MyMedR

Displaying publications 121 - 140 of 370 in total

Abstract:

Sort:

Multiboronic acid-conjugated chitosan scaffolds with glucose selectivity to insulin release

Siddiqui NA, Billa N, Roberts CJ

J Biomater Sci Polym Ed, 2017 Jun;28(8):781-793.
PMID: 28278045 DOI: 10.1080/09205063.2017.1301774

The principal challenge for the use of boronic acids (BA) as glucose sensors is their lack of specificity for glucose. We examined the selectivity of and insulin release from two boronic acids- (2-formyl-3-thienylboronic acid (FTBA) and 4-formylphenylboronic acid (FPBA)) conjugated chitosan scaffolds to glucose and fructose. Adsorption of glucose to BA: chitosan conjugates was dose-dependent up to 1:1 at 35 and 42% for FPBA and FTBA respectively but the FTBA conjugates adsorbed more glucose and fructose at respective FPBA ratios. The affinity of both BA conjugates to glucose decreased with increase in BA ratio. On the other hand, the affinity of both BA conjugates for fructose decreased from ratio 1:1 to 2:1 then rose again at 3:1. Insulin release from FPBA nanoparticles (FPBAINP) and FTBA nanoparticles (FTBAINP) were both concentration-dependent within glyceamically relevant values (1-3 mg/ml glucose and 0.002 mg/ml fructose). Furthermore, the total amounts of insulin released from FPBAINP in both the media were higher than from FTBAINP. Both FPBAINP and FTBAINP have the potential for development as a glucose-selective insulin delivery system in physiological settings.

Matched MeSH terms: Boronic Acids/chemistry*
Comparative study of the antioxidant activities of some lipase-catalyzed alkyl dihydrocaffeates synthesized in ionic liquid

Gholivand S, Lasekan O, Tan CP, Abas F, Wei LS

Food Chem, 2017 Jun 01;224:365-371.
PMID: 28159281 DOI: 10.1016/j.foodchem.2016.12.075

The solubility limitations of phenolic acids in many lipidic environments are now greatly improved by their enzymatic esterification in ionic liquids (ILs). Herein, four different ILs were tested for the esterification of dihydrocaffeic acid with hexanol and the best IL was selected for the synthesis of four other n-alkyl esters with different chain-lengths. The effect of alkyl chain length on the anti-oxidative properties of the resulted purified esters was investigated using β-carotene bleaching (BCB) and free radical scavenging method DPPH and compared with butylated hydroxytoluene (BHT) as reference compound. All four esters (methyl, hexyl, dodecyl and octadecyl dihydrocaffeates) exhibited relatively strong radical scavenging abilities. The scavenging activity of the test compounds was in the following order: methyl ester>hexyl ester⩾dodecyl ester>octadecyl ester>BHT while the order for the BCB anti-oxidative activity was; BHT>octadecyl ester>dodecyl ester>hexyl ester>methyl ester.

Matched MeSH terms: Caffeic Acids/chemistry*
Influences of superheated steam roasting on changes in sugar, amino acid and flavour active components of cocoa bean (Theobroma cacao)

Zzaman W, Bhat R, Yang TA, Easa AM

J Sci Food Agric, 2017 Oct;97(13):4429-4437.
PMID: 28251656 DOI: 10.1002/jsfa.8302

BACKGROUND: Roasting is one of the important unit operations in the cocoa-based industries in order to develop unique flavour in products. Cocoa beans were subjected to roasting at different temperatures and times using superheated steam. The influence of roasting temperature (150-250°C) and time (10-50 min) on sugars, free amino acids and volatile flavouring compounds were investigated.
RESULTS: The concentration of total reducing sugars was reduced by up to 64.61, 77.22 and 82.52% with increased roasting temperature at 150, 200 and 250°C for 50 min, respectively. The hydrophobic amino acids were reduced up to 29.21, 36.41 and 48.87% with increased roasting temperature at 150, 200 and 250°C for 50 min, respectively. A number of pyrazines, esters, aldehydes, alcohols, ketones, carboxyl acids and hydrocarbons were detected in all the samples at different concentration range. Formation of the most flavour active compounds, pyrazines, were the highest concentration (2.96 mg kg-1 ) at 200°C for 10 min.
CONCLUSION: The superheated steam roasting method achieves the optimum roasting condition within a short duration Therefore, the quality of cocoa beans can be improved using superheated steam during the roasting process. © 2017 Society of Chemical Industry.

