Cyanide Laetrile

Nitrile groups can be introduced into molecules by reacting potassium cyanide with alkyl halides. The organic nitrile group has quite different properties associated with lethal inorganic cyanide Laetrile, for example, is extracted from apricot kernels, and was once developed as an anticancer drug. It was later proposed that the name be spelt liar-trial since the results of the clinical trials on laetrile turned out to have been falsified ... 

Cyanide compounds have been prescribed by physicians for treatment of hypertension and cancer (Sprine et al. 1982). Sodium nitroprusside (Na2Fe(CN)5NO 2H20) was widely used for more than 30 years to treat severe hypertension and to minimize bleeding during surgery (Solomon-son 1981 Vesey 1987). Laetrile, an extract of ground apricot kernels, has been used for cancer chemotherapy and, in deliberate high intakes, as an attempted suicide vehicle (Gee 1987). 

Basu TK. 1983. High-dose ascorbic acid decreases detoxification of cyanide derived from amygdalin (laetrile) Studies in guinea pigs. Can J Physiol Pharmacol 61 1426-1430. 

N.A. Laetrile, cyanide, beta-carotene, thiamine, ascorbic acid, malic acid, citric acid, oligopeptides, polysaccharide.158-159 Internally for chronic coughs, externally for fungal skin infections, warts, improving blood fluidity, has immunochemical characterization. 

At one time amygdalin, sold as Laetrile, was promoted as a treatment for cancer, presumably based on the hope that the cancer cells would be poisoned by the released cyanide.1 The tubers and leaves of the cassava plant provide a major source of food in many tropical countries. However, unless the cyanogenic glycosides are removed by boiling the tubers and pulping the leaves cassava is... 

Benzaldehyde Cyanohydrin. This cyanohydrin, also known as mande-lonitrile, is a yellow, oily liquid, insoluble in water, but soluble in alcohol and dieihyl eiher. Mandcloniirile is a component of the glycoside amyg-daiin, a precursor of laetrile found in the leaves and seeds on most Prunus species (plum, peach, apricot, etc). It is commercially prepared from benzaldehyde and hydrogen cyanide. 

Laetrile, found in the seeds of apricots and bitter almonds, has considerable toxicity because it releases hydrogen cyanide on hydrolysis. It has been purported to be useful in the treatment of cancer, but controlled studies have shown no evidence of effectiveness. Show how hydrogen cyanide is produced on hydrolysis of laetrile. 

Hall, A.H., Linden, C.H., Kulig, K.W., Rumack, B.H. (1986). Cyanide poisoning from laetrile ingestion role of nitrite therapy. Pediatrics 78 269-72. 

This is perfectly understandable and many patients use unproven methods, including medicines (see complementary medicine). Innumerable methods are and have been offered for cancer. A prominent remedy was laetrile, a preparation of apricot seeds (pits, pips), which contains amygdalin (a p-glucoside) which incorporates cyanide. It was claimed to relieve pain, prolong survival and even to induce complete remission of cancer. Benefit was reputed to result from release of cyanide in the body which... 

A 67-year-old woman with lymphoma presented with a neuromyopathy following treatment with laetrile. She had high blood and urinary thiocyanate and cyanide concentrations (7). Sural nerve biopsy specimen showed a mixed pattern of demyelination and axonal degeneration, the latter being prominent. Gastrocnemius muscle biopsy specimen showed a mixed pattern of denervation and myopathy with type II atrophy. 

Kalyanaraman UP, Kalyanaraman K, CuUinan SA, McLean JM. Neuromyopathy of cyanide intoxication due to laetrile (amygdahn). A clinicopathologic study. Cancer 1983 51(ll) 2126-33. 

In addition, cyanides can be found in the seeds of the apple, peach, plum, apricot, cherry, and almond in the form of amygdatin, a cyanogenic glycoside. Amygdatin (Laetrile) has been used as an... 

Compounds that release cyanide spontaneously, by thermal decomposition, or by chemical reaction, such as cyanogen, cyanogen bromide, cyanogen chloride, calcium cyanide, acetonitrile, laetrile, amygdalin, lethane, thanate, sodium nitroprusside, cassava root... 

Even the controversial cyanic anticancer substance known as laetrile, or amygda-lin, is thought to be detoxified by a particular enzyme or enzymes in normal cells that is not ordinarily present, or in sufficient concentrations, in cancer cells. The answer is not clear-cut, however, and laetrile remains suspect, if effective at all. More than this, there are certain other food enzymes that may cause laetrile to give off deadly hydrogen cyanide or hydrocyanic acid, or HCN, itself an enzyme inhibitor that acts against bodily processes, notably respiration. (Deadly cyanide, incidentally, is listed as an inhibitor for tyrosinase, the enzyme involved in melanoma.)... 

