CA1214162A - Method for a specific depolymerization of a polysaccharide having a rod-like helical conformation - Google Patents
Method for a specific depolymerization of a polysaccharide having a rod-like helical conformationInfo
- Publication number
- CA1214162A CA1214162A CA000420799A CA420799A CA1214162A CA 1214162 A CA1214162 A CA 1214162A CA 000420799 A CA000420799 A CA 000420799A CA 420799 A CA420799 A CA 420799A CA 1214162 A CA1214162 A CA 1214162A
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- Prior art keywords
- polysaccharide
- solution
- solvent
- process according
- depolymerization
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K31/00—Medicinal preparations containing organic active ingredients
- A61K31/70—Carbohydrates; Sugars; Derivatives thereof
- A61K31/715—Polysaccharides, i.e. having more than five saccharide radicals attached to each other by glycosidic linkages; Derivatives thereof, e.g. ethers, esters
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
- C07H3/00—Compounds containing only hydrogen atoms and saccharide radicals having only carbon, hydrogen, and oxygen atoms
- C07H3/06—Oligosaccharides, i.e. having three to five saccharide radicals attached to each other by glycosidic linkages
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
ABSTRACT:
The description describes a process for depolymerization of a polysaccharide having a rod-like helical structure, comprising a step for forcing a solution of the polysaccharide in a solvent (solvent A) through a capillary at a high shear rate, to produce a lower molecular weight degraded polysaccharide, which has the same repeating unit and the same helical structure, as those of the original polysaccharide.
The description describes a process for depolymerization of a polysaccharide having a rod-like helical structure, comprising a step for forcing a solution of the polysaccharide in a solvent (solvent A) through a capillary at a high shear rate, to produce a lower molecular weight degraded polysaccharide, which has the same repeating unit and the same helical structure, as those of the original polysaccharide.
Description
iE i2 BACKGROUND O~ THE INVENTION
The present invention relates to the specific depolgrnerization of a polysaccharide having a rod-like helical conformation.
Several viscous polysaccharides such as xanthan, lentinan, 5 schizophyllan, scleroglucan or curdlan, have been found to have two or three stranded helical structures. (T. Norisuye, et. al;
J. Polymer Science, Polymer Physics Ed. 18, 547-558 (1980):
E.D.T. Atkins and K.D. Parker; J. Polymer Science Part C. 28, 69-81 (1969): T. L. Bluhm and A. Sarko; Can. J. Chem. 55, 10 293-299 (1977): R.H. Marchessault, et. al; Can. J. Chem. 55, 300-303 ~1977): E.R. Morris; A.C.S. Symposium Series, n, 45, 81 (1977): E.R. Morris, et. al; J. Mol. Biol. 110, 1 (1977)3.
Exploitation of the potentials of these polysaccharides has been investigated and some were developed as thickening agents for foo-l 15 industry based on their high viscosities, and others were found to have potent, host-mediated anti-tumor activities. But in some cases, the extremely high viscosities of their solutions make their utilizations difficult .
In order to reduce their viscosities properly, we invented 20 an ultrasonic method for depolymerization of the polysaccharides~
(Japanese Patent Laid open No. (Kokai) 57335/1977~
Our investigations on the mode of the ultrasonic depolymerization confirmed that it is caused mainly by the cledvages of the main chain of the polysaccharide and that neither side s~hain nor carbon-carbon 25 ~ond in glucose residue is cleaved during the sonic depolymellzation.
Thus, the resulting degraded polysaccharide consists of the same repeating unit and also has the same helical conLormation, as those of the original polysaccharide.
Recently, we found that the ultrasonic depolymerization method does not suit for industrial depolymerization of a large bulk of the polysaccharide, because of its low efficiency. The ultrasonic depolymerization method is also involved in high noise-level and erosion of the vibrating rod of the ultrasonic oscillator.
The present invention was derived from a finding that the treatment of a solution of the polysaccharide under a high shear rate also depolymerizes the polysacchalide in a manner similar to that o~ the ultrasonic treatment; i.e., only main chain of the polysaccharide but neither other glucosidic linkage nor carbon-carbon bond in glucose residue is cleaved during the present depolymerization treatment.
The helical-structural polysaccharide is known to disperse into single chains in a specific condition; for example, beta-1,3-D-glucan disperses to single chains in dimethyl sulfoxide or alkaIine solution.
~5 When the dimethyl sulfoxide solution is diluted with wa~er or the alkaline solution is neutralized with acid, the helical structure of the polysaccharide is not recoveredj but, by random association, large aggregate is formed. The present invention is useful only for a solution of the polysaccharide having a helical structure, but not for that having single chain structure or aggregated conformation.
