FTIR spectrum of Na alginate from
Seaweed has attracted a great deal of interest as excellent sources of nutrients. Seaweeds contain polysaccharides, proteins, amino acids, lipids, peptides, minerals, and some vitamins. Polyphenols of seaweed was used as cosmetics and pharmacological as antioxidants, protection from radiation, anti-inflammatory, hypoallergenic, antibacterial, and antidiabetic. Besides that seaweed also has a high content of antioxidant that can be used to ward off free radicals that increase due to the condition of hyperglycemia in a patient with diabetes mellitus. Hence, a great deal of attention has been directed at isolation and characterization of seaweed polysaccharides because of their numerous health benefits, especially for diabetes mellitus. This paper is expected to provide information on the effect of alginate from two seaweeds on blood glucose and lipid profiles of diabetic rats.
- Sargassum crassifolium
- Turbinaria ornata
- diabetes mellitus
Diabetes mellitus (DM) is a disease caused by hyperglycemia due to a relative or absolute insulin insufficiency. Chronic hyperglycemia can cause complications such as neuropathy, retinopathy, nephropathy, and cardiovascular disease . Hyperglycemia can also cause impaired balance metabolism of carbohydrates, fats, and proteins . International Diabetes Federation (IDF) estimates that in 2013 there were 382 × 106 people with diabetes and 316 × 106 people suffer from impaired glucose tolerance and increased risk of diabetes. These results are expected to increase to 471 × 106 in 2035 and predicted less than 25 years; there would be 592 × 106 people have diabetes without quick and precise prevention .
Seaweeds are the most abundant resources in the ocean. Seaweeds contain polysaccharides, proteins, amino acids, lipids, peptides, minerals, and some vitamins. Polyphenols of seaweed was used as cosmetics and pharmacological as antioxidants, protection from radiation, antibiotics, anti-inflammatory, hypoallergenic, antibacterial, and antidiabetic . Polyphenol extracts from seaweed, for example,
2. Extraction of polysaccharides from marine algae
Na alginate from
3. Alginate characterizations (structural and physical properties)
FTIR spectroscopy was used to identify the polysaccharide structures. A pellet of sodium alginate was prepared with KBr. FTIR spectrum was recorded on Shimadzu-FTIR Prestige 21 with a resolution of 4 cm−1 in the 4000–400 cm−1 region, with a scan speed of 0.20 cm s−1. The FTIR spectrum of sodium Na alginate of
|Wave number (cm−1)||Assignments|
|Na alginate standard ||Na alginate of |
|1620.21||1627.92||ν asym COO- b|
|1419.61||1427.32||δ C–O–H, νsym COO− (carboxylate ion)1,3|
|1095.57||1087.85||ν C-O, ν C-C (pyranose ring)1,2,3|
|948.98||948.98||ν C-O (uronic acid residues)1,3|
|894.97||871.82||δ C1-H (β-mannuronic residues)1,3|
The peak infrared spectrum of standard alginate and
|Wavelength (cm−1)||Type of vibration|
|Na alginate standard ||Na alginate of ||Reference|
|—||779.24||778.201||Guluronic acid residues|
|1095.57||1087.85||1100–10503||OCO ring (shoulder)|
|1419.61||—||1460–14002||C-O asymmetric stretching|
4. Biological activity of polysaccharides from marine algae
4.1. Effect of Na alginate of
T. ornataon body weight of rats
Alloxan-induced diabetic rats did not show a significant decrease in body weight after the injection of alloxan. Five groups of diabetic rats had decreased in body weight on 15 days treatment, and there were significant differences between the groups of rats. There was no significant difference between diabetic control (negative control) compared to positive control, and the positive control was not significantly different compared to alloxan diabetic rats treated with Na alginate 200 mg/kg. Alloxan-induced diabetic rats treated with Na alginate(s) (200, 400, 600 mg/kg) did not show significant difference between each other. Administration of Na alginate(s) (400, 600 mg/kg) showed a significant difference compared to negative control. The body weight of alloxan-induced diabetic rats treated with Na alginate 600 mg/kg was not significantly different compared to normal control.
The lowering of rats’ body weight treated with alginate from
4.2. Effect of Na alginate of
S. crassifoliumon body weight of rats
Diabetic mice showed weight loss in all treatment groups except the normal control group. Normal control group gained weight of 24.1 g. The negative control group had a very significant weight loss of 51.6 g. The positive control group had a weight loss of 47.2 g. The treatment group of extract 200 mg/kg had a weight loss of 58.8 g. The treatment group of 400 mg/kg extract had a weight loss of 45.3 g. Meanwhile, the treatment group giving 600 mg/kg extract experienced a decrease in body weight by 43.1 g. Streptozotocin (STZ)-induced diabetic rats are one of the animal models of type 1 diabetes mellitus. It is well known for its selective pancreatic islet beta-cell cytotoxicity and has been extensively used to induce type 1 diabetes in an experimental rat model. Glibenclamide is often used as a standard antidiabetic drug in STZ-induced diabetes to compare the efficacy of a variety of hypoglycemic drugs .
