AU2021103807A4

AU2021103807A4 - Method for decolorizing and deproteinizing brown algae polysaccharides

Info

Publication number: AU2021103807A4
Application number: AU2021103807A
Authority: AU
Inventors: Xiaoyong Chen; Lijun YOU
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2021-09-09
Anticipated expiration: 2029-07-02

Abstract

A method for decolorizing and deproteinizing brown algae polysaccharides belongs to the field of deep processing of brown algae. The method combines ultraviolet (UV) with hydrogen peroxide (H202) , including the following steps: extracting dried and pulverized 5 brown algae by hot water to obtain brown algae polysaccharide, dissolving the brown algae polysaccharide in an aqueous solution containing H202 and irradiating under ultraviolet light, wherein the mass concentration of the brown algae polysaccharide is 2.5-10.0 mg/mL, the concentration of the H202 is 25-150 mmol/L, and the UV irradiation time is 1.0-2.0 h, so as to deproteinize and decolorize the brown algae. The invention does not use acids, bases and 0 organic solvents, which is green with no pollution, simple in operation, safe, economical and time-saving. Abstract Drawing - Fig 1 17844994_1 (GHMatters) P116644.AU 1/5 100 75-- Untreated -- UV alone 50 - -0- 150mmol/L H202 alone -A- 25 mmol H2 0 2 /L+UV 25- -0- 75 mmol H202/L+UV -E- 150 mmol H2 0 2 /L+UV 0. 0 30 60 90 120 Time/min Fig. 1 A 1.3 Untreated 1.0 ' - UV alone - - 150mmoI/L H202 alone 0.7- -- 25 mmol/L H2 02 +UV -o- 75 mmol/LH2+U 0.4- -- 150 mmol/L H2 0 2 +UV 0.1 200 300 400 500 600 700 800 Wavelength (nm) Fig. 2a 17841106_1 (GHMatters) P116644.AU

Description

1/5

100

75-- Untreated -- UV alone

50 - -0- 150mmol/L H202 alone -A- 25 mmol H2 0 2 /L+UV 25- -0- 75 mmol H2 0 2/L+UV -E- 150 mmol H 2 0 2 /L+UV 0.

0 30 60 90 120 Time/min

Fig. 1

A 1.3 Untreated 1.0 ' - UV alone - - 150mmoI/L H202 alone 0.7- -- 25 mmol/L H2 0 2 +UV -o- 75 mmol/LH2+U 0.4- -- 150 mmol/L H2 0 2 +UV

0.1

200 300 400 500 600 700 800 Wavelength (nm)

Fig. 2a

17841106_1 (GHMatters) P116644.AU

Method for decolorizing and deproteinizing brown algae polysaccharides

Technical field

The invention belongs to the technical field of polysaccharide separation and purification,

and specifically relates to a method for decolorizing and deproteinizing brown algae

polysaccharides.

Background

Polysaccharides are natural macromolecular carbohydrates composed of at least 10

monosaccharides, which can be divided into plant polysaccharides, animal polysaccharides

and microbial polysaccharides according to their sources. Brown algae are high level algae

with about 1,500 species. The commonly seen brown algae in China include Laminaria

japonica, Undariapinnatifida,Macrocystis pyrifera, Ectocarpus confervoides,

Sphaerotrichia,Desmarestiaviridis, Scytosiphon lomentaria, Colpomenia sinuosa, Chorda

filum, Myosoton aquaticum, Dictyota dichotoma, Padina,Sargassum, Silvetia siliquosa,

Sargassumpallidum, Sargassum muticum, and Sargassumfusiforme. etc., which are

important sources of plant polysaccharides. At present, brown algae in China are mainly used

to produce algin, which is widely used in industry, but recent studies have shown that brown

algae polysaccharides have a variety of biological activities, such as anti-oxidation,

anti-coagulation, anti-virus, hypoglycemic effect, immune regulation, and so on, and thus they

have gradually been noticed by researchers. However, brown algae polysaccharides are often

mixed with impurities such as proteins and pigments, which hinder the purification,

classification, structure identification, and pharmacological activity analysis of the

polysaccharides. In addition, the commonly used decolorization methods such as activated

carbon method, hydrogen peroxide method and macroporous resin method and

deproteinization methods such as Sevage method, sodium chloride method, calcium chloride

method, trichloroacetic acid method and hydrochloric acid method have many shortcomings

including too many repetitions, cumbersome operation, large loss of polysaccharide

components, low purity, or the use of acids and organic solvents. Therefore, how to remove

17844994_1 (GHMatters) P116644.AU impurities such as proteins and pigments conveniently, effectively and environmentally has become a hot issue in the study of brown algae polysaccharides.

