Displaying publications 1 - 20 of 46 in total

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  1. Effects of metsulphuron-methyl on amylase, invertase and xylanase activities in two soil types
    Ismail BS, Ampong N, Omar O
    Microbios, 2000;103(405):73-83.
    PMID: 11092189
    Effects of metsulphuron-methyl on the activities of amylase, invertase and xylanase in loamy sand and clay were evaluated for up to 28 days under laboratory conditions. Metsulphuron-methyl at 1.0 microg/g caused a significant reduction in amylase, invertase and xylanase activities for the entire period of study, especially at 28 days incubation in both soils. The lowest activities of the three enzymes were observed in the presence of 5.0 microg/g at 28 days incubation.
    Matched MeSH terms: Amylases/metabolism*
  2. Microwave-assisted extraction of polysaccharides from Micromelum minutum leaves using citric acid monohydrate-glycerol based deep eutectic solvents and evaluation of biological activities
    Md Yusoff MH, Shafie MH
    Anal Chim Acta, 2024 Dec 01;1331:343351.
    PMID: 39532430 DOI: 10.1016/j.aca.2024.343351
    BACKGROUND: The extraction of polysaccharides using an acidic extraction media has been extensively reported, highlighting its effectiveness in yielding high-quality polysaccharides. A higher concentration of acidic solution could hydrolyze the structure of polysaccharide, while a low concentration reduces the extraction efficiency. Despite this challenges, deep eutectic solvents (DES) were introduced as an alternative extraction medium due to additional interactions such as inter and intra-molecular interactions, Van de Waals, hydrogen bond, and electrostatic interactions, which could improve the polysaccharide extraction efficiency and biological activities. Furthermore, the extraction conditions such as extraction medium and extraction parameters could affect the properties of polysaccharides as well as influence their structure-activity relationship for biological activities.

    RESULTS: The result showed that the microwave-assisted extraction of Micromelum minutum leaf polysaccharide (MMLP) using DES as an extraction media (MMLP-DES) gave a higher yield (improvement of 101.20 %) than citric acid monohydrate (CAM) (MMLP-CAM) and required a lower percentage of microwave power (19.83 % less) and time (0.78 min less). The properties of MMLPs significantly differ based on their pH, molecular weight, viscosity, degree of esterification and monosaccharide molar ratio which influenced the biological activities. Compared to MMLP-CAM, MMLP-DES had a more branched and less linear structure. The bioactivities study revealed that MMLP-DES exhibited higher antioxidant and anti-α-amylase activities (i.e.

    , DPPH: 74.52 %, FRAP: 2.87 mM FeSO4 and α-amylase inhibition: 86.23 %) compared to MMLP-CAM (i.e.

    , DPPH: 49.33 %, FRAP: 1.49 mM FeSO4, and α-amylase inhibition: 81.76 %). The mechanism and structure-activity relationship of MMLPs on bioactivities were also hypothesized.

    SIGNIFICANCE: Based on our previous study, the citric acid monohydrate-glycerol based DES as an extraction medium has enhanced the extraction yield of polysaccharides from M. minutum. This study highlights the DES combined with microwave-assisted extraction to improve the yield of MMLP and evaluate the biological activities compared to CAM as a classical solvent. In conclusion, the DES showed the advantages for extraction of polysaccharides with desired biological activities.

    Matched MeSH terms: alpha-Amylases/metabolism
  3. Fulltext Tropical plant extracts as potential antihyperglycemic agents
    Manaharan T, Palanisamy UD, Ming CH
    Molecules, 2012;17(5):5915-23.
    PMID: 22609782 DOI: 10.3390/molecules17055915
    Preliminary investigations on 14 plant extracts (obtained by ethanolic and aqueous extraction) identified those having high antioxidant and a significant total phenolic content. Antihyperglycemic, α-amylase and α-glucosidase inhibition activities were also observed. A correlation between the antihyperglycemic activity, total phenolic content and antioxidant (DPPH scavenging) activity was established. To further substantiate these findings, the possibility of tannins binding non-specifically to enzymes and thus contributing to the antihyperglycemic activity was also investigated. Our study clearly indicated that the antihyperglycemic activity observed in the plant extracts was indeed not due to non-specific tannin absorption.