The present method was confirmed to be able to overcoroe the foregoing disadvantages, such as low ef~lciency, high noise-level, or erosion of the vibrating rod of the ultrasonic oscillator, as seen in the ultrasonic depolymerization method.
Acid-hydrolysis and enzymic degradation of a polysaccharide have been known. Acid-hydrolysis cleaves equally all glucosidic linkages of the polysaccharide, while enzymic degradation causes hydrolysis of a specific glucosidic linkage.
~L4~L6~
But their depolymerization-modes are quite different from those of the ultrasonication and the present method. They liberate very low moleeular mono- or oligo-saeeharicles and can not afford quantitatively clegraded polysaceharide, whieh has the same ehemical and eonforma-5 tional structures as those of the original polysaeeharide.
SUMMARY OF THE IN~rENTION
It is an objeet of the present invention to depolymerize a poly-saccha~de having a rod-like helical strueture by forcing its solution to flow at a high shear rate.
Another objeet of the present invention is to provide a special degraded polysaeeharide, which eonsists of the same repeating unit and the helieal eonformation as those of the starting polysaeeharide.
A solution of the degraded polysaccharide exhibits extremely lower viseosity in comparison with that of the starting polysaecharide, and 15 the polysaecharide still holds the ehemieal and physieal features sueh as antitumor aetivity of the original polysaceharide except for the molecular weight and viscosity. The reduetion in the viscosity of the solution is helpful for its industrial utilization. For example, it makes administration of the polysaeeharide easy in a case of its elinieal uses 20 as an antieaneer drug, or a thixotropie solution of the starting poly-saceharide turns Newtonian fluid, improving the fluidity of a food eontaining the polysaecharide.
The depolymerization according to the present invention is per-formed by foreing ~ solution of the polysaceharide to pass through a . 25 eapillary at a high shear rate,~~higher than 1 x 104 see 1 Examples of the polysaecharide used in the present method are beta-1, 3-D-glueans and xanthan gum.
~2~
The depolymerization-efffciency of the present method was found to become higher, as the concentration of the polysaccharide-solution increases~ especially when it is higher than 0.1 wt.%. The addition of a solvent (solvent B) to the polysaccharide-solution was also found 5 to increase the efficiency of the depolymerization according to the present method, where solvent B is miscible with the solvent (solvent A) of the polysaccharide-solution and does not dissolve the polysac-charide .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The depolymerization of the polysaccharide is performed by forc-ing a solution of the polysaccharide to pass through a capillary such as nozzle, slit, or porous sintered plate or ceramics, using a high pressure-driving force.
The depolymerization-velocity depends only on the value of the 15 shear rate applied, which results from the driving force, pressure, diameter and length of the capillary used, and the viscosity of the solution. While repetition of the passage of the solution through a capiLlary in a certain condition, the molecular weight of the polysac-charide gradually decreases, approaching a minimum value, from which 20 no further depolymerization occurs. The minimum molecular weight also depends on the value of the shear rate applied; higher shear rate gives lower minimum molecular weight.
Thus, the value of the shear rate applied is a dominant factor for the present method. ~o substantial depolymerization occurs at ~3~ 25 too low shear rate. Generally, a shear rate~e~ higher than 1 x 104 sec 1 is necessary for the present depolymelization method.
In order to give such a high shear rate, the pressure applied to the polysaccharide-solution and the cross-secl:ional area of the 6i2 capi~lary are ~0-800 kglcm2 and 1 x 10 ~ -100 mm2, respectively.
But these values are not limited.
The present invention includes the finding that 1. Increase in the concentration of the polysaccharide-solution 5 increases the efficiency of the depolymerization.
The present invention relates to the specific depolgrnerization of a polysaccharide having a rod-like helical conformation.
Several viscous polysaccharides such as xanthan, lentinan, 5 schizophyllan, scleroglucan or curdlan, have been found to have two or three stranded helical structures. (T. Norisuye, et. al;
J. Polymer Science, Polymer Physics Ed. 18, 547-558 (1980):
E.D.T. Atkins and K.D. Parker; J. Polymer Science Part C. 28, 69-81 (1969): T. L. Bluhm and A. Sarko; Can. J. Chem. 55, 10 293-299 (1977): R.H. Marchessault, et. al; Can. J. Chem. 55, 300-303 ~1977): E.R. Morris; A.C.S. Symposium Series, n, 45, 81 (1977): E.R. Morris, et. al; J. Mol. Biol. 110, 1 (1977)3.
Exploitation of the potentials of these polysaccharides has been investigated and some were developed as thickening agents for foo-l 15 industry based on their high viscosities, and others were found to have potent, host-mediated anti-tumor activities. But in some cases, the extremely high viscosities of their solutions make their utilizations difficult .
