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PubMed1986

Biodegradable microspheres. IV: Factors affecting the distribution and degradation of polyacryl starch microparticles.

Polyacryl starch microparticles have been suggested as lysosomotropic drug carriers. In this paper we report the study of the distribution and elimination of polyacryl starch microparticles after intravenous administration in mice. The half-life of the particles in the circulation is short (less than 5 min) and they are efficiently taken up by the reticuloendothelial (RES) system, mainly in the liver (50-90%). The stability of the particles, as studied both in vitro (with serum and lysosome preparations) and in vivo (via the elimination from the liver), depends on two factors, the amount of initiator of the polymerization process (N,N,N',N'-tetramethylethylenediamine, TEMED) and the degree of derivatization of the starch. TEMED, used for the polymerization of the acryl groups forming the hydrocarbon chains, determines the number and the length of the cross-links between the starch molecules. The results indicate that large amounts of TEMED induce the formation of particles with many and short cross-links, which are easily degraded and dissolved in serum and more rapidly eliminated from the liver. The stability in serum can be improved by coadministration of soluble starch. Prolonged treatment of the starch with acrylic acid glycidyl ester leads to a high degree of derivatization and, consequently, to less degradable particles remaining in the lysosomes of the RES. The extent of biodegradation of the polyacryl starch particles could be anticipated from in vitro degradation of the monomers (acryloylated starch) with amyloglucosidase.

Animals↗
PubMed1993

The growth of preneoplastic lesions by 1,2-dimethylhydrazine in rat colon is inhibited by dietary starch.

The effect of dietary starch and sucrose on colon proliferation and the growth of foci of dysplastic crypts in the colon (FDC) were studied in female Sprague-Dawley rats, treated p.o. with 1,2-dimethylhydrazine (DMH). The animals were fed for 30 and 105 days with high fat (23% w/w corn oil) diets in which carbohydrates were represented by corn starch (starch diet) or sucrose (sucrose diet) (46% w/w). After 105 days of feeding, proliferation was markedly reduced in animals fed the starch diet. The number of FDC was not significantly affected by dietary treatments. However, after 30 and 105 days the percent of small FDC (formed by one-two dysplastic crypts) was higher in the animals fed the starch diet when compared to the sucrose diet. In the cecum of the animals fed the starch diet the percent of butyrate, propionic, isovaleric, and valeric over total short-chain fatty acids (SCFA) was increased, whereas the percent of acetic acid was decreased. Cecal pH was also decreased in the animals fed starch. The results suggest that starch diets have a protective role against DMH-colon carcinogenesis in the rat, mediated by a drop in cecal pH and an increased concentration of some SCFA.

1,2-Dimethylhydrazine↗
PubMed1994

Properties of starch and dietary fibre in raw and processed quinoa (Chenopodium quinoa, Willd) seeds.

We investigated certain properties of starch in raw and in heat-treated samples of quinoa, properties that are of importance to the nutritional quality of an infant food currently being developed. Scanning electron microscopy of the starch in raw seeds showed polygonal granules (0.6 to 2.0 microns diameter) to be present both singly and as spherical aggregates. Thermograms (DSC) of the flours showed one transition phase for gelatinisation of the starch and another for the amylose-lipid complex. The gelatinisation temperature of the starch was 67 degrees C. Cooked samples manifested the highest degree of gelatinisation (97%), followed by the drum-dried (96%) and autoclaved (27%) samples. Separation of the starch on a SEPHAROSE CL-2B column showed the quinoa starch to be affected by the heat treatment, manifesting changes in the degree and extent of degradation. The amylograph viscosity of the quinoa flour showed no distinct peak for pasting, but the viscosity remained constant after gelatinisation. Cooking and autoclaving modified the viscosity of the paste. The drum-dried sample manifested a higher initial viscosity at 25 degrees C. The in vitro digestibility of raw quinoa starch determined by incubation for 60 min with alpha-amylase was 22%, while that of autoclaved, cooked and drum-dried samples was 32%, 45% and 73%, respectively. Saponins did not affect the digestibility of the starch, though they tended to increase the amylograph viscosity. The total dietary fibre content in the cooked sample (11.0%) was significantly lower than that in the autoclaved (13.2%), drum-dried (13.3%) or raw samples (13.3%), while the insoluble dietary fibre fraction in the samples did not change with heat treatment. However, as compared with that of raw quinoa, the soluble dietary fibre fraction was reduced significantly both by cooking (0.9%) and by autoclaving (1.0%).