Throughout the experiments, all the rats were monitored daily and/or weekly for the symptoms of type 1 diabetes mellitus, including polydipsia, polyuria, polyphagia, hyperglycemia, and muscle wasting leading to weight loss and insulin deficiency. Figure 1 shows the observations of body weight of treated rats during the whole period of experiments. The body weight was continuously increased in the normal group and decreased in all diabetes groups. A severe loss of body weight characterizes STZ-induced diabetes. Due to absolute or relative deficiency of insulin and decrease of the production of ATP, protein synthesis decreases in all tissues.
5. Effect of Na alginate on blood glucose
Alloxan is a urea derivative which causes selective necrosis of the pancreatic islet β-cells . Alloxan and its reduction product dialuric acid establish a redox cycle with the formation of superoxide radicals . Preprandial blood glucose levels were determined as fasting blood glucose. Fasting is defined as no calorie intake for at least 8 h . Diabetes is diagnosed when the fasting plasma glucose concentration is consistently ≥7 mmol/L (126 mg/dL) or when the 2 h plasma glucose concentration (after drinking a 75 g glucose load) is consistently ≥11.1 mmol/L (200 mg/dL) .
Administration of alloxan led to a significant increase of preprandial blood glucose levels in rats after 3 days. Administration of Na alginate(s) (200, 400, 400 mg/kg) significantly reduced the blood glucose level compared to diabetic control. The dose of 200 and 400 mg/kg of Na alginate did not show a significant difference compared to normal control and positive control (Table 3). The result was supported by previous studies using fiber to decrease preprandial blood glucose. Nelson et al.  used high indigestible fiber and low indigestible fiber diet to decrease preprandial blood glucose in diabetic dogs for 8 months which resulted in high indigestible fiber significantly that reduces preprandial blood glucose better than low indigestible fiber. Nelson et al.  used similar treatment in diabetic cats for 24 weeks and showed high indigestible fiber which gave a better effect on decreasing preprandial blood glucose than low indigestible fiber. Chandalia et al.  compared the amount of fiber that was given to diabetic patients according to the American Diet Association (8 g digestible fiber and 16 indigestible fiber) and fiber-rich diet (25 g digestible fiber and 25 indigestible fiber) for 6 weeks. Fiber-rich diet decreased 13% preprandial blood glucose lower than ADA diet.
|Group||Preprandial blood glucose (mg/dL)*|
|Normal control||106.06 ± 11.33b,c||126.30 ± 0.50a|
|Negative control||208.57 ± 70.60a||568.82 ± 46.40c|
|Positive control||86.29 ± 13.83b||316.35 ± 20.90b|
|Alginate (200 mg/kg)||108.50 ± 11.28c||279.45 ± 92.50b|
|Alginate (400 mg/kg)||96.55 ± 15.65b,c||336.63 ± 66.32b|
|Alginate (600 mg/kg)||99.03 ± 14.26b,c||257.66 ± 34.61b|
Normal postprandial blood glucose level is <180 mg/dL . In the normal state, the postprandial blood glucose level increases less than 50 mg/dL from the preprandial blood glucose level after carbohydrate intake . Alloxan-induced diabetic rats’ postprandial blood glucose level surpassed 200 mg/dL after 3 days of injection. After 15 days of treatment, the result was the administration of Na alginate(s) (200, 400, 600 mg/kg) which significantly reduces postprandial blood glucose levels on rats compared to diabetic control (P < 0.05). However, it failed to restore the level to that of normal control group and positive control group (P < 0.05). The positive control group could restore the postprandial blood glucose level at the same level as a normal control group (Table 4).
|Group||Postprandial blood glucose (mg/dL)*|
|Normal control||133.05 ± 15.81b||150.416 ± 5.1a|
|Negative control||360.48 ± 40.80a||633.470 ± 27.8c|
|Positive control||140.75 ± 9.16b||333.814 ± 64.5ab|
|Alginate (200 mg/kg)||257.08 ± 34.20c||421.652 ± 21.4bc|
|Alginate (400 mg/kg)||238.61 ± 21.48c||433.333 ± 21.8bc|
|Alginate (600 mg/kg)||196.05 ± 18.22d||381.250 ± 11.4ab|
Wolf et al.  used 1.5 g sodium alginate to show its effect on postprandial glucose peak and glucose uptake reduction after 3 h which resulted in line 32.80 ± 3.40 and 1429 ± 276 mg/dL. Sodium alginate had a reduction effect better than 1.2 g gum arabic and 0.3 g gum guar with postprandial glucose peak 40.40 ± 3.30 mg/dL and glucose uptake 1717 ± 433 mg/dL. A study on the effect of a meal containing alginate compared to testing a meal without alginate by Torsdottir et al.  showed that postprandial blood glucose levels by meal containing alginate decrease 31% lower than a meal without alginate.