In order to reduce their viscosities properly, we invented 20 an ultrasonic method for depolymerization of the polysaccharides~
(Japanese Patent Laid open No. (Kokai) 57335/1977~
Our investigations on the mode of the ultrasonic depolymerization confirmed that it is caused mainly by the cledvages of the main chain of the polysaccharide and that neither side s~hain nor carbon-carbon 25 ~ond in glucose residue is cleaved during the sonic depolymellzation.
Thus, the resulting degraded polysaccharide consists of the same repeating unit and also has the same helical conLormation, as those of the original polysaccharide.
Recently, we found that the ultrasonic depolymerization method does not suit for industrial depolymerization of a large bulk of the polysaccharide, because of its low efficiency. The ultrasonic depolymerization method is also involved in high noise-level and erosion of the vibrating rod of the ultrasonic oscillator.
The present invention was derived from a finding that the treatment of a solution of the polysaccharide under a high shear rate also depolymerizes the polysacchalide in a manner similar to that o~ the ultrasonic treatment; i.e., only main chain of the polysaccharide but neither other glucosidic linkage nor carbon-carbon bond in glucose residue is cleaved during the present depolymerization treatment.
The helical-structural polysaccharide is known to disperse into single chains in a specific condition; for example, beta-1,3-D-glucan disperses to single chains in dimethyl sulfoxide or alkaIine solution.
~5 When the dimethyl sulfoxide solution is diluted with wa~er or the alkaline solution is neutralized with acid, the helical structure of the polysaccharide is not recoveredj but, by random association, large aggregate is formed. The present invention is useful only for a solution of the polysaccharide having a helical structure, but not for that having single chain structure or aggregated conformation.
The present method was confirmed to be able to overcoroe the foregoing disadvantages, such as low ef~lciency, high noise-level, or erosion of the vibrating rod of the ultrasonic oscillator, as seen in the ultrasonic depolymerization method.
Acid-hydrolysis and enzymic degradation of a polysaccharide have been known. Acid-hydrolysis cleaves equally all glucosidic linkages of the polysaccharide, while enzymic degradation causes hydrolysis of a specific glucosidic linkage.
~L4~L6~
But their depolymerization-modes are quite different from those of the ultrasonication and the present method. They liberate very low moleeular mono- or oligo-saeeharicles and can not afford quantitatively clegraded polysaceharide, whieh has the same ehemical and eonforma-5 tional structures as those of the original polysaeeharide.
SUMMARY OF THE IN~rENTION
It is an objeet of the present invention to depolymerize a poly-saccha~de having a rod-like helical strueture by forcing its solution to flow at a high shear rate.
Another objeet of the present invention is to provide a special degraded polysaeeharide, which eonsists of the same repeating unit and the helieal eonformation as those of the starting polysaeeharide.
A solution of the degraded polysaccharide exhibits extremely lower viseosity in comparison with that of the starting polysaecharide, and 15 the polysaecharide still holds the ehemieal and physieal features sueh as antitumor aetivity of the original polysaceharide except for the molecular weight and viscosity. The reduetion in the viscosity of the solution is helpful for its industrial utilization. For example, it makes administration of the polysaeeharide easy in a case of its elinieal uses 20 as an antieaneer drug, or a thixotropie solution of the starting poly-saceharide turns Newtonian fluid, improving the fluidity of a food eontaining the polysaecharide.
The depolymerization according to the present invention is per-formed by foreing ~ solution of the polysaceharide to pass through a . 25 eapillary at a high shear rate,~~higher than 1 x 104 see 1 Examples of the polysaecharide used in the present method are beta-1, 3-D-glueans and xanthan gum.
~2~
The depolymerization-efffciency of the present method was found to become higher, as the concentration of the polysaccharide-solution increases~ especially when it is higher than 0.1 wt.%. The addition of a solvent (solvent B) to the polysaccharide-solution was also found 5 to increase the efficiency of the depolymerization according to the present method, where solvent B is miscible with the solvent (solvent A) of the polysaccharide-solution and does not dissolve the polysac-charide .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The depolymerization of the polysaccharide is performed by forc-ing a solution of the polysaccharide to pass through a capillary such as nozzle, slit, or porous sintered plate or ceramics, using a high pressure-driving force.
The depolymerization-velocity depends only on the value of the 15 shear rate applied, which results from the driving force, pressure, diameter and length of the capillary used, and the viscosity of the solution. While repetition of the passage of the solution through a capiLlary in a certain condition, the molecular weight of the polysac-charide gradually decreases, approaching a minimum value, from which 20 no further depolymerization occurs. The minimum molecular weight also depends on the value of the shear rate applied; higher shear rate gives lower minimum molecular weight.
