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stršljen · 27.03.2007., 00:42

Amygdalin
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Chemical structure of Amygdalin
Chemical structure of Amygdalin

Amygdalin (from Greek: ἀμυγδάλη, almond), C20H27NO11, is a glycoside isolated from bitter almonds by H. E. Robiquet and A. F. Boutron-Charlard in 1830, and subsequently investigated by Liebig and Wöhler, and others. Some sources claim Ernst T. Krebs was the discoverer of the substance, and Krebs is generally credited with popularizing it as a purported cancer cure and as "Vitamin B17."
Contents
[hide]

* 1 Chemistry
* 2 Nomenclature
* 3 Cancer cure
* 4 Famous case in history
* 5 Famous supporters of amygdalin
* 6 Amygdalin research
* 7 Government regulations
* 8 References
* 9 External links

[edit] Chemistry

Amygdalin is extracted from almond cake by boiling ethanol; on evaporation of the solution and the addition of diethyl ether, amygdalin is precipitated as white minute crystals. Sulfuric acid decomposes it into d-glucose, benzaldehyde, and prussic acid (hydrogen cyanide); while hydrochloric acid gives mandelic acid, d-glucose, and ammonia.[1]

The decomposition induced by enzymes may occur in two ways. Maltase partially decomposes it, giving d-glucose and mandelic nitrile glucoside, C6H5CH(CN)O·C6H11O5; this compound is isomeric with sambunigrin, a glucoside found by E.E. Bourquelot and Danjou in the berries of the common elder, Sambucus nigra. Emulsin, on the other hand, decomposes it into benzaldehyde, cyanide, and two molecules of glucose; this enzyme occurs in the bitter almond, and consequently the seeds invariably contain free cyanide and benzaldehyde. An "amorphous amygdalin" is said to occur in the cherry-laurel. Closely related to these glucosides is dhurrin, C14H17O7N, isolated by W. Dunstan and T. A. Henry from the common sorghum or "great millet," Sorghum vulgare; this substance is decomposed by emulsin or hydrochloric acid into d-glucose, cyanide, and p-hydroxybenzaldehyde.[citation needed]

[edit] Nomenclature

Amygdalin is also called laevomandelonitrile, or laetrile for short. This is a typical pharmaceutical abbreviation from laevomandelonitrile. Some claim that laetrile is derived from a Latin word meaning "joyfulness" as laetari is the Latin verb meaning "to rejoice or exult".[citation needed]

The National Cancer Institute explains that "the names Laetrile, laetrile, and amygdalin are often used in place of one another, but they are not the same product. The chemical make-up of Laetrile patented in the United States is different from the laetrile/amygdalin produced in Mexico. The patented laetrile is a partly synthetic (man-made) form of amygdalin, while the laetrile/amygdalin made in Mexico comes from crushed apricot pits." [2]

Though it is sometimes sold as "Vitamin B17", it is not a vitamin, as no disease is associated with a dietary deficiency of laetrile.

[edit] Cancer cure

Amygdalin has been advocated by some as a "cure" or a "preventative" for cancer, but due to a lack of scientifically accepted evidence of its efficacy, it has not been approved for this use by the United States' Food and Drug Administration.[2]

The US government's National Institutes of Health reports that two clinical trials with laetrile have been published. One Phase I study found that amygdalin caused minimal side effects; the side effects that were seen were similar to the symptoms of cyanide poisoning. One Phase II study with 175 patients had some patients reporting improvements in symptoms, but all patients showed cancer progression 7 months after completing treatment, and it was determined no further tests were necessary.

While no double-blind clinical trials may have been conducted, a clinical trial was carried out in 1982 by the Mayo Clinic [3] and three other U.S. cancer centers under NCI sponsorship. Laetrile and "metabolic therapy" were administered as recommended by their promoters to 178 patients with advanced cancer for which there was no proven treatment. None were cured or stabilized or had any improvement of cancer-related symptoms. The median survival rate was about five months. In survivors after seven months, tumor size had increased. Several patients suffered from cyanide poisoning.

In 1974, the American Cancer Society officially labelled laetrile as "quackery," but advocates for laetrile claim a conspiracy with regard to this label.[4] Pro-laetrile groups assert that financial motivations have tainted the published research. These advocates reason that a cure as cheap and plentiful as apricot kernels would not be welcomed by the pharmaceutical industry. So, even today, many American and Canadian cancer patients travel to Mexico for treatment with the substance, under the auspices of Dr. Ernesto Contreras. One of these patients was actor Steve McQueen, who died while undergoing treatment in Mexico after developing mesothelioma. Laetrile's foremost advocates within the United States can be found in all spectra of the political and science field from alternative newspapers like The Village Voice to individuals like the one-time chief chemist of the National Cancer Institute's cytochemistry laboratory[5], Dean Burk Ph.D.[6], and G. Edward Griffin, author of "The Discovery of Noah’s Ark".