Preprandial glucose levels for all treatment groups of alginate from
All treatment groups of extracts of
In general, the viscosity of dietary fiber can reduce the rise in blood glucose levels and reduce food intake by slowing the empty stomach and slowing the absorption of nutrients in the small intestine. Based on these two mechanisms, it is still not clear what mechanisms apply to sodium alginate, perhaps one or both . Different doses of alginate will affect the viscosity of the given test preparation. So, it will lead to differences in the viscosity of the fluid in the gastrointestinal tract and ultimately result in differences in the rate of glucose absorption from the gastrointestinal tract into the blood vessels .
6. Total cholesterol
Diabetes is associated with major abnormalities in fatty acid metabolism. The resulting disturbance results in an abnormal lipoprotein cascade from the large chylomicron through to the small HDL particle [31, 32]. Total cholesterol in the serum of negative control was not significantly different compared to positive control, Na alginate 200 and 400 mg/kg treatment, and normal control. Na alginate 600 mg/kg of
|Group||Total cholesterol (mg/dL)*|
|Normal control||70.40 ± 7.12b||41.55 ± 0.20a|
|Negative control||67.75 ± 16.02b||68.41 ± 12.50b|
|Positive control||72.40 ± 15.24b||45.79 ± 9.80a|
|Alginate (200 mg/kg)||55.80 ± 3.42a,b||49.05 ± 20.00ab|
|Alginate (400 mg/kg)||65.60 ± 14.47b||54.46 ± 11.00ab|
|Alginate (600 mg/kg)||47.80 ± 5.40a||34.20 ± 7.50a|
Several previous studies supported the result. Suzuki et al.  evaluated the effect of alginate-rich guluronic and mannuronic on cholesterol levels in rats fed with diets containing both alginates and cholesterol which resulted from reductions in liver cholesterol in rats fed with each alginate and significantly low cholesterol accumulation in mannuronic acid-rich alginate. Ren et al.  screened 26 species of seaweeds and six polysaccharides from algae to study their effect on lipid in rats fed with basal diet for 28 days of treatment. The six polysaccharides were sulfated glucuronoxylomannan (0.5%), fucoidin (1%), sodium alginate (1%), funorin (2.5%), porphyrin (2.5%), and agar (2.5%). Reduction effect of each polysaccharide was 64, 65, 68, 77, 88, and 95%, respectively, compared to control group. At the end of the study, the polysaccharides could restore the cholesterol level to the same level as the control group.
Total cholesterol levels of the normal control group, positive control, and alginate 600 mg/kg of
Wikanta et al.  reported that sodium alginate could lower total cholesterol in mice with hypercholesterolemia. Administration of sodium alginate with a viscosity of 450 cps significantly reduced total cholesterol levels compared to sodium alginate with lower viscosity. Because, sodium alginate is a water-soluble fiber compound, forming a viscous solution. The stomach fluid cannot digest this compound in the gastrointestinal tract. When dissolved in water, the sodium alginate fibers form a mesh-like grid that strongly binds many water molecules in a well-defended solute. Its properties as emulgator increasingly enhance the binding ability. A similar mechanism occurs against lipid molecules in bile acids in the gastrointestinal tract. The binding or bonding of lipids by the alginate makes lipid and cholesterol unable to absorb the body through the small intestine so that it eventually comes out with the stool. Suzuki et al.  also reported that alginate with various mannuronic acid and guluronic acid compositions can decrease total blood cholesterol levels.
Administration of Na alginate to alloxan-induced diabetic rats for 200 mg/kg alginate of
|Normal control||108.00 ± 6.59c||70.549 ± 1.50a|
|Negative control||59.75 ± 9.39a||75.549 ± 11.10a|
|Positive control||58.00 ± 7.78a||96.843 ± 14.10a|
|Alginate (200 mg/kg)||61.80 ± 5.57a||97.617 ± 11.50a|
|Alginate (400 mg/kg)||74.80 ± 10.08b||84.03 ± 28.20a|
|Alginate (600 mg/kg)||78.60 ± 10.60b||75.98 ± 17.70a|
According to Rohman  HDL is a protective lipoprotein, in addition to functioning to bring fat to the liver; HDL proved to inhibit the oxidation of LDL and adhesion molecules. HDL-c levels throughout the treatment group did not have a significant difference. The same is also shown in the study of Suzuki et al.  that there was no statistically significant difference in HDL-c levels in mice suffering from hypercholesterolemia treated with sodium alginate in comparison with different glucuronic acid and mannuronic acids.
