Extraction of aggrecan-peptide from cartilage by tissue autolysis.

Aggrecan is a cartilage specific proteoglycan containing chondroitin sulfate (CS) and keratan sulfate (KS). CS is an acidic polysaccharide having wide range of applications in pharmaceutical, cosmetic, and food industries. CS is extracted from cartilage by tissue proteolysis with an exogenous proteinase or by activating endogenous proteinases (autolysis) to release aggrecan-peptides from the tissue. This review is focused on the latter technique. Bovine nasal and tracheal cartilages, and broiler chicken sternum cartilage have been used for autolysis studies. To extract aggrecan-peptide, cartilage tissues are cut into small pieces, and incubated in a monovalent or divalent salt solution (e.g., 0.1 M sodium or calcium acetate) at pH 4.5 and 37 °C for 7 - 24 h. Most (~80% or more) of total tissue uronic acid, a constituent sugar of aggrecan, is extracted and released into the salt solution during incubation. Reextraction of the tissue residue results in release of a small amount of uronic acid. Aggrecan-peptides purified using anion exchange chromatography are large compounds containing CS and KS. On gel chromatography, they are excluded from the column of Sephacryl S-300. Chemical composition analysis demonstrated that aggrecan-peptides from either bovine or chicken cartilage contain >90% CS with small amount (< 10%) of either KS or peptide. Patent information included production of aggrecan-peptide substantially free of DNA. The bovine aggrecan-peptide prepared by tissue autolysis has been used as a plate coating antigen in enzyme- linked immunosorbent assay (ELISA) to determine KS.

In vitro retardation of glucose diffusion with gum extracted from malva nut seeds produced in Thailand.

Mucilage of malva nut fruit has been used as traditional medicine in Thailand. Our laboratory has succeeded in extracting malva nut gum (MNG) from malva nut seeds by using alkaline-extraction method. The extract had higher gelling properties compared to water-extracted MNG. This research was aimed to investigate the effect of MNG on the retardation of glucose diffusion in in vitro dialysis processes. The results showed that alkaline-extracted MNG significantly (p<0.05) reduced glucose content in dialysate compared to control containing no dietary fibre. MNG at 1% (w/w) concentration was more effective than that of 0.5% (w/w) concentration. The mixture of MNG and guar gum significantly (p<0.05) reduced glucose in dialysate by 50-82% compared to that of control. In starch digestion process, the mixture of MNG and guar gum showed greater reduction of glucose (3-7 folds) in dialysate at 15-30min.

In vitro intestinal glucose uptake is inhibited by galactomannan from Canadian fenugreek seed (Trigonella foenum graecum L) in genetically lean and obese rats.

Galactomannan, a soluble fiber, has been reported to reduce postprandial blood glucose response. Using this fiber, extracted from Canadian-grown fenugreek seeds (Trigonella foenum graecum L), we conducted an in vitro study to determine if galactomannan affects intestinal glucose uptake in genetically determined lean and obese rats. The segments of jejunum and ileum from these animals were incubated with labeled glucose (2 or 32 mmol/L) in the presence of different concentrations of galactomannan ranging from 0.1% to 0.5% (wt/wt). The uptake of low or high concentration of glucose was significantly and progressively reduced by increasing concentrations of galactomannan in both lean and obese rats. No significant difference was observed in the uptake of glucose between the 2 groups. The viscosity of various concentrations of galactomannan solutions was determined after stirring for 60 minutes at a temperature-controlled (37 degrees C) fixed sheer rate of 1.29 (1/s). The inhibitory effect of galactomannan on glucose uptake was found to be in parallel with the degree of viscosity of the fiber solutions. These results suggest that the galactomannan, because of its viscous property, has the potential to reduce intestinal absorption of low or high concentrations of glucose and hence for the benefit of blood glucose management.

The Modifying Effects of Galactomannan from Canadian-Grown Fenugreek (Trigonella foenum-graecum L.) on the Glycemic and Lipidemic Status in Rats.

Using high sucrose-fed male Sprague-Dawley rats, a study was conducted to determine the effects of feeding Galactomannan (GAL), a soluble dietary fiber extracted from Canadian-grown fenugreek seeds, on blood lipid and glucose responses. Rats (n = 8, 175-200 g) were randomly assigned to one of three high sucrose diets containing 10% cellulose (control), 7.5% cellulose + 2.5% GAL, and 5% cellulose + 5% GAL, respectively for 4 weeks. After 3 weeks, an oral glucose tolerance test (OGTT) was performed on each rat. A week later blood samples were collected to determine the effect on blood lipids. A significant reduction in glycemic response was observed only in 5% GAL group at 120 min following OGTT, when compared with that of control and 2.5% GAL groups. The plasma level of insulin was also significantly reduced (p<0.001) in 5% GAL-fed rats but at all times during OGTT. These animals also showed a reduction in body weight gain (p<0.05) in parallel with less food intake (p<0.05). All GAL-fed (2.5% and 5.0%) rats had significantly reduced plasma levels of triglycerides and total cholesterol in association with a reduction in epididymal adipose weight. Overall, this study demonstrated that feeding GAL from Canadian-grown fenugreek seeds has the potential to alter glycemic and lipidemic status and reduce abdominal fat in normal rats.