Thus, the value of the shear rate applied is a dominant factor for the present method. ~o substantial depolymerization occurs at ~3~ 25 too low shear rate. Generally, a shear rate~e~ higher than 1 x 104 sec 1 is necessary for the present depolymelization method.
In order to give such a high shear rate, the pressure applied to the polysaccharide-solution and the cross-secl:ional area of the 6i2 capi~lary are ~0-800 kglcm2 and 1 x 10 ~ -100 mm2, respectively.
But these values are not limited.
The present invention includes the finding that 1. Increase in the concentration of the polysaccharide-solution 5 increases the efficiency of the depolymerization.
2. Addition of a solvent (solvent B), which is miscible with the solvent (solvent A) of the polysaccharide-solution and does not dissolve the polysaccharide3 to the polysaccharide-solution also increases the efficiency of the depolymerization.
The effect of the increase in the concentration of the polysac-charide-solution reveals significantly, when it is higher than 0.1 wt.~6.
Although the concentration is desirable to be as high as passible, a part of the polysaccharide tends to remain undissolved at too high concentration, because of its low solubility. Thus9 practically, the concentration is preferably 0.1 - 10 wt.~6.
The solvent B is exemplified by acetone, methanolJ ethanol, iso- or n-propanol, tetrahydrofuran, etc. when the solvent A is water.
In most cases, water is useful as the solvent A, but, for a water-insoluble derivative of the polysacchalide such as N-alkylol amide 20 derivative of the polysaccharide, that still has a helical conformation similar to that of the original polysacchalide, acetone or benzene is used as the solvent A., and water, as solvent B.
Although the depolymerization e~iciency increases as the amount of the solvent B a.dded increases, its amount must be limited so that 25 no insoluble precipitate of the polysaccharide is formed.
The temperature gives no significant influence upon the result of the present depolymeIization method. Therefore, the depolymeriza-tion is usually performed at a temperature lower than 10ûC.
z In order to depolymerize the polysaccharide to a certain molecular weight, its solution is forced through a capillary repeatedly until it8 molecular weight reaches the desired value.
Particles suspending in the polysaccharide-solution often cloggs the capillary, leading to interruption of the operation. Thus, the solution is preferably ~ltrated before its passage through the capillary.
Since a solution of the polysaccharide is viscous and adhesive, a considerable amount of the solution remains in vessels or other equipments used, after its discharge from them. In order to prevent the adhesion of the solution on inner surfaces of the vessels or equip-ments, it is desirable to agitate the solution moderately. The moderate agitation also prevents retenffon of a part of the solution adhering on the equipment-walls, resulting in uniform depolyme~ization of the polysàccharide .
EXAMPLE 1:
Schizophyllan having 5.6 x 106 molecular weight was dissolved in water, to prepare a 0.2 wt.% solution. The solution was forced to pass through a no~.zle of 0.16 mm radius, by being driven by a plunger pump. The flow rate of the solution was adjusted to each 0.23 cm3/sec., 0.90 cm31sec., 14.5 cm3/sec. and 35.4 cm3/sec. by control of the speed of the pump. The shear rate computed ~r each flow rate from the following ormula was 7.1 x 104 sec 1 for 0.23 cm3/
sec flow rate, 2.8 x 105 sec 1 for 0.90 cm3/sec flow rate, 4.5 x 10 sec 1 for 14. 5 cm3 /sec flow rate ~ and 1.1 x 107 sec 1 for 35. 4 C1113 /.
25 sec flow rate, respectively.
4 x flow rate shear rate = 11 x ~radius of the capillary)3 ~2~ 2 Eig. 1 shows the relationship between the retention time of the solution in the nozzle and the molecular weight of the polysaccharide.
The starting schizophyllan and all the depolymerized schizophyllans were methylated by the Hakomori method and then hydrolyzed with 5 formic acid and subsequently trifluoro acetic acid. The hydrolyzate was acetylated with anhydrous acetic acid in pyridine. The sugar-components in the product were analyzed by gas-liquid chromatography, resulting in that it contained 1,5-di-O-acetyl-2,3,4,6-tetra-O-methyl-D-glucitol, 1,3,5-tri-O-acetyl-2,4,6-tri-O-methyl glucitol and 1,3,5,6-10 tetra-O-acetyl-2,4-di-O-methyl-D-glucitol in a molar ratio 1: 2: 1.
The starting schizophyllan and all the depolymerized schizophyllans were oxidized with 0.01N sodium meta-periodate and the amounts of sodium meta-periodate consumed and formic acid formed were determined by iodometry followed by the titration with sodium hydro~nde solution.