LDL-c after administration of alginate(s) from
|Normal control||58.80 ± 7.19a||34.07 ± 0.90a|
|Negative control||60.75 ± 16.52a||55.34 ± 8.30b|
|Positive control||65.00 ± 14.05a||27.51 ± 10.00a|
|Alginate (200 mg/kg)||49.60 ± 3.13a,b||31.81 ± 11.80a|
|Alginate (400 mg/kg)||55.60 ± 13.13a,b||33.91 ± 5.30a|
|Alginate (600 mg/kg)||41.00 ± 5.83b||28.78 ± 5.30a|
Administration of sodium alginate from
Triglyceride management on type 2 diabetes is targeting for <150 mg/dL . When the glucose levels excess in the blood, glucose will be converted to triglycerides in which triacylglycerol synthesis process is known as lipogenesis. Carbohydrate-rich meal can lead to increase the process of lipogenesis in the liver and adipose tissue. However, the occurrence of insulin resistance inhibits lipogenesis process making glucose and free fatty acid levels in blood plasma increased. In the liver, triglyceride accumulation can cause malfunctioning of the liver (fatty liver) or liver cirrhosis in the long term . Triglyceride of alloxan-induced diabetic rats did not show a significant difference between the groups of treatment using alginate of
|Normal control||75.80 ± 10.33a||28.73 ± 12.20a|
|Negative control||77.75 ± 20.90a||77.73 ± 14.10b|
|Positive control||80.40 ± 13.14a||24.31 ± 9.60a|
|Alginate (200 mg/kg)||63.40 ± 25.41a||24.12 ± 17.70a|
|Alginate (400 mg/kg)||60.80 ± 13.80a||31.73 ± 2.90a|
|Alginate (600 mg/kg)||54.80 ± 10.91a||37.67 ± 8.50a|
Paxman et al.  reported that a drink containing alginate in the obese patient had no effect on tryglyceride level. Triglyceride levels did not show a significant difference between alginate treatment group and control group. Ren et al.  used six polysaccharides from algal species as a treatment for rats given with basal diet for 28 days. All of the polysaccharides used in this research could reduce triglyceride levels as good as their ability reducing LDL-c in blood serum. Funoran and sulfated glucuronoxylorhamman reduced triglyceride levels between 46 and 64% compared to the control group. Sodium alginate could decrease the triglyceride level to 29% compared to the control group. Fucoidan can reduce the triglyceride levels to 12–20% .
The levels of triglycerides during the experiment using alginate of
All groups treated with DM except for the normal control group showed elevated triglyceride levels. Levels of triglycerides increased up to 574.867 mg/dL. The condition of hypertriglyceridemia can be diagnosed if the triglyceride level >150 mg/dL . According to Pujar et al. , this can be due to direct damage from the pancreatic tissue by high free fatty acids. The concentration of high free fatty acid will decrease the pH and may activate trypsinogen. Also, high triglyceride levels can also be caused by the destruction of chylomicron which is a triglyceride carrier. This changes the acinar function and opens the pancreatic tissue to triglycerides.
10. Necrosis of pancreas
Necrosis is defined as the type of cell death caused by changing the morphology of the nucleus, including chromatin condensation and fragmentation, minor changes in cytoplasmic organelles, and overall causes of cell shrinkage (apoptosis) and autophagic accumulation of two vacuole membranes in the cytoplasm . In type I diabetes mellitus, patients found changes in the pancreas in the form of the reduced size of the pancreas, atrophy in the exocrine pancreas, and atrophy of the acinar cells around the degenerated Langerhans island. On the other hand, in type II diabetes mellitus, an imbalance of exocrine secretion of the pancreas and impaired control of blood glucose occur .
Normal controls show normal cell conditions (Figure 3). Negative controls show some damage to the cell. The positive control treatment group also shows the same. The treatment group of sodium alginate extract is entirely damaged in cells (necrosis). The treatment group of
Administration of alginate from
Research Grants Flagship Universitas Gadjah Mada supported this research through DIPA UGM 2014 number LPPM-UGM/478/LIT/2014.
Conflict of interest
The authors declare no conflict of interest.