Agric. BioL Chem., 45 (3), 641 -643, 1981 641 AminoSugar Components and Characterization of Antibiotic K-52B Yutaka Kido, Syuichi Hayakawa and Motoo Shibata Laboratory of Medicinal Microbiology, Faculty of Pharmaceutical Sciences, KumamotoUniversity, Kumamoto862, Japan Received August 8, 1980 Di-, tri- and tetra-saccharides containing amino sugar I were newly isolated as amino sugar components from the partial acid hydrolysate of antibiotic K-52B. From methylation analyses and complete hydrolyses of these oligosaccharides, the structures were elucidated as -* 1)-Glcp- (4-0-amino sugar I for the disaccharide (amino sugar II) ; Ga)p-(1 -> l)-Glcp-(4-^)-amino sugar I for the trisaccharide (amino sugar III) ; and Ara/-(1 ^4)-Galp-(l -^i)-Glc:p-(4-»)-amino sugar I for the tetrasaccharide (amino sugar IV). From these results and structures of constituent neutral oligosaccharides, the structure of antibiotic K-52B was proposed to be: Formyl Gkv(l -+4)-GaV(l ~ 4)-Fuc-(l->4) -Glcy (1->5) -Arar (1-»4) -GaJp- (1-^ 1) -Gicp- (4->) -amino sugar I. In the previous papers,1"3* methylation ated by modified Hakomori's method.5) Complete analysis and Smith degradation of antibiotic methylation was confirmed from the infrared spectrum. K-52B, sugar components of the constituent The methylated amino sugar IV was hydrolyzed, re- neutral oligosaccharides and physicochemical duced with sodium borohydride and acetylated. properties of the constituent amino sugar I Analysis. Paper chromatography was usually were reported. Di-, tri- and tetra-saccharides performed on WhatmanNo. 1 paper by the ascending method with the following solvent systems (v/v); (a) containing amino sugar I were newly isolated butanol-pyridine-water (6: 4: 3), (b) butanol-acetic from the partial acid hydrolysate of anti- acid-water (5: 1: 2), Alkaline silver nitrate6) or p- biotic K-52B and the constituent sugars were anisidine hydrochloride7) reagent and Elson-Morgan8) examined by methylation analysis and com- or ninhydrin9) reagent were used for the detection of plete acid hydrolysis. We describe here the sugars or amino sugars, respectively. Hexosamine was detected by the method of Elson-Morgan-Blix,10) constituent sugars of di-, tri- and tetra-saccha- and glucosamine was used as a standard. Gas-liquid rides and their glycosidic linkages and also chromatography (GLC) was carried out with a Shima- refer to the structure of antibiotic K-52B. dzu model CG-3BF chromatograph using a glass column packed with a 15% butanediol succinate MATERIALSAND METHODS polyester on Neosorb NC (Nishio Ind. C6^) for the detection of methylglycosides and 3 % ECNSS-Mon Materials. Antibiotic K-52B was prepared and Gas Chrom Q (Nishio Ind, Co.) for the detection of purified as described in the previous paper.4) The alditol acetate. Nitrogen was used as a carrier gas at a methyl- and alditol-derivatives of glucose, galactose and flow rate of 60 ml/min. arabinose used as reference compounds were prepared in our laboratory. RESULTS ANDDISCCUSION Acid hydrolysis. K-52B was heated with 3.6n sulfuric acid for 10 hr in a boiling water bath to obtain Isolation of amino sugar components amino sugar components. For complete hydrolysis After the acid hydrolysis of K-52B (1.6 g), amino sugars were heated with 3.6 n sulfuric acid for the hydrolysate was neutralized with solid 6 hr in a boiling water bath, while for partial Hydrolysis BaCO3and filtered. After concentration to a amino sugars were heated with 0.5 n sulfuric acid for syrup, the hydrolysate was applied on a column 2 hr in a boiling water bath. (2.8 X 35 cm) of Amberlite CG-120 (H+-form) Methylation analysis. Aminosugars were methyl- and washed with 1000nil of water and then 642 Y. Kido, S. Hayakawa and M. Shibata eluted with 0.3 n HC1. Aminosugar components As shown in Fig. 1, amino sugar components (A) Amino sugar I (AI). As already describ- were fractionated into four fractions and named ed in the previous paper,3} amino sugar I is amino sugar I, II, III and IV in their reversed colorless needles of diaminohexose derivative. order of elution. Further purification by car- (B) Amino sugar II (All). Some properties bon column chromatography gave purified and methylation analyses of amino sugar II, amino sugarI (40 mg). II (80 mg), III (80 mg) III and IV were shown in Tables I and II, re- and IV (55 mg). spectively. All was colorless leaflet crystals with melting point of 179°C and with specific rotation of [a]^-56°. The complete hydroly- sis gave AI and glucose, though the methyla- Amino sugar tion analysis gave only 2,3,6-tri-O-methyl AminosugarII /°\ 500 'V glucoside. The Rfvalue of All (0.36, solvent 400 A) was almost the same as that of galactose. 