While some people believe that cancer is related to such a lack of "B17," and thus that it can be used as cancer treatment, it has not been firmly established as medical fact. The lack of information and the self-medication of patients with amygdalin causes severe problems in cancer treatment.[7]

A review of the clinical evidence was published in 2006 with the conclusion "Therefore, the claim that laetrile has beneficial effects for cancer patients is not supported by sound clinical data."[8]

[edit] Famous case in history

Jason Vale was the nation's leading spokesman for the legalization of laetrile. He was a national arm wrestling champion after he was cured of kidney, pancreatic and spleen cancer, purportedly by eating apricot seeds. However, in 2004 he was convicted[9] of fraud and sentenced to 63 months in prison for his methods of marketing laetrile, for defrauding the U.S. government by claiming that he qualified for Legal Aid, and for criminal contempt. Representatives of the Memorial Sloan-Kettering Cancer Center testified on the side of the prosecution during Vale's criminal trial.

[edit] Famous supporters of amygdalin

Dr Dean Burk, biochemist with a Ph.D. from Cornell Medical College,[6] became Head of National Cancer Institute (NCI) Cytochemistry Section in 1937 and headed this department for over three decades. Andrew McNaughton of the McNaughton Foundation requested a scientific experiment by Dr. Burk of the (NCI), the results were a famous comment which was used in a G. Edward Griffin documentary "A World Without Cancer" [10] that “When we add "laetrile" (amygdaline) to a cancer culture under the microscope,” “providing the enzyme glucosidase also is present, we can see the cancer cells dying off like flies.” [11] He also claimed in Congressional testimony that laetrile was less toxic than sugar[12]. Dr Dean Burk then went on to become a life long supporter of laetrile / amygdaline as a Cancer prevention and cure.