15 As the results, 0~48-0~55 mol sodium meta-peliodate was consumed and 0.21 - 0.27 mol formic acid was formed, per 1 mol glucose residue in schi zophyllan .
The starting schizophyllan and all the depolymerized schizophyllans were degraded with exo-beta~1,3-D-glucanase. The degraded product 20 was confirmed to contain glucose and gentiobiose in a molar ratio 2: 1.
The molecular weights of the starting schizophyllan and all the depolymerized schizophyllans in water and also in dimethyl sulfoxide were determined by the ultracentrifugal method. Each ratio of the molecular weight in water to that in dimethyl sulfoxide was in the 25 range between 2.8 and 3;3.
These results indicated that each depolymerized poiysaccharide had the same chemical and conformational structures as those of the starting polysaccharide.
~2~
_ 9 _ EXAMPLE 2:
Scleroglucan having 5 x 106 molecular weight and xanthan gum having 1.4 x 10 molecular weight were dissolved in water, to prepare each 0. 5 wt . ~6 aqueous solution.
A pressure, 200 kg/cm2, was applied to each solution and it was allowed to pass through a nozzle of 0.1 mm radius and 5 cm length.
The flow rates were 1.4 cm3/sec for scleroglucan and 7.4 x 10 1 cm3/
sec for xanthan gum, respectively. Thus, shear rates calculated from the following formula were 1.8 x 10 sec 1 for scleroglucan cmd 9. 4 x 105 sec 1 for xanthan gum.
shear rate = 4 x flow rate Il x (radius of the capillary) Each solution was allowed to pass through the nozzle ten-times in the foregoing condition. The depolymelized scleroglucan has mole-cular weight, 8 x 105 and the depolymerized xanthan gum, 1. 05 x 106, 15 respectively.
The starting and resultlng polysaccharides were methylated and subsequently acetylated as desclibed in Example 1, and then the components in the products were analyzed by gas-liquid chromatography.
The analyses showed that each depolymerized polysaccharide had 20 essentially the same primary structure as that of the corresponding starting polysaccharide. The ratios of the molecular weights in water to those in dimethyl sulfoxide of the starting and depolymerized scleroglucans were close to three, showing t}le resemblance between the conformational structures of both scleroglucans. The intrinsic 25 viscosities of the starting xanthan gum and tlle depolymelized one were 12000 dl/g and 1070 dllg, respectively. The relationship between the intrinsic viscosity and the n~olecular weig~ht of ecach stc~ting and ~L2~4~iZ
depolymerized xanthan gum was consistent with the relationship determined by Holzwarth et. al (G. Holzwarth; Carbohydrate P~esearch 66, 173-186 (1978)), indicating that both xanthan gum had similar helical structures.
5 EXAMPLE 3:
Schizophyllan having 2 x 106 molecular weight was dissolved in water, a mixture of 20 wt.% acetone and 80 wt.% of water, and a mixture of Z0 wt.% ethanol and 80 wt.% of water, in each 0.8 wt.%
concentration. Each solution was forced to pass through a sintered 10 plate having 1 cm thickness and 50 micron mean pore size, with 400 kg/cm2 pressure. It was ivident from the following formula that the shear rate for each solution was higher than 2.5 x 106 sec 1.
(pressure) x (diameter of the capiliary) Shear rate 2xIviscosity of the solution)x(length of the capillary) The viscosity of each solution was lower than 38 c.p.
After 5-times passages of each solution through the sintered plate, polysaccharide had the following molecular weight.
Molecular wei~ht Aqueous ethanol solution 5. 3 x 105 Aqueous acetone solution 6. 0 x 105 Water 7.8 x 105 EXAMPLE 4:
Scleroglucan having 5. 2 x 106 molecular weight was dissolved in water, to prepare each 0.1 wt.%, 0.45 wt.% and 0.90 wt.% aqueous solution. Each solution was driven by 170 kglcm2 pressure to pass 25 through a nozzle of 0.16 mm radius. After 20-times passage, the polysaccharide in each solution had the following molecular weight.
Concentration of the solution Molecular wei~ht ~.1 wt.% 5.8x ~0~
0.45 wt.% ~.2 x 105 0.90 wt.~6 2.8 x 105 5 EXAMPLE S:
A 1.0 wt.% aqueous solution of the schizophyllan used in Example 1 was filtrated using a ceramic-fillter having 0.1 mm pores. A pressure of 50 kg/cm2 was applied to a vessel filled with the filtrate, to force it to pass through a nozzle of 0.15 mm radius and recirculated to the 10 vessel. The filtrate was a~,itated in the vessel at P~eynold's number=120.
The operation continued Ior 8 hours. The molecular weight of schizophyllan was 3.7 x 106 after the operation. After the solution was discharged from the veseel, 100 ml of the solution remained in the vessel adhering on its inner surface.
