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May 196'7
2
-
A
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L) I C A~ ~ ~ B~A M~OLAMINO Y~ ~ACIDS ~ ~
and the sodium salts of the appropriate amino acids to 130-170'. Leucyl hydantoin mercaptan (111) precipitated in moderate yields from the aqueous extracts of the reaction mixtures. In all other cases only very small amounts of the corresponding hydantoin mercaptans were obtained. Upon acidification and elimination of HSO, followed by extractions of the residues with alcohol and CHCls, the filtrates gave the desired products (11), which mere identified by their infrared spectra, chemical properties, and elemental analyses. In some cases, conversion to the cyclohexylamine salts was necessary to obtain analytically pure samples. f
RCHC0,H I
~
~
~
~
~
4'73
respectively) in intestine and none in tumor. With the derivatives of the four other amino acids, phenylalanine (11, R = CEHsCH,), L-methionine (11, R = CH3SCH2CH,),L-aspartic acid (11, R = HOOCCH,), and @-alanine,little or no cysteamine was found in the tissues of normal Sprague-Dawley rats to which they were administered.? It is of interest that neither of the two active compounds nor the six others were hydrolyzed to cysteamine when tested with rat kidney homogenate? with denionstrable acylase activity.8 Presumably the tissues in stomach, which cysteamine was found-intestine, spleen, and thymus- contain an enzynie(s) other than acylase capable of hydrolyzing the particular Pmercaptoethylcarbamylamino acid. Experimental Sectiong
0
RCH-CO
I
I
1 IV
Leucyl hydantoin mercaptan (111) gave, upon oxidation with 3% hydrogen peroxide, the corresponding high-melting hydantoin disulfide IT', identified by the infrared spectra and analytical data. Earlier, the esters I of the mercaptoethylcarbamoyl derivatives of a series of eight amino acids were prepared by reaction of the corresponding isocyanates4 with 2-mercaptoethylamine. The esters I mere isolated in good yields as oils difficult to purify. Attempts to hydrolyze these esters (I) to the corresponding acids I1 were unsuccessful. The only identifiable products isolated under mild alkaline conditions were the hydantoin disulfides IT: of leucine and methionine, and the hydantoin mercaptan I11 of leucine (identified as t'he disulfide) under acid conditions. RCHC02Et N H ~ C H ~ C H ? S HRCHC0,Et
kc0
-
I
XHCOSHCH2CH1SH
Biological Studies.-In our initial screen for biological activity these compounds were administered to Sprague-Damley rats bearing the Walker 256 tumor. After 10 min the treated animals and appropriate controls mere sacrificed and 15 tissues, including intestine, bone marrow, and tumor, were assayed for ~ysteamine.~The methodology is described in detail in a previous paper6 in this series. Of the six compounds studied to date the glycine derivative (11, R = H) and the L-ala.nine derivative (11, R = CH3) gave evidence of significant release of cysteamine in three tissues; and interestingly both derivatives produced small but significant concentration of cysteamine (0.3 and 0.5 mpmole/mg of tissue, (4) S. Goldschmidt and AI. \Tick, A n n . , 575, 2 1 i (1952). (Z) I1 1 2 0 2 . Colorless crystals soon appeared which were filt,ered :tiid dried, mp 180-183', iderit,ified as 1,2-[1-(4-isobut,~.lhydaiitoiii)]ethyl disulfide by infrared spectra and mixture meltitig p h i . The product of acid hydrolysis was therefore the hydaiitoin mercapt,an I11 [ R = (CHIj&HCH>]. N-( 2-Mercaptoethyl)carbamoylaminoAcids.---The prepara~ioii of the glycine derivative is described as a represeiit,ative example. The other seven compound.: for which data are giveii i i i Table I were prepared by essentially the same procedure. N-(2-Mercaptoethyl)carbamoylglycine (11, R = H).- -Giyciiie (0.75 g, 0.01 mole) aitd 1.03 g (0.01 mole) of 2-thictzolid i i i t r i i e , prepared by the procedure of Michels c id were tlissolved i n 2 ml of 1 .I' NaOH (0.02 mole). The solvent W R ~ i.cincned iiiider vacuum, arid the residue m-as heated to 140" for 35 miri, dissolved iti 10 ml of water, arid acidified t,o pH 3 with .\mherlitel' cation-exchange resiii. Or1 gradual removal of solvrii(, wystals deposited. A total of 1.55 g wits collected in forir vixips, nip 121-123'. The iiif'rareti spectriiin IKBr) iriclitded S, 27.5.
IO
txiiida ~ l l2.!J5-2.45 (111, b r ( d j , 5.9 Caj, ti.15 i.)?t 7.S (m), 8.2 (s), 9.4 iw1, 10.8 .I nul. (.I:tl1d for C ' j I I 1 , S 2 S , 1,j.i: S, L Y . 0 . b ' i i i i t i i l S , 15.6, 1,5.5: S j 1S.Z. 18.32. 1,2-[l-(4-Isobutylhydantoin)]ethyl Mercaptan (111, R (CH1)1CHcH~].---1.-T,eucine (5.26 g ) was heat,ed F5-it.h 8.26 g i l f 2-t,hiazOlidiiiOiiU m i t i the react,ioii mixture wa.: esti.ac:t~eti wit ti \v:iter i i i i~ fashioii LLS described al)ove. The 3eparated hyt1;ttitoiii wits collected uti a filter, washed with water, aiid air dried t i ) yield 1.13 g (1;S.l rsij of melcaptaii hydaiitoiii, mp Si-89.5". The crude 1iyd:iiituiii was diswlvetl in CHC1, siid treated w i t h caharcosl. 1~:vapor:ttion gave :t white c W B S collected with ether to yield the pii hands at 5.65 (w), 53.5 is), (i.!)ini),
(Mcd f ( l I ( I g I I 1 ~ s y o (', .-~tl,ll; II, i.4. ~ ' ~ I I I I I ~ . 11, i.:X 1,2-[1-(4-1sobutylhydantoin)lethylDisulfide [LV,H = ( ( X I j s CHCH?].--;\Iercapt,sri hydaiitoiii (0.3 g j was dissolved i i i 10 it11 of met,hariol and added to t i sLirred solution of aii escees of 2 1 1 2 0 2 . The mixtiire was st,irred overriight at room temperatur the solveiits were removed under reditred pressure, aiid the rc dLke was estracteti three times (CEICla). The combined estrm~i were dried (?;a2Y01) :iiid the solvcnts were removed t>o give :I white solid (0.35 g, ioc;),mp 16
Acknowledgment.--lye gluclly ~ickiiowlctlgev:du:ik)l(~ tarico hy 3 1 ~ Cathcriiie . 73illo1i, 1io1i:ilcI J:wviiien, :hiid Steplicii I;inc.
