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678. Isolation of cocarcinogen A1 from croton oil
CANCER RESEARCH
517
676. Watch that space
Chem. Engng News--special report (1964). Man, space and life support systems. 42(17), 79. If hurtling through space at nearly 5 miles/sec were not risky enough, the possibility of poisoning from within the space capsule has now been suggested. Some of the less apparent difficulties of space travel outlined in this paper are the problems of carbon dioxide removal, the supply of oxygen and food, the management of waste and water, and the special control of trace contaminants. The control of water is, perhaps, the simplest of these problems and a number of methods have been devised for the recovery and purification of waste water from condensation, washing, urine and faeces. The most recently noticed and possibly most serious problem is that of trace contaminants. In earlier spacecraft there was so much leakage that the problem did not present itself, but since the construction of more airtight space simulators more than 20 materials have been identified during normal operations. The greatest source of contaminants appears to be man himself. Investigations using Beekmann instruments have discovered 149 materials in effluents from the mouth alone; 271 from the skin, 196 from faeces and 183 from urine have also been detected. In addition to these, contamination from equipment may occur and interactions between various trace materials may give rise to new ones. Control of contaminants will probably be by a three pronged attack; a unit to kill bacteria, adsorption on activated charcoal and catalytic oxidation to remove metabolites. The ideal system for the control of all the biological problems of space flight is to simulate the ecology of the earth on a small scale. After all, the earth can be regarded as a giant spacecraft on which various organisms produce substances that sustain life and man produces waste products which keep the organisms functioning. A number of algae have been used experimentally. The algae are fed on waste products and allowed a certain amount of light for photosynthesis; they are then used for food. As a food they are very nutritive, containing more than 55 ~o protein. But a diet of algae alone presents psychological as well as physiological problems and undoubtedly would need to be supplemented with dehydrated food to provide variety. It is possible that the difficulties associated with prolonged space flight are only in their infancy. 677. Stress and N A D levels
Yasin, R. & Bergel, F. (1963). Effect of injection on nicotinamide adenine dinucleotidelevels. Nature, Lond. 200, 783. The authors have shown that ratios and levels of the coenzymes nicotinamide adenine dinucleotide (NAD) and its reduced form NADH, can be altered by the intraperitoneal injection to rats of 1 ml of distilled water/100 g body weight. Following each injection, the rats were sacrificed, and the liver, kidney, spleen, tumour tissue and left hind muscle examined. The variations observed led the authors to invoke a stress-induced phenomenon.
CANCER RESEARCH 678. Isolation of cocarcinogen A1 from croton oil
Hecker, E., Bresch, H. &von Szczepanski, Ch. (1964). Cocarcinogen A1---der erste reine, hochaktive Wirkstoff aus Croton61. dngew. Chem. 76, 225. Croton oil has been known for some time to exert a eoearcinogenie effect (Cited in F.C.T. 1963, 1, 106) and has been used in studies relating to a possible two-stage mechanism of cancer development. Hecker (Angew. Chem. int. ed. 1962, 1, 602) isolated two amorphous
518
CANCER RESEARCH
substances, A and B, which together formed the pharmacologically-active principle of croton oil. He and his co-workers have now succeeded in separating an inactive component A2 and a highly active component A 1 from their original substance A. The coearcinogen A1 (Ca6Hs6Os) has been purified and characterized as a non-aromatic compound, with art x,fl-unsaturated carbonyl group artd 3 free and 2 esterified (acetate and myristate) hydroxyl groups. The biological activity of A1 has been compared with that of the basic alcohol (I) formed by hydrolysis of the ester groups, and of the triacetate (II) produced by acetylation of AI. In toxicity tests on frogs, the LDs0 (/~g/50 g) for A1 was 10, compared with 150 for II and 5000 for I. Similarly a high activity was shown by A I in tests of inflammation induced on application to the mouse ear, while I and II were much less active (A1 0.009 /ag/ear; 11--1.5; I--2-4). In a test for cocarcinogenicity, A1 produced papillomas in the mouse skin when applied after a subliminal dose of the carcinogen 9,10dimethylbenz[a]anthracene, but failed to do so when given alone. I and II exerted no significant coearcinogenic effect. 679. Early metabolism of azo compounds