Matched MeSH terms: Amino Acids/chemistry*
Removal of fluoride ion from aqueous solution by a cerium-poly(hydroxamic acid) resin complex

Haron MJ, Yunus WM

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001 May;36(5):727-34.
PMID: 11460327

A cerium-loaded poly(hydroxamic acid) chelating ion exchanger was used for fluoride ion removal from aqueous solution. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.001 mM in acidic pH between 3 and 6. The sorption followed a Langmuir model with a maximum capacity of 0.5 mmol/g. The removal is accomplished by an anion exchange mechanism. The rate constant for the sorption was found to be 9.6 x 10(-2) min-1. A column test shows that the fluoride ion was retained on the column until breakthrough point and the fluoride sorbed in the column can be eluted with 0.1 M NaOH. The column can be reused after being condition with hydrochloric acid at pH 4. The resin was tested and found to be effective for removal of fluoride from actual industrial wastewater.

Matched MeSH terms: Hydroxamic Acids/chemistry*
Sorption of acid dyes by chemically modified peanut hulls

Low KS, Lee CK, Koo WH

Bull Environ Contam Toxicol, 1999 Apr;62(4):428-33.
PMID: 10094725
Matched MeSH terms: Acids/chemistry
Fulltext Effects of Caffeic Acid and Its Derivatives on Bone: A Systematic Review

Ekeuku SO, Pang KL, Chin KY

Drug Des Devel Ther, 2021;15:259-275.
PMID: 33519191 DOI: 10.2147/DDDT.S287280

PURPOSE: Caffeic acid is a metabolite of hydroxycinnamate and phenylpropanoid, which are commonly synthesized by all plant species. It is present in various food sources that are known for their antioxidant properties. As an antioxidant, caffeic acid ameliorates reactive oxygen species, which have been reported to cause bone loss. Some studies have highlighted the effects of caffeic acid against bone resorption.
METHODS: A systematic review of the literature was conducted to identify relevant studies on the effects of caffeic acid on bone. A comprehensive search was conducted from July to November 2020 using PubMed, Scopus, Cochrane Library and Web of Science databases. Cellular, animal and human studies reporting the effects of caffeic acid, as a single compound, on bone cells or bone were considered.
RESULTS: The literature search found 226 articles on this topic, but only 24 articles met the inclusion criteria and were included in this review. The results showed that caffeic acid supplementation reduced osteoclastogenesis and bone resorption, possibly through its antioxidant potential and increased expression of osteoblast markers. However, some studies showed that caffeic acid did not affect bone resorption in ovariectomized rats and might impair bone mechanical properties in normal rats.
CONCLUSION: Caffeic acid potentially regulates the bone remodelling process by inhibiting osteoclastogenesis and bone resorption, as well as osteoblast apoptosis. Thus, it has medicinal values against bone diseases.

Matched MeSH terms: Caffeic Acids/chemistry
Fulltext Improved prediction and characterization of anticancer activities of peptides using a novel flexible scoring card method

Charoenkwan P, Chiangjong W, Lee VS, Nantasenamat C, Hasan MM, Shoombuatong W

Sci Rep, 2021 Feb 04;11(1):3017.
PMID: 33542286 DOI: 10.1038/s41598-021-82513-9

As anticancer peptides (ACPs) have attracted great interest for cancer treatment, several approaches based on machine learning have been proposed for ACP identification. Although existing methods have afforded high prediction accuracies, however such models are using a large number of descriptors together with complex ensemble approaches that consequently leads to low interpretability and thus poses a challenge for biologists and biochemists. Therefore, it is desirable to develop a simple, interpretable and efficient predictor for accurate ACP identification as well as providing the means for the rational design of new anticancer peptides with promising potential for clinical application. Herein, we propose a novel flexible scoring card method (FSCM) making use of propensity scores of local and global sequential information for the development of a sequence-based ACP predictor (named iACP-FSCM) for improving the prediction accuracy and model interpretability. To the best of our knowledge, iACP-FSCM represents the first sequence-based ACP predictor for rationalizing an in-depth understanding into the molecular basis for the enhancement of anticancer activities of peptides via the use of FSCM-derived propensity scores. The independent testing results showed that the iACP-FSCM provided accuracies of 0.825 and 0.910 as evaluated on the main and alternative datasets, respectively. Results from comparative benchmarking demonstrated that iACP-FSCM could outperform seven other existing ACP predictors with marked improvements of 7% and 17% for accuracy and MCC, respectively, on the main dataset. Furthermore, the iACP-FSCM (0.910) achieved very comparable results to that of the state-of-the-art ensemble model AntiCP2.0 (0.920) as evaluated on the alternative dataset. Comparative results demonstrated that iACP-FSCM was the most suitable choice for ACP identification and characterization considering its simplicity, interpretability and generalizability. It is highly anticipated that the iACP-FSCM may be a robust tool for the rapid screening and identification of promising ACPs for clinical use.