    Matched MeSH terms: alpha-Amylases/metabolism
  4. Hydrolysis of native and heat-treated starches at sub-gelatinization temperature using granular starch hydrolyzing enzyme
    Uthumporn U, Shariffa YN, Karim AA
    Appl Biochem Biotechnol, 2012 Mar;166(5):1167-82.
    PMID: 22203397 DOI: 10.1007/s12010-011-9502-x
    The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.
    Matched MeSH terms: alpha-Amylases/metabolism*
  5. Cloning and characterization of two new thermostable and alkalitolerant α-amylases from the Anoxybacillus species that produce high levels of maltose
    Chai YY, Rahman RN, Illias RM, Goh KM
    J Ind Microbiol Biotechnol, 2012 May;39(5):731-41.
    PMID: 22246222 DOI: 10.1007/s10295-011-1074-9
    Two genes that encode α-amylases from two Anoxybacillus species were cloned and expressed in Escherichia coli. The genes are 1,518 bp long and encode 506 amino acids. Both sequences are 98% similar but are distinct from other well-known α-amylases. Both of the recombinant enzymes, ASKA and ADTA, were purified using an α-CD-Sepharose column. They exhibited an optimum activity at 60°C and pH 8. Both amylases were stable at pH 6-10. At 60°C in the absence of Ca²⁺, negligible reduction in activity for up to 48 h was observed. The activity half-life at 65°C was 48 and 3 h for ASKA and ADTA, respectively. In the presence of Ca²⁺ ions, both amylases were highly stable for at least 48 h and had less than a 10% decrease in activity at 70°C. Both enzymes exhibited similar end-product profiles, and the predominant yield was maltose (69%) from starch hydrolysis. To the best of our knowledge, most α-amylases that produce high levels of maltose are active at an acidic to neutral pH. This is the first report of two thermostable, alkalitolerant recombinant α-amylases from Anoxybacillus that produce high levels of maltose and have an atypical protein sequence compared with known α-amylases.
    Matched MeSH terms: alpha-Amylases/metabolism*
  6. Fulltext Distribution of Polysulfide in Human Biological Fluids and Their Association with Amylase and Sperm Activities
    Ikeda M, Ishima Y, Chuang VTG, Sakai M, Osafune H, Ando H, et al.
    Molecules, 2019 Apr 30;24(9).
    PMID: 31052207 DOI: 10.3390/molecules24091689
    Intracellular polysulfide could regulate the redox balance via its anti-oxidant activity. However, the existence of polysulfide in biological fluids still remains unknown. Recently, we developed a quantitative analytical method for polysulfide and discovered that polysulfide exists in plasma and responds to oxidative stress. In this study, we confirmed the presence of polysulfide in other biological fluids, such as semen and nasal discharge. The levels of polysulfide in these biological fluids from healthy volunteers (n = 9) with identical characteristics were compared. Additionally, the circadian rhythm of plasma polysulfide was also investigated. The polysulfide levels detected from nasal discharge and seminal fluid were approximately 400 and 600 μM, respectively. No correlation could be found between plasma polysulfide and the polysulfide levels of tear, saliva, and nasal discharge. On the other hand, seminal polysulfide was positively correlated with plasma polysulfide, and almost all polysulfide contained in semen was found in seminal fluid. Intriguingly, saliva and seminal polysulfide strongly correlated with salivary amylase and sperm activities, respectively. These results provide a foundation for scientific breakthroughs in various research areas like infertility and the digestive system process.
    Matched MeSH terms: Amylases/metabolism*
  7. Crystal structure of a compact α-amylase from Geobacillus thermoleovorans
    Mok SC, Teh AH, Saito JA, Najimudin N, Alam M
    Enzyme Microb Technol, 2013 Jun 10;53(1):46-54.
