T. S. Kahlon

Remodeling the isoprenoid pathway in tobacco by expressing the cytoplasmic mevalonate pathway in chloroplasts.

Metabolic engineering to enhance production of isoprenoid metabolites for industrial and medical purposes is an important goal. The substrate for isoprenoid synthesis in plants is produced by the mevalonate pathway (MEV) in the cytosol and by the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway in plastids. A multi-gene approach was employed to insert the entire cytosolic MEV pathway into the tobacco chloroplast genome. Molecular analysis confirmed the site-specific insertion of seven transgenes and homoplasmy. Functionality was demonstrated by unimpeded growth on fosmidomycin, which specifically inhibits the MEP pathway. Transplastomic plants containing the MEV pathway genes accumulated higher levels of mevalonate, carotenoids, squalene, sterols, and triacyglycerols than control plants. This is the first time an entire eukaryotic pathway with six enzymes has been transplastomically expressed in plants. Thus, we have developed an important tool to redirect metabolic fluxes in the isoprenoid biosynthesis pathway and a viable multigene strategy for engineering metabolism in plants.

In Vitro Binding of Bile Acids by Rice Bran, Oat Bran, Wheat Bran, and Corn Bran

ABSTRACT The in vitro bile acid binding by rice, oat, wheat, and corn brans was determined using a mixture of bile acids normally secreted in human bile at a physiological pH of 6.3. The objective of the study was to relate bile acid binding of cereal brans to health promoting properties. Three experiments were conducted testing substrates on an equal weight (dry matter) basis, an equal total dietary fiber (TDF) basis, and an equal TDF and equal fat basis. Each experiment was repeated to validate the results (for a total of six experiments). The relative in vitro bile acid binding of the cereal brans on an equal TDF basis considering cholestyramine as 100% bound was rice bran 51%, wheat bran 31%, oat bran 26%, and corn bran 5%. The data suggest that cholesterol lowering by rice bran appears to be related to bile acid binding. The primary mechanism of cholesterol lowering by oat bran may not be due to bile acid binding by soluble fiber. Bile acid binding did not appear to be proportional to the soluble fib...

In vitro binding of bile acids by rice bran, oat bran, barley and β-glucan enriched barley

ABSTRACT The in vitro bile acid binding by rice bran, oat bran, dehulled barley, and β-glucan enriched barley was determined using a mixture of bile acids at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted testing substrates on an equal protein basis. The relative in vitro bile acid binding of the cereal brans on an equal total dietary fiber (TDF) and insoluble dietary fiber (IDF) basis considering cholestyramine as 100% bound was rice bran 45 and 49%; oat bran 23 and 30%; dehulled barley 33 and 57%; and β-glucan enriched barley 20 and 40%, respectively. Bile acid bindings on equal protein basis for the respective cereals were 68, 26, 41, and 49%. Bile acid binding by rice bran may account to a great extent for its cholesterol-lowering properties, while bile acid binding by oat bran suggests that the primary mechanism of cholesterol lowering by oat bran is not due to the bile acid binding by its soluble fiber. Bile acid binding was not proportional to the solubl...

In vitro bile-acid-binding of whole vs. pearled wheat grain.

ABSTRACT Health benefits of consuming whole grains are reduced risk of heart disease, stroke, and cancer. The U.S. Health and Human Services and USDA dietary guidelines recommend consumption of 6–10 oz of grain products daily and one-half of that amount should contain whole grains. Whole grains contain vitamins, minerals, fiber, and phytonutrients. Bile-acid-binding capacity has been related to cholesterol lowering potential of food fractions. Lowered recirculating bile acids results in utilization of cholesterol to synthesize bile acid and reduced fat absorption. Secondary bile acids have been associated with increased risk of cancer. Bile-acid-binding potential has been related to lowering the risk of heart disease and that of cancer. It has been reported that bile-acid-binding of wheat bran is not related to its total dietary fiber (TDF) content. Whole (W) grain as well as pearled (P) hard red winter wheat (Hrw), hard white winter wheat (Hww), and durum wheat (DU) cooked grains were evaluated for in vi...

Extrusion conditions modify hypocholesterolemic properties of wheat bran fed to hamsters

ABSTRACT Wheat bran was extruded in a twin-screw extruder at five specific mechanical energy (SME) levels (0.120, 0.177, 0.234, 0.291, and 0.358 kWh/kg, dwb) and the cholesterol-lowering effects were compared with those of unprocessed wheat bran when fed to four-week-old male golden Syrian hamsters (n = 10/treatment) for three weeks. Diets contained 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.4% cholesterol. Plasma total cholesterol and very-low-density lipoprotein cholesterol were significantly lower with 0.120 kWh/kg extruded wheat bran diet compared with the unextruded wheat bran control. Total triglycerides were significantly lower with 0.120 and 0.177 kWh/kg wheat bran diets compared with those fed 0.291 and 0.358 kWh/kg extruded wheat bran diets. Cholesterol digestibility, total liver cholesterol, and total liver lipids were significantly lower with all the extruded wheat bran diets compared with the unextruded wheat bran control. Cholesterol digestibility for the 0.291 kWh/kg wheat bran ...