The same schizophyllan solution was forced to pass through the same nozzle with neither its filtration with the ceramic filter nor agitation during its treatment. The operation was interrupted several times due to the clogging of the nozzle \,v;th particles suspending in the solution. After the solution was discharged from the vessel, 20 2,500 ml of the solution collected in the bottom of the veseel, running down along the wall.
The effect of the increase in the concentration of the polysac-charide-solution reveals significantly, when it is higher than 0.1 wt.~6.
Although the concentration is desirable to be as high as passible, a part of the polysaccharide tends to remain undissolved at too high concentration, because of its low solubility. Thus9 practically, the concentration is preferably 0.1 - 10 wt.~6.
The solvent B is exemplified by acetone, methanolJ ethanol, iso- or n-propanol, tetrahydrofuran, etc. when the solvent A is water.
In most cases, water is useful as the solvent A, but, for a water-insoluble derivative of the polysacchalide such as N-alkylol amide 20 derivative of the polysaccharide, that still has a helical conformation similar to that of the original polysacchalide, acetone or benzene is used as the solvent A., and water, as solvent B.
Although the depolymerization e~iciency increases as the amount of the solvent B a.dded increases, its amount must be limited so that 25 no insoluble precipitate of the polysaccharide is formed.
The temperature gives no significant influence upon the result of the present depolymeIization method. Therefore, the depolymeriza-tion is usually performed at a temperature lower than 10ûC.
z In order to depolymerize the polysaccharide to a certain molecular weight, its solution is forced through a capillary repeatedly until it8 molecular weight reaches the desired value.
Particles suspending in the polysaccharide-solution often cloggs the capillary, leading to interruption of the operation. Thus, the solution is preferably ~ltrated before its passage through the capillary.
Since a solution of the polysaccharide is viscous and adhesive, a considerable amount of the solution remains in vessels or other equipments used, after its discharge from them. In order to prevent the adhesion of the solution on inner surfaces of the vessels or equip-ments, it is desirable to agitate the solution moderately. The moderate agitation also prevents retenffon of a part of the solution adhering on the equipment-walls, resulting in uniform depolyme~ization of the polysàccharide .
EXAMPLE 1:
Schizophyllan having 5.6 x 106 molecular weight was dissolved in water, to prepare a 0.2 wt.% solution. The solution was forced to pass through a no~.zle of 0.16 mm radius, by being driven by a plunger pump. The flow rate of the solution was adjusted to each 0.23 cm3/sec., 0.90 cm31sec., 14.5 cm3/sec. and 35.4 cm3/sec. by control of the speed of the pump. The shear rate computed ~r each flow rate from the following ormula was 7.1 x 104 sec 1 for 0.23 cm3/
sec flow rate, 2.8 x 105 sec 1 for 0.90 cm3/sec flow rate, 4.5 x 10 sec 1 for 14. 5 cm3 /sec flow rate ~ and 1.1 x 107 sec 1 for 35. 4 C1113 /.
25 sec flow rate, respectively.
4 x flow rate shear rate = 11 x ~radius of the capillary)3 ~2~ 2 Eig. 1 shows the relationship between the retention time of the solution in the nozzle and the molecular weight of the polysaccharide.
The starting schizophyllan and all the depolymerized schizophyllans were methylated by the Hakomori method and then hydrolyzed with 5 formic acid and subsequently trifluoro acetic acid. The hydrolyzate was acetylated with anhydrous acetic acid in pyridine. The sugar-components in the product were analyzed by gas-liquid chromatography, resulting in that it contained 1,5-di-O-acetyl-2,3,4,6-tetra-O-methyl-D-glucitol, 1,3,5-tri-O-acetyl-2,4,6-tri-O-methyl glucitol and 1,3,5,6-10 tetra-O-acetyl-2,4-di-O-methyl-D-glucitol in a molar ratio 1: 2: 1.
The starting schizophyllan and all the depolymerized schizophyllans were oxidized with 0.01N sodium meta-periodate and the amounts of sodium meta-periodate consumed and formic acid formed were determined by iodometry followed by the titration with sodium hydro~nde solution.
15 As the results, 0~48-0~55 mol sodium meta-peliodate was consumed and 0.21 - 0.27 mol formic acid was formed, per 1 mol glucose residue in schi zophyllan .
The starting schizophyllan and all the depolymerized schizophyllans were degraded with exo-beta~1,3-D-glucanase. The degraded product 20 was confirmed to contain glucose and gentiobiose in a molar ratio 2: 1.
