease designated Aristolochic Acid Nephropathy (AAN, theretofore known as Chinese Herbs Nephropathy (CHN). This unusual nephropathy leads to a total renal failure. The late complication of this disease is the development of tumours in urothelial tissue of patients. AA can form persistent stable covalent DNA adducts. Formation of these DNA adducts lead to AT→TA transversion, the unique mutation in tumour suppressor gene p53 responsible for tumour formation. Balkan Endemic Nephropathy (BEN) is associated with AA, too. In this instance is supported also influence of another factors, e.g. mycotoxins (ochratoxin A). However, in all probability AA contribute to a development of this disease particularly. This hypothesis is supported by finding of AA-DNA adducts in tissues of patients suffering from AAN and BEN and that of...
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