VOl. 78
G. I. Poos AND L. H. SARETT
4100 [CONTRIBUTION FROM T H E
RESEARCH LABORATORIES OF THE
CHEMICAL
DIVISIONO F MERCK& CO.,
INC.]
Synthesis of a Tricyclic Analog of Cortisone BY G. I. Poos
AND
L. H. SARETT
RECEIVED FEBRUARY 27, 1956 T h e conversion of tricyclic methyl hydroxy ketone I in ten steps t o the open D-ring arialog XIV of cortisone propionate is described. Biological tests failed to show appreciable cortisone-like activity for XIV.
The goal of a number of investigators' in the hydroxyl group of this diol proved to be somewhat past few years has been the preparation of a simple difficult. Several of the conditions normally used analog of an adrenal steroid hormone which might to methylate sugars (silver oxide-methyl iodide show the biological activity of the natural material and sodium hydride-methyl sulfate) failed to give after which it was modeled. Although very weak appreciable yields of ethers. When I11 was heated life maintenance activity has been claimed for with potassium in benzene and then treated with benzoylcarbinol and several dibenzyl deriva- methyl iodide,8 a mixture of 1-monoether IV (3 tives,'"sb and certain cyclic glycoloylcarbinols parts) and 4-monoether V (2 parts) was obtained show deposition of liver glycogen a t very high dose along with either unchanged diol I11 or the dilevels,'" there seems to be no evidence that any of methyl ether VI, depending upon the conditions. the numerous synthetic analogs that have been Alumina chromatography served to separate the prepared' have more than a faint trace of adrenal products in a satisfactory manner. The least polar bis-ether VI was eluted first followed by the cortical hormone activity. Despite this lack of success with simple analogs, two monoethers (IV and V). On the basis of the the possibility remains that a compound more expected lesser polarity of the 4-hydroxy than the ~ desired 1-methyl ether closely related in structure to the adrenal cortical 1-hydroxy g r o ~ p ,the hormones than those heretofore prepared might structure IV seemed likely for the monoether first have appreciable biological activity. The high eluted. Attempted acetylation of the latter subestrogenic potency of the open D-ring doisynolic stanee with acetic anhydride in pyridine returned acids2 suggested that a completed steroid D-ring 97% of the starting compound, while under similar might not be necessary for hormonal activity. conditions both diol I11 and monoether V were conWe decided accordingly to investigate the syn- verted to the 1-acetates. Thus the less-polar thesis of structure XIV, an open D-ring analog very monoether must be compound IV. Conversion of the allyl side chain in IV to a disimilar to cortisone and yet reasonably easy to prepare from our steroid total synthesis3 interme- hydroxy acetonyl group was carried out as follows: selective hydroxylation of the terminal double bond diates. Alkylation of methyl hydroxy ketone I* with of IV with osmium tetroxide provided a mixture allyl iodide proceeded in the same manner as with of stereoisomeric glycols VII. This mixture was methallyl iodide5 to yield 2P-methyl-2cu-allyl hy- subjected to acylation with a limited amount of droxy ketone II.6 Sodium borohydride reduction propionic anhydride in a mixture of benzene and of the latter provided a good yield of the corre- pyridine a t room temperature. Preparation of tlic sponding 1/3,4P-diol 111.' Methylation of the C1- propionate was chosen in order to augment selective acylation of the primary hydroxyl group atid (1) For example see (a) W. H. Linnell and 1. M. Roushdi, Quart. J . Pharm., 14, 270 (1941); Nature, 148, 595 (1941); (b) G . Brownlee a t the same time yield a final product that couIJ be and W. M. Duffin, British Patent 550,262, May 14, 1942; U. S. Patent tested biologically as the