Heterocyclic amine
Heterocyclic amines,also sometimes referred to asHCAs, are chemical compounds containing at least oneheterocyclicring, which by definition has atoms of at least two different elements, as well as at least oneamine(nitrogen-containing) group. Typically it is a nitrogen atom of an amine group that also makes the ring heterocyclic (e.g.,pyridine), though compounds exist in which this is not the case (e.g., the drugZileuton). The biological functions of heterocyclic amines vary, includingvitaminsandcarcinogens.Carcinogenic heterocyclic amines are created by high temperature cooking of meat and smoking of plant matter liketobacco.Some well known heterocyclic amines areniacin(vitamin B3), nicotine (psychoactive alkaloid and recreational drug), and thenucleobasesthat encode genetic information in DNA.
Five-membered heterocyclic amines
[edit]The compoundpyrrolidineis composed of molecules that contain a saturated ring of five atoms. This cyclic structure is composed of one atom of nitrogen and four carbon. Nicotineis a molecule containing a pyrrolidine ring attached to a ring of pyridine (other heterocyclic amine). Nicotine belongs to a group of compounds known asalkaloids,which are naturally occurring organic compounds with nitrogen in them. Pyrroleis another compound made up of molecules with a five-membered heterocyclic ring. These molecules are unsaturated and contain a nitrogen atom in the ring. Four pyrrole rings are joined in a ring structure called aporphyrin. The rings ofporphyrinare components ofhemoglobin,myoglobin,vitamin B12,chlorophyll,andcytochromes.In the centers ofhemein hemoglobin, myoglobin, and cytochromes, iron is an ion; in the first two, iron ion is bound to oxygen.
Six-membered heterocyclic amines
[edit]The structure ofpyridineis similar to that ofbenzeneexcept that a nitrogen atom replaces one carbon atom. Pyridine is used as a flavoring agent. The pyridine ring is part of two B vitamins:niacinandpyridoxine. Niacin, also called nicotinic acid, is found in most organisms. Via metabolism, it becomes nicotinamide adenine dinucleotide NAD, acoenzymewhich is involved in oxidation and reduction in metabolic cells. A deficiency of niacin leads to a disease calledpellagra. Pyridoxine or vitamin B6, it becomes a major compound in the metabolism ofamino acids.
Pyrimidineis a heterocyclic amine that contains two nitrogen atoms in an unsaturated six-membered ring. An example of a molecule that contains pyrimidine isthiamine,which is also known as vitamin B1. Thiamine deficiency producesberiberi. Pyrimidine is a component of thenucleobasescytosine, uracil, and thymine. The other two nucleobases,adenineandguanine,are also heterocyclic amines calledpurines;they are composed of a fused pyrimidine andimidazole.
Heterocyclic amines and cancer
[edit]
Some heterocyclic amines (HCAs) found in cooked and especially burned meat are knowncarcinogens.Research has shown thatheterocyclic amine formation in meatoccurs at high cooking temperatures.[1]Heterocyclic amines are the carcinogenic chemicals formed from the cooking of muscle meats such asbeef,lamb,pork,fish and poultry.[1][2]HCAs form whenamino acidsandcreatine(a chemical found in muscles) react at high cooking temperatures.[1]
Colorectal canceris associated with high intakes of HCAs found in meat cooked at high temperature.[3]
Heterocyclic amines and neurological disorders
[edit]Harmane,a β-carboline alkaloid found in meats is "highly tremorogenic" (tremor inducing).[4][5]While harmane has been found in roughly 50% higher concentrations in patients withessential tremorthan in controls,[6]there is no direct correlation between blood-levels and levels of daily meat consumption, suggesting a difference in metabolism of this chemical plays a greater role.[5]These chemicals are formed during the cooking process of meat, particularly the longer they are cooked, and the more they are exposed to high temperatures during cooking.[7][8]
Marinades
[edit]Six hours of marinating in beer or red wine cut levels of two types of HCA in beef steak by up to 90% compared with unmarinated steak.[9]
See also
[edit]References
[edit]- ^abc"National Cancer Institute – Heterocyclic Amines in Cooked Meats".Cancer.gov. September 15, 2004.Archivedfrom the original on December 21, 2010.RetrievedMay 1,2010.
- ^"Does eating processed and red meat cause cancer?".cancerresearchuk.org. Retrieved 14 December 2022.
- ^"Risk factors for colorectal cancer".Canadian Cancer Society.Retrieved7 March2024.
- ^Guan Y, Louis ED, Zheng W (December 2001)."Toxicokinetics of tremorogenic natural products, harmane and harmine, in male Sprague-Dawley rats".Journal of Toxicology and Environmental Health, Part A.64(8): 645–60.Bibcode:2001JTEHA..64..645G.doi:10.1080/152873901753246241.PMC4992346.PMID11766171.
- ^abLouis ED, Zheng W, Applegate L, Shi L, Factor-Litvak P (August 2005)."Blood harmane concentrations and dietary protein consumption in essential tremor".Neurology.65(3): 391–6.doi:10.1212/01.wnl.0000172352.88359.2d.PMC4993192.PMID16087903.
- ^Louis ED, Jiang W, Pellegrino KM, et al. (March 2008)."Elevated blood harmane (1-methyl-9H-pyrido[3,4-b]indole) concentrations in essential tremor".Neurotoxicology.29(2): 294–300.doi:10.1016/j.neuro.2007.12.001.PMC2291546.PMID18242711.
- ^Chemicals in Meat Cooked at High Temperatures and Cancer Risk: NCI (accessed 13 February 2011).
- ^Louis ED, Zheng W, Jiang W, Bogen KT, Keating GA (June 2007)."Quantification of the neurotoxic beta-carboline harmane in barbecued/grilled meat samples and correlation with level of doneness".Journal of Toxicology and Environmental Health, Part A.70(12): 1014–9.Bibcode:2007JTEHA..70.1014L.doi:10.1080/15287390601172015.PMC4993204.PMID17497412.
- ^Melo A, Viegas O, Petisca C, Pinho O, Ferreira IM (November 2008). "Effect of beer/red wine marinades on the formation of heterocyclic aromatic amines in pan-fried beef".Journal of Agricultural and Food Chemistry.56(22): 10625–32.doi:10.1021/jf801837s.PMID18950185.
External links
[edit]- Sugimura T, Nagao M, Wakabayashi K (May 1996)."Carcinogenicity of food mutagens".Environmental Health Perspectives.104(Suppl 3): 429–33.doi:10.2307/3432798.JSTOR3432798.PMC1469643.PMID8781358.
- Louis ED, Zheng W, Jiang W, Bogen KT, Keating GA (June 2007)."Quantification of the neurotoxic beta-carboline harmane in barbecued/grilled meat samples and correlation with level of doneness".Journal of Toxicology and Environmental Health, Part A.70(12): 1014–9.Bibcode:2007JTEHA..70.1014L.doi:10.1080/15287390601172015.PMC4993204.PMID17497412.