DKSCniIPTIONS OF ANTIBIOTICS 



258 



;uitil)io(i<- 106-7 (22), ;uitil)iotic PA 94, seromycin, 

 ami antibiotic JN 21 (35). 



Method of extraction: I. Ads()rl)e(l from culture- 

 filtrates on Dowex 2 (OH" form) or other strong 

 basic anion exchange resin and fluted with dilute 

 sulfuric acid. Eluate decolorized with charcoal at 

 pH 7.0. Cycloserine precipitated as the silver salt 

 on addition of silver nitrate at pH (15. Converted 

 to the base by decomposing an aqueous solution of 

 the salt with dilute HCl, and freeze drying. Crys- 

 tallized from water with alcohol or acetone (9, 35, 

 3(3). II. Broth clarified with charcoal, adjusted 

 to pH 1.5 to 3.0, and adsorbed on IR-120 (OH" 

 cycle). Elution with 0.1 to 0.2 N NH4OH. (a) 

 Chromatographed on Amberlite XE-98 (()H+ 

 form) and eluted with 0.3 A^ acetic acid. Eluate 

 treated with charcoal, adjusted to pH 10.0 to 10.5, 

 concentrated, and treated with isoproi)anol, 

 ethanol, or acetone to separate out impurities. 

 Adjustment of supernatant to pH 6.0 with acetic 

 acid and cooling precipitated cycloserine. Crys- 

 tals dissolved in water and adjusted to pH 12 

 with KOH. Solution treated with ethanol and iso- 

 propanol and mixture filtered. Filtrate cooled, 

 atljusted to pH 5.8 with glacial acetic acid to re- 

 l)recipitate cyclo.serine (8, 23). (b) Chromato- 

 graphed on alumina with 50 per cent methanol as 

 solvent and developer. Concentration first precipi- 

 tates impurities, then cycloserine. Recrystallized 

 from hot methanol or from water on addition of 

 ethanol (2). 



Chemical and phi/sical properties: Amphoteric 

 substance (0, 20). Fine white needles; m.p. 153- 

 156°C (decomposition) (5, 6, 8, 9), or 149-150°C 

 (29). Sulilimes in vacuo at 100°C (35). Very soluble 

 in water; soluble in methanol; slightly soluble in 

 acetone; very slightly soluble or insoluble in most 

 other organic solvents (2). Ultraviolet absorption 

 spectrum maximum at 22(5 m/x iEilm 402) (water, 

 jjH G.O) (8). Infrared spectrum given in references 

 1, 9, and 20. [a]f;^ = +112° (c = 5 per cent in 2 N 

 NaOH). [a]546i = 137° ± 2° (c = 5 per cent in 2 

 A^ NaOH). pK,^ = 4.4 to 4.5 and 7.3 to 7.4 (8, 9, 

 20). Exists in solution as a dipolar ion (9). Positive 

 FeCl.j test (2). Green color with cupric ions in 

 aqueous solution; reddish l)rown with iron; bio- 

 logical activity destroyed in Ijoth cases (35). De- 

 composes in glacial acetic acid (22). Rf = 0.4 (80 

 per cent ethanol-water), producing a brown-yel- 

 low color with ninhydrin. Highly dif'fusil)le (3). 

 Stable to heat (2). Stable to alkali; unstable at 

 acid or neutral pH (5). Crystallographic data 

 on the anhydrous and hydrous forms given in 

 reference 22. C = 35.4%; H = 5.98%; N = 26.9%,. 

 Equivalent weight, 101 to 104. Structural formula, 

 D-4-amino-3-isoxazolichnone (C-sHeNaOs) (8, 9) is 



given in Chapter 6. Prolonged acid hydrolysis 

 yields DL-serine and hydroxylamine. In solution, 

 cyclo.serine dimerizes to 2,5-bis(aminoxymethyl)- 

 3,6-diketopiperazine; m.p. 190-200°C (decomposi- 

 tion) (8). Calcium salt: m.p. 215--221°C (decom- 

 position) (8, 22). Macjnesiuni salt: m.p. 224-228°C 

 (22). Silver salt: Square platelets (35). Cycloserine 

 and some of its analogues have been synthesized 

 (10, 30). L-4-A)nino-3-isoxazolidinone: m.p. 148- 

 149°C. [alf = -119° (c = 1 per cent in water) (29). 

 D-1 -Cycloserine (racemic): m.p. 136-137°C (29). 



Biological activity: In vitro: Very limited (6.25 

 to 500 fig per ml) activity on gram-positive and 

 gram-negative bacteria. Most active on mycobac- 

 teria at pH 6.4 to 7.0. Activity otherwise unaffected 

 in a range of 4.5 to 8.0. Not active on fungi (4, 11, 

 14, 15). Active on bacteria-free Endamoeba histo- 

 lytica; 'loofh as active on E. histolytica in bac- 

 teria-containing cultures (25). Competitively 

 inhibits the growth factor for mycobacteria, myco- 

 bactin; cycloserine contains an iso-oxazole ring, 

 mycobactin an oxazole ring (7). Reversibly and 

 noncompetitively inhibits catalase activity in 

 mycobacteria, as well as purified beef liver cata- 

 lase. Also blocks purified peroxidase and the 

 peroxidase activity of tubercle bacilli (39). Block- 

 ing the amino group destroys the activity on E. 

 coli (32). In vivo: More active in vivo than could 

 be expected from in vitro tests. Active in mice on 

 infections caused by Hurrelia n(n'yi , Staph, aureus, 

 K. pneumoniae, Sal. schottmuelleri, E. coli, Ps. 

 aeruginosa. Streptococcus pyogenes, and D. pneu- 

 moniae (4). Active in mice, but not in vitro, on 

 Nocardia asteroides (37). Moderately active on 

 mouse leprosy (33). Active against tuberculosis 

 in monkeys, but has limited to no activity in mice, 

 guinea pigs, and rabbits because of differences in 

 attainable blood levels of the drug (16). Slightly 

 active in mice and eggs on Rickettsia )nooseri , and 

 in eggs on feline pneumonitis. Not active on SK 

 encephalomyelitis or swine influenza virus. Not 

 active in vivo on protozoa, except slightly on Plas- 

 modium, gallinaceuni (chickens) and Endamoeha 

 histolytica (rats). No anthelmintic activity (4). 



d- Versus I- and h'acemic Cycloserine 



d-Cycloserine is most active on bacteria; 1-cy- 

 closerine is almost inactive. The racemic mixture 

 has activity equal to the d-form, although it 

 contains only 50 per cent of tlie d-form (26). 1-Cy- 

 closerine is twice as active as the racemic mixture, 

 and 10 times as active as d-cycloserine against 

 human strains of M. tuberculosis (27). The race- 

 mate is more active than either the d- or 1-form 

 against pnevmiococcus type I, but not against Sal. 

 enteritidis (30). The racemic form is more active 



