354 



DESCRIPTIONS OF ANTIBIOTICS 



Na^COs solution acidified to procipitate anti- 

 biotic. 



Chemiial and phi/sical properties: Dark red 

 powder. Gradual darkening hut no melting point 

 up to 300°C. Red in acidic solution, blue in al- 

 kaline. Blue form: Soluble in water, but rapidly 

 destroyed under these conditions. Red form: Insol- 

 ulile in water. Soluble in ethylene glycol, mono- 

 methyl ether, ethyl ether, acetone, acetic acid, 

 and various alcohols. Ultraviolet al)sorption spec- 

 trum maxima at 235, 540, and 580 m/x, or at 525 

 niju (concentrated H2SO4). Reddish violet in con- 

 centrated H2SO4 . Ethanolic solution becomes 

 amber on addition of alcoholic FeClg . Alcoholic 

 solution stable at 70°C for 10 minutes at pH 4.5 

 to 9.3. Least stable at alkaline pH. N = >1 per 

 cent (Kjeldahl and Dumas). Reduced by zinc 

 dust with heating in presence of acid or base; 

 cooling restores color, indicator properties, and 

 antibiotic activity. No reaction with zinc dust at 

 room temperature or in absence of acid or base. 

 Decolorized to yellow by sodivun hydrosulfite ; 

 reversibly oxidized to red by air. Not affected by 

 sodium bisulfite. 



Biological activity: Active on gram-positive l)ac- 

 teria. Slightly active on mycobacteria. Not active 

 on gram-negative bacteria or fungi. Not active in 

 mice against Staph, aureus infections. 



Toxicity: Mice tolerate 25 mg per kg intraperi- 

 toneally, and 200 mg per kg subcutaneously. 



Reference: 1. Shockman, (!. and Waksman, S. A. 

 Antibiotics & Chemotherapy 1: 08-75, 1951. 



Rhodomycins 



Produced by: Streptoinyces purpurcxscens cul- 

 tures, which also produce isorhodomycin A (2, 7, 

 9); S. cinereoruber (9). 



Remarks: It was found that the biologically 

 active chromophores of the various rhodomycins, 

 as well as other related chromophoric moieties 

 which were l)iologically inactive, exist in the my- 

 celium and culture-filtrate in greater quantities 

 than the antibiotics themselves (7). It was also 

 found that true »S. purpurascens strains produce 

 the glycoside of /J-rhodomycinon {i.e., rhodo- 

 mycin A) as the major component, and the glyco- 

 sides of a-, 7-, 6-, and e-rhodomycinons in only 

 minor amounts. On the other hand, strains of S. 

 cinereoruber produce the glycosides of both /3- 

 and 7-rhodomycinons as the major components, 

 with the latter often in greater ciuantity than the 

 former; a-rhodomycinon is occasionally fo\ind 

 in small quantities, but 5- and e-rhodomycinon 

 are usually absent from these broths (9). 



Method of exlractiati : Rhodomycin (■(implex: I. 



Concentrated l)roth-filtrate extracted with ether 

 at pH 3.0. Aqueous phase passed through a Le- 

 watit KSN column (Na"^ form), h^luted with am- 

 monia-methanol. Eluate neutralized, and concen- 

 trated in vacuo. Residue taken up in water and 

 jjrecipitated as the picrate (7). II. Impurities 

 precipitated from concentrated culture-filtrate by 

 addition of acetone and basic lead acetate. Fil- 

 tered. Filtrate extracted with l>utanol at pH 8.6. 

 Re-extracted into 10 ])er cent acetic acid. Precipi- 

 tated as the picrate (4). Rhodomycin A: b)ry, 

 finely pulverized mycelivun exhaustively extracted 

 with 0.5 A'^ HCl -containing acetone. Extract neu- 

 tralized, concentrated in vacuo, then successively 

 extracted with ether. Aqueous acetone phase 

 adjusted to pH 8.5, treated with a concentrated 

 methanol-lead acetate solution, centrifuged, and 

 the supernatant extracted with chloroform- 

 ethanol (3:1). Extract evaporated in vacuo. Resi- 

 due distributed i>etween butanol and pH 5.8 phos- 

 phate buffer to give major Fraction A and minor 

 Fraction B. Fraction A crystallized as red needles 

 from isopropanol-ethanol (1:1) on the addition of 

 a drop of concentrated HCl. Further purification 

 by countercurrent distril)ution (butanol-pH 6.0 

 ])hosphate buffer). Active fraction then separated 

 into rhodomycin A, isorhodomycin A, and a third 

 zone containing rhodomycin B, isorhodomycin B, 

 and rhodomycinons, by ring paper chromatog- 

 raphy [(10 per cent acetic acid (stationary phase) 

 and butanol saturated with 10 per cent acetic acid 

 (mobile phase)]. Zones cut apart and eluted with 

 methanol-water. Eluates concentrated in vacuo, 

 taken up in chloroform-methanol (4:1) and evap- 

 orated in vacuo. Rhodomycin B: Cultvu'e-filtrate 

 adjusted to pH 8.5 and stirred with chloroform- 

 methanol (5:2). Chloroform phase concentrated 

 //( vacuo. Concentrate extracted with 10 per cent 

 acetic acid. Extract shaken with ether, adjusted 

 to pH 8.5, and treated with lead acetate to precipi- 

 tate impurities. Filtrate adjusted to pH 8.5 and 

 extracted with chloroform-ethanol (4:1). Purifica- 

 tion of concentrated extract by ring paper chro- 

 matography (formamide-butanol, 1:1) and enough 

 water to give two phases. The upper phase is 

 mobile; the lower, stationary. Five zones are 

 obtained, corresponding to isorhodomycin A, 

 rhodomycin A, isorhodomycin B, rhodomycin B, 

 and rhodomycinons. Paper stri]) containing rhodo- 

 mycin B eluted with chloroform and i)recipitated 

 as the hydrochloride (3, 6, 7). 



Chemical and physical properties: Rhodomycins 

 are glycosides of rhodomycinons a, /3, 7, 5. and e 

 (9). Complex: Dark red powder. At pH 8.6 (isoelec- 

 tric point of the rhodomycin complex), soluble in 



