DESCRIPTIONS OF ANTIBIOTICS 



373 



Properties"). At thi.s point the organic solution of 

 the streptomycin-wetting agent salt may be: (a) 

 chromatographed on acid-washed alumina at pH 

 4.0 and eluted with 0.1 A" HCl in anhydrous metha- 

 nol; (b) transformed to the trihydrochloride or 

 trinitrate bj- adding the concentrated acid of the 

 salt desired, or a methanolic solution thereof, 

 along with the calcium salt of the acid. Trihydro- 

 chloride is recrystallized from aqueous solution on 

 addition of methanol or methanolic CaCl2 ; or (c) 

 transformed to the sulfate or phosphate formed by 

 adding the appropriate aqueous acid or amine salt 

 thereof. The sulfate crystallizes out of the aqueous 

 phase. The phosphate precipitates from the or- 

 ganic phase on addition of methanol (39, 59, GO). 

 inc. Precipitated as the pentachlorophenate, 

 taken up in methanol, and filtered. Fractional pre- 

 cipitation as the sulfate. Fractionally precipitated 

 from an aqueous solution of the pentachlorophen- 

 ate with aqueous sodium pentachlorophenate or as 

 the double pentachlorophenate-sulfate salt (74). 

 IV. Broth-filtrates or aqueous solutions containing 

 streptomycin adjusted to pH 12, solid NaCl added, 

 and the whole extracted with 2-aminoheptane or 

 other liquid primary alkj'l or aralkyl amines. Ex- 

 tract concentrated in vacuo, filtered, and water and 

 chloroform or amyl acetate added, the water to 

 extract the streptomycin, the chloroform or amyl 

 acetate to extract the amine. Aqueous extract 

 washed with CHCI3 and acetone, acidified, and 

 dried (37). V. Separated from mannosidostrep- 

 tomycin (occurring with streptomycin in broths) 

 by (a) the formation of the streptomycin-CaCl2 

 complex (mannosidostreptomycin does not form 

 this complex) ; (b) countercurrent distribution us- 

 ing an aqueous phase containing 0.5 per cent 

 NaHCOg and 1.0 per cent NaCl, and a solvent 

 phase containing Pentasol (mixed synthetic amyl 

 alcohols) and 5 per cent stearic acid. Active frac- 

 tions agitated with 7 A^ H2SO4 and benzene to 

 transfer streptomycin to the aqueous phase (23). 

 Other systems include: aqueous 0.125 M phos- 

 phate-0.375 M borate buffer (pH 7.15) versus 15 

 per cent lauric acid in Pentasol (24). VI. Purified 

 by stirring an aqueous solution with phenol-CCl4 

 (7:3) at pH 9.5. Back-extracted from solvent layer 

 into dilute H2SO4 at pH 6.5 (74). 



Chemical and physical properties: Strongly basic 

 substance (25). Base: Amorphous, light yellow 

 powder (9). Positive Sakaguchi, Fehling (boiling), 

 hydroxyl group, and ammoniacal AgNOs tests. 

 Negative nitrous acid, ninhydrin, Hopkins-Cole, 

 Millon, xanthoproteic, biuret, and Pauly diazo 

 tests (4, 18). Gives a garnet-red color with cold 

 alkaline aqueous sodium nitroprusside, which be- 



comes slowly pink, then yellow, on standing or 

 heating. Color is yellow in acetic acid (18). Stable 

 to moderatel}^ acidic and alkaline solutions. Maxi- 

 mal stability at pH 3 to 7 at <25°C. Solutions of 

 the sulfate show a 50 per cent loss of activity at 

 95°C for 4^2 hours (25). Aqueous acid hydrolysis 

 yields streptidine: optically inactive needles, 

 C8H18N6O4 . Streptidine sulfate: prisms; dipicrate: 

 needles or stout prisms. Both decompose with 

 charring at >250°C. Streptomycin reacts with bro- 

 mine water to give biologically inactive strepto- 

 mycinic acid, a light pink-colored amoiphous 

 product (containing 5 per cent moisture). Sinters 

 at 22G°C; m.p. 231°C (decomposition), [af^ = 

 —92° (c = 1.52 per cent in water) (5, 11). Treat- 

 ment of streptomycin with methanolic HCl yields 

 a derivative (I) of streptobiosamine , methyl strep- 

 tobiosaminide dimethylacetal, as well as strepti- 

 dine. Strong acid hydrolysis of I decomposes the 

 streptose moiet}- to yield a pentaacetyl derivative 

 of N-methyl-L-glucosamine. Mild alkaline hydrol- 

 ysis products of streptomycin include the 7-pyrone 

 maltol formed from the streptose moiety. Catalytic 

 hydrogenation yields dihydrostreptomycin {q.v.}. 

 A resume of the key steps in the determination of 

 the structure of streptomycin is given in reference 

 25, as well as in the references concerning degrada- 

 tive studies. C21H39N7O12 . Structural formula 

 given in Chapter 6. The difficulty experienced in 

 obtaining crystalline salts of streptomycin is at- 

 tributed to the fact that it exists in two tautomeric 

 forms. It is believed that only the form containing 

 a free aldehyde group may be crystallized as an 

 inorganic acid salt. The amorphous and crystalline 

 forms of the various salts of pure streptomycin 

 differ very little in physical properties (59). Tri- 

 hydrochloride (dihydrate) : Monoclinic prisms. 

 Decomposes gradually without melting (17). Sol- 

 uble in water and methanol. Slightly soluble in 

 ethanol (15). Insoluble in ether, chloroform, bu- 

 tanol, pyridine, and acetic acid (4, 15). Only end- 

 absorption in ultraviolet light (below 230 m/.t) 

 (2, 4). [a],,*" " = —86.1° (c = 1 per cent in water) 

 (17). Crystallographic data given in reference 55. 

 Trinitrate: Regular tetrahedrons. Decomposes 

 gradually without melting (59). Sesquisulfate: Rec- 

 tangular prisms. Soluble in water. Insoluble in 

 butanol-saturated water and methanol (59, 83). 

 Calcium chloride complex (streptomycin trihydro- 

 chloride-calcium chloride double salt) : Elongated 

 needles; m.p. 200-230°C (decomposition). [a]f = 

 — 76° (c = 1 per cent in water) (3, 25). Helianthatc: 

 Hydrate: Dark red crystals (9). Anhydrous: Amor- 

 phous coppery powder. Darkens at 205°C and melts 

 at 220-226 °C (decomposition) (2). C = 50.34%; H = 



