We have investigated the influence exerted by different fatty acids, conjugated and nonconjugated, upon various carcinogens. In a first group of experiments we studied this influence in vitro, and chose the quenching of the fluorescence of the carcinogen as criterion of activity.

This part of the research was made in collaboration with C. Huesca Mejia and P. Teitelbaum.

The quenching effect has been studied as follows:

The fluorescence of carcinogenic hydrocarbons is measured by means of the fluorescent attachment to the Beckman spectrophotometer using a wave length around 365 m. The sensitivity of the apparatus is adjusted to show a value of 100 for the fluorescent light utilizing the concentration of the hydrocarbon having the maximum fluorescence. The carcinogenic hydrocarbons are dissolved in alcohol, iso octans or cyclohexane, the last two being purified and thus rendered optically inactive by passage through a silica column.

The fatty acids are dissolved in varying dilutions in the same solvents and added to the solution of hydrocarbon carcinogen which has been previously chosen to give a fluorescent value of 100. The fluorescence of the mixture is immediately determined. The quenching effect of the fatty acid is shown by the percent of the residual fluorescence of the carcinogen when mixed with different solutions of a mixture of conjugated fish oil fatty acids. Table XXXVI shows the quenching effect of mixtures of fatty acids conjugated by treatment with KOH upon different carcinogenic and related hydrocarbons.

Conjugation method

Fig. 280. Conjugation method. The use of ethylic alcohol as solvent for conjugation changes the amount of polyconjugated members obtained for cod liver oil fatty acids (a) as compared with those obtained when the conjugation is made at higher temperatures using ethyleneglycol, (b) glycerol or other solvents. Dilution 0.002% in ethyl alcohol.

Table XXXVI. Quenching Effect Of Conjugated Fatty Acid Mixtures Upon The Fluorescence Of Carcinogenic And Related Hydrocarbons

Hydrocarbon

% Concentration

Quenching Agent

% Residua Fluorescenc

Mixture of conjugated fatty acids from cod liver oil

0.0062

(0.1% solution)

25.0

3, 4 Benzpyrene

0.0062

36.0

1, 2 Benzanthracene

0.0031

"

24.0

1, 2, 5, 6 Dibenzanthracene

Sat. Sol. (alcohol)

"

15.2

9, 10 Dimethyl -1, 2 Benzanthracene

0.0062

"

23.0

Mixture of conjugated fatty acids from fish oil

Benzanthracene 12 ol -7 Methylacetate

0.005

(0.2% solution)

5.7

7 ChIoro-10 Methyl -1, 2 Benzanthracene

0.005

"

7.9

0.005

"

10.0

0.005

11.2

0.001

"

6.5

7 Cyano-10 Methyl -1, 2 Benzanthracene

0.0057

"

4.0

5 Chloro-10 Methyl -1,2 Benzanthracene.

0.0025

"

5.8

6 Chloro-10 Methyl -1, 2 Benzanthracene .*

0.01

"

5.2

0.005

"

13.0

* Fluorescence set at 45.

Table XXXVII. Quenching Effect Of Various Nonconjugated And Conjugated Fatty Acid Mixtures Upon The Fluorescence Of Carcinogenic And Related Hydrocarbons

Hydrocarbon

%

Concentration

Fatty Acids from

Conjugated Fatty Acids from

B-

Eleostearic Acid

Linoleic Acid

Conj. Linoleic Acid

Oleic Acid

Cod Liver Oil

0.1%

0.1%

0.1%

0.1%

0.1%

0.1%

Methylcholanthrene

0.0062

92.5

25.0

95.8

95.0

89.8

3, 4 Benzpyrene

0.0062

82.8

36.0

100.0

1,2 Benzanthracene

0.0031

93.4

24.0

94.8

100.5

97.0

100.8

1, 2, 5, 6 Dibenzanthracene

Sat. Sol. (alcohol)

89.0

15.2

100.0

97.0

98.0

100.0

9, 10 Dimethyl -1,2 Benzanthracene

0.0062

90.8

23.0

97.8

93.5

100.0

96.0

Fish Oil

0.2%

0.2%

0.2%

0.2%

0.2%

0.2%

Benzanthracene 12 ol -7 Methylacetate

0.005

66.0

5.7

89.0

87.0

80.0

92.1

7 Chloro-10 Methyl -1,2 Benzanthracene

0.005

67.0

7.9

84.0

85.0

87.0

87.0

1 Cholanthrene -3 Methyl

0.005

110.0

10.0

110.0

110.0

110.0

110.0

Benzo (d) Pyrene -5 Methyl

0.005

88.0

11.2

88.0

70.0

90.0

91.0

3, 10 Dimethyl -1,2 Benzanthracene

0.001

72.0

6.5

63.0

78.0

74.0

73.0

7 Cyano-10 Methyl -1,2 Benzanthracene

0.0057

83.5

4.0

91.0

90.2

88.5

91.0

5 Chloro-10 Methyl -1,2 Benzanthracene

0.0025

89.0

5.8

92.0

95.0

92.0

93.5

6 Chloro-10 Methyl -1,2 Benzanthracene*

0.01

47.0

5.2

43.0

45.0

42.0

45.0

4 Methoxy -3, 4 Benzpyrene

0.005

88.0

13.0

86.0

90.0

89.0

91.0

* Fluorescence set at 45.