Calorimetry, Differential Scanning↗
PubMed1987

Super-efficient starch absorption. A risk factor for colonic neoplasia?

We tested the hypothesis that super-efficient starch absorption, by reducing the supply of carbohydrate to the colon, may be associated with and possibly promote colonic neoplasia. By means of breath hydrogen measurements following a potato meal and comparison with the hydrogen response to lactulose, the amount of starch escaping small bowel absorption was measured in 10 patients who had a colonic adenoma removed endoscopically and in 10 controls. The subjects' consumption of starch and fiber was assessed. Percentage unabsorbed starch was approximately half as much in the patients (5.3%) compared with the controls (10.9%, P less than 0.05). Consumption of starch and dietary fiber, and mouth-to-cecum transit times were not significantly different. Unabsorbed starch was calculated to contribute to 6.0 g/day colonic carbohydrate in the patients and 10.9 g/day in the controls (P less than 0.05). This study confirms that unabsorbed starch provides an important quantity of colonic carbohydrate and suggests that super-efficient starch absorption, by reducing this provision, may promote colonic neoplasia.

Breath Tests↗
PubMed2003

Puroindoline A-gene expression is involved in association of puroindolines to starch.

Puroindolines largely influence cereal grain hardness. In order to understand how they exert this influence, we carried out a molecular analysis of the pina and pinb genes of many Italian wheat cultivars. On the basis of their pin genotypes they could be divided into three groups: Pina-D1a/Pinb-D1a; Pina-D1a/Pinb-D1b; and Pina-D1b/Pinb-D1a. Five cultivars from each group were chosen to be studied to examine the quantity of puroindolines associated with starch (friabilin) and the amount not associated with starch. In addition, the level of pina expression was measured using RT-PCR. Soft cultivars ( Pina-D1a/Pinb-D1a) exhibited the highest level of expression of pina; among the hard cultivars, those with the Pina-D1a/Pinb-D1b genotype showed a lower level of expression, while those with the Pina-D1b/Pinb-D1a genotype did not express pina. Total puroindoline and friabilin content was then measured by flow cytometry. Soft Pina-D1a/Pinb-D1a cultivars displayed high puroindoline content that was primarily starch associated. Hard Pina-D1b/Pinb-D1a cultivars had very low puroindoline content with no puroindoline bound to starch. Hard Pina-D1a/Pinb-D1b cultivars were highly heterogeneous with respect to both the content of puroindolines and the level of association with starch. The accurate quantification of puroindolines in starch-bound and not starch-bound forms in association with molecular analysis, indicates that pina expression and presence controls the abundance of total puroindoline and its association with starch.

Base Sequence↗
PubMed1999

Purification and properties of a novel raw starch degrading cyclomaltodextrin glucanotransferase from Bacillus firmus.

A novel raw starch degrading cyclomaltodextrin glucanotransferase (CGTase; E.C. 2.4.1.19), produced by Bacillus firmus, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The molecular weight of the pure protein was estimated to be 78,000 and 82,000 Da, by SDS-PAGE and gel filtration, respectively. The pure enzyme had a pH optimum in the range 5.5-8.5. It was stable over the pH range 7-11 at 10 degrees C, and at pH 7.0 at 60 degrees C. The optimum temperature for enzyme activity was 65 degrees C. In the absence of substrate, the enzyme rapidly lost its activity above 30 degrees C. K(m) and kcat for the pure enzyme were 1.21 mg/ml and 145.17 microM/mg per minute respectively, with soluble starch as the substrate. For cyclodextrin production, tapioca starch was the best substrate used when gelatinized, while wheat starch was the best substrate used when raw. This CGTase could degrade raw wheat starch very efficiently; up to 50% conversion to cyclodextrins was obtained from 150 g/l starch without using any additives. The enzyme produced alpha-, beta- and gamma-cyclodextrins in the ratio of 0.2:9.2:0.6 and 0.2:8.6:1.2 from gelatinized tapioca starch and raw wheat starch with 150 g/l concentration respectively, after 18 h incubation.