The molecular weights of the starting schizophyllan and all the depolymerized schizophyllans in water and also in dimethyl sulfoxide were determined by the ultracentrifugal method. Each ratio of the molecular weight in water to that in dimethyl sulfoxide was in the 25 range between 2.8 and 3;3.
These results indicated that each depolymerized poiysaccharide had the same chemical and conformational structures as those of the starting polysaccharide.
~2~
_ 9 _ EXAMPLE 2:
Scleroglucan having 5 x 106 molecular weight and xanthan gum having 1.4 x 10 molecular weight were dissolved in water, to prepare each 0. 5 wt . ~6 aqueous solution.
A pressure, 200 kg/cm2, was applied to each solution and it was allowed to pass through a nozzle of 0.1 mm radius and 5 cm length.
The flow rates were 1.4 cm3/sec for scleroglucan and 7.4 x 10 1 cm3/
sec for xanthan gum, respectively. Thus, shear rates calculated from the following formula were 1.8 x 10 sec 1 for scleroglucan cmd 9. 4 x 105 sec 1 for xanthan gum.
shear rate = 4 x flow rate Il x (radius of the capillary) Each solution was allowed to pass through the nozzle ten-times in the foregoing condition. The depolymelized scleroglucan has mole-cular weight, 8 x 105 and the depolymerized xanthan gum, 1. 05 x 106, 15 respectively.
The starting and resultlng polysaccharides were methylated and subsequently acetylated as desclibed in Example 1, and then the components in the products were analyzed by gas-liquid chromatography.
The analyses showed that each depolymerized polysaccharide had 20 essentially the same primary structure as that of the corresponding starting polysaccharide. The ratios of the molecular weights in water to those in dimethyl sulfoxide of the starting and depolymerized scleroglucans were close to three, showing t}le resemblance between the conformational structures of both scleroglucans. The intrinsic 25 viscosities of the starting xanthan gum and tlle depolymelized one were 12000 dl/g and 1070 dllg, respectively. The relationship between the intrinsic viscosity and the n~olecular weig~ht of ecach stc~ting and ~L2~4~iZ
depolymerized xanthan gum was consistent with the relationship determined by Holzwarth et. al (G. Holzwarth; Carbohydrate P~esearch 66, 173-186 (1978)), indicating that both xanthan gum had similar helical structures.
5 EXAMPLE 3:
Schizophyllan having 2 x 106 molecular weight was dissolved in water, a mixture of 20 wt.% acetone and 80 wt.% of water, and a mixture of Z0 wt.% ethanol and 80 wt.% of water, in each 0.8 wt.%
concentration. Each solution was forced to pass through a sintered 10 plate having 1 cm thickness and 50 micron mean pore size, with 400 kg/cm2 pressure. It was ivident from the following formula that the shear rate for each solution was higher than 2.5 x 106 sec 1.
(pressure) x (diameter of the capiliary) Shear rate 2xIviscosity of the solution)x(length of the capillary) The viscosity of each solution was lower than 38 c.p.
After 5-times passages of each solution through the sintered plate, polysaccharide had the following molecular weight.
Molecular wei~ht Aqueous ethanol solution 5. 3 x 105 Aqueous acetone solution 6. 0 x 105 Water 7.8 x 105 EXAMPLE 4:
Scleroglucan having 5. 2 x 106 molecular weight was dissolved in water, to prepare each 0.1 wt.%, 0.45 wt.% and 0.90 wt.% aqueous solution. Each solution was driven by 170 kglcm2 pressure to pass 25 through a nozzle of 0.16 mm radius. After 20-times passage, the polysaccharide in each solution had the following molecular weight.
Concentration of the solution Molecular wei~ht ~.1 wt.% 5.8x ~0~
0.45 wt.% ~.2 x 105 0.90 wt.~6 2.8 x 105 5 EXAMPLE S:
A 1.0 wt.% aqueous solution of the schizophyllan used in Example 1 was filtrated using a ceramic-fillter having 0.1 mm pores. A pressure of 50 kg/cm2 was applied to a vessel filled with the filtrate, to force it to pass through a nozzle of 0.15 mm radius and recirculated to the 10 vessel. The filtrate was a~,itated in the vessel at P~eynold's number=120.
The operation continued Ior 8 hours. The molecular weight of schizophyllan was 3.7 x 106 after the operation. After the solution was discharged from the veseel, 100 ml of the solution remained in the vessel adhering on its inner surface.
The same schizophyllan solution was forced to pass through the same nozzle with neither its filtration with the ceramic filter nor agitation during its treatment. The operation was interrupted several times due to the clogging of the nozzle \,v;th particles suspending in the solution. After the solution was discharged from the vessel, 20 2,500 ml of the solution collected in the bottom of the veseel, running down along the wall.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for depolymerization of a polysacc-haride having a rod-like helical structure, comprising a step for forcing a solution of the polysaccharide in a solvent (solvent A) through a capillary at a high shear rate, higher than 1 x 104 sec-1, to produce a lower mole-cular weight degraded polysaccharide, which has the same repeating unit and the same helical structure, as those of the original polysaccharide.