    PMID: 23683704 DOI: 10.1016/j.enzmictec.2013.03.009
    A truncated form of an α-amylase, GTA, from thermophilic Geobacillus thermoleovorans CCB_US3_UF5 was biochemically and structurally characterized. The recombinant GTA, which lacked both the N- and C-terminal transmembrane regions, functioned optimally at 70°C and pH 6.0. While enzyme activity was not enhanced by the addition of CaCl2, GTA's thermostability was significantly improved in the presence of CaCl2. The structure, in complex with an acarbose-derived pseudo-hexasaccharide, consists of the typical three domains and binds one Ca(2+) ion. This Ca(2+) ion was strongly bound and not chelated by EDTA. A predicted second Ca(2+)-binding site, however, was disordered. With limited subsites, two novel substrate-binding residues, Y147 and Y182, may help increase substrate affinity. No distinct starch-binding domain is present, although two regions rich in aromatic residues have been observed. GTA, with a smaller domain B and several shorter loops compared to other α-amylases, has one of the most compact α-amylase folds that may contribute greatly to its tight Ca(2+) binding and thermostability.
    Matched MeSH terms: alpha-Amylases/metabolism*
  8. Synthesis of alpha amylase inhibitors based on privileged indole scaffold
    Noreen T, Taha M, Imran S, Chigurupati S, Rahim F, Selvaraj M, et al.
    Bioorg Chem, 2017 06;72:248-255.
    PMID: 28482265 DOI: 10.1016/j.bioorg.2017.04.010
    Twenty five derivatives of indole carbohydrazide (1-25) had been synthesized. These compounds were characterized using 1H NMR and EI-MS, and further evaluated for their α-amylase inhibitory potential. The analogs (1-25) showed varying degree of α-amylase inhibitory potential. ranging between 9.28 and 599.0µM when compared with standard acarbose having IC50 value 8.78±0.16µM. Six analogs, 25 (IC50=9.28±0.153µM), 22 (IC50=9.79±0.43µM), 4 (IC50=11.08±0.357µM), 1 (IC50=12.65±0.169µM), 8 (IC50=21.37±0.07µM) and 14 (IC50=43.21±0.14µM) showed potent α-amylase inhibition as compared to the standard acarbose (IC50=8.78±0.16µM). All other analogs displayed good to moderate inhibitory potential. Structure-activity relationship was established through the interaction of the active compounds with enzyme active site with the help of docking studies.
    Matched MeSH terms: alpha-Amylases/metabolism
  9. Synthesis and biological evaluation of indole derivatives as α-amylase inhibitor
    Imran S, Taha M, Selvaraj M, Ismail NH, Chigurupati S, Mohammad JI
    Bioorg Chem, 2017 08;73:121-127.
    PMID: 28648924 DOI: 10.1016/j.bioorg.2017.06.007
    A series of twenty indole hydrazone analogs (1-21) were synthesized, characterized by different spectroscopic techniques such as 1H NMR and EI-MS, and screened for α-amylase inhibitory activity. All analogs showed a variable degree of α-amylase inhibition with IC50 values ranging between 1.66 and 2.65μM. Nine compounds that are 1 (2.23±0.01μM), 8 (2.44±0.12μM), 10 (1.92±0.12μM), 12 (2.49±0.17μM), 13 (1.66±0.09μM), 17 (2.25±0.1μM), 18 (1.87±0.25μM), 20 (1.83±0.63μM), and 19 (1.97±0.02μM) showed potent α-amylase inhibition when compared with the standard acarbose (1.05±0.29μM). Other analogs showed good to moderate α-amylase inhibition. The structure activity relationship is mainly focusing on difference of substituents on phenyl part. Molecular docking studies were carried out to understand the binding interaction of the most active compounds.
    Matched MeSH terms: alpha-Amylases/metabolism
  10. 2'-Aryl and 4'-arylidene substituted pyrazolones: As potential α-amylase inhibitors
    Yousuf S, Khan KM, Salar U, Chigurupati S, Muhammad MT, Wadood A, et al.
    Eur J Med Chem, 2018 Nov 05;159:47-58.