In addition to the traditional decolorization and deproteinization methods, the currently

studied decolorization and deproteinization methods includes that: CN201710249849.6

discloses a purification method for decolorizing and deproteinizing champion bean

polysaccharides, which is mainly based on D113 weakly acidic cation exchange resin to

achieve decolorization and deproteinization; CN201710394098.7 discloses a method for

deproteinizing and decolorizing polysaccharides in the by-product of mango processing,

which mainly comprises deproteinizing by TCA combined with n-butanol, and then further

decolorizing by activated carbon.

At present, the decolorization effect of H202 alone has been confirmed, but in order to

achieve a more ideal decolorization effect, a higher concentration of H202 is often required; in

addition, there are no reports about using either UV or H202 and UV combined with H202 for

simultaneous decolorization and deproteinization.

Summary of the invention

In view of the existing problems in the separation and purification of brown algae

polysaccharides, a purpose of the present invention is to provide a method for decolorization

and deproteinization in the purification process of brown algae polysaccharides to solve the

above problems. The whole process does not use acids, bases and organic solvents, which is

green with no pollution, simple in operation, safe, fast, and has good decolorization and

deproteinization effects.

The purpose of the present invention is achieved by the following technical solutions.

A method for decolorizing and deproteinizing brown algae polysaccharides comprises

dissolving the brown algae polysaccharides in water, adding a hydrogen peroxide solution,

and placing the resulting mixed solution under ultraviolet light for decolorization and

deproteinization.

17844994_1 (GHMatters) P116644.AU

Preferably, the brown algae polysaccharides are prepared by hot water extraction,

acid-base extraction, ultrasonic-assisted extraction, microwave-assisted extraction, or

biological enzymatic extraction.

Preferably, the brown algae is at least one of Laminariajaponica, Undariapinnatifida,

Macrocystispyrifera, Ectocarpusconfervoides, Sphaerotrichia,Desmarestiaviridis,

Scytosiphon lomentaria, Colpomenia sinuosa, Chordafilum, Myosoton aquaticum, Dictyota

dichotoma, Padina,Sargassum, Silvetia siliquosa, Sargassumpallidum, Sargassum muticum,

and Sargassumfusiforme.

Preferably, preparation of the brown algae polysaccharides comprises the following steps:

(1) raw material pretreatment: pulverizing washed and dried brown algae, refluxing with

ethanol, centrifuging to collect the precipitate and drying to obtain brown algae powder;

(2) extraction of brown algae polysaccharides: extracting the brown algae powder

pretreated in step (1) by hot water, centrifuging and removing the residue; concentrating the

obtained supernatant by a vacuum rotary evaporator, adding ethanol, shaking to mix

uniformly, standing, centrifuging again and removing the supernatant; washing the obtained

precipitate with ethanol, dissolving again in water, concentrating by a vacuum rotary

evaporator and lyophilizing to obtain the brown algae polysaccharides.

More preferably, the concentration of the ethanol is 95 vol%.

More preferably, the temperature of the standing in step (2) is 4°C.

More preferably, in the hot water extraction of step (2), the ratio of material-to-liquid is 1

g:30 mL-1 g:50 mL, the extraction temperature is 60-100 °C , and the extraction time is 4-6 h.

Preferably, the concentration of the brown algae polysaccharides in the mixed solution is

2.5-10 mg/mL.

Preferably, the concentration of the hydrogen peroxide in the mixed solution is 25-150

mmol/L, more preferably 100-150 mmol/L.

17844994_1 (GHMatters) P116644.AU

Preferably, the irradiation intensity of the ultraviolet light is 4000-7000 mJ/cm2

. Preferably, the irradiation time of the ultraviolet light is 1.0 - 2.0 h.