ester. There was ob2,376,415, May 22, 1945; (c) L. Long and A. Burger, J . Org. Chem., 6 , tained a mixture that was separated chromato852 (1941); (d) J . Walker, J . Chem. Soc., 347 (1942); (e) W. C. J . Ross, ibid., 538 (1945); (f) G . P . Hager and H . A. Shonle. THIS graphically into 25% of a diester fraction and 65% JOURNAL, 68, 2167 (1946); (g) G . P. Hager and R . M. Burgison, J . Am. of a monoester fraction (VIII). The latter, withPharm. Asrn. Sci. E d . , 39, 7 (1950); (h) A. L. Wilds, et al., THIS out further purification, was oxidized with the JOURNAL, 71, 2132, 3946 (1949); 72, 2388 (1950); 76, 1733, 1737 chromium trioxide-pyridine reagent Chroma(1954); (i) D. R. Satriana, A. Loter and M. M. Baizer, ibid., 73, 866 tography of this product yielded 45y0 of ketol pro(1951); (j) K. Rorig. Abstracts of Papers, 119th Meeting, Am. Chem. SOC.,Boston, Mass., April, 1951, p. 2 0 M ; (k) J . H. Burckhalter, et ai., pionate IX along with 2OY0 of a non-reducing more THISJ O U R N A L , 74, 187 (1952); 76, 4112 (1954); (I) D. Papa, H. F. polar mixture that appeared to be incompletely Ginsberg and F. J. Villani, ibid., 76. 4441 (1954); (m) G . W. Stacy, oxidized. Reoxidation of the latter substance proR . A. Mikulec and L. D. Starr, Abstracts of Papers, 128th Meeting, vided an additional 15% of IX. Compound I X Am. Chem. Soc., Minneapolis, Minn., Sept., 1955, p. 49-0; (n) J. D. Billimoria, et ai., J . Chem. SOC.,2626 (1953); 3257 (1954); 1126 (1955). reduced blue tetrazolium reagent and showed infra (2) L. F. Fieser and M. Fieser, "Natural Products Related t o absorption bands a t 5.75 p (propionate carbonyl), Phenanthrene," Reinhold Publ. Corp., New York, N. Y.,1949, pp. 5.8 . p (ketol carbonyl) and 5.87 p (4-carbonyl). 346-354. (3) G. I. Poos, R . M. Lukes, G. E. Arth and L. H. Sarett, THIS Mild acid hydrolysis of I X gave X , the open DJOURNAL, 76, 5031 (19541, and references therein. ring analog of 11-dehydrocorticosterone propi(4) R . M . Lukes, G. I. Poos, R. E. Beyler, W. F . Johns and L. H . onate. With hydrogen cyanide, IX was converted Sarett, ibid., 'IS, 1707 (1953). (5) L. H. Sarett, W, F. Johns, R. E. Beyler, R . M. Lukes, G. I. Poos in excellent yield to the corresponding cyanohydrin and G. E. Arth, ibid., 7 6 , 2112 (1953). XI. Dehydration of the latter led to qp-unsatu(6) This compound was first prepared by Dr. W. F.Johns in connection with some earlier work in these laboratories. (7) A 1p (equatorial) configuration was assigned to the new hydroxyl group by analogy with results of lithium aluminum hydride reduction of the C-1 keto group in a related tricyclic hydroxy ketone; G. 1.
Poos, G . E. Arth, R. E. Beyler and L. H. Sarett, THISJ O U R N A L , 76, 422 (1953). (8) J. R . Lewis and C. W. Shoppee, J . Chem. S O L ,1375 (1955); Chemistry and Industry, 897 (1953).
Aug. 20, 1956
I
SYNTHESIS OF A
IX
VI11
XI
4101
IV
XI11
I
C=O
OP
Ud /
XIV
rated nitrile XI1 (55%) which was hydroxylated with potasium ~ e r m a n g a n a t e . ~As might be expected the yield of desired dihydroxy acetone derivative was low; 247, of compound XI11 was obtained. It was hydrolyzed with p-toluenesulfonic acid in acetone to produce the analog of cortisone propionate XIV. Open D-ring analog XIV was tested in the local granuloma,'Oa eosinophillOb and liver glycogenlOC assays against cortisone propionate as positive control. A weak, equivocal inhibition of granuloma formation in the local test was produced by X I V but no effect was obtained in the eosinophil and liver glycogen assays ; cortisone propionate was fully active in the same tests. The analog X of (9) R. Tull, R. E . Jones, S. A. Robinson and M . Tishler, THIS 77, 196 (1955). (10) Tests carried out by (a) Drs. C . A. Winter, (b) R. C. Mason and ( c ) C . C . Porter of the Merck Institute for Therapeutic Research.
