Aristolochic acid

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Aristolochic acid I
Aristolochic acid.png
Aristolochic acid molecule
Names
IUPAC name
8-Methoxy-6-nitrophenanthro[3,4-d][1,3]dioxole-5-carboxylic acid
Other names
Aristinic acid; Aristolochia yellow; Aristolochic acid A; Aristolochin;Aristolochine; Descresept; Tardolyt;TR 1736
Identifiers
313-67-7 YesY
ChEMBL ChEMBL93353 YesY
ChemSpider 2149 YesY
Jmol-3D images Image
KEGG C08469 YesY
PubChem 2236
Properties
C17H11NO7
Molar mass 341.28 g·mol−1
Appearance yellow powder
Melting point 260 to 265 °C (500 to 509 °F; 533 to 538 K)
Slightly soluble
Hazards
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 YesY verify (what isYesY/N?)
Infobox references

Aristolochic acids are a family of carcinogenic, mutagenic, and nephrotoxic compounds commonly found in the Birthwort (Aristolochiaceae) family of plants. Aristolochic acid (AA) I is the most abundant of the aristolochic acids.[1] The Aristolochiaceae family includes the Aristolochia genus and the Asarum (wild ginger) genus, which are commonly used in Chinese herbal medicine.[2][3] Although these compounds are widely associated with kidney problems and urothelial cancers, the use of AA-containing plants for medicinal purposes has a long history, and there is controversy regarding their toxicity. Nevertheless, the FDA has issued warnings regarding consumption of AA-containing supplements.

History[edit]

Early medical uses[edit]

Aristolochic acid first appeared in Chinese medicine in the 5th century AD, however the Birthwort plants in which it is found are mentioned in ancient Greek and Roman medical texts dating back even earlier. In these ancient times, it was used to treat kidney and urinary problems, as well as gout, snakebites, and a variety of other ailments. It was also considered to be an effective contraceptive. In many of these cases, Birthwort plants, and the aristolochic acids they contain, were just some of the many ingredients used to create ointments or salves. In the early 1st century, in Roman texts, aristolochic acids are first mentioned as a component of frequently ingested medicines to treat things such as asthma, hiccups, spasms, pains, and expulsion of afterbirth.[4]

Discovery of toxicity[edit]

Aristolochic acid poisoning was first diagnosed at a clinic in Brussels, Belgium, when cases of nephritis leading to rapid kidney failure were seen in a group of women who had all taken the same weight-loss suplement, Aristolochia fangchi, which contained aristolochic acid. This nephritis was termed “Chinese Herbs Nephropathy” (CHN) due to the origin of the weight-loss supplement.[5] It was later discovered that a similar condition previously known as Balkan endemic nephropathy (BEN), first characterized in the 1950’s in southeastern Europe, was also the result of aristolochic acid (AA) consumption. BEN is more slowly progressive than the nephritis that is seen in CHN, but is likely caused by low-level AA exposure, possibly from contamination of wheat flour seeds by a plant of the Birthwort family, Aristolochia clematitis.[6] CHN and BEN fall under the umbrella of what is now known as Aristolochic Acid Nephropathy (AAN), the prevalent symptom of AA poisoning.[5]

Aristolochia clematitis plant.
Aristolochia clematitis, the plant responsible for BEN.

Biosynthesis[edit]

The aristolochic acids are among a group of substituted 10-nitro-1-phenantropic acids, biogenetically derived from benzylisoquinoline precursors, which in turn originate from tyrosine.[7] The biosynthesis of aristolochic acid therefore begins at tyrosine (2), which is converted to L-DOPA (3). DOPA is subsequently converted into dopamine (4) and further converstion of dopamine into 3,4-dihydroxyphenylacetaldehyde (5) results in the formation of norlaudanosoline (6) via a spontaneous Pictet-Spengler condensation of the two molecules.[8] Evidence of these precursors was confirmed by 14C experiments where labeled compounds were administered to Aristolochia sipho and aristolochic acid was successfully extracted. Modification of norlaudanosoline is continued with a methylation of two alcohol groups to give orientaline (7). Orientaline undergoes a cyclization event to give the addition of the 5-membered ring into orientalinol (8), subsequently undergoing a methyl shift and aromatization event (9) to yield prestephanine (10).[9] The final steps are the formation of stephanine (11) and the addition of a carboxylate to yield aristolochic acid (12). Comer et al. originally proposed a postulated pathway from norlaudanosoline to aristolochic acid in 1968 very similar to the described pathway but Sharma et al. confirmed the presence of the intermediate compounds via DL-[3-14C] tyrosine trapping experiments in Aristolochia bracteata in 1982. After the general backbone of aristolochic acid is synthesized, post-synthetic modifications are performed; for example, aromatization of one of the rings yields aristolochic acid I as seen at the top of the page.