Preferably, a method for decolorizing and deproteinizing brown algae polysaccharides

includes the following steps:

(1) Raw material pretreatment: washed and dried brown algae (such as Laminaria

japonica, Undariapinnatifida,Macrocystis pyrifera, Ectocarpus confervoides,

Sargassumpallidum, Sargassum muticum, and Sargassumfusiforme, etc.) are pulverized,

refluxed with 95% ethanol to remove lipids and other small molecules, centrifuged to collect

the precipitate, and the precipitate is dried for later use.

(2) Extraction of brown algae polysaccharides: polysaccharides are extracted from the

pretreated brown algae powder by hot water, wherein the extraction conditions includes: a

material-to-liquid ratio of 1:30-1:50 (g/mL), an extraction temperature of 60-100 °C, and an

extraction time of 4-6 hours. The supernatant obtained from the centrifugation of the extract is

concentrated by a vacuum rotary evaporator followed by slowly adding an appropriate

amount of 95% ethanol. The mixture is shaken to mix uniformly and allowed to stand

overnight at 4 °C. Centrifugation is carried out on the next day, and the supernatant is

removed; the precipitate is washed with 95% ethanol followed by dissolving again in an

appropriate amount of pure water, and finally concentrated by a vacuum rotary evaporator and

lyophilized to obtain the brown algae polysaccharides.

(3) decolorization and deproteinization treatment: an appropriate amount of the brown

algae polysaccharides is dissolved in pure water, and an appropriate amount of H202 is added,

so that the final concentration of the brown algae polysaccharides in the solution is 2.5-10

mg/mL, and the final concentration of H202 in the solution is 25-150 mmol/L. Then the

solution is placed under ultraviolet light for decolorization and deproteinization.

17844994_1 (GHMatters) P116644.AU

The invention combines UV with H202 to remove pigments and proteins in brown algae

polysaccharides, wherein no organic solvents are involved in the operation. The method is

safe, environmentally friendly, low cost, simple and time-saving in operation, and has good

decolorization and deproteinization effects as well as good application prospect.

Compared with the prior art, the present invention has the following beneficial effects:

The materials used in the method of decolorizing and deproteinizing brown algae

polysaccharides of the present invention and their dosages are reasonable, so that the

decolorization and deproteinization can be carried out at the same time with simple operation,

mild condition, no pollution, and outstanding decolorization and deproteinization effects of

brown algae polysaccharides. The decolorization rate of Sargassumfusiformepolysaccharide

is up to 92.26%, and the protein content of the brown algae polysaccharides is down to 9.75

[g/mL after being processed by the method of the present invention.

Brief description of the drawings

Fig. 1 is a graph showing the variation of decolorization rate of Sargassumfusiforme

polysaccharides treated with UV/H202 for different time in Example 1.

Fig. 2a is a graph showing the full-wavelength scanning results indicating the protein

content of the Sargassumfusiformepolysaccharide solution treated with UV/H202 in

Example 1.

Fig. 2b is the result of the Coomassie Brilliant Blue method indicating the protein content

of the Sargassumfusiformepolysaccharide solution treated with UV/H202 in Example 1.

Fig. 3 is a graph showing the variation of decolorization rate of Laminariajaponica

polysaccharides treated with UV/H202 for different time in Example 2.

Fig. 4a is a graph showing the full-wavelength scanning results indicating the protein

content of the Laminariajaponicapolysaccharide solution treated with UV/H202 in Example

2.

17844994_1 (GHMatters) P116644.AU

Fig. 4b is the result of the Coomassie Brilliant Blue method indicating the protein content

of the Laminariajaponicapolysaccharide solution treated with UV/H202 in Example 2.

Fig. 5 is a graph showing the variation of decolorization rate of Undariapinnatifida

polysaccharides treated with UV/H202 for different time in Example 3.

Fig. 6a is a graph showing the full-wavelength scanning results indicating the protein

content of the Undariapinnatifidapolysaccharide solution treated with UV/H202 in Example

3.

Figure 6b is the result of the Coomassie Brilliant Blue method indicating the protein

3.

Detailed description

The technical solutions of the present invention are described in detail below through

embodiments, but the technical solutions of the present invention are not limited to the

following embodiments.