Bacillus↗
PubMed2004

In vitro starch digestibility and in vivo glucose response of gluten-free foods and their gluten counterparts.

BACKGROUND: Recently there has been increasing interest in the production of gluten-free (GF) foods and studies on minor cereals and pseudocereals without celiac activity in order to fulfill the specific needs of people affected by celiac disease. GF bread, pasta, biscuits are usually manufactured using different combinations of thickenings and particular food processing procedures that could affect starch digestibility. Carbohydrates, mainly starch from cereals, play an important part in a balanced diet, and dietary guidelines suggest a diet with low glycemic index foods, that is to say rich in slowly digested carbohydrates. AIM: The present study was aimed at evaluating: 1) the importance of some GF food characteristics in relation to their effects on in vitro starch accessibility to digestion, in comparison with traditional gluten products; 2) the in vivo metabolic responses to GF foods. METHODS: Firstly, starch digestibility of several products was evaluated in vitro. Then, an in vivo study was performed on a group of healthy volunteers. Postprandial glucose and insulin responses were evaluated after administration of three GF foods and traditional bread. Triglycerides and free fatty acids (FFA) were also evaluated. Attempts were also made to explore differences in metabolic responses to GF foods in healthy subjects with respect to celiac subjects. RESULTS: The area under the curve (AUC) of digested starch of GF bread was slightly higher than that of the traditional counterpart. No significant difference was observed in AUCs of digested starch between GF pasta and the traditional pasta. The AUCs of digested starch of quinoa and the two samples of pasta were not statistically different. Significant differences were observed between GF bread and bread-like products. Statistic differences in glucose responses to GF pasta were observed between healthy and celiac subjects. In healthy subjects, the AUCs of glucose response after GF bread were higher than those after bread with gluten. No significant differences were observed between the AUCs of insulin responses to all products tested. Glycemic index (GI) for GF pasta was similar to GI for GF bread while GI for quinoa was slightly lower than that of GF pasta and bread. Two-way ANOVA revealed that quinoa induced lower FFA levels with respect to GF pasta. In addition, triglyceride concentrations were significantly reduced for quinoa with respect to GF bread and bread. CONCLUSIONS: Our results indicate that the different formulations and the food processing procedures used in the manufacturing of GF products may affect the rate of starch digestion both in vitro and in vivo. It may be worthwhile improving the formulation of these products. Furthermore, quinoa seems to represent a potential alternative to traditional foods, even if further and larger studies are required to demonstrate its hypoglycemic effects.

Adult↗
PubMed2006

Enzymatic modification of cassava starch by bacterial lipase.

Enzymatic modification of starch using long chain fatty acid makes it thermoplastic suitable for a myriad of industrial applications. An industrial lipase preparation produced by Burkholderia cepacia (lipase PS) was used for modification of cassava starch with two acyl donors, lauric acid and palmitic acid. Reactions performed with palmitic acid by liquid-state and microwave esterification gave a degree of substitution (DS) of 62.08% (DS 1.45) and 42.06% (DS 0.98), respectively. Thermogravimetric analysis showed that onset of decomposition is at a higher temperature (above 600 degrees Celsius) for modified starch than the unmodified starch (280 degrees Celsius). Modified starch showed reduction in alpha-amylase digestibility compared to native starch (76.5-18%). Swelling power lowered for modified starch as esterification renders starch more hydrophobic, making it suitable for biomedical applications as materials for bone fixation and replacements, carriers for controlled release of drugs and bioactive agents. Thus enzymatic esterification is ecofriendly.

Burkholderia cepacia complex↗
PubMed2006

ABI4 mediates the effects of exogenous trehalose on Arabidopsis growth and starch breakdown.

