2()t) 



DESCRIPTIONS OF ANTIBIOTICS 



acetate removed by distillation in vacuo. Salted 

 into acetone at pH 10 and precipitated from ace- 

 tone by addition of water. Crystallized from ace- 

 tone as a mixture of A and B. Mixture dissolved 

 in an aqueous solvent at pH 1.4. Standing at this 

 pH for 40 minutes destroys A. B is precipitated 

 on addition of NaOH, crystallized from water- 

 acetone, and recrystallized from dry acetone (7). 



Chemical and physical properties: Basic sub- 

 stance. Rectangular plates; m.p. 198°C or 201- 

 203°C (uncorrected). Soluble in ether, acetone, 

 chloroform, ethyl acetate, and benzene. Sparingly 

 soluble in water. Ultraviolet absorption spectrum 

 maximum at 289 niju {E = 36.4). Infrared spectrum 

 given in reference 2. [a]f = — 78° (c = 2 per cent 

 in ethanol). pKa' = 8.8. Molecular weight, 730. 

 More stable to acid than erythromycin, a property 

 which permits their separation. Rf = 0.6 (metha- 

 nol-acetone-water, 19:6:75); erythromycin Rf = 

 0.7. Water-soluble acid salts: Hydrochloride, m.p. 

 149-150°C; Stearate, m.p. 54-57°C. Base: C^v- 

 H„NO,., : C = 62.08%; H = 9.56%; N = 1.99%; 

 C— CH, = 14.61%; O— CHs = 4.79%. Mild acid 

 hydrolysis products include: neutral oil, cladinose, 

 C8H16O4 , and two crystalline bases, one optically 

 active, C29H56NO9 (m.p. 119-121°C), and the other 

 optically inactive, C29H51NO8 (m.p. 239-240°C). 

 Strong acid hydrolysis produces desosamine, 

 CsHnNOs . Structural formula of erythromycin B 

 (1, 2, 4, 6, 7) given in Chapter 6. 



Biological activity: Qualitatively, B has the same 

 antimicrobial activity as erythromycin, but is 

 only 75 to 85 per cent as active quantitatively. 

 Cross-resistance exists between A and B. Resist- 

 ance to B develops more readily than to A (2, 5). 



Toxicity: Twice as toxic as erythromycin (3). 



References: 



1. Pettinga, C. W. et al. Abstr. 124th Meeting 



Am. Chem Soc. 47 O, 1953. 



2. Pettinga, C. W. et al. J. Am. Chem. Soc. 



76: 569-571, 1954. 



3. Sylvester, J. C. and Josselyn, L. E. Antibi- 



'otics Ann. 283-285, 1954-1955. 



4. Clark, R. K. and Taterka, M. Antibiotics & 



Chemotherapy 5:206-211, 1955. 



5. Grundy, W. E. et al. Antibiotics & Chemo- 



therapy 5: 212-217, 1955. 



6. Wiley, F. F. et al. J. Am. Chem. Soc. 79: 



6070-6074, 1957. 



7. Denison, F. W. et al. U. S. Patent 2,834,714. 



May 13, 1958. 



Erytliromyciii C 



Produced by: Streptomyces erythreus. This cul- 

 ture also produces erythomycins A and B. 



Method of cctracliun: Broth-filtrate extracted 

 with chloroform at pH 9.75. Extracts concentrated 

 in vacuo and chilled to precipitate erythromycin 

 and erythromj'cin B. Supernatant dried in vacuo, 

 dissolved in upper phase of an equilibrated methyl 

 isobutyl ketone -0.1 A' sodium phosphate buffer 

 (pH 6.5)-acetone system (20:20:1) and subjected 

 to countercurrent distribution to separate C from 

 erythromycin. Active fractions containing C ad- 

 justed to pH 9.75 and extracted with chloroform. 

 Extract dried over anhydrous Na2S04 , filtered, 

 and concentrated in vacuo to precipitate C. 



Chemical and physical properties: Basic sub- 

 stance. Needle-shaped crystals; m.p. 121-125°C. 

 Can be separated from erythromycin by chroma- 

 tography' on cellulose, developed with 0.01 A' 

 NH4OH saturated with methyl isobutyl alcohol. 

 Soluble in chloroform, acetone, and ether. Rela- 

 tively insoluble in water. pKa' = 8.5. Ultraviolet 

 absorption spectrum maximum at 292 ni/i (E = 

 108). Infrared spectrum given in reference 1. 

 CseH^jNOu : C = 59.75%; H = 9.10%; N = 

 1.95%; O = 29.49%. Molecular weight, 730. Acid 

 methanolysis yields erythralosamine and a neutral 

 sugar, C7H14O4 . Although this formula is the same 

 as that of mycarose from carbomycin, the two 

 sugars are not the same. Erythromycin C differs 

 from erythromycin by the absence of the meth- 

 oxyl group in cladinose (see Chapter 6) . 



Biological activity: Similar to erythromycin and 

 erythromycin B. 



Reference: 1. Wiley, P. F. et al. J. Am. Chem. 

 Soc. 79: 6074-6077, 1957. 



Etaniyciii (Viridogrisein) 



Produced by: Streptomyces sp. resembling S. 

 lavendulae (1), S. griseus (2, 5), and S. griseoviri- 

 dus (5). 



Synonyms: Antibiotic K 179 (11), viridogrisein. 

 Possible synonym: antibiotic 6613 (12, 13). 



Remarks: Etamycin contains four amino acids 

 not previously found in nature (9). 



Method of extraction: I. Broth extracted with 

 methyl isobutyl ketone or ethylene dichloride. 

 E.xtract concentrated and: (a) concentrate added 

 to 10 volumes of Skellysolve B, which forms a pre- 

 cipitate of crude etamycin. Crude etamycin dis- 

 solved in acetone and jjrecipitated as the hydro- 

 chloride; or (b) chromatographed on alumina 

 adjusted to pH 5.0 to 7.0 with HCl. Eluted with 50 

 per cent ethyl acetate, 40 per cent methanol, and 

 10 per cent water. Purification bj^ countercurrent 

 distribution (benzene-methanol-water-n-heptane- 

 (Na)2S04 , 7:10:6:6:0.125 by weight with respect 

 to water) (1, 2). II. Precipitates almost quanti- 



