Sept. 5, 1955
COMMUNICATIONS TO TIIE
The calculated molar ratios of these keto-acids are : KGA:PA:DhlPA = 0.25:1.2:2.8. The accumulation of these keto-acids was not due to acidification of the media, because they also occurred in biotin-deficient culture with calcium carbonate added. On the contrary, no accumulation of keto-acids occurred in biotin-rich media, or when preformed biotin-rich mycelial felts were floated on media adjusted to PH 4.6 with phosphoric acid. I n thiamine-deficient culture, the accumulation of PA and KGA was observed but no DMPA could be found. The accumulation of DMPA is, therefore, to be attributed to biotin-deficiency. Grateful acknowledyrnent is made to Prof. S. Tanaka for his in ttrest and encouragement. DEPARTMENT OF CHEMISTRY FACULTY OF SCIENCE KYOTOUNIVERSITY HIROHIKO KATSUKI JAPAN KYOTO, RECEIVED JULY20, 1955
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attained, from which both tetracycline and quatrimycin were re-isolated. The ultra violet absorption spectra, in 0.1 N HCI, for tetracycline and quatrimycin are presented in the graph. 2.0 r-
1.5
5 9
P
s
1.0
3
< 0.5
REVERSIBLE ISOMERIZATIONS IN THE TETRACYCLINE FAMILY
Sir: 0 I I I I '.We have recently observed a reversible iso200 250 300 350 400 merization reaction creating for each of four memA, mp. bers of the tetracycline family-chlorotetracycline, Fig. 1.-Tetracycline hydrochloride, 50.0 mg./l. in 0.1 ,1' bromotetracycline, oxytetracycline, and tetraquatrimycin, ammonium salt, 50.6 mg./l. i r i cycline3-a new, isomeric substance. For each H&04--; of the four tetracycline family members above, sets 0.1 P;. HZSOr--. of conditions have been found catalyzing the formathe equilibration of either tetracycline tion of an equilibrium mixture of two components. or Similarly, quatrimycin can be accomplished in various For example, in the case of tetracycline itself, a such as formate, acetate or citrate, or in twenty-four hour aging a t 25' of a 15y0 tetra- buffers, distilled water if sufficient time is allowed. The cycline solution in 1 molar NaH2P04 in 2 : 1 meth- equilibrium can also be attained in various organic anol-water (PH about 4.6) produced an equilibrium solvent systems, as methanol. The solid mixture judged spectrophotometrically and micro- crystalline materialssuch are stable. biologically to be about a 1,5:1 mixture of tetraA similar series of observations holds for chlorocycline and its new isomer, designated quatri- tetracycline, and oxytetramycin. Quatrimycin was isolated from the equilib- cycline. Theirbromotetracycline, new isomers, chloroquatrimycin, rium mixture as the crystalline, homogeneous ammonium salt. Quatrimycin differs greatly in bromoquatrimycin, and oxyquatrimycin, are all some of its properties from the starting tetracycline. of lowered in vitro antibiotic activities and are For example, its isoelectric form is more water changed in their ultraviolet spectra in the manner soluble. Its in vitro antibiotic activity against a described for tetracycline. Preliminary animal variety of tetracycline-susceptible microorganisms work4 shows each of the four new isomers to possess is substantially less than that of tetracycline; broad in vivo antibiotic activity. (4) This work was done under the direction of Dr. J. S. Kiser, for example, toward the turbidimetric assay using E. coli, quatrimycin shows 2 4 % the activity of Research Division, American Cyanamid Company. PROCESS IMPROVEMENT DEPT., tetracycline. The possibility exists that the in CHEMICAL LEDERLE LABORATORIES DIVISION,ALBERT P . DOERSCHUK vitro activity is actually zero, with partial equili- AMERICAN CYANAMID Co., BARBARA A. BITLER bration under the test conditions accounting for the PEARLRIVER, NEWPORK J. R . D. MCCORMICK observed bioactivity, Re-equilibration of the isoRECEIVED JULY27, 1955 lated quatrimycin under the conditions used for tetracycline resulted in a reappearance of in vitro antibiotic activity and alteration in the ultraON THE STEREOCHEMISTRY OF RESERPINE violet absorption spectrum until the approximately 1.5:1 equilibrium mixture was again Sir: I n a recent communication1 we presented evi(1) The trademark of the American Cyanamid Company for chlorodence for the relative and absolute configuration tetracycline is Aureomycin. (2) The trademark of Charles Pfizer and Company for oxytetraof four asymmetric centers (15, 16, 18 and 20) in cycline is Terramycin. reserpine (I). 13) The trademark of the American Cyanamid Company for tetracycline is Acbromycin. The trademark of Charles Pfizer and Company for tetracycline is Tetracyn.
(1) P. A. Diassi, F. L. Weisenborn, C . 31. Dylion and 0. Wintersteiner, THISJOURNAL, 77, 2028 (1955).