Matched MeSH terms: Amino Acids/chemistry
Fulltext Choline Chloride-urea Deep Eutectic Mixture Water for the Synthesis of an Amphiphilic Compound of Glyceryl Monocaffeate

Gonawan FN, Bakar PNMA, Kamaruddin AH

J Oleo Sci, 2021 Oct 05;70(10):1437-1445.
PMID: 34497176 DOI: 10.5650/jos.ess21010

The Lipase-catalyzed synthesis of glyceryl monocaffeate (GMC) in choline chloride-urea of natural deep eutectic solvent (NADES) media is reported to provide amphiphilic character to caffeic acid (CA). The modification of CA into GMC could potentially increase its solubility and widen the application of CA's biological activities in water and oil-based systems. The high conversion was achieved when the reaction was carried out with the addition of more than 20 %v/v water, at a high molar ratio of glycerol and 40°C. It was found that the lipase-catalyzed transesterification of ethyl caffeate (EC) and glycerol in choline chloride-urea of DES media obeyed ping-pong bi-bi mechanism with Vmax = 10.9 mmol.min-1, KmEC = 126.5 mmol and KmGly = 1842.7 mmol.

Matched MeSH terms: Caffeic Acids/chemistry*
Saccharobesus litoralis gen. nov., sp. nov., a novel alginate-degrading bacterium isolated from the surface of intertidal algal turf

Amrina RA, Furusawa G, Lau NS

Int J Syst Evol Microbiol, 2021 Nov;71(11).
PMID: 34752210 DOI: 10.1099/ijsem.0.005087

A novel rod-shaped, Gram-stain-negative, strictly aerobic and alginate-degrading marine bacterium, designated CCB-QB4T, was isolated from a surface of algal turf collected from a coastal area of Penang, Malaysia. The cells showed motility by a lateral flagellum. The rod-shaped cells formed long chains end-to-end. Phylogenetic analysis based on the 16S rRNA gene sequence of strain CCB-QB4T showed 94.07, 92.69, 91.52 and 90.90 % sequence similarity to Algibacillus agarilyticus RQJ05T, Catenovulum maritimum Q1T, Catenovulum agarivorans YM01T and Catenovulum sediminis D2T, respectively. Strain CCB-QB4T formed a cluster with A. agarilyticus RQJ05T. Strain CCB-QB4T was catalase-negative, oxidase-positive, and degraded agar, alginate, and starch. Cell growth was observed at 15-40 °C, at pH 7.0-10.0 and in the presence of 1-6 % (w/v) NaCl and glucose. The major fatty acids were summed feature 3 (C16 : 1 ω7c/iso-C15 : 0 2-OH), C16 : 0 and C18 : 1 ω7c. The polar lipids were phosphatidylethanolamine, two unidentified aminolipids, two unidentified glycolipids, an unidentified phospholipid and unidentified lipid. The major respiratory quinone was ubiquinone-8. The genomic DNA G+C content was 46.7 mol%. Based on the phenotypic, chemotaxonomic and phylogenetic data, strain CCB-BQ4T represents a novel species in a new genus, for which the name Saccharobesus litoralis gen. nov., sp. nov. is proposed. The type strain is CCB-QB4T (=JCM 33513T=CCB-MBL 5008T).