Biosynthetic pathway of Aristolochic acid

Symptoms and diagnosis[edit]

Exposure to aristolochic acid is associated with a high incidence of uroepithelial tumorigenesis,[10] and is linked to urothelial cancer.[11][12] Since aristolochic acid is a mutagen, it does damage over time. Patients are often first diagnosed with aristolochic acid nephropathy (AAN), which is a rapidly progressive nephropathy and puts them at risk for renal failure and urothelial cancer. However, urothelial cancer is only observed long after consumption. One study estimates that it takes on average ten years from the start of daily aristolochic acid consumption for detectable cancer to develop.[5]

If a patient is thought to have AAN, this can be confirmed through phytochemical analysis of plant products consumed and detection of aristolochic acid DNA adducts in the renal cells. Additionally, mutated proteins in renal cancers as a result of transversion of A:T pairings to T:A are characteristically seen in aristolochic acid-induced mutations. In some cases, early detection resulting in cessation of aristolochia-product consumption can lead to reverse of the kidney damage.[6][13]

Pharmacology[edit]

ADME[edit]

Absorption[edit]

Once orally ingested, aristolochic acid I is absorbed through the gastrointestinal track into the blood stream.[6]

Distribution[edit]

It is distributed throughout the body via the blood stream.[6]

Metabolism[edit]

Aristolochic acids are metabolized by oxidation and reduction pathways, or phase I metabolism. Reduction of aristolochic acid I produces aristolactam I which has been observed in the urine. Further processing of aristolactam I by O-demethylation results in aristolactam Ia, the primary metabolite.[6][14] Additionally, nitroreduction results in an N-acylnitrenium ion, which can form DNA-base adducts, thus giving aristolochic acid I its mutagenic properties.[5][6][14]

Excretion[edit]

Excretion of aristolochic acids and their metabolites is through the urine.[6]

Mechanism of action[edit]

The exact mechanism of action of aristolochic acid is not known, especially in regards to nephropathy. It is thought that the carcinogenic effects of aristolochic acids are a result of mutation of the tumor supressor gene TP53, which seems to be unique to aristolochic acid associated carcinogenesis.[13] Nephropathy caused by aristolochic acid consumption is not mechanistically understood, however DNA adducts characteristic of aristolochic acid induced mutations are found in the kidneys of aristolochic acid nephropathy (AAN) patients, indicating that these might play a role.[13]

Regulation[edit]

In April 2001, the Food and Drug Administration issued a consumer health alert warning against consuming botanical products, sold as "traditional medicines" or as ingredients in dietary supplements, containing aristolochic acid.[15] The agency warned that consumption of aristolochic acid-containing products was associated with "permanent kidney damage, sometimes resulting in kidney failure that has required kidney dialysis or kidney transplantation. In addition, some patients have developed certain types of cancers, most often occurring in the urinary tract."[15]

In August 2013, two studies identified an aristolochic acid mutational signature in upper urinary tract cancer patients from Taiwan.[16][17] The carcinogenic effect is the most potent found thus far, exceeding the amount of mutations in smoking-induced lung cancer and UV-exposed melanoma. Exposure to aristolochic acid may also cause certain types of liver cancer.[16]

Controversy[edit]

Due to the prevalence of aristolochic acid containing plants in Chinese herbal medicine, there is some controversy regarding the toxicity of these compounds. Much of this debate centers on the cause of the renal failure observed in weight-loss supplement consumers in Belgium. Although, aristolochic acid was originally cited as the cause of nephritis, proponents of Chinese herbal medicine argue that renal failure is generally prevalent in Belgium, and that the patients were on a variety of drugs.[18] Although a variety of animal studies have shown proof of toxicity in the form of nephritis and urothelial cancers,[6] and these studies have been confirmed in human urothelial and renal carcinoma as well.[19][20][21]

See also[edit]

References[edit]