It is emphasized in John Heinerman s The Treatment of Cancer with Herbs (1984) that although laetrile is sometimes viewed favorably as a cancer treatment, due to enzymatic action it can interact with some other foods to produce HCN internally and cause cyanide poisoning. Specifically forbidden is using laetrile tablets with such health foods as nuts, bean and alfalfa sprouts, fresh fruits (peaches), and other uncooked foods found in salads (lettuce, celery, mushrooms), which are high in hydrolytic enzymes that can cause the release of cyanide (Heinerman, 1984, pp. 175,176). Never mix these foods with laetrile ... 

The idea has been advanced that the action of cyanide from cyanogenic gluco-sides such as laetrile or amygdalin is related to the absence or presence of an enzyme... 

For perhaps a last word, it is said that amygdahn or laetrile will release cyanide in the stomach by the action of the enzyme P glucosidase, also called emulsin (Smith, in Amdiu et al., 1991, p. 277). Not found in mammalian tissues, such enzymes occur in normal human intestinal flora, or gut flora. For this reason, amygdalin is about 40 times more toxic by mouth than by intravenous injection. Thus amygdalin or laetrile could be given safely by parenteral routes. (The term parenteral signifies routes other than oral administration.)... 

Thus, laetrile or amygdahn injection may or may not be an effective anticancer agent, and has both proponents and detractors. In any event, if cyanide poisoning should occur, there are means for remediation. 

However, as distinguished from the aerobic metabolism of normal cells, cancer cell metabolism is in the main anaerobic and does not invoke the carboxylic acid cycle, dependent on oxygen and fimdamental to cell respiration, as set forth in Chapter 3 for glycolysis. Thus, respiration of the cancerous cell is excluded from consideration. Hence, from this standpoint, the anticancer claims for amygdalin or laetrile can be viewed as missing the mark. That is, under this interpretation, cyanide would affect aerobic normal cells but not anaerobic cancerous cells. 

The inhibition of the enzyme tyrosinase may very well be a key to the control of melanoma, and some of the known inhibitors include eommon substances. Thus, vitamin C, among other common and uncommon substances, has been listed as an enzyme inhibitor for tyrosinase in M.K. Jain s Handbook of Enzyme Inhibitors, 1965-1977 (1982). In addition to ascorbic acid (vitamin C), these other substances include the following halide ion (e.g., from the chloride of common salt, or from iodides and fluorides) butyric acid (from rancid butter) lactic acid (the end product of cancer cell metabolism, found naturally in sour milk products) oxalic acid (ordinarily considered toxic, although it occurs naturally in rhubarb and wood sorrel, etc.) formic acid (a component of ant stings) tyrosine itself and deadly cyanide (which is a chemically bound component of laetrile), as found in almonds (notably bitter almonds), in apricot seeds, and in certain legumes such as beans, etc., although the heat from cooking may drive off the cyanide content. 

Perhaps the most well-publicized, cussed and diseussed, instance of a proposed herbal remedy/cure for cancer is laetrile, whieh was introduced in the previous ehapter. Also called amygdalin, it is a class of cyanide-containing organic compounds known as cyanoglucosides, or cyanoglycosides. A recapitulation follows. 

Heinerman (1984) views this substance favorably as a cancer treatment, although it is stressed that owing to enzymatic action, laetrile can interact with some other foods to produce HCN internally and thus cause cyanide poisoning. We therefore repeat the following warning ... 

The prefix thio- implies sulfur in the molecular structure. Cyanates are compounds derived from cyanic add [HOCN]. There is a strong similarity with cyanides, as derived from hydrogen cyanide [HCN]. These would seem to be a parallel here with laetrile, or amygdalin, as used in cancer treatment.)... 

Laetrile has already been covered earher in this chapter, and we reiterate that consuming laetrile with such foods as nuts, bean and alfalfa sprouts, fresh fruits (peaches), and uncooked lettuce, celery, and mushrooms may lead to cyanide poisoning. 

Otherwise, laetrile is regarded as nontoxic, but it should be used with vitamins A and C to be effective. Among those who have researched laetrile is Dr. Harold W. Maimer, head of the Department of Biology at Loyola University in Chicago. He observes that laetrile contains cyanide, but so do lima beans, lentil beans, buckwheat, and many other food products. In fact, vitamin B12 is loaded with cyanide. If part of a chemical complex, however, it is not toxic as such. 

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