Example 1

Sargassumfusiformepolysaccharides were decolorized and deproteinized by a UV/H202

method including the following steps:

(1) After the washed and dried Sargassumfusiformeis superfinely pulverized, 100 g of it

was mixed with 400 mL of 95 vol% ethanol and refluxed for 3 times in a slightly boiling state

for a total of 5 hours to remove lipids, pigments and small molecules. Then centrifugation was

carried out, the precipitate was collected and dried to obtain the pretreated Sargassum

fusiforme superfine powder.

(2) After the pretreatment, the superfine Sargassumfusiformepowder was extracted by

hot water at a material-liquid ratio of 1 g:50 mL. The extraction was under 100 °C for 4 h, and

the extract was centrifuged to obtain the supernatant. The supernatant was concentrated by a

17844994_1 (GHMatters) P116644.AU vacuum rotary evaporator, and then 95 vol% ethanol was slowly added to reach a final concentration of 80 wt%. The solution was shaken to mix uniformly, and then allowed to stand at 4 °C for 12 h. Centrifugation was carried out on the next day, the supernatant was removed, and the precipitate was washed with 95 vol% ethanol followed by standing at room temperature. After the ethanol was volatilized, an appropriate amount of pure water was added to dissolve the precipitate again, and finally the solution was concentrated by a vacuum rotary evaporator and lyophilized to obtain the Sargassumfusiformepolysaccharides.

(3) an appropriate amount of Sargassumfusiformepolysaccharides obtained above was

dissolved in pure water containing H202 so that the final concentration of the polysaccharides

was 2.5 mg/mL and the final concentration of H202 was 25, 75 and 150 mmol/L. Then the

solution was placed under ultraviolet light for decolorization and deproteinization for 2 h,

wherein the irradiation intensity was 6500 mJ/cm 2 . Then the decolorization and

deproteinization rates before and after UV/H202 treatment were measured. In addition, in

order to further evaluate the enhancement effect of combining UV with H202, the

decolorization and deproteinization effects of Sargassumfusiformepolysaccharide after UV

treatment or H202 treatment alone were further determined.

(4) Detection of decolorization and deproteinization effects of Sargassumfusiforme

polysaccharide solution by the UV/H202 method:

Decolorization rate detection: the wavelength of 420 nm is often used in the study of the

decolorization rate of polysaccharides; appropriate amounts of the polysaccharide solutions

treated for different time were centrifuged at 12000 r/min for 30 sec, and the absorbances at

420 nm were measured. The decolorization rate is calculated according to the following

formula, the results being shown in Fig. 1.

decolorization rate(%) absorbance before decolorization AO - absorbance after decolorization At 25 = x100 absorbance before decolorization AO

Deproteinization detection: protein has a maximum absorption peak at a wavelength of

17844994_1 (GHMatters) P116644.AU

280 nm; at the same concentration, the absorbance indicates the concentration of the protein.

Therefore, the absorbance at the wavelength of 280 nm can be used as one of the evaluation

indicators of the deproteinization ability. Ultraviolet-visible spectrophotometer was used to

scan through a wavelength range of 200-800nm. The result is shown in Fig. 2a. In addition,

the protein content was further determined by the Coomassie Brilliant Blue method, and the

results are shown in Fig. 2b.

It can be seen from Fig. 1 that compared with the untreated Sargassumfusiforme

polysaccharide solution, the color of the polysaccharides becomes darker after UV treatment

alone, while the color of the polysaccharide solution becomes lighter after the 150 mmol/L of

H202 treatment alone, indicating that it has a certain effect on decolorization of the

Sargassumfusiformepolysaccharide solution. In the cases of treating with 25, 75 and 150

mmol/L of H202 combined with UV, the decolorization rates increase greatly. With the

increase of H202 concentration, the decolorization effect is better, indicating that the

treatment combining H202 with UV is a feasible and effective decolorization method for

Sargassumfusiformepolysaccharides.

