Tech. Bull. Fac. Agr,, Kagawa Univ.
A NOTE ON T H E IDENTIFICATION OF SUGARS FROM
SOYBEANS THROUGH CRYSTALLINE DERIVATIVES
Sin'itir6 KAWAMURA and Tamotu KIMURA*
I t is well known that the soybean contains sucrose, raffinose, and stachyose (e.g. see FRENCH('))
.
KAWAMURA(~) reported that a sample of the soybean contained 3.7 % sucrose, 1.0 % raffinose, and 3.2 % stachyose by quantitative paper chromatography.
KAWAMURA et al.@) have extended such analyses to several varieties of soybeans. The range and average of sugar contents were for whole full -f at soybeans : arabinose, trace. 0.006, 0.002%; fructose, 0-0.1, trace; glucose, 0.002-0 3 , 0.03%; sucrose 2.7-6.4, 4.6%; raffinose, 0.5-1.2, 1.0 %; stachyose, 2.3-5.3, 3.5 5%; and verbascose, 0-trace, trace. These analyses were made again by quantitative paper chromatography. It is not certain whether arabinose is contained in the free state. Arabinose was identified especially in soybean hulls, which contain water-soluble polysaccharides consisting a t least partly of arabinose
.
This note concerns the identification of oligosaccharides from soybeans, through acetyl derivatives.
Sample. As the sample was used the soybean Hawkeye (1962 crop) produced i n Illinois, U. S. A . , after extraction of oil with hexane.
Extraction of sugars. Reflux defatted soybean meal (20 g) with 200 ml 80% ethanol (pH 6.8) for 1 hr. Centrifuge. Wash the residue 3 times with 80% ethanol. Stir 30 min after adding some water. Combine the filtrate and washings. Add saturated lead acetate solution to deproteinize. Centrifuge to remove precipitated protein. Add 2
N
sodium carbonate solution to remove excess lead acetate. Adjust the pH to 6.8-7.0. Centrifuge. Concentrate the sugar extract to 150ml below 40' with a rotary evaporater. Treat the concentrated extract with 130 ml of a mixture of ion-exchange resins Amberlite IRC-50 and IR-45 (1 : 1) packed into a tube of 18mmx
220mm.Separation of sugars. Column chromatography was applied according to WHISTLER and D u ~ s o . c4) Thus put 70 g Darco G-60 and 70 g Celite 545 slurried with 50
%
ethanol in a tube of 35 mmx
450 mm. Wash with water. Add the desalted sugar solution on the column. Connect the column chromatograph to a fraction collector. Use water, 3 %, 5 %,and 7 % ethanol as subsequent eluating solvents. Take each fraction of 20ml. Determine sugar content on 1 rnl of each fraction by the phenol-sulfuric acid coIori~~letry.(~)
Detection of sugars. Collect some fractions containing the sugar and detect i t by paper chromatography with butanol-pyridine-water (6 : 4 : 3) as the solvent system and 3 %
P -
anisidine hydrochloride in water-saturated butanol as the spraying reagent. The color develops by heating at 100-105°.Isolations of sugars. Collect the fractions containing the same sugar as revealed by
*
P~esent address: Tsuyama City High School, Tsuyama , Okayama-kenVol, 17, No. 1 (1965) 27 paper ohromatography. Concentrate to sirupy state under pressure below 40'. Recrystal- lize from 95
%
ethanol.Identification of sugars by acetylation. Preliminary experiment with sucrose and raffinose showed that acid catalyst (zinc chloride) gave lower yield (about 40 %) than basic catalyst (sodium acetate) (about 70 %)
.
The latter method was applied: use 7 ml acetic anhydride and 0.5 g sodium acetate per 1 g sugar. Boil the mixture of reagents, add the sugar, and boil again the whole mixture to complete the reaction. Allow t h e reaction mixture to cool, put into ice water, and recrystallize from 95%
ethanol.The result is shown in Table 1.
Table 1, Characteristics of the acetates of the sugars from soybeans
Acetate ---m. p
.
---
7--- [ a ] ~found lterature found literature
Sucrose octaacetate 87" 870 (6) (al:+58.50 +59.6Oc6'
(CHCls) (CHCIy)
Raffinose hendecaacetate 92-3' 99-101" (9) [ a 1 5 + 9 2 50 f 92" (9)
(AcOH , EtOH) (EtOH)
Stachyose tetradecaacetate 58-60"
-
[ a ) Y + l m o( AcOH)
-
Sucrose octaacetate recrystallized twice from ethanol followed by treatment with active carbon was observed to be white needles. I t s m.p. in the literature@) is 69-70'? 72-75', and 87'. Thus sucrose octaacetate is trimorphous. We happened to prepare the acetate with the highest m. p.
The respective data for raffinose and stachyose acetates are not available by Micheel.c8) French") states, "No CI ystalline characterizing derivatives of raffinose a r e known."
However, according to Whistler and BeMiller") raffinose hendecaacetate shows m a p . 99- 101" and (a]:+92' (c 8 , ethanol). The present datum of m. p. (92-3') is a little lower, but that of [ a l D agrees fairly. (Raffinose hendecaacetate recrystallized twice from ethanol gave m. p. 92-8'. I t was assumed not to be pure enough. Thus i t was again recrystal- lized.) The data for stachyose tetradecaacetate could not be found in the literatre.(1.6.7) I t may be desirable that the preparation of this report should be purified further.
(Received May 31, 1965) References
(1) FRENCH, D. : Adv Carbohydrate Chem , 9 ,
149-84 (1 954)
.
(2) KAWAMURA, S : Nippon Nogez Kagaku Kar- shi, 28, 851-3 (1954)
(3) KAWAMURA, S , TACA, M , N A R A S A K ~ , T, :
Presented before the 19 th General Meeting of Japanese Society of Food and Nutrition at Utsu- nomiya, May 14, 1965; Summary, Ezy6 t o Sho-
ku7y6, 18, 13 (1965).
(41 WHISILER, R L , DURSO, D F : J A m . Chem
SOC , 72, 677-9 (1950)
15) DUBOIS, M , GILLES, K A , HAMILION, J K , REBERSP A , SMITH, F : Anal. Chem , 28, 350-6 (1956)
(6) MICHEEL, F : Chemie der Zucker und Poly-
saccharide 512 pp Leipzig, Akademische
Verlagsges Geest & Portig K -G (1956). (7) WHISTLER, R L , BEMILLER, J N : Methods
in Carbohydrate Chemistry 1 , 396-8 New Yor k , Academic Press(1962)
Tech. Bull. Fac. Agr. Kagawa Univ.