Dijkstra, J. (1963). Early stage in the metabolism of aminoazo dyes in the liver of rats. Brit. J. Cancer 17, 355. The statement (Cited in F.C.T. 1963, 1, 101) that the published literature on the fate of azo dyestuffs used in food colouring is not extensive is still substantially true. The protein binding of azo compounds, which has been described as a necessary requirement for the induction of liver tumours (Miller & Miller, J. nat. Cancer Inst. 1955, 15, 1571), has been previously studied by the present author (Dijkstra & Louw, Brit. J. Cancer 1962, 15, 757) and he has now extended this work to investigate the binding process after the administration of a single dose. Three compounds were used in the investigation: carcinogenic 3'methyl-4-dimethylaminobenzene (I) and non-carcinogenic 2-methyl-4-dimethylaminoazobenzene (II)--both of which are strongly bound to liver proteins--and finally non-carcinogenic 4-aminoazobenzene (III) which is very weakly bound to liver proteins. In each case, 50 mg in 2 ml olive oil were given by stomach tube to rats which had been fasted for 6 hr; normal feeding was resumed after dosing. Art unknown azo metabolite (UAM) appeared in trichloracetic acid (TCA) extracts of livers shortly after administering either I or II and maximum levels of each UAM were reached in 5 or 6 hr. By 10 hr the levels were again low. In sharp contrast with these results, when III was given, neither this nor any other azo compound could be detected in liver extracts up to 90 hr after dosing. The UAM was distinguishable from administered I and II, and from their known N-demethylation and hydroxylation metabolic products by its failure to be extracted from TCA with ether or acetone-benzene. When 0.002 ~o solutions of I or II in TCA were prepared, 99.7 ~o could be removed in 2 ether extractions. If the residue from the first TCA extraction of livers containing low ot high concentrations of UAM was repeatedly re-extracted with TCA, the concentration of UAM in subsequent extracts decreased slowly, suggesting that the amount of UAM extracted is independent of its solubility. The author concludes that the appearance of UAM may represet a~t etrly stage in the binding of aminoazo compounds to protein or alternatively may originate from a reactive intermediate involved in the binding process. Whereas carcinogenicity did not appear to be a prerequisite for the formation of UAM, protein binding did. The author hastened to point out that this observation did not lessen the importance of UAM in the carcinogenic process since pIotein binding has been described as a necessary requirement for the production of liver tumours.
517
676. Watch that space
Chem. Engng News--special report (1964). Man, space and life support systems. 42(17), 79. If hurtling through space at nearly 5 miles/sec were not risky enough, the possibility of poisoning from within the space capsule has now been suggested. Some of the less apparent difficulties of space travel outlined in this paper are the problems of carbon dioxide removal, the supply of oxygen and food, the management of waste and water, and the special control of trace contaminants. The control of water is, perhaps, the simplest of these problems and a number of methods have been devised for the recovery and purification of waste water from condensation, washing, urine and faeces. The most recently noticed and possibly most serious problem is that of trace contaminants. In earlier spacecraft there was so much leakage that the problem did not present itself, but since the construction of more airtight space simulators more than 20 materials have been identified during normal operations. The greatest source of contaminants appears to be man himself. Investigations using Beekmann instruments have discovered 149 materials in effluents from the mouth alone; 271 from the skin, 196 from faeces and 183 from urine have also been detected. In addition to these, contamination from equipment may occur and interactions between various trace materials may give rise to new ones. Control of contaminants will probably be by a three pronged attack; a unit to kill bacteria, adsorption on activated charcoal and catalytic oxidation to remove metabolites. The ideal system for the control of all the biological problems of space flight is to simulate the ecology of the earth on a small scale. After all, the earth can be regarded as a giant spacecraft on which various organisms produce substances that sustain life and man produces waste products which keep the organisms functioning. A number of algae have been used experimentally. The algae are fed on waste products and allowed a certain amount of light for photosynthesis; they are then used for food. As a food they are very nutritive, containing more than 55 ~o protein. But a diet of algae alone presents psychological as well as physiological problems and undoubtedly would need to be supplemented with dehydrated food to provide variety. It is possible that the difficulties associated with prolonged space flight are only in their infancy. 677. Stress and N A D levels
Yasin, R. & Bergel, F. (1963). Effect of injection on nicotinamide adenine dinucleotidelevels. Nature, Lond. 200, 783. The authors have shown that ratios and levels of the coenzymes nicotinamide adenine dinucleotide (NAD) and its reduced form NADH, can be altered by the intraperitoneal injection to rats of 1 ml of distilled water/100 g body weight. Following each injection, the rats were sacrificed, and the liver, kidney, spleen, tumour tissue and left hind muscle examined. The variations observed led the authors to invoke a stress-induced phenomenon.