The disaccharide trehalose has dramatic effects on plant metabolism, growth and development. Arabidopsis seedlings grown on trehalose-containing medium without sucrose display increased expression of the starch synthesis gene ApL3, hyper-accumulation of starch in the cotyledons and inhibition of root growth. Here we show that the ABI4 transcription factor mediates the effects of trehalose on starch metabolism and growth, independently of abscisic acid (ABA) synthesis and hexokinase (HXK1) signaling. Surprisingly, although the abi4 mutation partially rescued trehalose inhibition of root elongation, ApL3 expression levels were still enhanced. Gene expression analysis suggests that trehalose affects both starch synthesis and starch breakdown. The expression of genes involved in starch breakdown, such as SEX1 and the beta-amylase gene BMY8/BAM3, was strongly down-regulated in WT plants grown on trehalose but not in abi4 mutants. Addition of trehalose to liquid-grown WT seedlings also significantly reduced SEX1 expression after 6 h. Bypassing the need for starch breakdown by growth in continuous light or addition of sucrose rescued root growth on trehalose medium similar to the abi4 mutation. These results suggest that inhibition of starch mobilization rather than increased synthesis is involved in growth inhibition by exogenous trehalose. Trehalose also significantly enhanced ABI4 expression but reduced its sucrose induction, providing a possible molecular mechanism for the trehalose effect on plant gene expression and growth.

Arabidopsis↗
PubMed1986

Colonic metabolism of wheat starch in healthy humans. Effects on fecal outputs and clinical symptoms.

To study the intracolonic digestion of starch, 5 healthy volunteers were maintained on a constant diet for 7 days. On the fourth day, the cecum was intubated and a suspension of raw wheat starch (50 g, in 500 ml of 154 mM NaCl and containing 10 g of polyethylene glycol 4000) was infused into the distal ileum at 2 ml/min. Hydrogen excretion in breath was measured, cecal contents were sampled, and symptoms were recorded. For the 2-3 days before and after starch infusions, fecal weight, pH, and percentage of dry matter were monitored; fecal outputs of starch, volatile fatty acids, lactic acid, ethanol, polyethylene glycol, alpha-amylase, nitrogen, and ammonia were also measured. A lactulose (10 g) hydrogen breath test was performed 5-7 days after the starch infusions. After the infusion of starch, concentrations of lactic and volatile fatty acids increased and pH decreased markedly in cecal contents. None of the fecal values changed significantly after starch, however, indicating that carbohydrate catabolism was nearly complete and that the colon absorbed the catabolic products efficiently. Abdominal symptoms, especially bloating, were noted by all subjects, and 2 subjects complained of cramping pain. No subject experienced diarrhea. The amounts of starch metabolized in the colon (47.3 +/- 2.9 g), as calculated from the excretion of H2 in breath compared to the hydrogen breath test after lactulose, were close to the actual load (50 g).

Adult↗
PubMed1991

Does starch taste like Polycose?

Rats are capable of tasting or detecting maltooligosaccharides (e.g., Polycose) and starch in water, two substances that are bland to humans. Because both substances are glucose polymers, it has been suggested that they may be detected by the same mechanism. The present experiments examined whether rats conditioned to avoid one of these substances also avoid the other. Rats were injected with lithium chloride after being allowed to drink a 3% corn starch suspension. These rats subsequently avoided corn, potato, rice, and waxy maize (high-amylopectin) starch but did not avoid 0.1-3% Polycose Rats treated with lithium chloride after ingesting 3% Polycose avoided 3% and 0.5% Polycose, but they did not avoid 3% corn starch, 6% corn starch, or 3% waxy maize starch. These results indicate that rats can discriminate between starch and Polycose (maltooligosaccharides). It therefore seems likely that Polycose and starch have different sensory qualities.

Animals↗
PubMed1990

Cloning and expression of raw-starch-digesting alpha-amylase gene from Bacillus circulans F-2 in Escherichia coli.

The raw potato-starch-digesting alpha-amylase gene of Bacillus circulans F-2 was cloned for the first time in Escherichia coli C600, using plasmid pYEJ001. The recombinant plasmid, named pYKA3, has a 5.4 kb insert from a chromosome of the donor bacterium. Subcloning of this amylase gene gave plasmid pHA300 which carried 3.15 kb of the inserted DNA. The transformed bacterium, E. coli C600 (pYKA3), produced the amylase in the periplasmic space, whereas it is secreted outside the cell in the donor bacterium. The cloned raw-starch-digesting alpha-amylase has a molecular weight of 93,000 on SDS-PAGE, and its action pattern was absolutely the same as that of the potent raw-starch-digestible amylase produced by B. circulans F-2. The periplasmic amylase produced by the transformed E. coli (pHA300) could digest raw starch granules such as potato, corn and barley raw starch granules, indicating that the raw-starch-digesting amylase is active in E. coli. Furthermore, this amylase crossreacted with the rabbit antiserum raised against the raw potato-digesting alpha-amylase of B. circulans F-2. From these results it was concluded that the cloned amylase is the same amylase protein as B. circulans F-2 amylase, which has a potent raw-starch digestibility. Thus, this paper is to our knowledge the first describing the molecular cloning of raw-starch-digesting alpha-amylase from Bacillus species and its successful expression in E. coli.

