Beneficial effects of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats

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Diabetes is a chronic health problem and major cause of death in most of the countries. Diet management plays an important role in controlling diabetes and its complications along with insulin and drugs. We have examined the effect of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats. Our results indicated that banana flower and pseudostem have low glycemic index and have a high content of dietary fiber and antioxidants. Diabetic symptoms like hyperglycemia, polyuria, polyphagia, polydipsia, urine sugar, and body weight were ameliorated in banana flower- and pseudostem-treated rats. Increased glomerular filtration rate in the diabetic group (5.1 ± 0.22 ml/min) was decreased in banana flower-fed (2.5 ± 0.37 ml/min) and pseudostem-fed (3.0 ± 0.45 ml/min) groups and were significant at P < 0.001 and P < 0.01, respectively. Fructosamine and AGEs formed during diabetes were inhibited in treated groups when compared with the diabetic group. The diabetic group showed 11.5 ± 0.64 ìg of AGEs/mg protein in kidney, whereas, in banana flower- and pseudostem-fed groups, it was reduced to 9.21 ± 0.32 and 9.29 ± 0.24 ìg/mg protein, respectively, and were significant at P < 0.01. These findings suggest that banana flower and pseudostem have anti-diabetic and anti-AGEs properties and are beneficial as food supplements for diabetics (AU)

Beneficial effects of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats.

Diabetes is a chronic health problem and major cause of death in most of the countries. Diet management plays an important role in controlling diabetes and its complications along with insulin and drugs. We have examined the effect of banana (Musa sp. var. elakki bale) flower and pseudostem on hyperglycemia and advanced glycation end-products (AGEs) in streptozotocin-induced diabetic rats. Our results indicated that banana flower and pseudostem have low glycemic index and have a high content of dietary fiber and antioxidants. Diabetic symptoms like hyperglycemia, polyuria, polyphagia, polydipsia, urine sugar, and body weight were ameliorated in banana flower- and pseudostem-treated rats. Increased glomerular filtration rate in the diabetic group (5.1 ± 0.22 ml/min) was decreased in banana flower-fed (2.5 ± 0.37 ml/min) and pseudostem-fed (3.0 ± 0.45 ml/min) groups and were significant at P < 0.001 and P < 0.01, respectively. Fructosamine and AGEs formed during diabetes were inhibited in treated groups when compared with the diabetic group. The diabetic group showed 11.5 ± 0.64 µg of AGEs/mg protein in kidney, whereas, in banana flower- and pseudostem-fed groups, it was reduced to 9.21 ± 0.32 and 9.29 ± 0.24 µg/mg protein, respectively, and were significant at P < 0.01. These findings suggest that banana flower and pseudostem have anti-diabetic and anti-AGEs properties and are beneficial as food supplements for diabetics.

Lower efficacy in the utilization of dietary ALA as compared to preformed EPA + DHA on long chain n-3 PUFA levels in rats.

We made a comparative analysis of the uptake, tissue deposition and conversion of dietary alpha-linolenic acid (ALA) to its long chain metabolites eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with preformed EPA + DHA. Diets containing linseed oil [with ALA at approximately 2.5 (4 g/kg diet), 5 (8 g/kg diet), 10 (16 g/kg diet), 25% (40 g/kg diet)] or fish oil [with EPA + DHA at approximately 1 (1.65 g/kg diet), 2.5 (4.12 g/kg diet), 5% (8.25 g/kg diet)] or groundnut oil without n-3 polyunsaturated fatty acids (n-3 PUFA) were fed to rats for 60 days. ALA and EPA + DHA in serum, liver, heart and brain increased with increments in the dietary ALA level. When preformed EPA + DHA were fed, the tissue EPA + DHA increased significantly compared to those given ALA. Normalized values from dietary n-3 PUFA to tissue EPA + DHA indicated that 100 mg of dietary ALA lead to accumulation of EPA + DHA at 2.04, 0.70, 1.91 and 1.64% of total fatty acids respectively in liver, heart, brain and serum. Similarly 100 mg of preformed dietary EPA + DHA resulted in 25.4, 23.8, 15.9 and 14.9% of total fatty acids in liver, heart, brain and serum respectively. To maintain a given level of EPA + DHA, the dietary ALA required is 12.5, 33.5, 8.3 and 9.1 times higher than the dietary EPA + DHA for liver, heart, brain and serum respectively. Hence the efficacy of precursor ALA is lower compared to preformed EPA + DHA in elevating serum and tissue long chain n-3 PUFA levels.