    PMID: 30268823 DOI: 10.1016/j.ejmech.2018.09.052
    Acarbose and voglibose are well-known α-amylase inhibitors used for the management of type-II diabetes mellitus. Unfortunately, these well-known and clinically used inhibitors are also associated with several adverse effects. Therefore, there is still need to develop the safer therapy. Despite of a broad spectrum of biological significances of pyrazolone, it is infrequently evaluated for α-amylase inhibition. Current study deals with the synthesis and biological screening of aryl and arylidene substituted pyrazolones 1-18 for their potential α-amylase inhibitory activity. Structures of synthetic derivatives 1-18 were identified by different spectroscopic techniques. All compounds 1-18 (IC50 = 1.61 ± 0.16 μM to 2.38 ± 0.09 μM) exhibited significant to moderate inhibitory potential when compared to standard acarbose (IC50 = 1.46 ± 0.26 μM). A number of derivatives including 8-12 (IC50 = 1.68 ± 0.1 μM to 1.97 ± 0.07 μM) and 14-16 (IC50 = 1.61 ± 0.16 μM to 1.93 ± 0.07 μM) were found to be significantly active. Limited SAR suggested that different substitutions on compounds do not have any significant effect on the inhibitory potential. Compounds were found to be mixed-type inhibitors revealed by kinetic studies. However, in silico study was identified a number of key features participating in the interaction with the binding site of α-amylase enzyme.
    Matched MeSH terms: alpha-Amylases/metabolism
  11. Fulltext Potential Roles of α-amylase in Alzheimer's Disease: Biomarker and Drug Target
    Chen WN, Tang KS, Yeong KY
    Curr Neuropharmacol, 2022;20(8):1554-1563.
    PMID: 34951390 DOI: 10.2174/1570159X20666211223124715
    Alzheimer's disease (AD), the most common form of dementia, is pathologically characterized by the deposition of amyloid-β plaques and the formation of neurofibrillary tangles. In a neurodegenerative brain, glucose metabolism is also impaired and considered as one of the key features in AD patients. The impairment causes a reduction in glucose transporters and the uptake of glucose as well as alterations in the specific activity of glycolytic enzymes. Recently, it has been reported that α-amylase, a polysaccharide-degrading enzyme, is present in the human brain. The enzyme is known to be associated with various diseases such as type 2 diabetes mellitus and hyperamylasaemia. With this information at hand, we hypothesize that α-amylase could have a vital role in the demented brains of AD patients. This review aims to shed insight into the possible link between the expression levels of α-amylase and AD. Lastly, we also cover the diverse role of amylase inhibitors and how they could serve as a therapeutic agent to manage or stop AD progression.
    Matched MeSH terms: alpha-Amylases/metabolism
  12. Kojic acid production by Aspergillus flavus using gelatinized and hydrolyzed sago starch as carbon sources
    Rosfarizan M, Ariff AB, Hassan MA, Karim MI
    Folia Microbiol (Praha), 1998;43(5):459-64.
    PMID: 9867479
    Direct conversion of gelatinized sago starch into kojic acid by Aspergillus flavus strain having amylolytic enzymes was carried out at two different scales of submerged batch fermentation in a 250-mL shake flask and in a 50-L stirred-tank fermentor. For comparison, fermentations were also carried out using glucose and glucose hydrolyzate from enzymic hydrolysis of sago starch as carbon sources. During kojic acid fermentation of starch, starch was first hydrolyzed to glucose by the action of alpha-amylase and glucoamylase during active growth phase. The glucose remaining during the production phase (non-growing phase) was then converted to kojic acid. Kojic acid production (23.5 g/L) using 100 g/L sago starch in a shake flask was comparable to fermentation of glucose (31.5 g/L) and glucose hydrolyzate (27.9 g/L) but in the 50-L fermentor was greatly reduced due to non-optimal aeration conditions. Kojic acid production using glucose was higher in the 50-L fermentor than in the shake flask.
    Matched MeSH terms: alpha-Amylases/metabolism
  13. Purification and characterization of alpha-amylase from Aspergillus flavus
    Khoo SL, Amirul AA, Kamaruzaman M, Nazalan N, Azizan MN
    Folia Microbiol (Praha), 1994;39(5):392-8.