Matched MeSH terms: Fatty Acids/chemistry
Fulltext Phosphorus Removal and Phytonutrients Retention in the Refining of Solvent Extracted Palm-Pressed Mesocarp Fiber Oil

Lau HLN, Tee YS, Chan MK, Teh SS

J Oleo Sci, 2022;71(2):177-185.
PMID: 35110462 DOI: 10.5650/jos.ess21256

Phosphoric acid is used in the refining of palm oil for the removal of phosphatides. The high concentration of phosphorus in solvent extracted palm-pressed mesocarp fiber oil hinders palm oil mills to recover this phytonutrients-rich residual oil in pressed fiber which typically contains 0.1 to 0.2% of total oil yield. This study aimed to refine the palm-pressed mesocarp fiber oil and determine the optimum dosage of phosphoric acid for acid-degumming of palm-pressed mesocarp fiber oil while retaining its phytonutrients. The refining process was carried out with combination of wet degumming, acid degumming, neutralisation, bleaching and deodorization. The optimum dose of phosphoric acid was identified as 0.05 wt.% by incorporating the wet degumming process. The refined palm-pressed mesocarp fiber oil showed a reduction in phosphorus content by 97% (from 901 ppm to 20 ppm) and 97% free fatty acid content removal (from 6.36% to 0.17%), while the Deterioration of Bleachability Index increased from 1.76 to 2.48, which showed an increment of 41%. The refined oil retained the key phytonutrients such as carotenoids (1,150 ppm) and vitamin E (1,540 ppm) that can be further developed into high-value products. The oil meets the quality specification of refined, bleached, and deodorized palm oil while preserving the heat-sensitive phytonutrients, which in turn provides a new resource of nutritious oil.

Matched MeSH terms: Phosphoric Acids/chemistry
Health benefits, enzymatic production, and application of medium- and long-chain triacylglycerol (MLCT) in food industries: a review

Lee YY, Tang TK, Lai OM

J Food Sci, 2012 Aug;77(8):R137-44.
PMID: 22748075 DOI: 10.1111/j.1750-3841.2012.02793.x

Medium- and long-chain triacylglycerol (MLCT) is a modified lipid containing medium- chain (C6-C12) and long-chain fatty acids (C14-C24) in the same triacylglycerol (TAG) molecule. It can be produced either through enzymatic (with 1,3 specific or nonspecific enzyme) or chemical methods. The specialty of this structured lipid is that it is metabolized differently compared to conventional fats and oils, which can lead to a reduction of fat accumulation in the body. Therefore, it can be used for obesity management. It also contains nutritional properties that can be used to treat metabolic problems. This review will discuss on the health benefits of MLCT, its production methods especially via enzymatic processes and its applications in food industries.

Matched MeSH terms: Fatty Acids/chemistry*
Phosphorus removal using nanofiltration membranes

Leo CP, Chai WK, Mohammad AW, Qi Y, Hoedley AF, Chai SP

Water Sci Technol, 2011;64(1):199-205.
PMID: 22053475

A high concentration of phosphorus in wastewater may lead to excessive algae growth and deoxygenation of the water. In this work, nanofiltration (NF) of phosphorus-rich solutions is studied in order to investigate its potential in removing and recycling phosphorus. Wastewater samples from a pulp and paper plant were first analyzed. Commercial membranes (DK5, MPF34, NF90, NF270, NF200) were characterized and tested in permeability and phosphorus removal experiments. NF90 membranes offer the highest rejection of phosphorus; a rejection of more than 70% phosphorus was achieved for a feed containing 2.5 g/L of phosphorus at a pH <2. Additionally, NF90, NF200 and NF270 membranes show higher permeability than DK5 and MPF34 membranes. The separation performance of NF90 is slightly affected by phosphorus concentration and pressure, which may be due to concentration polarization and fouling. By adjusting the pH to 2 or adding sulfuric acid, the separation performance of NF90 was improved in removing phosphorus. However, the presence of acetic acid significantly impairs the rejection of phosphorus.

Matched MeSH terms: Sulfuric Acids/chemistry
Fulltext Improvement of physicochemical characteristics of monoepoxide linoleic acid ring opening for biolubricant base oil