JOURNAL,
CORTISONE
CHzOCOCzH6
I
X
VI1
XI1 CHzOCOCzHs
'd
TRICYCLIC ANALOG OF
11-dehydrocorticosterone was also tested and showed no significant activity in the same assays. This result points up further the high degree of structural specificity inherent in adrenal cortical hormone activity. In the cortisone analog, all of the functional groups are present and in the sanie general relationship as in cortisone. The stereochemistry a t all of the carbon atoms hut CZ? (CI,-steroid nomenclature) is known to he thc same as in the adrenal steroids. The ether oxygen ntorn a t C1 is in the position (p) of the steroid Clnmethylene group while the ether-methyl group can occupy the steroid Cls-position. At Cza the situation is not so straightforward since two isomers are possible and only one was obtained from permanganate hydroxylation of the unsaturated precursor X I I . From an inspection of molecular models, i t appeared that the isomer of XI1 most
4102
G. I. Poos
AND
closely related to AL7-20-cyanopregneneswas definitely favored. Hydroxylation of this isomer from the less hindered (rear) side of the molecule to produce the same configuration a t Cza as in cortisone a t Cl7 (hydroxyl a-oriented) seems probable. Thus it would appear from the bio1,ogical results that free rotation about C1 and Cz in the tricyclic analog allows a different constellation of atoms than in the more rigid tetracyclic steroid. Acknowledgment.-The authors are indebted to A h . Rae Taub for valuable technical assistance. Experimental'
L. H. SARETT
Vol. 78
Anal. Calcd. for C22H3404:C, 72.89; H, 9.45. Found: C, 72.94; H , 9.82.
Further elution with 4 : G ether-petroleum ether gave mixtures followed by 44 mg. (17%) of 4-methyl ether, m.p. 108-1 13'. A sample recrystallized from petroleum ether melted a t 112-115', showed A, 2.82 and 6.08 p and began t o melt at 95" when mixed with IV. Acetylation (acetic anhydride-pyridine, looo, 20 minutes) gave the corresponding I-acetate, m.p. 122-124', from petroleum ether; A,, 5.78 and 6.08 (weakj p . Finally, the column was eluted with ether which gave 60 mg. of impure recovered starting diol. IVhen the reaction was run using a larger proportion o f potassium (100 mg. for 200 mg. of diol) and under reflux overnight, chromatography yielded from the 1 : 9 etherether fractions 25Yc of t h e 1,4-dimethyl ether. 2p,4b-Dimethyl-2-allyl-7-ethylenedioxy-l,2,3,4,4a~~,4b ,- petroleum It was purified by recrystallization from methanol and pe5,6,7,8,10,10ap-dodecahydrophenanthrene-4p-ol-l-one (11).6 troleum ether and had m . p . 92-93', , , ,A 6.08 p . I n this -Four grams of methyl hydroxy ketone I 4 in 80 ml. of benzene was dried by distilling ca. 30 ml. of the solvent. T h e case, each of the monoethers described above was found, b u t no starting diol mas recovered. solution was cooled t o about 40" and treated with 20 mi. of Attempted Acetylation of IV.--=1 solution of 37 mg. of IV t-butyl alcohol containing 0.8 g. of potassium followed b y 3 ml. of redistilled allyl iodide. -4fter 50 minutes, the po- in 0.5 ml. of pvridine and 0.25 ml. of acetic anhydride was heated in the steam-cone for 15 minutes. T h e cooled mixtassium iodide which had separated was collected on a filter ture was diluted with water, whereupon 36 mg. of una n d washed with benzene. T h e filtrate was diluted with changed I V , m.p. 125' and 135", precipitated. ether, washed with water, dried and concentrated t o dryHydroxylation and Acylation of 1V.