Chilkunda D. Nandini

Carbohydrate composition of wheat, wheat bran, sorghum and bajra with good chapati/roti (Indian flat bread) making quality

Varieties of wheat, sorghum and bajra having good chapati/roti making quality were studied for carbohydrate profile. Polysaccharide fractions (water-soluble, barium hydroxide-soluble, alkali-soluble and insoluble) were isolated from these cereals and wheat bran and their carbohydrate profiles were studied. Arabinoxylans were the major polysaccharides, other than starch and cellulose. The ratio of arabinose to xylose in whole-wheat flour and wheat bran was nearly 1.25:1 but the hemicellulose A in wheat flour was mainly xylan-type. Among the pentosans in barium hydroxide extract of sorghum, the hemicellulose A had more arabinose than xylose, but the hemicellulose B contained nearly equal amounts of arabinose and xylose. Bajra had arabinose and xylose in nearly equal amounts in both the barium hydroxide extract and alkali-soluble fractions. The alkali-insoluble residues were complexes of pentosans with cellulose and were strongly bound. Contents of dietary fibre varied between the cereals. Wheat bran had the highest among the four.

Structural features of arabinoxylans from sorghum having good roti-making quality

Abstract Arabinoxylans (AX) from an Indian variety of sorghum (M354) having good roti(Indian flat bread)-making quality were isolated with barium hydroxide and 10% sodium hydroxide (Hemicellulose B). Arabinoxylans from both fractions were further purified by alcohol precipitation at acidic pH and glucoamylase digestion. Structural features of the purified arabinoxylans were studied by a combination of methylation analysis involving GC–MS, 13C NMR, oxidation studies and FT-IR spectroscopy. The results indicated a xylan backbone in β-1,4 linkage, which is occasionally branched at O-3 or at O-2 and O-3. The branches contained arabinosyl residues in furanose form, linked mainly by α-1,3. Fully branched arabinosyl residues were also present.

Dietary fibres ameliorate decreased synthesis of heparan sulphate in streptozotocin induced diabetic rats

The role of dietary fibers in diabetes has been studied by several workers. Long term dietary treatment with increased amounts of fiber-rich low-glycaemic index natural foods improves blood glucose and reduces the number of hypoglycemic events in type I diabetic patients. On the other hand Rohrbach and Martin and Cohen and Surma described changes in the general and biochemical structure of renal tissues such as the glomerular basement membranes. One of these changes was the reduction and undersulfation of the glycoconjugate and glycosaminoglycan heparan sulfate, which plays an important role in renal structure and function. The purpose of the present study was to determine specific effects of two types of dietary fiber on the composition of kidney glycoconjugates in an animal model of diabetes type I. Streptozotocin-treated diabetic rats were fed either a control diet or diets containing 10% wheat bran (insoluble dietary fiber) or 5% guar gum (soluble dietary fiber). Effects of these fibers on glycaemic control and nephropathy were assessed using previously described methodologies. The effect of dietary fiber in the glycoconjugate composition of kidneys of control and diabetic animals was studied by estimating their total hexose content, sulfated glycosaminoglycans, hexosamines and uronic acids. The activities of enzymes that participate in the synthesis of saccharides and glycoconjugates (L-glutamine-fructose-6-phosphate aminotransferase) and their degradation (N-acetyl-beta-glucosaminidase and beta-glucuronidase) were also evaluated. Results indicated that both soluble and insoluble dietary fibers ameliorated a significant increase in the activity of GFAT. Heparan sulfate was also isolated and quantified. Results indicated that the renal content of heparan sulfate decreased in diabetic animals and that this decrement was ameliorated by the ingestion of both soluble and insoluble fiber in the diet.

Modulatory effect of butyric acid-a product of dietary fiber fermentation in experimentally induced diabetic rats.

The effect of feeding of butyric acid on alleviation of diabetic status was studied. Diabetes was induced in rats using streptozotocin. Rats were fed with basal diet containing wheat bran (5%) as a source of insoluble dietary fiber and guar gum (2.5%) as a source of soluble dietary fiber. The experimental group received butyric acid at 250, 500 and 750 mg/kg body weight/day. The diabetic animals lost weight in spite of high diet consumption. The levels of water intake, urine output, urine sugar, fasting blood sugar increased during diabetic condition compared to control and these were reduced by nearly 20% in the fiber-fed diabetic group. Further supplementation of butyric acid at 500 mg/kg body weight/day ameliorated the diabetic status by nearly 40%. Urine sugar level during the diabetic state was reduced from 7.2 g/day to 3.6 g/day and fasting blood glucose from 270 mg/dl to 180 mg/dl. Butyric acid feeding at 500 mg/kg body weight/day was most effective in controlling the diabetic status.

