spectra of 2,3,4,7-tetrarnethoxy-!)-(@-hydroxyethyl)-fluorene (ITA) [ni. p. 100-101 *; -4nnZ. Calcd. for C19Hz206: C,69.07; H, 6.71, Found: C, 69.05; H, 6.74) and 2,3,4,7-tetramethoxyfluorene (IIB) (m. p. 9T-97.5'; A n d . Calcd. for CI7Hl8O4:C, 71.31; HI 6.34. Found: C,'71.30; I-I, (i.65) are included for comparison. There is a considerable body of evideiice"' indicating that non-planarity in biphenyls, induced by blocking effects of substituted groups, results in decreased and changed absorption characteristics over the range 210-300 nip. lTeryfew compounds related to IC are dvailable for study, but the spectral characteristics found here in the colchinol series suggest that the threemembered bridge does not introduce a major hindrance to the assumption of co-plmaritv by the A-C rings in the colchinol series.
hepatoma kindly supplied by Dr. Julius White of the National Cancer Institute. The pertinent data as given in Table I suggest that i itty acid oxidation may represent a major source of energy in tumors. TABLE I ACETIC ACIDS BY &'OWE TUMORS i n vitro Approximately 2 g. of tumor slices was used in 20 ml. of Ca-free Ringer phosphate. Experiments run 3-3.5 hours in oxygen a t 38' O Y I D A T I O N O F PALMITIC LVD
Tissue
Respiratory COza Relative (rM. sp Act.
Substrate
Palmitate, 450 4.5 0.001 M 300 4.4 0.01 M Acetate, COOHlabeled 320 12.5 0.01 M Acetate, CHsFollowing the submission of thi., communication, Kapo300 14.8 labeled port, Willianis and Cisney confirmed Cook's structure for Palmitate, 0.001 M 250 6.7 dihydrodeaniinocolchinol methyl ether by synthesis, ab- Khabdomyosarstract 59, Division of Organic Chemistry, Phila Meeting of coma 0.01 M Acetate, COOHthe American Chemical Society, April 9-14, 1950 Irl pre210 4.0 labeled senting the paper, Dr. Rapoport announced concluiions on 0.01 iM Acetate, CHAthe basis of spectral data that racemic colchinol methyl labeled "10 4.4 ether had been synthesized and except for configuration was identical with the n:ituril nutpri,3l Palmitate, 212 7.0 liver SMITH, KLISRA N D X HORO~YI I zli 0 001 31 42.; 7 5 kidney FRENCH LABORATORIES G. E VLLIOT * Relative specific activity is defined as: ( 5 I x t . of UNIVERSITY OF PENNSYLVAVIA E. C. HORNINC resp. C02 (measured as BaC03) X lOO)/(sp a c t OF fatty PHILADELPHIA, PRSN.4 11.G. HORNIXG .icid (measured as BaCOs)). J. K O O ' ~ bf. S. FISHi3 TABLE I1 J A PARKER'+ 3 . br.4LKERI3 ACTIVITYOF QUINIDINECITRATE RECEIVED APRIL6 , 1950 Evperimental conditions as in Table I. Activities are counts per minute per 5 sq. cm. dish a t "infinite thickriess." (10) (a) Pirkett, Croth, Duckworth and Cunliffe, THISJ O U R N A L Approximately 100 nig. of carrier citrate added in each 72, 44 (1950), (b) O'Shaughnesay atid Rodehush, rbrd , 62, 2906 ryperirnent (1940), (c) Williamson and Rodebu4i. r b r d 63, 3018 (1911), r l ) Jones, rbtd , 63, 1658 (1941) (11) Research Associate (12) American Cancer Society Postdoctoral Fellow (13) American Cancer Society Research Assistant f 14) Natioiial Institute> of Health Predoctoral Fellov
OCCURRENCE OF THE CITRIC ACID CYCLE I N TUMORS'
Sir: In a survey of possible substrates which may contribute to the respiration of tumor tissues it has been found that fatty acids, such as palmitic or acetic, are oxidized by surviving slices of tumors about as readily as they are by normal tissues. The procedure used was to measure the radioactivity of the respiratory carbon dioxide produced by the tissue in the presence of 0.001 M sodium palmitate labeled in the carboxyl carbon with C14, as described previously for normal tissue.' The results apply to three transplanted mouse tumors: a rhabdomyosarcoma and a cinoma, both of which have ely in this IriStitute; and a (1) hided by @&fits frrm the ?J. S. Atomic Energy Commission, the American &Wrf Societg a d the U.S.Public Health Wtrice. (0) Weinb.e#a;a, %hih#t.lilg W-14, J , B i d . Ck*n*., W 181 t 8980) I
Hepatoma Mammary carcinoma
1 umor
Substrate
Mammary adenocarc1nom.t Hepatoma
Acetate Pdlmitate Palmitate
Quinidine lsstimated citrate activity of 4ctivity metabolic Amt. cts / citrate mg min. Counts/iniu
151 213 133
293 74
4 X 10' 1 X 10-
138
The citric acid cycle is the only process now known for the complete oxidation of fatty acids in normal tissues. Confirmation for the occurrence of this process in these tumors was obtained by isolating pure, radioactive quinidine citrate as a product of the oxidation of the labeled fatty acids (Table 11). In the experiments with the mammary tumor 0.2 M trans-aconitate was added to cause accumulation of citrate3; in the experiment with hepatoma 0.01 M citrate was added to "trap" metabolic citrate. From the amounts of citrate expected in the presence of trans-aconitate and the amount of camer added, it can be estimated that the metabolic citrate was of high specific activity and could have arisen (3) Advantage was taken ofthe observation of Saffr8n and Prado, J . Biol. Chcm., 180,1301 (1949), t h a t trans-aconitate is un Inhibitor of aconiwse 8nd causes accumulation of citrate in respiring tissues I% atro. T his procedure has provided f u r t h a evidence for the mkic acid cy& In turnere, and will be reported scpsratelj.
Sept., 1950
COMMUNICATIONS TO THE EDITOR
4333
of cis-aconitate by increase in absorption of light a t 240 mp, using a Beckman spectrophotometer. The assay was made in a quartz absorption cell containing phosphate FROM THE LANKENAU HOSPITAL buffer, PH 7.4, 0.05 M,citrate, 0.03 M , and tissue extract RESEARCH INSTITUTE AND in a total volume of 3 ml. The extract was prepared by THEINSTITUTEFOR homogenizing the tissue with 20 volumes of 0.1 M phosCANCER RESEARCH; AND THE phate buffer, PH 7.4, and centrifuging off the residue. A DEPARTMENT OF CHEMISTRY SIDNEY WEINHOUSE unit of enzyme activity is the amount producing a change TEMPLEUNIVERSITY RUTHH. MILLINCTON in optical density a t 240 mp of 0.001 per minute a t 25”. PHILADELPHIA, PA. CHARLES E. WENNER Isocitric dehydrogenase was determined on extracts of acetone powders by the optical method of Mehler, et a1.,6 RECEIVED JULY27, 1950 a unit of activity being defined as the amount required t o produce a change in optical density of 0.01 per minute a t 25’. Citrate formation in complete system without ENZYMES OF THE CITRIC ACID CYCLE IN tissue was 0.21 pM. Citrate content of all tissues was TUMORS’