-The monoether ITness. Chromatography on 170 g. of acid-washed alumina (1.62 g.) and 1.26 g . of osmium tetroxide Tyere dissolved in gave 3.9 g. of crude crystalline I1 from t h e 3 : 7 ether-petro50 ml. of ether. After 2 h r . a t room temperature, the preleum ether fractions. Recrystallization from ethanol and then ether przvided 2 . 5 g. ( 5 5 % ) of allyl derivative 11, cipitated osmate ester >vas dissolved in 70 ml. of ethanol and then shaken vigorously with a solution of 14 g. of sodium m . p . 145-147 . X sample n-as recrystallized from ether sulfite in 50 ml. of water. T h e mixture was diluted to 500 2.81, 5.94, 6.07 p . for analysis, m.p. 148-150°; , , ,A ml. with ethanol and filtered. The filtrate was concenAnal. Calcd. for C21H3004:C, 72.80; H , 8.73. Found: trated in z'acuo t o a small volume and diluted with water, C , 72.68; H , 8.13. and the crystalline precipitate of VI1 was collected, washed 2p,4b-Dimethyl-2-allyl-7-ethylenedioxy-l,2,3,4,4a~~,4b,5,and dried; 1.44 g., m.p. 155-1'75'. 6,7,8,10,10ap-dodecahydrophenanthrene-lp,4p-diol(III).This crude glycol mixture (1.44 g., m . p . 155-1T5') was Five grams of methyl allyl hydroxy ketone I1 in 50 ml. of dissolved in 6 ml. of pyridine and 6 ml. of benzene containmethanol was treated with 1.0 g. of sodium borohydride. ing 0.605 g. of propionic anhydride and kept at room temAfter 1.8 h r . at room temperature, the reaction mixture was perature overnight. Ice and dilute sodium bicarbonate heated under reflux for 10 minutes. Dilution with mater solution were added, and the reaction mixture was extracted followed b y distillation of t h e methanol in nacuo provided a with ether. T h e ether solution was washed with water, suspension of crystals which were collected by filtration, dried and evaporated t o dryness. T h e 1.65 g. of residue washed with water and dried. Recrystallization from acewas dissolved in benzene and adsorbed onto 60 g . of acidtone gave 3.99 g. (8070), m.p. 191-194'. il sample re- washed alumina. II-ith ether there was eluted ,540 mg. crystallized from acetone and then ether for analysis showed ( 2 8 % ) of a dipropionate fraction. Chloroform elution prom.p. 194-195.5'; A,,,2.85,2.9 and 6.10 (weak) p . vided 1.03 g. (62yc)of crude crystalline monopropionate A n d . Calcd. for CZiH32O4:C, 72.38; H, 9.26. Found: V I I I , m . p . 90-125'. Zp,4b-Dimethyl-lp-methoxy-Z-( ~-propionoxyacetonyl)-7C , 72.28; H, 8.96. ethylenedioxy- 1,2,3,4,4a0,4b,5,6,7,8,10,10ap-dodecahydroAcetylation o f 100 mg. of I11 was carried out iii 1 nil. of phenanthrene-4-one (IX).-The entire crude motinpropiii~iyridineand 0.5 ml. of acetic anhydride on the steam-bath nate fraction above (1.03 8 . ) was dissolved in 15 ml. of pyrifor 25 minutes. The cooled mixture was diluted with water dine and added t o the complex prepared from 1 g . of cliruand t h e crystalline I-monoacetate was collected, washed and dried; 103 mg., m . p . 