Protein has a maximum absorption peak at a wavelength of 280 nm; at the same

concentration, the absorbance indicates the concentration of the protein. It can be seen from

Fig. 2a that, compared with the untreated Sargassumfusiformepolysaccharide solution, the

absorbances at 280 nm do not change significantly after UV treatment alone and 150 mmol/L

of H202 treatment alone, while after treating with 25, 75 and 150 mmol/L of H202 combined

with UV, the absorbances at 280 nm of the Sargassumfusiforme polysaccharide solution are

greatly reduced, indicating that the protein contents in the solution are reduced. Further

determination by the Coomassie brilliant blue method (Fig. 2b) shows that the protein

contents in the solutions after UV treatment alone and 150 mmol/L of H202 treatment alone

do not change significantly compared to that of the untreated solution, but in the cases of

treating with 25, 75 and 150 mmol/L of H202 combined with UV, the protein contents

decrease significantly, which is consistent with the full-wavelength scan results. And as the

concentration of H202 increases, the protein content decreases. In summary, the treatment

17844994_1 (GHMatters) P116644.AU combining H202 with UV is a feasible and effective method for deproteinizing Sargassum fusiforme polysaccharides.

Example 2

Laminariajaponicapolysaccharide solution was decolorized and deproteinized by a

UV/H202 method including the following steps:

(1) After the washed and dried Laminariajaponicawas pulverized, 100 g of it was mixed

with 400 mL of 95 vol% ethanol and refluxed for 2 times in a slightly boiling state for a total

of 3 hours to remove lipids, pigments and small molecules. Then centrifugation was carried

out, the precipitate was collected and dried to obtain the pretreated Laminariajaponica

powder.

(2) After the pretreatment, the Laminariajaponicapowder was extracted by hot water at

a material-liquid ratio of 1 g:30 mL. The extraction was under 60 °C for 4 h, and the extract

was centrifuged to obtain the supernatant. The supernatant was concentrated by a vacuum

rotary evaporator, and then 95 vol% ethanol was slowly added to reach a final concentration

of 80 wt%. The solution was shaken to mix uniformly, and then allowed to stand at 4 °C for

12 h. Centrifugation was carried out on the next day, the supernatant was removed, and the

precipitate was washed with 95 vol% ethanol followed by standing at room temperature. After

the ethanol was volatilized, an appropriate amount of pure water was added to dissolve the

precipitate again, and finally the solution was concentrated by a vacuum rotary evaporator and

lyophilized to obtain the Laminariajaponicapolysaccharides.

(3) an appropriate amount of Laminariajaponicapolysaccharides obtained above was

was 5.0 mg/mL and the final concentration of H202 was 25, 50 and 75 mmol/L. Then the

solution was placed under ultraviolet light for decolorization and deproteinization for 1 h,

order to further evaluate the enhancement effect of combining UV with H202, the 17844994_1 (GHMatters) P116644.AU decolorization and deproteinization effects of Laminariajaponicapolysaccharide after UV treatment or H202 treatment alone were further determined.

(4) Detection of decolorization and deproteinization effects of Laminariajaponica

polysaccharide solution by the UV/H202 method was carried out according to step (4) of

Example 1. The result of decolorization rate is shown in Fig. 3, and the result of

deproteinization is shown in Fig. 4a and Fig. 4b.

It can be seen from Fig. 3 that compared with the untreated Laminariajaponica

alone, while the color of the polysaccharide solution becomes lighter after the 50 mmol/L of

H202 treatment alone, indicating that it has a certain effect on decolorization of the Laminaria

japonica polysaccharide solution. In the cases of treating with 25, 50 and 75 mmol/L of H202

combined with UV, the decolorization rates increase greatly. With the increase of H202

concentration, the decolorization effect is better, indicating that the treatment combining H202

with UV is a feasible and effective decolorization method for Laminariajaponica

polysaccharides.

Protein has a maximum absorption peak at a wavelength of 280 nm; at the same

Fig. 4a that, compared with the untreated Laminariajaponicapolysaccharide solution, the

absorbances at 280 nm do not change significantly after UV treatment alone and 50 mmol/L

of H202 treatment alone, while after treating with 25, 50 and 75 mmol/L of H202 combined

with UV, the absorbances at 280 nm of the Laminariajaponicapolysaccharide solution are

determination by the Coomassie brilliant blue method (Fig. 4b) shows that the protein

contents in the solution after UV treatment alone and 50 mmol/L of H202 treatment alone do

not change significantly compared to that of the untreated solution, but in the cases of treating

with 25, 50 and 75 mmol/L of H202 combined with UV, the protein contents decrease

significantly, which is consistent with the full-wavelength scan results. And as the

17844994_1 (GHMatters) P116644.AU concentration of H202 increases, the protein content decreases. In summary, the treatment combining H202 with UV is a feasible and effective method for deproteinizing Laminaria japonica polysaccharides.