Salimon J, Salih N, Abdullah BM

J Biomed Biotechnol, 2011;2011:196565.
PMID: 22131799 DOI: 10.1155/2011/196565

For environmental reasons, a new class of environmentally acceptable and renewable biolubricant based on vegetable oils is available. In this study, oxirane ring opening reaction of monoepoxide linoleic acid (MEOA) was done by nucleophilic addition of oleic acid (OA) with using p-toluene sulfonic acid (PTSA) as a catalyst for synthesis of 9(12)-hydroxy-10(13)-oleoxy-12(9)-octadecanoic acid (HYOOA) and the physicochemical properties of the resulted HYOOA are reported to be used as biolubricant base oils. Optimum conditions of the experiment using D-optimal design to obtain high yield% of HYOOA and lowest OOC% were predicted at OA/MEOA ratio of 0.30 : 1 (w/w), PTSA/MEOA ratio of 0.50 : 1 (w/w), reaction temperature at 110°C, and reaction time at 4.5 h. The results showed that an increase in the chain length of the midchain ester resulted in the decrease of pour point (PP) -51°C, increase of viscosity index (VI) up to 153, and improvement in oxidative stability (OT) to 180.94°C.

Matched MeSH terms: Linoleic Acids/chemistry*
Fulltext NIR spectroscopic properties of aqueous acids solutions

Omar AF, Atan H, Matjafri MZ

Molecules, 2012 Jun 15;17(6):7440-50.
PMID: 22706373 DOI: 10.3390/molecules17067440

Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R² above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918-925 nm and 990-996 nm, while at 975 nm for water.

Matched MeSH terms: Acids/chemistry*
Fulltext Effect of acid and base catalyzed hydrolysis on the yield of phenolics and antioxidant activity of extracts from germinated brown rice (GBR)

Sani IM, Iqbal S, Chan KW, Ismail M

Molecules, 2012 Jun 19;17(6):7584-94.
PMID: 22713349 DOI: 10.3390/molecules17067584

The influence of both acidic and basic hydrolysis on the yield, total phenolic content and antioxidative capacity of methanolic extract of germinated brown rice (GBR) was studied. Total phenolic content (TPC), total flavonoid content (TFC), 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation scavenging, and ferric reducing antioxidant power (FRAP) tests were used for the measurement of antioxidant ability. There was a significant difference p < 0.05) in the TPC and DPPH radical scavenging assay results when comparing neutral with acidic and basic catalysed hydrolysis. The yield of the crude extract was slightly higher in acidic hydrolysis than in basic hydrolysis p > 0.05). The TPC and TFC were highest in acidic hydrolysis. A significant correlation was observed between ABTS radical cation scavenging and FRAP. The antioxidant activity measured using DPPH radical scavenging assay showed high activity in acidic hydrolysis, while the ABTS radical cationscavenging activity and FRAP showed the highest values in basic hydrolysis. The samples were further evaluated using HPLC to determine the individual phenolic concentrations in different hydrolytic media contributing to the antioxidant effects. This study revealed that acidic and basic hydrolysis can improve the yield, phenolic content, and antioxidant activity of germinated brown rice.

Matched MeSH terms: Acids/chemistry
Fulltext Production of chemoenzymatic catalyzed monoepoxide biolubricant: optimization and physicochemical characteristics

Salimon J, Salih N, Abdullah BM

J Biomed Biotechnol, 2012;2012:693848.
PMID: 22346338 DOI: 10.1155/2012/693848

Linoleic acid (LA) is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435). This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12)-10(13)-monoepoxy 12(9)-octadecanoic acid (MEOA) was optimized using D-optimal design. At optimum conditions, higher yield% (82.14) and medium oxirane oxygen content (OOC) (4.91%) of MEOA were predicted at 15 μL of H(2)O(2), 120 mg of Novozym 435, and 7 h of reaction time. In order to develop better-quality biolubricants, pour point (PP), flash point (FP), viscosity index (VI), and oxidative stability (OT) were determined for LA and MEOA. The results showed that MEOA exhibited good low-temperature behavior with PP of -41(°)C. FP of MEOA increased to 128(°)C comparing with 115(°)C of LA. In a similar fashion, VI for LA was 224 generally several hundred centistokes (cSt) more viscous than MEOA 130.8. The ability of a substance to resist oxidative degradation is another important property for biolubricants. Therefore, LA and MEOA were screened to measure their OT which was observed at 189 and 168(°)C, respectively.