125-135'. T h e analytical sample mium trioxide and 10 ml.. of pyridine. After stirring a t room temperature overnight, t h e mixture was diluted with melted at 137-140' after recrj-stallization from methanol and 2C) ml. of water nnri extracted with four portions o f etlier. ether--petroleum ether; A&,, 2.82, 5.85, 6.10 (weak) p . T h e combined extract vas washed xvitli wxter and conceii.Inal. Calcti. for C?&,O:,: C, 70.74; H, 8.78. Found: trated t o dryness. Recrystallizatim of the residue from C, 71.05; H , 8.90. ether-petroleum ether, methanol, ether and chloroform2p,4b-Dimethyl-lp-methoxy-2-allyl-7-ethylenedioxy-l,2-ether gave 293 mg. (29%) of I X , m.p. 139-143'. The 3,4,4a~~,4b,5,6,7,8,10,10~@ - dodecahydrophenanthrene - 46- analytical sample melted a t 143.5-144.5' after recrj-stalli01-(IV).-The diol 111, 260 mg., was dissolved in 10 ml. of zation from ether and gave a positive reducing test with d r y benzene and t o t h e solution was added 50 mg. of potetrazolium reagent; A,,, 5.75, 5.81 and 5.87 p . tassium metal. The mixture was heated under reflux with A n a l . Calcd. for C<iOi: C, 00.94; H , 8.09. Found: rapid stirring for 1 h r . and then was cooled t o room temperaC, 66.50; H , 8.21. ture atid treated with 0 . 5 nil. o f methyl i(idide. The r w c ticin mixture W:LS stirred a t room ternpenture for 3 hr., and Clironixtograpliy o f the remainitig inaterial gave firat 2iO then excess potassium was destroyed by the ctddition of ethanol. The reaction mixture was distributed between m g . of crude I S which after recrj-stullization ainouiited t o water and ether, and the aqueous phase was extracted wit11 179 mg., m . p . 142-144.5', bringing the yield of 1X to 472 mg. (46%). Following IX was 325 mg. of a more polar ether. Tlic combined ether solution n-as washed with substance which failed to give a reducing test. It was rewater, dried and concentrated t o dryness under vacuum oxidized and the product chromatographed t o provide ail t o vield 270 mg. of a yellow gum. T h e entire residue was dissolved iii 25 mi. of 1:9 ether-petroleum ether and ad- additional 144 mg. of I X , m.p. 142--144', total yield 616 mg. (60%). surbed onto 11 g. of acid-washed alumina. Elution with 2~,4b-Dimethyl-lg-methoxy-2-(y-propionoxyacetonyl)-l ,2,2 : 8 , 3 : 7 and 4:G ether-petroleum ether gave 150 mg. of 3,4,4aa,4b,5,6,7,9,10,lOapdodecahydrophenanthrene - 4,7crude crystalline I-methyl ether IV which after recrystallization from petroleum ether amounted t o 108 mg. (40Y0), dione (X).-To 22 mg. of I X in 1 ml. of acetone was added m . p . 121-124' and 136-137'. Several recrystallizations 5 mg. of p-toluenesulfonic acid. T h e solution was kept overnight a t room temperature, water was added, and the from petroleum ether provided a sample with m . p . 125.product was extracted with chloroform. The dried cx126' and 135-137'; A,, 3.08 and 6.09 p . tract was concentrated t o dryness and the crystalline residue recrystallized from ether; 18 mg., m . p . 167-169c; A,,;, 5.7:j ( I I ) Melting points were determined o n a Kofler micrn hot-stage a n d infrared qpectra are of t h e crystalline solids in S u j r B l . (shoulder), 5.78, 5.86, 6.03 ant1 6.18 p .
