NOTES
n'ovemher 1969
1119
TIBLEI AUTITUMOR SCREEKING DATA FOR ETHYLENE-MILEIC ACIDCOPOLYMERS AND THEIRS I L T S a laM t-e-----Po14 mer
Metal
L1210 leukemia of mice Dose, mg/k% T/C
content-
Calcd for 1 1 complex,
Found,
%
Kone
A
Ni(I1) Cu(I1)
29.06 30.60 29.03
400 25 20 100
8.78 14 57 6 25
1.00 1.01 0.89 1.24 1.14 0.9,i 0.91 0.89 1.02 0.88 0.90 0.90
Intramuscular Walker sarcoma of rats Dose, mg/k T/C
400
0.83
0.25 15 0.28 Ni(I1) 29 06 8.60 10 10 1.25 Cu(I1) 30.60 8.86 10 20 0.5.5 29 03 3.48 10 20 0.48 Co(I1) c None 7 10 0 41 Ni(II) 29 06 8.99 20 10 0.80 7 10 0.80 CIIIII) 30.60 10.01 Co(I1) 29.03 6.87 J 10 0.45 The screenin5 data were sipplied t h r o y h the kindness of Dr. Harry B. Wood, Jr., of the Cancer Chemotherapy National Service Center, Xational Inqtitiiteq of Health, Rethesda, 3rd. Assays were performed according to CCXSC specifications a4 reported in the referrrice 111 ref 6.
Co(I1) None
R
7
Polymers wit,h higher molecular weight, averages have greater antitumor activities, but their toxicities per gram increase also. Other functional derivatives such as the amide ammonium salt, and the amide acid of the ethylene-maleic acid copolymers are less toxic and ?ornewhat less effective therapeutically when equal weights are used. The purpose of this work was to study several copolymers of ethylene and maleic acid of different molecular weights in order to discover some physical or chemical property which could be related to their antitumor activities. These polymers are produced by the reaction of ethylene and maleic anhydride under conditions designed to give different average molecular weights. When the anhydrides are stirred in warm water for a few minutes they are converted to mater-soluble acids without destruction of the polymer chain as follows. [-CH,CH?CHCH-]n I
I
oc co
+ %Hi0+[-CH,CH,yHCH-]c I
Y
Since these polymeric acids are good chelating agents we first attempted to determine the abilities of three polymers with different molecular weight averages to complex with copper(II), cobalt(II), and nickel(I1) ions using the potentiometric method described by Albert and Serjeant.4 Since complexation of the metals with the lowering of the pH of the the acids releases Hf, solution caused by addition of the metal ions is a qualitative measure of the extent of complexing between the metal and the acid. Although our results did not allow us to calculate absolute values for the stability constants of the complexes of the polymeric acids and these metal ions, it was clearly demonstrated that the three polymers do not differ significantly from one another in their abilities to complex these metals. Stability constants for the complexes of one ethylenemaleic acid copolymer (polymer B) with several metals have been determined ;5 the mean values of K M A (where
(4) A. Albert a n d E . P. Serjeant, "Ionization Constants of Acids a n d Bases,'' J o h n Wiley and Sons, Ino., New York, N. Y.. 1962, pp 154-167. ( 5 ) B. J. Felber, E. hl. Hodnett, a n d N. Purdie, J . P h y s . Chem., 72, 2496 (1968).
400
is the mean activity coefficient of the divalent ions) for Co(II), Xi(II), and Cu(I1) are 4.29 X lo8, 3.76 X lo8, and 4.45 X lO'O, respectively. I n an aqueous solution a t pH 7.00 with metal and polymer (based on monomer) concentrations of 1 X 10-5 -11,the percentage of Co(II), Ni(II), and Cu(I1) complexed by the polymer would be approximately 91, 90, and 99%, respectively. Cu(II), Co(II), and Ki(I1) salts of the three polymers were prepared in order to test their antitumor activities in experimental animals. Since these are polymeric acids the salts do not contain a stoichiometric equivalent of metal; they also contain about lOy0 of the solvent from which they precipitated. The metal contents of the salts are listed in Table I with the theoretical values for the 1 : 1 complexes. The antitumor activities of the polymeric acids and their Cu(II), Co(II), and Ni(I1) salts have been determined in two tumor systems with the results shown in the table. Significant activity against L1210 mouse leukemia was shown by none of the metal salts6 Significant activity against intramuscular Walker sarcoma of the rat was evidenced by some salts of each polymer and by some salts of Co(I1) and C U ( I I ) . ~ The polymeric acids appear to have as much antitumor activity as the salts. The Co(I1) salts appear to be more active against the Walker sarcoma than the Cu(I1) and Ni(I1) salts.
fi
Experimental Section Ethylene-Maleic Anhydride Copolymers.-The inhibition of Sarcoma 180 of mice by the three polymers used in this work x a s known from an earlier study;a the polymers m r e supplied to us for this work by Dr. John Johnson of Monsanto Company, St. Louis, Mo., who had furnished the polymers for the earlier work.* These samples were dried under vacuum a t 144" for several hours. The average molecular weights of polymers -4and B, determined in anhydrous AcMe by means of a Coleman 115 molecular weight apparatus, were 4100 and 17,000, respectively. (6) T h e effectiveness of a compound against mouse leukemia L1210 is determined b y the ability of the compound t o lengthen the lives of treated (T) mice bearing this leukemia compared t o those not treated ( C ) : the value of T/C must be a t least 1.25 for the antileukemia activity t o be significant: Came? Chemotherapy R e p t . , 25, 1 (1962). (7) Effectiveness against intramuscular Kalker sarcoma of the rat is measured b y weights of tumors of treated rats ( T ) compared t o the tumors of control rats ( C ) : the value of T / C must be no more than 0.63 for significant activity: see reference in ref 6.
New Compounds Synthesis of 3-Hydroxy- and ~3-Methou~indole-2-carhouamides and Esters
SO
I
L' I I
ti
i
!I
111
Exoerimental Section2
C6€Liv:is theii removed wider rediiced pressure slid I he
rritliic:
(1) SociBt6 d'Ltiide\ scientifiques et induutrielles de I ' I ' I e - d e - l ~ r ~ r ~ ~ f ~ .i i i (a) \f-. .I. Jacolisand AI. Heidelberger, .I. Biol. C h r m . . 21, 103 ( l U l 5 j i l l ) 1'. AIalrttesta and (:. !dieliaceso. Pnrmaco. K i f . S r t . , 11, 113 (19581: l r i French Patent 1627 ( N o v 12. 1962); Chem. . 4 h + t r . , 68, i Y l l n 11963). .\, L. Kemizov and N . V liliromo\~I%ori70v,Zh. Oh ( 9 ) l l e l t i n g points are uncorrected. l