Example 3

Undariapinnatifidapolysaccharide solution was decolorized and deproteinized by a

UV/H202 method including the following steps:

(1) After the washed and dried Undariapinnatifida was pulverized, 40 g of it was mixed

with 1000 mL of 95 vol% ethanol and refluxed in a slightly boiling state for a total of 3 hours

to remove lipids, pigments and small molecules. Then centrifugation was carried out, the

precipitate was collected and dried to obtain the pretreated Undariapinnatifida powder.

(2) After the pretreatment, the Undariapinnatifidapowder was extracted by hot water at

a material-liquid ratio of 1 g:40 mL. The extraction was under 100 °C for 4 h, and the extract

lyophilized to obtain the Undariapinnatifida polysaccharides.

(3) an appropriate amount of Undariapinnatifidapolysaccharides obtained above was

was 10.0 mg/mL and the final concentration of H202 was 25, 50 and 100 mmol/L. Then the

deproteinization rate before and after UV/H202 treatment was measured.

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(4) Detection of decolorization and deproteinization effects of Undariapinnatifida

Example 1. The result of decolorization rate is shown in Fig. 5, and the result of

deproteinization is shown in Fig. 6a and Fig. 6b.

It can be seen from Fig. 5 that compared with the untreated Undariapinnatifida

alone, while the color of the polysaccharide solution becomes lighter after the 100 mmol/L of

H202 treatment alone, indicating that it has a certain effect on decolorization of the Undaria

pinnatifidapolysaccharide solution. In the cases of treating with 25, 50 and 100 mmol/L of

H202 combined with UV, the decolorization rates increase greatly. With the increase of H202

with UV is a feasible and effective decolorization method for Undariapinnatifida

polysaccharides.

Protein has a maximum absorption peak at a wavelength of 280 nm; at the same

Fig. 6a that, compared with the untreated Undariapinnatifidapolysaccharide solution, the

absorbances at 280 nm do not change significantly after UV treatment alone and 100 mmol/L

of H202 treatment alone, while after treating with 25, 50 and 100 mmol/L of H202 combined

with UV, the absorbances at 280 nm of the Undariapinnatifida polysaccharide solution are

determination by the Coomassie brilliant blue method (Fig. 6b) shows that the protein

with 25, 50 and 100 mmol/L of H202 combined with UV, the protein contents decrease

combining H202 with UV is a feasible and effective method for deproteinizing Undaria

pinnatifidapolysaccharides.

17844994_1 (GHMatters) P116644.AU

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

17844994_1 (GHMatters) P116644.AU

Claims

1. A method for decolorizing and deproteinizing brown algae polysaccharides,

characterized in that, the method comprises dissolving the brown algae polysaccharides in

water, adding a hydrogen peroxide solution, and placing the resulting mixed solution under

ultraviolet light for decolorization and deproteinization.

2. The method of claim 1, characterized in that, the brown algae polysaccharides are

prepared by hot water extraction, acid-base extraction, ultrasonic-assisted extraction,

microwave-assisted extraction, or biological enzymatic extraction.

3. The method of claim 2, characterized in that, the hot water extraction of the brown algae

polysaccharides comprises the following steps:

(1) raw material pretreatment: pulverizing washed and dried brown algae, refluxing

with ethanol, centrifuging to collect the precipitate and drying to obtain brown algae powder;

obtained supernatant, adding ethanol, shaking to mix uniformly, standing, centrifuging again

and removing the supernatant; washing the obtained precipitate with ethanol, dissolving again

in water, concentrating and lyophilizing to obtain the brown algae polysaccharides.

4. The method of claim 3, characterized in that, in the hot water extraction of step (2), the

ratio of material-to-liquid is 1 g:30 mL-1 g:50 mL, the extraction temperature is 60-100 °C ,

and the extraction time is 4-6 h.

5. The method of claim 1, characterized in that, the concentration of the brown algae

polysaccharides in the mixed solution is 2.5-10 mg/mL;

the concentration of the hydrogen peroxide in the mixed solution is 25-150 mmol/L;

the irradiation intensity of the ultraviolet light is 4000-7000 mJ/cm2;

the irradiation time of the ultraviolet light is 1.0 - 2.0 h.

17844994_1 (GHMatters) P116644.AU