-lug. 20, 1936
COMPOSITION OF FATTY ACIDSFROM BLOODLIPOPROTEIN FRACTIONS
4103
A n d . Calcd. for C ~ ~ H ~ 2 0C,6 :68.29; H, 7.9i. Found: was cooled t o 0" and treated with 90 mg. of powdered poC, 67.64; H, 7.61. tassium permanganate. The mixture was stirred cold for 1 hour, allowed to Lvarm t o room temperature and treated 2@,4b-Dimethyl-lp-methoxy-Z-( ;.-propionoxy-@-hydroxywith 0.2 ml. of acetone containing 0.002 ml. of acetic acid. 8-cyanopropyl)-7-ethylenedioxy-1,2,3,4,4aa,4b,5,6,7,8,10,loa@-dodecahydrophenanthrene-4-one (XI).-.4 solution of After stirring another hour a t room temperature, the reac500 mg. of IX in 4 mi. of ethylene chloride was treated with tion mixture was rinsed into a separatory furinel with chloroform and the manganese dioxide was reduced with limited 0.07 ml. of triethylamine, 3 nil. of ether and 0.6ml. of h!.acidified sodium bisulfite solution. T h e chloroform layer drogen cyanidc. After 5 miiiutes, crystals of product began \vas separated and the aqueous part extracted with chlorot o separate. 'The tnixture xvac kept a t 0" overnight and form. To the combined chloroform \vas added 12 in].of then diluted u.ith petroleum ether to complete precipitation .iy0potassium carbonate solution and the total volunie \vah of the product uvhicli \v:ts collected, washed with petroleum reduced to rti. 20 ml. itt :'(mu). After 0.75 hr. stirring :It ether and dried; 510 mg. (96%), n1.p. 174-180" tiec. ~ v a qsepnrated, washed, 2P ,4b-Dimethyl- l p -methoxy- 2-( propionoxy - 8- cyano- 1- room temperature, the clili~rofc~rm dried a i d concentr:~tetl giving 917 mg. of :i gum, Cliromapropenyl 1- 7 - ethylenedioxy - 1,2,3,4,4aa,4b,5,6,7,8,10,IOa,cdodecahydrophenanthrene-4-one (XII).---C!.;ttiohydrin S I , tograpliy over 5 g. of :icicl-waslictl ~rlutninaprovided from 500 m g . , was dissolved in 2 . 5 mi. of pl-ridine anti treated the ethcr-chlorofcrm fractious 51 mg. of crude cryst:tlline X I I I . Recrystallization f r i m ether-petroleum ether gave with 0.25 ml. of phosphorus oxychloride. T h e reaction 29 rng. (24%j, m . p . 181-184', positive tetrazolium test; solution was kept at room temperature owrnight, ice and A,,,,, 2.9-2.95, 5.74,5.78 and 5.86 p . dilute sodium bicarbonate were added, and thc prc~duct\vas 2~,4b-Dimethyl-lp-methoxy-2-( -,-propionoxy-a-hydroxyestracted with ether. The ether solution WLS wtsheti with acetony1)-1,2,3,4,4a~,4b,5,6,7,9,10,10a@-dodecahydrophen\v;iter, dried and concentrated t o provide 1 0 X mg. o f crude anthrene-4,7-dione (XIV).-Eighteen milligrams of XI11 crystalline residue. Recrystallization from ether- petru\vas treated with a imall amount of p-toluenesulfonic arid i n leum ether gave 260 mg. (54%) of uriiaturated nitrile S I I , xcetone .It rooni temperature overnight. Recovery o f tlle m . p . 12s5-l~3110. Ether recrystallization provided purc S I I , product :is described previousl! gave 11 ing. of purc X I \ ' , i n . p . l:j4-13iio; A 4.59,5.X and 5.86 p . .t?iu/. Calcd. for CntiI-iaiOaS: C , 68.23; I-!, 7.71; S , n i .p. I X1-186" after recr?-stallizatioli from ether. I t retluced tetrazolium reagent aiitl showed A,,,:,, 2.9-2.93, ,i,74, 3.06. F o u n d : C , 67.9i;H , 7.54; S.3 2 C I . 5.78, 5.84, 6.08, 6.19, X . 1 2 a n d 9 . 1 4 p . 28,4b-Dimethyl- l&methoxy-2-( -,-propionoxy-a-hydroxy.4nu/. Cdctl. for C2311:r207: C , fj5.69; 11, 7.67. I~ouiici: acetonyl) - 7-ethylenedioxy - 1,2,3,4,4aa,4b,5,6,7.8,lO,lOa@dodecahydrophenanthrene-4-one (XIII).-.A solution of 120 C , 65.67; H ,7.55. mg. of S I 1 in 3 . 5 ml. of acetime and 0.1 ml. of piperidine KAHWAY,SEK JERSEY