Matched MeSH terms: Linoleic Acids/chemistry*
Fulltext SPRITE and ASSAM: web servers for side chain 3D-motif searching in protein structures

Nadzirin N, Gardiner EJ, Willett P, Artymiuk PJ, Firdaus-Raih M

Nucleic Acids Res, 2012 Jul;40(Web Server issue):W380-6.
PMID: 22573174 DOI: 10.1093/nar/gks401

Similarities in the 3D patterns of amino acid side chains can provide insights into their function despite the absence of any detectable sequence or fold similarities. Search for protein sites (SPRITE) and amino acid pattern search for substructures and motifs (ASSAM) are graph theoretical programs that can search for 3D amino side chain matches in protein structures, by representing the amino acid side chains as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. Both programs require the input file to be in the PDB format. The objective of using SPRITE is to identify matches of side chains in a query structure to patterns with characterized function. In contrast, a 3D pattern of interest can be searched for existing occurrences in available PDB structures using ASSAM. Both programs are freely accessible without any login requirement. SPRITE is available at http://mfrlab.org/grafss/sprite/ while ASSAM can be accessed at http://mfrlab.org/grafss/assam/.

Matched MeSH terms: Amino Acids/chemistry
Fulltext Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment

Ashraf MA, Maah MJ, Yusoff I

ScientificWorldJournal, 2012;2012:125608.
PMID: 22566758 DOI: 10.1100/2012/125608

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

Matched MeSH terms: Acids/chemistry
Phenolic acid composition and antioxidant properties of Malaysian honeys

Khalil MI, Alam N, Moniruzzaman M, Sulaiman SA, Gan SH

J Food Sci, 2011 Aug;76(6):C921-8.
PMID: 22417491 DOI: 10.1111/j.1750-3841.2011.02282.x

The phenolic acid and flavonoid contents of Malaysian Tualang, Gelam, and Borneo tropical honeys were compared to those of Manuka honey. Ferric reducing/antioxidant power assay (FRAP) and the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging activities were also quantified. All honey extracts exhibited high phenolic contents (15.21 ± 0.51- 42.23 ± 0.64 mg/kg), flavonoid contents (11.52 ± 0.27- 25.31 ± 0.37 mg/kg), FRAP values (892.15 ± 4.97- 363.38 ± 10.57 μM Fe[II]/kg), and high IC₅₀ of DPPH radical-scavenging activities (5.24 ± 0.40- 17.51 ± 0.51 mg/mL). Total of 6 phenolic acids (gallic, syringic, benzoic, trans-cinnamic, p-coumaric, and caffeic acids) and 5 flavonoids (catechin, kaempferol, naringenin, luteolin, and apigenin) were identified. Among the Malaysian honey samples, Tualang honey had the highest contents of phenolics, and flavonoids, and DPPH radical-scavenging activities. We conclude that among Malaysian honey samples, Tualang honey is the richest in phenolic acids, and flavonoid compounds, which have strong free radical-scavenging activities.

Matched MeSH terms: Carboxylic Acids/chemistry
Kinetics of enzyme-catalyzed cross-linking of feruloylated arabinan from sugar beet

Zaidel DN, Arnous A, Holck J, Meyer AS

J Agric Food Chem, 2011 Nov 9;59(21):11598-607.
PMID: 21954887 DOI: 10.1021/jf203138u

Ferulic acid (FA) groups esterified to the arabinan side chains of pectic polysaccharides can be oxidatively cross-linked in vitro by horseradish peroxidase (HRP) catalysis in the presence of hydrogen peroxide (H(2)O(2)) to form ferulic acid dehydrodimers (diFAs). The present work investigated whether the kinetics of HRP catalyzed cross-linking of FA esterified to α-(1,5)-linked arabinans are affected by the length of the arabinan chains carrying the feruloyl substitutions. The kinetics of the HRP-catalyzed cross-linking of four sets of arabinan samples from sugar beet pulp, having different molecular weights and hence different degrees of polymerization, were monitored by the disappearance of FA absorbance at 316 nm. MALDI-TOF/TOF-MS analysis confirmed that the sugar beet arabinans were feruloyl-substituted, and HPLC analysis verified that the amounts of diFAs increased when FA levels decreased as a result of the enzymatic oxidation treatment with HRP and H(2)O(2). At equimolar levels of FA (0.0025-0.05 mM) in the arabinan samples, the initial rates of the HRP-catalyzed cross-linking of the longer chain arabinans were slower than those of the shorter chain arabinans. The lower initial rates may be the result of the slower movement of larger molecules coupled with steric phenomena, making the required initial reaction of two FAs on longer chain arabinans slower than on shorter arabinans.

Matched MeSH terms: Coumaric Acids/chemistry*

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links