Method B. Inhibition of Chemically Induced Lysis of a Preformed Plasma Clot.-The clot,s were prepared from human plasma containing lz~I-labeledhuman fibrinogen by the addition of CaClp and bovine thrombin. After thorough washing to remove loosely bound radioactivity, fibrinolysis was initiated by the addition of c-thymotic acid (6-methyl-3-isopropylsalicylic acid) to the suspending medium and was measured by the release of radioactivity into the medium. Lysis was prevented if an aiitifibrinolytic compound was present in the ambient solution. Illhibition of the release of radioactivity from the plasma clot into the ambient solution is directly proport,ional to inhibition From these data, the relative potency of the anti( i f lysis. fibrinolytic compound was calculated.
Acknowledgments.-The authors acknouledge the valuable advice and encouragement of Dr. James 11. Sprague during the course of this work, as well as the assistance of Alr. J . Schwering who prepared many chemical intermediates and Drs. G. S.Brenner and D. F. Hirikley who prepared the dimethyl cubane-l,4dicarboxylate. Analytical data were obtained by lllessrs. K. B. Streeter and T.C. Lee and their staff, ir and nmr spectra by A h . W. R. JIcGaughran, and glc analyses by I I r . A. Augenblick, to whom the authors are indebted for these services.
Potential Anticancer Agents. 111. Schiff Bases from Benzaldehyde Nitrogen Mustards and Aminophenylthiazoles J. D. A I O D I , ~S.~ S. SABSIS,AND C. V. DELIJVALA~~' Department of Chemotherapy, Hafflcine Institute, Bombay 12, India Received March 4, 2970 Several Schiff bases from different benzaldehyde nitrogen mustards and amines such as 4-(p-aminophenyl)2,5-disubstitut,ed-thiazoles and 4-[(4'-amino-2'-chloro)phenyl]-2-~1~bstitut~ed-thiazoles have been synthesized and screened for ant,itumor activity. Many of the compounds displayed significant activity against I, 1210 lymphoid leukemia, Walker 256 (intramuscular), and Ilunning leukemia (solid).
The nonspecific cytotoxic effect of the K mustards has limited their use in the chemotherapy of cancer. The concept of "latent activity" v-hereby the drug is so designed as to be inactive p e r se but gets modified into an active form by processes taking place in the target cells has been very fruitful in the search for better antitumor agents. Ross and coworkers2 synthesized azomustards while Popp3 studied several Schiff bases of benzaldehyde S mustards and found them active enough in an experiniental tumor system to merit clinical trials. Following this lead we have reported4 in an earlier communication the synthesis and study of Schiff bases from substituted benzaldehyde S mustards arid various arylamines. A number of compounds from this series displayed significant activity against Dunning leukemia (solid), lymphoid leukemia (L-1210), and Walker carcinosarcoma 236 (intramuscular). The wbstituent on the benzaldehyde S mustard greatly influenced the activity and specificity and the presence of a halogen in the ineta pobition of the arylamine induced activity of a high order. Another significant observation in our earlier work was that among arylamines, the 4-(p-aminophenyl) thiazoles afforded more active Schiff bases. I n view of these findings the work has now been extended and Schiff bases of structure I from substituted benzaldehyde IY mustards and various 4-(p-aminophenyl)thiazoles have been prepared arid screened to study the role of difTerent substituenth in the molecule. (1) (a) Government of India Research Scholar. (b) T o whom communications regarding this paper should be addressed. (2) (a) W, C. J. Ross and G . P. Warwick, J . C h e m . Soc., 1364, 1719, 1724 Connors and W. C . J. Ross, C h e m . Ind. ( L o n d o n ) , 492 (1Y56); (b) T. .i. (1960). (3) (a) F. D. Popp, J . Ore. C h e m . , 26, 1666 (1961); (b) F. D. Popp and TI-. Kirsh, ibid.. 26, 3855 (1961); (c) F. D. Popp, S. Roth, and J. Kirby, .I. . ] l e d . C h e m . . 6, 83 (1963): (d) F. D. Popp, ibid., 7 , 210 (1964). (4) (a) S. S. Sabnis a n d IC. U . Kulkarni, I n d i a n J . Chent., 1, 447 (1963); ( 1 ) ) S , Y. Sabnia. { b i d . , 6 , 619 (1Y67); (c) hI. G. Dhapalapur, S. S . Sabnis. ;:n,l c'. V. l>eli\vala, J . .\fed. Chem.. 11, 1014 (1968).