    PMID: 7729774
    Aspergillus flavus produced approximately 50 U/mL of amylolytic activity when grown in liquid medium with raw low-grade tapioca starch as substrate. Electrophoretic analysis of the culture filtrate showed the presence of only one amylolytic enzyme, identified as an alpha-amylase as evidenced by (i) rapid loss of color in iodine-stained starch and (ii) production of a mixture of glucose, maltose, maltotriose and maltotetraose as starch digestion products. The enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography and was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme had a molar mass of 52.5 +/- 2.5 kDa with an isoelectric point at pH 3.5. The enzyme was found to have maximum activity at pH 6.0 and was stable in a pH range from 5.0 to 8.5. The optimum temperature for the enzyme was 55 degrees C and it was stable for 1 h up to 50 degrees C. The Km and V for gelatinized tapioca starch were 0.5 g/L and 108.67 mumol reducing sugars per mg protein per min, respectively.
    Matched MeSH terms: alpha-Amylases/metabolism
  14. Anaerobic fermentation of gelatinized sago starch-derived sugars to acetone-1-butanol-ethanol solvent by Clostridium acetobutylicum
    Madihah MS, Ariff AB, Khalil MS, Suraini AA, Karim MI
    Folia Microbiol (Praha), 2001;46(3):197-204.
    PMID: 11702403
    A study of the kinetics and performance of solvent-yielding batch fermentation of individual sugars and their mixture derived from enzymic hydrolysis of sago starch by Clostridium acetobutylicum showed that the use of 30 g/L gelatinized sago starch as the sole carbon source produced 11.2 g/L total solvent, i.e. 1.5-2 times more than with pure maltose or glucose used as carbon sources. Enzymic pretreatment of gelatinized sago starch yielding maltose and glucose hydrolyzates prior to the fermentation did not improve solvent production as compared to direct fermentation of gelatinized sago starch. The solvent yield of direct gelatinized sago starch fermentation depended on the activity and stability of amylolytic enzymes produced during the fermentation. The pH optima for alpha-amylase and glucoamylase were found to be at 5.3 and 4.0-4.4, respectively. alpha-Amylase showed a broad pH stability profile, retaining more than 80% of its maximum activity at pH 3.0-8.0 after a 1-d incubation at 37 degrees C. Since C. acetobutylicum alpha-amylase has a high activity and stability at low pH, this strain can potentially be employed in a one-step direct solvent-yielding fermentation of sago starch. However, the C. acetobutylicum glucoamylase was only stable at pH 4-5, maintaining more than 90% of its maximum activity after a 1-d incubation at 37 degrees C.
    Matched MeSH terms: Amylases/metabolism
  15. Study of an inhibitory effect of plant polyphenolic compounds against digestive enzymes using bench-working experimental evidence predicted by molecular docking and dynamics
    Vyas K, Prabaker S, Prabhu D, Sakthivelu M, Rajamanikandan S, Velusamy P, et al.
    Int J Biol Macromol, 2024 Feb;259(Pt 1):129222.