Cholesterol Response and Foam Cell Formation in Hamsters Fed Rice Bran, Oat Bran, and Cellulose + Soy Protein Diets With or Without Added Vitamin E

ABSTRACT Four-week-old male golden Syrian hamsters were fed diets containing cellulose (control, CC), cellulose + soy protein (CS), CS + vitamin E, (CSE), rice bran (RB), RB + vitamin E (RBE), oat bran (OB), and OB + vitamin E (OBE) for six weeks (n = 10/treatment). Diets contained (by weight) 10% total dietary fiber, 3% N, 20% fat, 0.5% cholesterol, and some diets had an additional 0.1% vitamin E. After six weeks, RB and OB diets resulted in significantly higher weight gain than the CC diet. Plasma low-density lipoprotein cholesterol (LDL-C) values and the LDL-C/high-density lipoprotein cholesterol ratio in hamsters fed CSE, RBE, OB, and OBE diets were significantly lower than in those fed CC diet. There were no significant differences in total plasma cholesterol values among the hamsters fed any of the diets. Liver cholesterol in animals fed OB and OBE diets was significantly lower than in all other groups. Foam cell areas in the inner bend of the aortic arch in animals fed all treatment diets were sign...

In Vitro Bile Acid Binding Capacity of Milled Wheat Bran and Milled Extruded Wheat Bran at Five Specific Mechanical Energy Levels

ABSTRACT The in vitro binding of bile acids of milled wheat bran (MWB) and milled extruded wheat bran (MEB) at five specific mechanical energy (SME) levels of 120 (MEB-120), 177 (MEB-177), 234 (MEB-234), 291 (MEB-291), and 358 (MEB-358) Whr/kg on a fat-free dry weight basis was determined using a mixture of bile acids secreted in human bile at duodenal physiological pH 6.3. Relative to cholestyramine (bile acid binding, cholesterol lowering drug) in vitro bile acid binding capacity on dry matter, total dietary fiber (TDF), and insoluble dietary fiber (IDF) basis was for MWB: 21, 43, 45%; the range for MEB was 18–21%, 34–41%, and 36–43%, respectively. MWB resulted in significantly higher bile acid binding than that of MEB at 120, 234, and 291 Whr/kg on a dry matter, TDF, and IDF basis. These results demonstrate the relative health-promoting potential of MWB = MEB-177 = MEB-358 > MEB-120 = MEB-234 = MEB-291 as indicated by the bile acid binding on a dry matter basis. Data suggest that significant improvemen...

Effect of Wheat Bran Fiber and Bran Particle Size on Fat and Fiber Digestibility and Gastrointestinal Tract Measurements in the Rat

ABSTRACT The effect of wheat bran (AACC hard red) and bran particle size on fat and fiber digestibility and gastrointestinal tract measurements were investigated with diets containing 5.7–10.7% dietary fiber. Fifty-six male weanling Sprague-Dawley rats were randomly assigned to four diets containing 5% cellulose (C5); 10.5% cellulose (C10); 21.5% coarse (2 mm) wheat bran (CB); or 22.2% fine (0.5 mm) wheat bran (FB) in a sixweek study. Dietary fiber digestibilities were significantly different (P FB > C5 > C10) but there was no effect in fat digestibility among treatments. High-fiber diets fed to rats resulted in significantly greater wet and dry fecal weights than low-fiber diets. Bran diets resulted in significantly higher fecal moisture than cellulose diets. Cecum lengths increased significantly with bran diets compared with cellulose diets. The CB diet resulted in significantly higher stomach weights than with cellulose diets. Stomachs were heavier and cecal lengths ...

Lipidemic Response of Hamsters to Rice Bran, Uncooked or Processed White and Brown Rice, and Processed Corn Starch

ABSTRACT This study was undertaken to evaluate the lipidemic response of rice bran and the possible enhancement of its healthful properties by using raw or processed white or brown rice in place of corn starch. All diets contained 10% total dietary fiber, 15% fat, and 0.5% cholesterol. Weanling male golden Syrian hamsters were fed cellulose control (CC), processed corn starch (PCS), cellulose with processed brown rice (CPBR), rice bran (RB), RB with white rice (RBWR), RB with processed white rice (RBPWR), RB with brown rice (RBBR), and RB with processed brown rice (RBPBR) diets. After three weeks, the PCS diet significantly lowered total plasma cholesterol (TC) compared with the CC, CPBR, RBWR, and RBPBR diets. RB and RBBR diets significantly lowered TC and LDL-C compared with CPBR diet. All the RB-containing and PCS diets significantly lowered liver cholesterol and liver lipid content. Processing white rice increased TDF content 240% and insoluble dietary fiber (IDF) 360%, whereas soluble dietary fiber (...

In Vitro Bile Acid Binding Capacity of Wheat Bran Extruded at Five Specific Mechanical Energy Levels

ABSTRACT The in vitro binding of bile acids of extruded wheat bran (EWB) at five specific mechanical energy (SME) levels of 120 (EWB-120), 177 (EWB-177), 234 (EWB-234), 291 (EWB-291), and 358 (EWB-358) Wh/kg on a dry weight basis, was determined using a mixture of bile acids secreted in human bile at a duodenal physiological pH 6.3. Experiments were conducted using six treatments and two blank incubations to test unextruded and extruded wheat bran samples on an equal dry matter (DM) basis. Relative to cholestyramine (bile acid binding, cholesterol-lowering drug), in vitro bile acid binding ability of unextruded and extruded wheat bran treatments on an equal DM basis was 14–23%. The bile acid binding ability of the total dietary fiber (TDF) was 28–51% and insoluble dietary fiber (IDF) was 29–53%. Bile acid binding on DM, TDF, and IDF bases for EWB-177 was significantly (P ≤ 0.05) higher, and EWB-358 was significantly lower than UWB, EWB-120, EWB-234, and EWB-291. Bile acid binding for EWB-120 was significa...