Regression of preestablished cholesterol gallstones by dietary garlic and onion in experimental mice.

We have recently reported the health beneficial potential of dietary garlic and onion in reducing the incidence and severity of cholesterol gallstone (CGS) during its experimental induction in mice. In the current study, the efficacy of dietary garlic and onion in regressing preestablished CGS was investigated in experimental mice. After inducing CGS in mice with a lithogenic diet for 10 weeks, they were maintained on basal diets containing 0.6% dehydrated garlic or 2% dehydrated onion for a further 10 weeks. Dietary garlic and onion, either raw or heat processed, regressed preformed CGS in mice up to 53% to 59%, whereas the regression in the basal control diet group was only 10%. The antilithogenic potency of garlic was decreased by its heat processing, but not in the case of onion. Biliary cholesterol was significantly decreased in garlic- and onion-fed animals. Biliary cholesterol saturation index and hydrophobicity index were significantly lowered by dietary garlic and onion. Serum and liver cholesterol levels were decreased by feeding these spices during post-CGS induction period. Hepatic hydroxymethylglutaryl-coenzyme A reductase activity was increased after feeding garlic and onion, whereas activities of the cholesterol-degrading enzymes cholesterol-7α-hydroxylase and sterol-27-hydroxylase were increased in spice-fed groups. These results indicate that feeding garlic and onion effectively accelerates the regression of preformed CGS by promoting cholesterol desaturation in bile. This observation is significant in the context of evolving dietary intervention strategy to address regression of existing CGS and stopping the possible recurrence.

Effect of dietary garlic and onion on biliary proteins and lipid peroxidation which influence cholesterol nucleation in bile.

Formation of cholesterol gallstones in gallbladder is controlled by procrystallizing and anticrystallizing factors present in bile. Dietary garlic and onion have been recently observed to possess anti-lithogenic potential in experimental mice. In this investigation, the role of biliary proteins from rats fed lithogenic diet or garlic/onion-containing diet in the formation of cholesterol gallstones in model bile was studied. Cholesterol nucleation time of the bile from lithogenic diet group was prolonged when mixed with bile from garlic or onion groups. High molecular weight proteins of bile from garlic and onion groups delayed cholesterol crystal growth in model bile. Low molecular weight (LMW) proteins from the bile of lithogenic diet group promoted cholesterol crystal growth in model bile, while LMW protein fraction isolated from the bile of garlic and onion groups delayed the same. Biliary LMW protein fraction was subjected to affinity chromatography using Con-A and the lectin-bound and unbound fractions were studied for their influence on cholesterol nucleation time in model bile. Major portion of biliary LMW proteins in lithogenic diet group was bound to Con-A, and this protein fraction promoted cholesterol nucleation time and increased cholesterol crystal growth rate, whereas Con-A unbound fraction delayed the onset of cholesterol crystallization. Biliary protein from garlic/onion group delayed the crystallization and interfered with pronucleating activity of Con-A bound protein fraction. These data suggest that apart from the beneficial modulation of biliary cholesterol saturation index, these Allium spices also influence cholesterol nucleating and antinucleating protein factors that contribute to their anti-lithogenic potential.

Effects of rice bran oil enriched with n-3 PUFA on liver and serum lipids in rats.

Lipase-catalyzed interesterification was used to prepare different structured lipids (SL) from rice bran oil (RBO) by replacing some of the fatty acids with alpha-linolenic acid (ALA) from linseed oil (LSO) and n-3 long chain polyunsaturated fatty acids (PUFA) from cod liver oil (CLO). In one SL, the ALA content was 20% whereas in another the long chain n-3 PUFA content was 10%. Most of the n-3 PUFA were incorporated into the sn-1 and sn-3 positions of triacylglycerol. The influence of SL with RBO rich in ALA and EPA + DHA was studied on various lipid parameters in experimental animals. Rats fed RBO showed a decrease in total serum cholesterol by 10% when compared to groundnut oil (GNO). Similarly structured lipids with CLO and LSO significantly decreased total serum cholesterol by 19 and 22% respectively compared to rice bran oil. The serum TAGs level of rats fed SLs and blended oils were also significantly decreased by 14 and 17% respectively compared to RBO. Feeding of an n-3 PUFA rich diet resulted in the accumulation of long chain n-3 PUFA in various tissues and a reduction in the long chain n-6 PUFA. These studies indicate that the incorporation of ALA and EPA + DHA into RBO can offer health benefits.