    PMID: 38185307 DOI: 10.1016/j.ijbiomac.2024.129222
    The substantial nutritional content and diversified biological activity of plant-based nutraceuticals are due to polyphenolic chemicals. These chemicals are important and well-studied plant secondary metabolites. Their protein interactions are extensively studied. This relationship is crucial for the logical development of functional food and for enhancing the availability and usefulness of polyphenols. This study highlights the influence of protein types and polyphenols on the interaction, where the chemical bindings predominantly consist of hydrophobic interactions and hydrogen bonds. The interaction between polyphenolic compounds (PCs) and digestive enzymes concerning their inhibitory activity has not been fully studied. Therefore, we have examined the interaction of four digestive enzymes (α-amylase, pepsin, trypsin, and α-chymotrypsin) with four PCs (curcumin, diosmin, morin, and 2',3',4'-trihydroxychalcone) through in silico and in vitro approaches. In vitro plate assays, enzyme kinetics, spectroscopic assays, molecular docking, and simulations were performed. We observed all these PCs have significant docking scores and preferable interaction with the active site of the digestive enzymes, resulting in the reduction of enzyme activity. The enzyme-substrate binding mechanism was determined using the Lineweaver Burk plot, indicating that the inhibition occurred competitively. Among four PCs diosmin and morin has the highest interaction energy over digestive enzymes with IC50 value of 1.13 ± 0.0047 and 1.086 ± 0.0131 μM. Kinetic studies show that selected PCs inhibited pepsin, trypsin, and chymotrypsin competitively and inhibited amylase in a non-competitive manner, especially by 2',3',4'-trihydroxychalcone. This study offers insights into the mechanisms by which the selected PCs inhibit the enzymes and has the potential to enhance the application of curcumin, diosmin, morin, and 2',3',4'-trihydroxychalcone as natural inhibitors of digestive enzymes.
    Matched MeSH terms: alpha-Amylases/metabolism
  16. Fulltext Characterisation of potential antidiabetic-related proteins from Pleurotus pulmonarius (Fr.) Quél. (grey oyster mushroom) by MALDI-TOF/TOF mass spectrometry
    Wahab NA, Abdullah N, Aminudin N
    Biomed Res Int, 2014;2014:131607.
    PMID: 25243114 DOI: 10.1155/2014/131607
    Pleurotus pulmonarius has been reported to have a potent remedial effect on diabetic property and considered to be an alternative for type 2 diabetes mellitus treatment. This study aimed to investigate the antidiabetic properties of ammonium sulphate precipitated protein fractions from P. pulmonarius basidiocarps. Preliminary results demonstrated that 30% (NH4)2SO4 precipitated fraction (F30) inhibited Saccharomyces cerevisiae α-glucosidase activity (24.18%), and 100% (NH4)2SO4 precipitated fraction (F100) inhibited porcine pancreatic α-amylase activity (41.80%). Following RP-HPLC purification, peak 3 from F30 fraction demonstrated inhibition towards α-glucosidase at the same time with meagre inhibition towards α-amylase activity. Characterisation of proteins using MALDI-TOF/TOF MS demonstrated the presence of four different proteins, which could be implicated in the regulation of blood glucose level via various mechanisms. Therefore, this study revealed the presence of four antidiabetic-related proteins which are profilin-like protein, glyceraldehyde-3-phosphate dehydrogenase-like protein, trehalose phosphorylase-like (TP-like) protein, and catalase-like protein. Hence, P. pulmonarius basidiocarps have high potential in lowering blood glucose level, reducing insulin resistance and vascular complications.
    Matched MeSH terms: alpha-Amylases/metabolism
  17. Fulltext Microencapsulation of purified amylase enzyme from pitaya (Hylocereus polyrhizus) peel in Arabic gum-chitosan using freeze drying
    Amid M, Manap Y, Zohdi NK
    Molecules, 2014;19(3):3731-43.
    PMID: 24662085 DOI: 10.3390/molecules19033731
    Amylase is one of the most important enzymes in the world due to its wide application in various industries and biotechnological processes. In this study, amylase enzyme from Hylocereus polyrhizus was encapsulated for the first time in an Arabic gum-chitosan matrix using freeze drying. The encapsulated amylase retained complete biocatalytic activity and exhibited a shift in the optimum temperature and considerable increase in the pH and temperature stabilities compared to the free enzyme. Encapsulation of the enzyme protected the activity in the presence of ionic and non-ionic surfactants and oxidizing agents (H₂O₂) and enhanced the shelf life. The storage stability of amylase is found to markedly increase after immobilization and the freeze dried amylase exhibited maximum encapsulation efficiency value (96.2%) after the encapsulation process. Therefore, the present study demonstrated that the encapsulation of the enzyme in a coating agent using freeze drying is an efficient method to keep the enzyme active and stable until required in industry.