Effect of dietary fibre on intestinal and renal disaccharidases in diabetic rats

Diabetes was induced in rats with streptozotocin. They were fed either with wheat bran as a source of insoluble dietary fibre or guar gum as soluble dietary fibre. The effect of these fibres on intestinal and renal disaccharidases in diabetic rats was studied. Activities of intestinal maltase, sucrase and lactase increased during diabetes, which was ameliorated to a considerable extent in fibre fed groups. The activities of disaccharidases in renal tissue was decreased in diabetic rats and there was an improvement in fibre fed group.

Stimulation of glucose uptake by Musa sp. (cv. elakki bale) flower and pseudostem extracts in Ehrlich ascites tumor cells

BACKGROUND Glucose uptake study plays a major role in diabetes research. Impaired glucose uptake has been implicated in the development of hyperglycemia during diabetes. Banana plant is known for its anti-diabetic properties and our earlier report revealed that banana flower and pseudostem of Musa sp. cv. elakki bale is beneficial during diabetes in rat models. The present study was designed to evaluate the potential effect of banana flower and pseudostem extracts on glucose uptake in Ehrlich ascites tumor (EAT) cells using 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG), a fluorescent analogue of 2-deoxyglucose. RESULTS Methanol and aqueous extracts of banana flower and pseudostem were more potent in promoting glucose uptake in EAT cells, in comparison to acetone and ethanol extracts. At 20 µg dosage, highest net glucose uptake was observed in aqueous extracts of banana flower (18.17 ± 0.43 nmol L⁻¹) and pseudostem (19.69 ± 0.41 nmol L⁻¹). Total polyphenol content was higher in methanol (9.031 ± 0.036 g kg⁻¹) and aqueous (6.862 ± 0.024 g kg⁻¹) extracts of banana flower compared to pseudostem, which were 0.442 ± 0.006 and 0.811 ± 0.011 g kg⁻¹, respectively. CONCLUSION Banana flower and pseudostem extracts are able to promote glucose uptake into the cells, presumably through glucose transporters 1 and 3, which could be beneficial in diabetes. Glucose uptake is likely promoted by phenolic acids besides other bioactives. It can be hypothesized that consumption of nutraceutical-rich extract of banana flower and pseudostem could replace some amount of insulin being taken for diabetes.

Structural characterization of N-linked oligosaccharides of laminin from rat kidney: changes during diabetes and modulation by dietary fiber and butyric acid.

Carbohydrates of laminin, a family of large multidomain glycoproteins, have been implicated in various cellular activities including maintaining the protein structure, its function and also basement membrane integrity. During the course of our investigation, we observed that purified laminin from kidneys of control, diabetic, and dietary fiber‐ and butyric acid‐treated diabetic rats showed differences in binding to extracellular matrix components. This prompted us to determine whether there are structural changes in laminin oligosaccharides. In this study, we have characterized a few major N‐linked oligosaccharides isolated from purified laminin in various experimental groups, viz. normal, diabetic and diabetic rats fed with dietary fiber and butyric acid. Sugar composition, as identified by GLC, revealed the presence of mannose, galactose and N‐acetylglucosamine. In order to study fine structures of the oligosaccharides, N‐linked oligosaccharides of laminin were released by Peptide‐N‐glycosidase F digestion, end‐labeled with 2‐anthranilic acid and fractionated by lectin affinity chromatography. Furthermore, structural elucidation carried out by MALDI‐TOF MS/MS analysis showed variations in the oligosaccharide sequence of laminin during diabetes which were altered by the feeding of dietary fiber and butyric acid.

Effect of dietary fibres on constituents of complex carbohydrates in streptozotocin induced diabetic rat tissues

The effect of dietary fibres on constituents of complex carbohydrates in various tissues of streptozotocin induced diabetic rats is presented by analysing different constituents of complex carbohydrates in presence and absence of dietary fibre. Wheat bran was effective in preventing the decrease (14%) in total sugars in spleen and an increase in total sugars in stomach (33%) during diabetes. Decrease in uronic acid content during diabetes in spleen was prevented to the extent of 25% by the presence of wheat bran in the diet. The other parameters which were affected by the presence of wheat bran in the diet during diabetes are amino sugar (brain and stomach), sulphates (liver) and protein (lungs and stomach). Guar gum was effective in preventing the decrease in total sugar content in spleen by 28% and sulphate content in liver by 14% during diabetes. Variation in protein content in lungs was observed in diabetes. The results indicated beneficial role of dietary fibres like wheat bran and guar gum on complex carbohydrates to varying extents in different tissues.