2. A process according to claim 1, wherein the polysaccharide is a beta-1,3-D glucan.
3. A process according to claim 1, wherein the polysaccharide is schizophyllan.
4. A process according to claim 1, wherein the polysaccharide is scleroglucan.
5. A process according to claim 1, wherein the polysaccharide is xanthan gum.
6. A process according to claim 1, 2 or 3, where-in the concentration of the polysaccharide solution is 0.1-10wt%.
7. A process according to claim 1, 2 or 3, where-in solvent A is water.
8. A process according to claim 1, 2 or 3, where-in a solvent (solvent B) other than solvent A, which is a poor solvent or non-solvent of the polysaccharide and also miscible with solvent A, is added in the polysaccharide solution.
9. A process according to claim 1, 2 or 3, where-in the polysaccharide solution is filtered before its treat-ment at the high shear rate.
10. A process according to claim 1, wherein the polysaccharide solution is moderately agitated during the treatment at the high shear rate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57023724A JPS58140094A (en) | 1982-02-16 | 1982-02-16 | Making polysaccharide having cylindrical helix structure into low-molecular weight polysaccharide |
| JP23724/1982 | 1982-02-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1214162A true CA1214162A (en) | 1986-11-18 |
Family
ID=12118262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000420799A Expired CA1214162A (en) | 1982-02-16 | 1983-02-03 | Method for a specific depolymerization of a polysaccharide having a rod-like helical conformation |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS58140094A (en) |
| KR (1) | KR900006211B1 (en) |
| CA (1) | CA1214162A (en) |
| CH (1) | CH653689A5 (en) |
| DE (1) | DE3304775A1 (en) |
| FR (1) | FR2521569B1 (en) |
| GB (1) | GB2116576B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2041640A1 (en) * | 1989-09-12 | 1991-03-13 | Hidemichi Akasaka | Process of production of low-molecular weight hyaluronic acid |
| ES2049561B1 (en) * | 1991-04-27 | 1994-12-16 | Andromaco Lab | PROCEDURE FOR OBTAINING POLYMERS WITH ACTIVITY ON THE HEMATOPOYETIC SYSTEM. |
| DE4434877A1 (en) * | 1994-09-29 | 1996-04-04 | Fresenius Ag | Process for the production of starch breakdown products |
| US6242035B1 (en) | 1998-11-23 | 2001-06-05 | Cp Kelco U.S., Inc. | Reduced molecular weight native gellan gum |
| AR107982A1 (en) * | 2016-03-28 | 2018-07-04 | Cargill Inc | METHOD FOR SOLUBILIZING BIOPOLIMERIC SOLIDS FOR IMPROVED OIL RECOVERY APPLICATIONS |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5919121B2 (en) * | 1975-10-31 | 1984-05-02 | タイトウ カブシキガイシヤ | Shinkinoyakurikatsuseitatoubunkaibutsuno Seizouhouhou |
| JPS581907B2 (en) * | 1980-08-07 | 1983-01-13 | 株式会社 柳屋鉄工所 | Forming device for kamaboko without board |
-
1982
- 1982-02-16 JP JP57023724A patent/JPS58140094A/en active Granted
-
1983
- 1983-01-26 GB GB08302088A patent/GB2116576B/en not_active Expired
- 1983-02-02 KR KR1019830000395A patent/KR900006211B1/en not_active IP Right Cessation
- 1983-02-03 CA CA000420799A patent/CA1214162A/en not_active Expired
- 1983-02-11 DE DE19833304775 patent/DE3304775A1/en active Granted
- 1983-02-14 FR FR8302332A patent/FR2521569B1/en not_active Expired
- 1983-02-15 CH CH843/83A patent/CH653689A5/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR840003645A (en) | 1984-09-15 |
| DE3304775C2 (en) | 1992-01-23 |
| GB2116576B (en) | 1985-08-14 |
| DE3304775A1 (en) | 1983-08-25 |
| JPS58140094A (en) | 1983-08-19 |
| KR900006211B1 (en) | 1990-08-25 |
| GB2116576A (en) | 1983-09-28 |
| FR2521569B1 (en) | 1986-10-10 |
| GB8302088D0 (en) | 1983-03-02 |
| JPS6411041B2 (en) | 1989-02-23 |
| CH653689A5 (en) | 1986-01-15 |
| FR2521569A1 (en) | 1983-08-19 |
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