Bacillus↗
PubMed1992

Proteolytic modification of raw-starch-digesting amylase from Bacillus circulans F-2 with subtilisin: separation of the substrate-hydrolytic domain and the raw substrate-adsorbable domain.

Raw starch-digesting amylase (BF-2A, 93,000 Da) from Bacillus circulans F-2 was converted into two components during digestion with subtilisin. The two components were separated and designated BF-2A' (63 kDa) and BF-2B (30 kDa), respectively. BF-2A' exhibited the same hydrolysis curve for soluble starch as the original amylase (BF-2A). Moreover, the catalytic activities of original and modified enzymes were indistinguishable in Km, Vmax and in their specific activity for soluble starch hydrolysis. However, its absorbability and digestibility on raw starch was greatly decreased. Furthermore, the enzymatic action pattern on soluble starch was differed greatly from that of BF-2A. The stability of the enzymes decreased below pH 5.5 and at 50 degrees C, while it was quite stable even at pH 12. On the other hand, the smaller peptide (BF-2B) could be adsorbed onto raw starch. From these results, it is suggested that the larger peptide (BF-2A') has a region responsible for the expression of the enzyme activity to hydrolyze soluble substrate, and the smaller peptide (BF-2B) plays a role on raw starch adsorption and also contributes to the original enzyme-to-enzyme stabilization. A proposed model of the raw-starch-digesting enzyme from this strain is extensively discussed.

Amylases↗
PubMed1994

Glucose- and ADPGlc-dependent starch synthesis in isolated cauliflower-bud amyloplasts. Analysis of the interaction of various potential precursors.

Recently, we have demonstrated that isolated cauliflower-bud amyloplasts incorporate glucose 6-phosphate at high rates into newly synthesized starch (Neuhaus et al. (1993) Plant Physiol. 101, 573-578). Here we have analyzed the incorporation of radioactively labeled glucose and ADPglucose into newly synthesized starch. It could be shown that glucose incorporation into starch exhibits a typical substrate saturation behaviour and is linear with time for at least 40 min. The incorporation of glucose is strongly dependent upon the intactness of the plastids and upon the presence of both, ATP and 3-phosphoglyceric acid. Using 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) we showed that glucose is taken up into isolated cauliflower-bud amyloplasts as the free glucose molecule, rather than as glucose 6-phosphate. Glucose incorporation into newly synthesized starch is strongly inhibited in the presence of low concentrations of glucose 6-phosphate. The radioactively labeled glucose moiety of ADPglucose is also incorporated into starch. This incorporation can be saturated at increased concentrations of ADPglucose. ATP significantly inhibits the incorporation of the glucose moiety of ADPglucose into starch. This inhibition can be reinforced by the additional presence of glucose 6-phosphate. Glucose 6-phosphate-dependent starch synthesis is not strongly inhibited in the presence of glucose or ADPglucose indicating that glucose 6-phosphate is the precursor for starch synthesis in isolated cauliflower-bud amyloplasts.

Adenosine Diphosphate Glucose↗
PubMed1988

Influence of partial replacement of starch by sucrose in high fat-cholesterol diet on serum lipoprotein responses of cynomolgus monkeys.

The influence of partial replacement of starch by sucrose on dietary cholesterol-induced serum lipoprotein responses was examined in 10 male cynomolgus monkeys (Macaca fascicularis). In a crossover design two semipurified diets provided either starch or starch and sucrose (1:1) as carbohydrate (49% by calories) with 0.4 mg cholesterol/kcal. Six weeks of starch + sucrose diet resulted in significantly reduced levels (mean +/- SE, mg/dl) of serum total cholesterol (264 +/- 9 vs 244 +/- 8) and apo B (110 +/- 6 vs 96 +/- 6) when compared with starch diet, whereas serum triglyceride levels remained similar between diets. With respect to changes in lipids and apolipoproteins (A-I or B) of very low (VLDL), low (LDL), intermediate (IDL), and high (HDL) density lipoproteins, starch + sucrose diet significantly increased VLDL-apo B (+34%), and decreased LDL-cholesterol (-18%) and LDL-apo B (-15%) as compared with starch alone; no differences were found in IDL and HDL between diets. The relative proportion of starch to sucrose in a diet appears to influence the magnitude of response of lipoproteins to dietary cholesterol.