27.03.2007., 00:42	#32
stršljen U samoizolaciji Registracija: Feb 2007. Postova: 272	Amygdalin From Wikipedia, the free encyclopedia (Redirected from Vitamin B17) Jump to: navigation, search This article may require cleanup to meet Wikipedia's quality standards. Please discuss this issue on the talk page or replace this tag with a more specific message. This article has been tagged since September 2006. Chemical structure of Amygdalin Chemical structure of Amygdalin Amygdalin (from Greek: ἀμυγδάλη, almond), C20H27NO11, is a glycoside isolated from bitter almonds by H. E. Robiquet and A. F. Boutron-Charlard in 1830, and subsequently investigated by Liebig and Wöhler, and others. Some sources claim Ernst T. Krebs was the discoverer of the substance, and Krebs is generally credited with popularizing it as a purported cancer cure and as "Vitamin B17." Contents [hide] * 1 Chemistry * 2 Nomenclature * 3 Cancer cure * 4 Famous case in history * 5 Famous supporters of amygdalin * 6 Amygdalin research * 7 Government regulations * 8 References * 9 External links [edit] Chemistry Amygdalin is extracted from almond cake by boiling ethanol; on evaporation of the solution and the addition of diethyl ether, amygdalin is precipitated as white minute crystals. Sulfuric acid decomposes it into d-glucose, benzaldehyde, and prussic acid (hydrogen cyanide); while hydrochloric acid gives mandelic acid, d-glucose, and ammonia.[1] The decomposition induced by enzymes may occur in two ways. Maltase partially decomposes it, giving d-glucose and mandelic nitrile glucoside, C6H5CH(CN)O·C6H11O5; this compound is isomeric with sambunigrin, a glucoside found by E.E. Bourquelot and Danjou in the berries of the common elder, Sambucus nigra. Emulsin, on the other hand, decomposes it into benzaldehyde, cyanide, and two molecules of glucose; this enzyme occurs in the bitter almond, and consequently the seeds invariably contain free cyanide and benzaldehyde. An "amorphous amygdalin" is said to occur in the cherry-laurel. Closely related to these glucosides is dhurrin, C14H17O7N, isolated by W. Dunstan and T. A. Henry from the common sorghum or "great millet," Sorghum vulgare; this substance is decomposed by emulsin or hydrochloric acid into d-glucose, cyanide, and p-hydroxybenzaldehyde.[citation needed] [edit] Nomenclature Amygdalin is also called laevomandelonitrile, or laetrile for short. This is a typical pharmaceutical abbreviation from laevomandelonitrile. Some claim that laetrile is derived from a Latin word meaning "joyfulness" as laetari is the Latin verb meaning "to rejoice or exult".[citation needed] The National Cancer Institute explains that "the names Laetrile, laetrile, and amygdalin are often used in place of one another, but they are not the same product. The chemical make-up of Laetrile patented in the United States is different from the laetrile/amygdalin produced in Mexico. The patented laetrile is a partly synthetic (man-made) form of amygdalin, while the laetrile/amygdalin made in Mexico comes from crushed apricot pits." [2] Though it is sometimes sold as "Vitamin B17", it is not a vitamin, as no disease is associated with a dietary deficiency of laetrile. [edit] Cancer cure Amygdalin has been advocated by some as a "cure" or a "preventative" for cancer, but due to a lack of scientifically accepted evidence of its efficacy, it has not been approved for this use by the United States' Food and Drug Administration.[2] The US government's National Institutes of Health reports that two clinical trials with laetrile have been published. One Phase I study found that amygdalin caused minimal side effects; the side effects that were seen were similar to the symptoms of cyanide poisoning. One Phase II study with 175 patients had some patients reporting improvements in symptoms, but all patients showed cancer progression 7 months after completing treatment, and it was determined no further tests were necessary. While no double-blind clinical trials may have been conducted, a clinical trial was carried out in 1982 by the Mayo Clinic [3] and three other U.S. cancer centers under NCI sponsorship. Laetrile and "metabolic therapy" were administered as recommended by their promoters to 178 patients with advanced cancer for which there was no proven treatment. None were cured or stabilized or had any improvement of cancer-related symptoms. The median survival rate was about five months. In survivors after seven months, tumor size had increased. Several patients suffered from cyanide poisoning. In 1974, the American Cancer Society officially labelled laetrile as "quackery," but advocates for laetrile claim a conspiracy with regard to this label.[4] Pro-laetrile groups assert that financial motivations have tainted the published research. These advocates reason that a cure as cheap and plentiful as apricot kernels would not be welcomed by the pharmaceutical industry. So, even today, many American and Canadian cancer patients travel to Mexico for treatment with the substance, under the auspices of Dr. Ernesto Contreras. One of these patients was actor Steve McQueen, who died while undergoing treatment in Mexico after developing mesothelioma. Laetrile's foremost advocates within the United States can be found in all spectra of the political and science field from alternative newspapers like The Village Voice to individuals like the one-time chief chemist of the National Cancer Institute's cytochemistry laboratory[5], Dean Burk Ph.D.[6], and G. Edward Griffin, author of "The Discovery of Noah’s Ark". While some people believe that cancer is related to such a lack of "B17," and thus that it can be used as cancer treatment, it has not been firmly established as medical fact. The lack of information and the self-medication of patients with amygdalin causes severe problems in cancer treatment.[7] A review of the clinical evidence was published in 2006 with the conclusion "Therefore, the claim that laetrile has beneficial effects for cancer patients is not supported by sound clinical data."[8] [edit] Famous case in history Jason Vale was the nation's leading spokesman for the legalization of laetrile. He was a national arm wrestling champion after he was cured of kidney, pancreatic and spleen cancer, purportedly by eating apricot seeds. However, in 2004 he was convicted[9] of fraud and sentenced to 63 months in prison for his methods of marketing laetrile, for defrauding the U.S. government by claiming that he qualified for Legal Aid, and for criminal contempt. Representatives of the Memorial Sloan-Kettering Cancer Center testified on the side of the prosecution during Vale's criminal trial. [edit] Famous supporters of amygdalin Dr Dean Burk, biochemist with a Ph.D. from Cornell Medical College,[6] became Head of National Cancer Institute (NCI) Cytochemistry Section in 1937 and headed this department for over three decades. Andrew McNaughton of the McNaughton Foundation requested a scientific experiment by Dr. Burk of the (NCI), the results were a famous comment which was used in a G. Edward Griffin documentary "A World Without Cancer" [10] that “When we add "laetrile" (amygdaline) to a cancer culture under the microscope,” “providing the enzyme glucosidase also is present, we can see the cancer cells dying off like flies.” [11] He also claimed in Congressional testimony that laetrile was less toxic than sugar[12]. Dr Dean Burk then went on to become a life long supporter of laetrile / amygdaline as a Cancer prevention and cure.