300 From these findings, All was found to be a 200 Amino sugar III disaccharide which was linked at the C-4 Amino sugar IV position of glucose to AI. (C) Amino sugar III (AIII). AIII was an 20 40 60 amorphous white powder with melting point at 164°C and with specific rotation of [a]l° Fig. 1. Separation ofAmino Sugars on an Amberlite -17°. The complete acid hydrolysis of AIII CG-120 Column. gave AI, glucose and galactose, whereas the The eluent was 0.3 n HC1. Each fraction of7 ml was partial acid hydrolysis gave only All and galac- collected at rate 7 ml/30 min. tose. The methylation analysis of AIII gave Table I. Physicochemical Properties of Amino Sugars AI All A III AIV Appearance Needle Leaflet White powder White powder Melting point (°C) 184°C 179°C 164°C 168°C [< -98° -56° -17° +13° Anal. Found C 33.83 31.85 38.21 40.14 (%) H 5.95 6.14 6.12 6.08 N 9.35 4.77 3.22 2.42 Rf value* 0.30 0.36 0.25 0.21 Componentsugars AI AI, Glc AI, Glc, Gal AI,Glc,Gal,Ara «-butanol-pyridine-water (6 : 4 : 3). Table II. Methylatton Analyses of Amino Sugars II, III and IV A m in o su g a rs 0 -M eth y l g ly c o sid e L in k a g e in d ic a te d 7l *aa R e l a ti v e mo l % A TT 2 , 3 , 6 - t r i - 0 - M e t h y l g l u c o s e - * 4 [ G l c J 1 - 3. 5 2, 4 . 7 8 10 0 A TT T 2 , 3 , 6 - t r i - O - M e t h y l g l u c o s e - > 4 [ G l c J 1 - 3 . 5 2, 4 . 7 6 4 5 2 , 3 , 4 , 6 - t e t r a - O - M e t h y l [ G a y 1 - g a l a c t o s e 1. 8 0 5 5 2 , 3 , 6 - t r i - O - M e t h y l g l u c o s e - > 4 [ G l c J 1 - 3. 5 2, 4. 7 6 3 0 A TV 2 ,3 , 6- t ri - O- M e t h y l g a l a c t o s e - ｻ 4 [ G a L ] 1 - 3. 2 0 , 4. 7 0 3 5 2 , 3 , 5 - t r i - O- M et h y l a r a b i n o s e [ A r a . 1 1 - 0 . 5 5 3 5 Relative to methyl 2,3,4,6-tetra-O-methyl glucoside. Characterization of Antibiotic K-52B 643 two peaks of 2,3,6-tri-(9-methyl glucoside and into their corresponding alditol acetates. 2,3,4,6-tetra-O-methyl galactoside in their ap- As shown in Fig. 2, l,4-di-O-acetyl-2,3,5- proximate ratio of.1: 1. These results sug- tri-O-methyl arabinitol, l,4,5-tri-0-acetyl-2,3, gested that AIII was a trisaccharide contain- 6-tri-(9-methyl-galactitol and -glucitol and an ing AI, GaV(l-> and -»l)-Glv(4-». unidentified peak (Peak 4) were detected in their On the other hand, only glucose and galac- approximate ratio of 1: 1: 1: 1. Peak 4 was tose were detected by P-anisidine hydrochlo- considered to be the alditol acetate of AI, fide reagent7] in the complete hydrolysate of because the complete acid hydrolysis of AIV AIII after reduction with NaBH4. Thus, the gave arabinose, glucose, galactose and AI. reducing end and non-reducing end of AIII Furthermore, the Tg value of peak 4 agreed were found to be AI and galactose, respectively. nearly with that of an unidentified alditol peak The results described above indicated that AIII from the Smith degradation product of K-52B was linked at C-l position of galactose to glu- which was already described in the preceding cose in All and hence the structure was eluci- paper.1} dated as Galp-(1 ->l)-Gkv(4->)-AI for AIII. From these results, the structure was eluci- (D) Amino sugar IV (AIV). AIV was an dated as AraH1^4)-Gal^l-^l)-Gkv(4->> amorphous white powder with melting point at AI for AIV. 166°C and with specific rotation of [a]|0+13o. The complete acid hydrolysis of AIV gave AI, Characterization of antibiotic K-52B glucose, galactose and arabinose, whereas the (A) Molecular weight. As already described partial acid hydrolysis gave only AIII and ara- in the preceding paper,4) the molecular weight binose. The non-reducing end was found to determination of K-52B by vapor pressure be arabinose from the methylation analysis of osmometer gave a value of 770.