Animals↗
PubMed2007

Laboratory composting of extruded starch acetate and poly lactic acid blended foams.

Composting of extruded foams made of starch acetate and poly lactic acid (PLA) with pre-conditioned yard waste was studied using a laboratory composting system. Extruded foams of high amylose starch were used as the control. Degradation was measured by analyzing the exhaust gases for carbon dioxide. There were significant differences in the amounts of carbon dioxide produced in the vessels containing foams of high amylose starch and foams of starch acetate blended with 20% or 30% PLA. The high amylose starch foams completely degraded within 15 days. The starch acetate foams with 0% PLA took longer, with evolution of carbon dioxide still measurable after 55 days. The rate of degradation was faster for foams with higher PLA contents. The starch acetate foams took even longer to degrade. The maximum time was found to be 130 days for the starch acetate foams.

Biodegradation, Environmental↗
PubMed2005

Starch biosynthesis: further evidence against the primer nonreducing-end mechanism and evidence for the reducing-end two-site insertion mechanism.

Two reactions were studied with three varieties of starch granules from maize, wheat, and rice. In Reaction-I, the granules were reacted with 1 mM ADP-[(14)C]Glc and in Reaction-II, a portion of the granules from Reaction-I was reacted with 1 mM ADP-Glc. The starch granules were solubilized and reacted with the exo-acting glucoamylase and beta-amylase to an extent of 50% or less of the (14)C-label. The amounts of (14)C-labeled products from glucoamylase and beta-amylase were nearly equal for Reaction-I and Reaction-II. If the addition had been to the nonreducing ends of primers, Reaction-II would not have given any labeled products from the hydrolysis of glucoamylase and beta-amylase. These results indicate that the elongation of the starch chain is the addition of D-glucose to the reducing end by a de novo two-site insertion mechanism and not by the addition of D-glucose to the nonreducing end of a primer. This is in conformity with previous results in which starch granules were pulsed with ADP-[(14)C]Glc and chased with nonlabeled ADP-Glc, giving (14)C-labeled D-glucitol from the pulsed starch and a significant decrease in (14)C-labeled D-glucitol from the chased starch on reducing with NaBH(4) and hydrolyzing with glucoamylase [Carbohydr. Res.2002, 337, 1015-1022]. It also is in conformity with the inhibition of starch synthesis that occurs when putative primers are added to starch granule-ADP-Glc digests, indicating that the elongation is not by the nonreducing-end primer mechanism [Carbohydr. Res.2005, 340, 245-255].

Adenosine Diphosphate Glucose↗
PubMed2006

Significant differences in the activities of alpha-amylases in the absence and presence of polyethylene glycol assayed on eight starches solubilized by two methods.

Starch is a reserve chemical source of the energy of the sun found in plants as a water-insoluble granule that differs in their chemical and physical properties, depending on the source. The granules can be solubilized by heating in water or by treatment with various reagents, such as 1M NaOH. alpha-Amylases are widely distributed enzymes that initiate the hydrolysis of starch into low molecular weight maltodextrins. We recently found that the activities of a single alpha-amylase on two different starches were significantly different. We then determined the activities of Bacillus amyloliquefaciens and porcine pancreas alpha-amylases, using eight different starches, solubilized by two methods: autoclaving at 121 degrees C and 1M NaOH at 20 degrees C. There were significant differences in the activities of both of the amylases on all eight of the starches. Previously, it had been found that polyethylene glycol (PEG) stabilized and activated the activities of both enzymes, using a soluble amylose as the substrate. Addition of PEG to the enzymes greatly increased the activities on the eight starches, but the activities still differed significantly. The different activities with the starches were hypothesized as differences in the amounts of secondary and tertiary structures that are partially retained when the different starches are solubilized; the activities on addition of PEG is hypothesized as the formation of highly active species from a series of less active forms.

Animals↗