    Matched MeSH terms: Amylases/metabolism
  18. Dual modification of starch via partial enzymatic hydrolysis in the granular state and subsequent hydroxypropylation
    Karim AA, Sufha EH, Zaidul IS
    J Agric Food Chem, 2008 Nov 26;56(22):10901-7.
    PMID: 18975963 DOI: 10.1021/jf8015442
    The effect of enzymatic pretreatment on the degree of corn and mung bean starch derivatization by propylene oxide was investigated. The starch was enzymatically treated in the granular state with a mixture of fungal alpha-amylase and glucoamylase at 35 degrees C for 16 h and then chemically modified to produce enzyme-hydrolyzed-hydroxypropyl (HP) starch. Partial enzyme hydrolysis of starch in the granular state appeared to enhance the subsequent hydroxypropylation, as judged from the significant increase in the molar substitution. A variable degree of granule modification was obtained after enzyme hydrolysis, and one of the determinants of the modification degree appeared to be the presence of natural pores in the granules. Enzyme-hydrolyzed-HP starch exhibited significantly different functional properties compared to hydroxypropyl starch prepared from untreated (native) starch. It is evident that the dual modification of starch using this approach provides a range of functional properties that can be customized for specific applications.
    Matched MeSH terms: alpha-Amylases/metabolism*
  19. alpha-Amylase inhibitory activity of some Malaysian plants used to treat diabetes; with particular reference to Phyllanthus amarus
    Ali H, Houghton PJ, Soumyanath A
    J Ethnopharmacol, 2006 Oct 11;107(3):449-55.
    PMID: 16678367
    Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of Anacardium occidentale, Lagerstroemia speciosa, Averrhoa bilimbiPithecellobium jiringa and Parkia speciosa were not active when tested without pre-incubation. Extraction and fractionation of Phyllanthus amarus hexane extract led to the isolation of dotriacontanyl docosanoate, triacontanol and a mixture of oleanolic acid and ursolic acid. Dotriacontanyl docosanoate and the mixture of oleanolic acid and ursolic acid are reported from this plant species for the first time. All compounds were tested in the alpha-amylase inhibition assay and the results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-amylase inhibition activity of the extract. Three pure pentacyclic triterpenoids, oleanolic acid, ursolic acid and lupeol were shown to inhibit alpha-amylase.
    Matched MeSH terms: alpha-Amylases/metabolism
  20. Fulltext Aqueous Extract of Nypa fruticans Wurmb. Vinegar Alleviates Postprandial Hyperglycemia in Normoglycemic Rats
    Yusoff NA, Ahmad M, Al-Hindi B, Widyawati T, Yam MF, Mahmud R, et al.
    Nutrients, 2015 Aug;7(8):7012-26.
    PMID: 26308046 DOI: 10.3390/nu7085320
    Nypa fruticans Wurmb. vinegar, commonly known as nipa palm vinegar (NPV) has been used as a folklore medicine among the Malay community to treat diabetes. Early work has shown that aqueous extract (AE) of NPV exerts a potent antihyperglycemic effect. Thus, this study is conducted to evaluate the effect of AE on postprandial hyperglycemia in an attempt to understand its mechanism of antidiabetic action. AE were tested via in vitro intestinal glucose absorption, in vivo carbohydrate tolerance tests and spectrophotometric enzyme inhibition assays. One mg/mL of AE showed a comparable outcome to the use of phloridzin (1 mM) in vitro as it delayed glucose absorption through isolated rat jejunum more effectively than acarbose (1 mg/mL). Further in vivo confirmatory tests showed AE (500 mg/kg) to cause a significant suppression in postprandial hyperglycemia 30 min following respective glucose (2 g/kg), sucrose (4 g/kg) and starch (3 g/kg) loadings in normal rats, compared to the control group. Conversely, in spectrophotometric enzymatic assays, AE showed rather a weak inhibitory activity against both α-glucosidase and α-amylase when compared with acarbose. The findings suggested that NPV exerts its anti-diabetic effect by delaying carbohydrate absorption from the small intestine through selective inhibition of intestinal glucose transporters, therefore suppressing postprandial hyperglycemia.
    Matched MeSH terms: alpha-Amylases/metabolism
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