X = M e and H Y = C1 and H
It = 31JPhCH2, PhOCHz 0- or p-toluoxymethyl, Ph, p-MePh, p-lfeOPh, aridp-C1Ph R, = H, OMe, Me, and F 11, = H , 0 M e and OEt R8 = H and OhIe
Chemistry.-The general method adopted for the preparation of Schiff bases, viz., heating a mixture of t8heamine and aldehyde in EtOH, though successful in cert,ain cases n-as not particularly useful when the aldehyde n-as a liquid. I n such cases the resulting compounds were invariably viscous oils which could not be induced to crystallize. I n a few cases the modified method recommended by Tipson and Clappj involving heating under reflux a mixture of amine and aldehyde in PhMe containing a few drops of piperidine was tried. The procedure, though successful when carried out with smaller amounts did not give pure products in larger quantities. The most suitable method found in the present work was the heating of pure amine hydrochloride with mustard aldehyde in E t O K f i I n a short time the highly colored hydrochloride of the Schiff base separated out and the product was invariably found to he analytically pure with yields varying between 60 and 'io% (Table I). The required aldehyde mustards were prepared by hydroxgethylatiori of various anilines with ethylene oxide' and then treating the products with POCI, in DT\IF.8 The requisite 4-(p-aminophenyl) thiazoles (5) (6) 17) (8)
R. S. Tipson and AI. A . Clapp, J . O w . C h e m . , 11, 292 (1946). AL. AI. Sprung. Chem. Re?., 26, 324 (1940). AI, Freifelder and G. R. Stone, J . O r g . C h e m . , 26, 1477 (1061). R . H. Wiley and G . Irick, { h i d . , 26, 593 (1961).
b
9 10 11 12
13 11
I1 CIb F OCHa II OCHa II
Journal of Medicinal Chemistry, 1970, Vol. 13, S o . 5 937
. h T I C . 4 N C C R SCHIFF BASES
T l B L E 1 (COntLnUCd) RZ
RI
NU.
R3
R 51 52 53 64 5 :i 56
H CH3
H H OCHj
I1
OC?I7,
OCIT3
I1
57 ;i8 59 60 61 62
H
H
63 64 6t5 66 67 68
H CH3
oca
H ; Y = CI H 203-204 H 218-220 H 194-196 H 200-202 II 130-132 OCHj 208-200
H
F H
hlp,
X
= CeHiOCHz;
=
II = o-CIT~CfiTT~OCH~; S = H ; Y = C1 H 210-212 H H 220-222 H H 208-210 OCH, H 198-199 OC2Hj H 165-167 H OCH3 185-187
CHI
F H H OCH,
R F H
H OCH,
=
H
H H OCH3 OCzHs H
H H H H OCHx
R H H H OCHa OCeHj H
69 70 71 72 73 74
H ; Y = C1 204-205 2 10-212 220-222 208-2 10 194-196 204-20.5
p-CH,CsH,OCHz; X
H
=
c ~ H 5 ;X = H ; Y H H H H H OCHa
=
C1 2 10-2 12 240-242 206-208 194-196 192-194 202-204
R = I)-CHICGHI;X = H ; Y = C1 75 76 77 78 79 80
H H H OCH3 OCzHs
H CH3
F H H OCEE,
H H H H H OCHa
H
R = p-CH,OCa&; 81 82 83 84 8.5 86
H H H OCHZ OCiHj H
87 88 89 90 91 92
H H H OCH, OC2Ho
It
=
H
H H H H OCH, = p-ClCeH,;
X
=
H H H H H OCHa
H R
X
203-20.5 249-250 235-237 210-212 208-210 212-214
RI
H ; Y = C1 212-214 242-244 218-220 225-227 180-182 2 12-214
H; Y
=
C1 208-210 260-262 230-232 217-219 148-150 210-212
Rz
X = Y = R3 = H CH, H 184 C?sHz,C12NaS.HC1 93' CGH~CH~ 94' P-CH~OC~H~CHZ H H 140 C Z ~ H Z ~ C I Z NHC1 ~OS. 102- 104 Cz8Hz7ClzPr'TO~S. HC1 95. CsHjOCH? H OCHI b Pure compounds were a 1Ielting points were taken in capillary tubes with a partial immersion thermometer and are corrected. obtained without recrystallization. e All compounds analyzed for S and S (see ref 10) except 71, 73, 86, 90, which were analyzed for S . e Reported earlier: S. S. Sahnis, Indian J. Cham., 5, 619 (1067). d .41~oanalyzed for C, H (see ref 10).
mere prepared by the condensation of different halo ketones with necessary thioamides. Some of these thiazoles utilized have been reported from this laboratory9 and those, not hitherto described, are given in Table 111. (9) R. $3. Kulkami, R . S. Fernandea, JI. R. Patel, R . A. Bellare, and C. V. Deliwala. J. Pharm. Sa'.,58, 852 (1969).