  1. ^ Wu, Tian-Shung et al. (2005). "Chemical constituents and pharmacology of Aristolochia species". In Rahman, Atta-ur. Studies in Natural Products Chemistry: Bioactive Natural Products (Part L). Gulf Professional Publishing. p. 863. ISBN 978-0-444-52171-2. 
  2. ^ Heinrich M, Chan J, Wanke S, Neinhuis C, Simmonds MS (August 2009). "Local uses of Aristolochia species and content of nephrotoxic aristolochic acid 1 and 2--a global assessment based on bibliographic sources". J Ethnopharmacol 125 (1): 108–44. doi:10.1016/j.jep.2009.05.028. PMID 19505558. 
  3. ^ Nolin, Thomas D. & Himmelfarb, Jonathan (2010). "Mechanisms of drug-induced nephrotoxicity". In Uetrecht, Jack. Adverse Drug Reactions. Springer. p. 123. ISBN 978-3-642-00662-3. 
  4. ^ Scarborough, John (2011). "Ancient Medicinal Use of Aristolochia: Birthwort’s Tradition and Toxicity". Pharmacy in History 53 (1): 3–21. Retrieved 3 May 2015. 
  5. ^ a b c d Arlt, Volker; Stiborova, Marie; Schmeiser, Heinz (2002). "Aristolochic acid as a probable human cancer hazard in herbal remedies: a review". Mutagenesis 17 (4): 265–277. doi:10.1093/mutage/17.4.265. 
  6. ^ a b c d e f g h Lunn, Ruth; Jameson, C.W.; Jahnke, Gloria (2 Sep 2008). "Report on Carcinogens Background Document for Aristolochic Acids" (PDF). National Toxicology Program. Retrieved 3 May 2015. 
  7. ^ Comer, F.; Tiwari, H.P.; Spenser, I.D. (1969), "Biosynthesis of aristolochic acid", Canadian Journal of Chemistry 47 (3): 481–487, doi:10.1139/v69-070 
  8. ^ Hoover, Larry K.; Moo-young, Murray; Legge, Raymond L. (1991), "Biotransformation of Dopamine to Norlaudanosoline by Aspergillus niger", Biotechnology and Bioengineering 38 (9): 1029–1033, doi:10.1002/bit.260380911 
  9. ^ Sharma, Vidur; Jain, Sudha; Bhakuni, Dewan S.; Kapil, Randhir S. (1982), "Biosynthesis of aristolochic acid", Journal of the Chemical Society, Perkin Transcations 1 1 (0): 1153–1155, doi:10.1039/p19820001153 
  10. ^ Ronco, Claudio et al., ed. (2008). Critical care nephrology. Elsevier Health Sciences. p. 1699. ISBN 978-1-4160-4252-5. 
  11. ^ Chen CH, Dickman KG, Moriya M, Zavadil J, Sidorenko VS, Edwards KL, Gnatenko DV, Wu L, Turesky RJ, Wu XR, Pu YS, Grollman AP (May 2012). "Aristolochic acid-associated urothelial cancer in Taiwan". Proc. Natl. Acad. Sci. U.S.A. 109 (21): 8241–6. doi:10.1073/pnas.1119920109. PMC 3361449. PMID 22493262. 
  12. ^ Lai, M.-N.; Wang, S.-M.; Chen, P.-C.; Chen, Y.-Y.; Wang, J.-D. (2009). "Population-Based Case-Control Study of Chinese Herbal Products Containing Aristolochic Acid and Urinary Tract Cancer Risk". JNCI Journal of the National Cancer Institute 102 (3): 179. doi:10.1093/jnci/djp467. 
  13. ^ a b c Go¨kmen, M. Refik; Cosyns, Jean-Pierre; Arlt, Volker M.; Stiborova, Marie; Phillips, David H.; Schmeiser, Heinz H.; Simmonds, Monique S.J.; Cook, Terence; Vanherweghem, Jean-Louis; Nortier, Joe¨lle L.; Lord, Graham M. (2013). "The Epidemiology, Diagnosis, and Management of Aristolochic Acid Nephropathy: A Narrative Review" (PDF). Annals of Internal Medicine 158 (6): 469–477. Retrieved 3 May 2015. 
  14. ^ a b "Plants Containing Aristolochic Acid" (PDF). IARC Monographs-100A: 347–361. Retrieved 3 May 2015. 
  15. ^ a b FDA Warns Consumers to Discontinue Use of Botanical Products that Contain Aristolochic acid. April 11, 2001.
  16. ^ a b Poon, S. L.; Pang, S.-T.; McPherson, J. R.; Yu, W.; Huang, K. K.; Guan, P.; Weng, W.-H.; Siew, E. Y.; Liu, Y. (2013). "Genome-Wide Mutational Signatures of Aristolochic Acid and Its Application as a Screening Tool". Science Translational Medicine 5 (197): 197ra101. doi:10.1126/scitranslmed.3006086. PMID 23926199. 
  17. ^ Hoang, M. L.; Chen, C.-H.; Sidorenko, V. S.; He, J.; Dickman, K. G.; Yun, B. H.; Moriya, M.; Niknafs, N.; Douville, C. (2013). "Mutational Signature of Aristolochic Acid Exposure as Revealed by Whole-Exome Sequencing". Science Translational Medicine 5 (197): 197ra102. doi:10.1126/scitranslmed.3006200. PMID 23926200. 
  18. ^ Dharmananda, Subhuti. "Are Aristolochia Plants Dangerous?". ITM. Institute for Traditional Medicine. Retrieved 3 May 2015. 
  19. ^ http://www.nature.com/ncomms/2014/141029/ncomms6135/full/ncomms6135.html
  20. ^ http://stm.sciencemag.org/content/5/197/197ra102
  21. ^ http://stm.sciencemag.org/content/5/197/197ra101

Further reading[edit]

External links[edit]