Dietary garlic and onion reduce the incidence of atherogenic diet-induced cholesterol gallstones in experimental mice.

Mice fed with diet containing 0.5 % cholesterol for 10 weeks resulted in cholesterol supersaturation in gallbladder bile which promoted the formation of cholesterol gallstones (CGS). In this study, dietary hypocholesterolaemic spices, garlic and onion (both raw or heat-processed) were examined for their antilithogenic potential by including at 0.6 and 2.0 % level, respectively, along with lithogenic (LG) diet for 10 weeks. Dietary garlic and onion reduced the CGS incidence by 15-39 %, the effect being maximum in the heat-processed onion group. Dietary garlic and onion markedly reduced biliary cholesterol. The cholesterol:phospholipid ratio which was 1.58 in the LG diet group was reduced to 0.73-0.96 in the garlic and onion groups. The biliary cholesterol saturation index was 0.92, 1.25, 1.09 and 0.86, respectively, in the heat-processed onion, raw garlic, heat-processed garlic and raw onion groups, while it was 1.9 in the LG group. The hydrophobicity index of bile was - 0.08, - 0.079, - 0.032 and - 0.073, respectively, in the heat-processed onion, raw garlic, heat-processed garlic and raw onion groups, while it was +0.054 in the LG group. Hepatic hydroxymethyl glutaryl-CoA reductase activity was lowered in the LG diet-fed group, while dietary garlic or onion countered this alteration and also increased the activities of hepatic cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase. Serum and liver cholesterol were decreased by feeding garlic or onion compared to the LG diet. Thus, dietary Allium spices exerted antilithogenic influence by decreasing the cholesterol hyper-secretion into bile and increasing the bile acid output thus decreasing the formation of lithogenic bile in experimental mice.

Spray-dried milk supplemented with alpha-linolenic acid or eicosapentaenoic acid and docosahexaenoic acid decreases HMG Co A reductase activity and increases biliary secretion of lipids in rats.

In our earlier study, we have shown that rats fed spray-dried milk containing alpha-linolenic acid (LNA 18:3 n-3) or eicosapentaenoic acid (EPA 20:5 n-3) and docosahexaenoic acid (DHA 22:6 n-3) had significantly lower amounts of serum and liver cholesterol. To evaluate the mechanism for hypocholesterolemic effect of n-3 fatty acids containing milk formulation, we fed male Wistar rats with spray-dried milk containing linseed oil (LSO) (source of LNA) or fish oil (FO) (source of EPA+DHA) for 8 weeks. Feeding n-3 fatty acid containing milk formulation lowered the hepatic 3-hydroxy-methylglutaryl coenzyme A (HMG Co A) activity by 17-22% compared to rats given control diet devoid of n-3 fatty acids. The cholesterol level in liver microsomes was found to be decreased by 16% and 20%, respectively, in LSO and FO containing formulation fed rats. The bile flow was enhanced to an extent of 19-23% in experimental groups compared to control animals. The biliary cholesterol and phospholipid secretion was increased to an extent of 49-55% and 140-146%, respectively, in rats fed n-3 fatty acid containing formulation. The increase in the total bile acids secretion in bile was mainly reflected on an increase in the levels of taurine conjugated bile acids. These results indicated that n-3 fatty acid containing spray-dried milk formulation would bring about the hypocholesterolemic effect by lowering HMG Co A reductase activity in liver and by increasing the secretion of bile constituents.

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.

Butyric acid modulates activities of intestinal and renal disaccharidases in experimentally induced diabetic rats.

To elucidate the effect of feeding of butyric acid on disaccharidase activities, the specific activities of the disaccharidases were measured in the intestinal mucosa and kidney cortex of control and diabetic rats. 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. Increased activities of intestinal maltase, sucrase and lactase in diabetic rats were significantly reduced in fiber-fed diabetic group. Supplementation of butyric acid at 500 mg/kg body weight/day showed a further decrease in their activities. The activity of disaccharidases in renal tissue was decreased in diabetic rats and was significantly improved in fiber-fed diabetic group. Butyric acid feeding at 500 mg/kg body weight/day showed further improvement in their activities.

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.