Biological Results.-Sevent een representative compounds were screened for their antitumor activity against Dunning leukemia (solid), L 1210 lymphoid leukemia, Walker carcinosarcoma 256 (intramuscular) and studied for toxicity under the auspices of Cancer Chemotherapy National Service Center; Bethesda, l € d . The screening results of 13 active compounds are pre-
SO.'
::L'
:I.-I
:w
14,:j !I,:< 1;%.2! I , : ;
I ,i;< 111
7 . 7 10.1) h.S l(t.2 1'1.7 1 :i.-I
10.0 ll1.0 10.1) I I) 4
I
I1
I1 I ti I' 49
a2
--i.o 54
0 - :13 , I1 - h.0
IO.0
I . 9 16. :3
J)OSC
(mg/kg)
Cures
400.0 200.0 100.0 150.0 100.0 66.6 14.4
-8.1 -2.8 -7.0 -1.7 -,j 8
-1,s
"2, .i 11.2 5 .6 2.8 45.0 2 2 . .i 11.2 ..i 6 2.8 72
-1
A h
1>L
0
0 0 2 .0 8 .0 - 12.0 -3.0 - 1 .o - 1 .o -2.0 -9.4
200.0 100 , 0 150.0 100.0 66.0 44.0 44.0 29.0 19.0 12.0 30.0 20.0 13.0 8.0
-6.1 -7.7 -7.3 -6.6 -3.8 -3.2 -3.1 -1.7 -0.8 -6.7 -4.3 -4.5 -3.7
100.0 33.0 10.0 3.0 200 I0 100.0 .io. 0 2.5.0 400.0 400.0 400.0 400.0 400.0 400.0
12.0 15.0 20.0 23.0 -1.7.0 - .I. 0 -6.0 3.0 -4 - 10 -9 - 17 - 1:; - 17
4
100.0 33.0 10.0 3.0 44.0 22.0 11.o 5.5 5.5
2.75 1.37 0 , 68
'rumor wtf or survival day@ T 'C
T 'C
11.3/9.5 l2.5/9.5 11.5,'s. 6 11.0/8.6 12.0/8.6 11.0:8.6
118 131 133 I27 I39 I27
0.616 . O 0.916 . 0 3 . ,516 . 0 6.0'6.0 0.7'8.7 1, l , ' 5 , 3 0.6; 3 . 3 2.0I5.3 3 , 8 .i ,3 I
8.018.4 14.0/8.4 13.31'9.3 13.3,!9.6 13.319.6 13.3/9.6 13.0/8.9 12.0,'8.9 11.5,;s.9 11.31'8.9 14.2l9.1 12.819.1 12.5/9.1 11.7,Ig.l
%
IO 1 .i 58 100 8 20 11
:37 71 9.5 166 138 138 138 138 146 134 129 126 156 140 137 128
30/15 20/15 19/15 15/15 1.416.7 0.417 . O 0.9,'5.7 0.6/4.8 0 , ,514.0 1 .1'8.8
200 133 126 100 20 5 15 12 10 1.ik
2 . 4 .'6.7 1.617.0 1.6/5.7
35 22 28 16 14
I 1 .o 11.0
100.0 33.0 10.0 3.0 400.0 400.0 400.0 400.0 400.0 400 0 9d
4nimal' 711 diff (9) (T - C)
16.0
13.0 -1
-1 -7 -12 -8 -8
0.814.8
0.71'4 . 9 2.318.8
26k
- 18
- 18 4
2 6 5
24 0 0 0 0 -3 -3 -4
-
.)
0/16 23/16 30/16 30/16 21/16 18/16 17/16 16/16
0
143 187 187 131 112 106 I no
1210 lymphoid louhemia 111 spite of high t u n w irihibitiori in Wallier c:minosarconia 236 (intramuscular), where three roiiipoutid:, (46, 93, and 94) h:ivc> \him I I (>onfirmedactivity. Compounds 93 :ind 95 sliontd Yignificant :ictivitj against Dunning 1euliemi:t (solid). The mo+t activv Schiff base 95 give cj,'Yi cuwa t i t 11.O mg k g pei' d : r j . Thri premicc of C1 in 54 dit1 not increabe the activit) :Lgainst 3 L1C i i i (.omparison wit11 95 hut it did rt.diici. the toxicity. 'I'he ;Lddition of Ale at the pu>itioii 111 the thiazole ring (lid iiot alter t h r . avtivity again+t :?,l,l
