amino cyclitol glycoside aminoglycoside antibiotic streptamine beta-L-arabinoside monosaccharide derivative netilmycin O-3-Deoxy-4-C-methyl-3-(methylamino)-beta-L-arabinopyranosyl-(1-6)-O-(2,6-diamino-2,3,4,6-tetradeoxy-alpha-D-glycero-hex-4-enopyranosyl-(1-4))-2-deoxy-N(1)-ethyl-D-streptamine CHEBI:7528 Netilmicin 1-N-Ethylsisomicin chebi_ontology