CANCER RESEARCH 678. Isolation of cocarcinogen A1 from croton oil
Hecker, E., Bresch, H. &von Szczepanski, Ch. (1964). Cocarcinogen A1---der erste reine, hochaktive Wirkstoff aus Croton61. dngew. Chem. 76, 225. Croton oil has been known for some time to exert a eoearcinogenie effect (Cited in F.C.T. 1963, 1, 106) and has been used in studies relating to a possible two-stage mechanism of cancer development. Hecker (Angew. Chem. int. ed. 1962, 1, 602) isolated two amorphous
518
CANCER RESEARCH
substances, A and B, which together formed the pharmacologically-active principle of croton oil. He and his co-workers have now succeeded in separating an inactive component A2 and a highly active component A 1 from their original substance A. The coearcinogen A1 (Ca6Hs6Os) has been purified and characterized as a non-aromatic compound, with art x,fl-unsaturated carbonyl group artd 3 free and 2 esterified (acetate and myristate) hydroxyl groups. The biological activity of A1 has been compared with that of the basic alcohol (I) formed by hydrolysis of the ester groups, and of the triacetate (II) produced by acetylation of AI. In toxicity tests on frogs, the LDs0 (/~g/50 g) for A1 was 10, compared with 150 for II and 5000 for I. Similarly a high activity was shown by A I in tests of inflammation induced on application to the mouse ear, while I and II were much less active (A1 0.009 /ag/ear; 11--1.5; I--2-4). In a test for cocarcinogenicity, A1 produced papillomas in the mouse skin when applied after a subliminal dose of the carcinogen 9,10dimethylbenz[a]anthracene, but failed to do so when given alone. I and II exerted no significant coearcinogenic effect. 679. Early metabolism of azo compounds
Dijkstra, J. (1963). Early stage in the metabolism of aminoazo dyes in the liver of rats. Brit. J. Cancer 17, 355. The statement (Cited in F.C.T. 1963, 1, 101) that the published literature on the fate of azo dyestuffs used in food colouring is not extensive is still substantially true. The protein binding of azo compounds, which has been described as a necessary requirement for the induction of liver tumours (Miller & Miller, J. nat. Cancer Inst. 1955, 15, 1571), has been previously studied by the present author (Dijkstra & Louw, Brit. J. Cancer 1962, 15, 757) and he has now extended this work to investigate the binding process after the administration of a single dose. Three compounds were used in the investigation: carcinogenic 3'methyl-4-dimethylaminobenzene (I) and non-carcinogenic 2-methyl-4-dimethylaminoazobenzene (II)--both of which are strongly bound to liver proteins--and finally non-carcinogenic 4-aminoazobenzene (III) which is very weakly bound to liver proteins. In each case, 50 mg in 2 ml olive oil were given by stomach tube to rats which had been fasted for 6 hr; normal feeding was resumed after dosing. Art unknown azo metabolite (UAM) appeared in trichloracetic acid (TCA) extracts of livers shortly after administering either I or II and maximum levels of each UAM were reached in 5 or 6 hr. By 10 hr the levels were again low. In sharp contrast with these results, when III was given, neither this nor any other azo compound could be detected in liver extracts up to 90 hr after dosing. The UAM was distinguishable from administered I and II, and from their known N-demethylation and hydroxylation metabolic products by its failure to be extracted from TCA with ether or acetone-benzene. When 0.002 ~o solutions of I or II in TCA were prepared, 99.7 ~o could be removed in 2 ether extractions. If the residue from the first TCA extraction of livers containing low ot high concentrations of UAM was repeatedly re-extracted with TCA, the concentration of UAM in subsequent extracts decreased slowly, suggesting that the amount of UAM extracted is independent of its solubility. The author concludes that the appearance of UAM may represet a~t etrly stage in the binding of aminoazo compounds to protein or alternatively may originate from a reactive intermediate involved in the binding process. Whereas carcinogenicity did not appear to be a prerequisite for the formation of UAM, protein binding did. The author hastened to point out that this observation did not lessen the importance of UAM in the carcinogenic process since pIotein binding has been described as a necessary requirement for the production of liver tumours.