. The actinomycetes. Actinomycetales. 58 NATURE, FORMATION, AND ACTIVrriES )!, which is pi'ochicod by certain Streptomijccs, cHft'ers from strepto- mycin in that it has a hych'oxymethyl group instead of a methyl group in the streptose moietv: CHO CH3 OH' Streptomycin CH,OH CHO OH Hydroxystrcptomycin This antibiotic seems to offer nf) advantage over streptomycin. Pseudostreptomycin is composed of two molecules of streptomycin linked together through their aldehyde groups by condensa- tion with ammonia. The formula is thus: ,—CHOH—XH—CHOH—SAI where Si\I stands for strep
. The actinomycetes. Actinomycetales. 58 NATURE, FORMATION, AND ACTIVrriES )!, which is pi'ochicod by certain Streptomijccs, cHft'ers from strepto- mycin in that it has a hych'oxymethyl group instead of a methyl group in the streptose moietv: CHO CH3 OH' Streptomycin CH,OH CHO OH Hydroxystrcptomycin This antibiotic seems to offer nf) advantage over streptomycin. Pseudostreptomycin is composed of two molecules of streptomycin linked together through their aldehyde groups by condensa- tion with ammonia. The formula is thus: ,—CHOH—XH—CHOH—SAI where Si\I stands for streptomycin minus the —CHO group. Pseudostreptomycin has little biological activity and is very toxic. It is converted to streptomycin in acjueous acidic sohition. neomycins B and C were later isolated. An antibiotically active degradation product, neomycin A or neamine, produced in the culture or by chemical hydrolysis, w^as also obtained. The ninhydrin and other color tests, as well as specific test bacteria, can be utilized for the separation of the various neomycins. Neomycin B is composed of fovn- cyclic moieties, three of which have a carbon skeleton composed of six carbons and one of five carbons. One diaminohexose moiety is linked to the pentose, D-ribose, to form a Cii fragment called neobiosamine, and an- other molecule of a diaminohexose is linked to a diaminotrihydroxycyclohexane (2- desoxystreptamine) to form a C12 moiety called neamine. Neamine has some antibiotic activity of its own. Neobiosamine and ne- amine are linked together to form the C23 molecule of neomycin B, which has thus a total of six amino groups. Neomycin C is an isomer of neomycin B which is somewhat less active biologicallv. The difference be- XH, C,H,O3(NH0a—1-0 I Diaminohexose !. OH OH d-Ribose I I I I I I "C«H802(XH2)2 Diaminohexose —O NH2 Neobiosamine Neomvcins The neomycins are very similar to the streptomycins, but they do not contain guanido groups. They are formed of cycl
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