-,-
LCOSTRIHUTIOS F K U X THE 1 ) U S X E R LAXORrlTORT, D I V I S I O S O F 1IEDICAL PHYSICS, A S D THE CHEMICAL L A B O K , 4 r U R Y , YSIVERSITY O F CALIFORSIA]
Composition of Fatty Acids from Certain Fractions of Blood Lipoproteins' BI- GEORGE-1.GILLIES,FRAPXT. LISDGREN ASD
JAMES
CASOK
RECEIVED FEBRL-ARY 6, 1956 The fatty acids from fractions SrO-20 and S120-400 of the blood lipoproteins have been analyzed. D a t a on t h e nlixed acids were combined with information obtained by chromatography on charcoal t o yield a n approximate composition for each lot of acids. Two significant differencesin composition were noted: ( a ) more than 207, of Ci6 monounsaturated acid (palmitolcic) is present in Fraction SIN-400, whereas this acid is either absent from Fraction S&20 or is present a t w r y ICJW abundance; (12) poly-unsaturated acids arc essentially absent froin Fraction Si30-400, whereas Fraction .Sf0-2O contains about .Cyotetra-unsaturated acid (arachidonic) and 18% di-unsaturated acid (linoleic).
Human sera contain fatty acids of a wide \.ariety, both with respect to chain length arid degree of unsaturation. Since nearly all the fatty acids found in the blood stream are present i n the form of lipoproteins, it is of interest to study the fatty acids present in some of the different classes of lipoproteins. Selected for the present study werc the SfO-20 and S$0-100 class'?lipoproteins. These classes are of particular interest for several reasons. First, 1i~)oj~roteins o f tlic .Sf124 0 0 class have hcwi showi:' t k i be inore xtlierogc.nic tliaii tliost. oi tliv .SLO - 1 L' class. ('I'hc. fractionation split a t .S f 10 or i5 a mo:ecule of the Si20 class. (3) J . T l ' Gofrnan. I3 Strison-Pr, 0.d e T.alla. A l ' ~ < r n ~ > II1 i n 11 J , , n c \ , i n t i 1. '1' 1.inriqren. l i
pholipid comprise most of the lipid present in thc StO--20 class molecules. Further, a relatioriship between these classes of molecules has been shown by i77 vii'o arid in zlitro heparin transformation stuc!ies4J which suggest that riiolecules of the S$0-400 class normally may be converted to .CrO-20 class lipoproteins during the process of fat absorption. Since the quantities of fatty acids available for iii\.cstigatiori were rather small ( 1 T O rng. i n the. CIW o f f r x . .YfO -?O'), analysis has I x ~ nbased primarily o r i a pm-tial separation acconiplisheil by chromatography on charcoal, employing thc: iriethotls described in detail in mother journal.G .inal\-ticaI d a t a on the mixed acids were coiiihincrl with the data obtained o n thc fractions froin chriiinatography in order to arrive a t the apprvxiiiiatc compositions shown in Table T. It may be noted that a significnnt difference in composition of thc tw-o fractioiis conccriis the content of poly-uri( 4 ) D. Graham, T. L j - n n , .T W. Gofmnn. H. R . Jones. A Ynnklpr. J . Sirni,ntoii a n d 5 , W h i l e , C ' i r o < l u l i o v ,4, li(i , l!l.il) '.?) 1'. 1 ' 1.induren. N I< T:reem:Ln m d n 11. (:rahain, ibicl,, 6 , 171 i i O . i 2 # n < i n t i (; .i (;ill:vs, .i. Or< i.'hr,iii , 20, I l ! ) ( I
