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Fulltext An adult patient with congenital heart disease

Choo WS

Malays Fam Physician, 2010;5(3):153-4.
PMID: 25606210
Effect of extraction conditions on the yield and chemical properties of pectin from cocoa husks

Chan SY, Choo WS

Food Chem, 2013 Dec 15;141(4):3752-8.
PMID: 23993545 DOI: 10.1016/j.foodchem.2013.06.097

Different extraction conditions were applied to investigate the effect of temperature, extraction time and substrate-extractant ratio on pectin extraction from cocoa husks. Pectin was extracted from cocoa husks using water, citric acid at pH 2.5 or 4.0, or hydrochloric acid at pH 2.5 or 4.0. Temperature, extraction time and substrate-extractant ratio affected the yields, uronic acid contents, degrees of methylation (DM) and degrees of acetylation (DA) of the extracted pectins using the five extractants differently. The yields and uronic acid contents of the extracted pectins ranged from 3.38-7.62% to 31.19-65.20%, respectively. The DM and DA of the extracted pectins ranged from 7.17-57.86% to 1.01-3.48%, respectively. The highest yield of pectin (7.62%) was obtained using citric acid at pH 2.5 [1:25 (w/v)] at 95 °C for 3.0 h. The highest uronic acid content (65.20%) in the pectin was obtained using water [1:25 (w/v)] at 95 °C for 3.0 h.
Fulltext Cardiac imaging in valvular heart disease

Choo WS, Steeds RP

Br J Radiol, 2011 Dec;84 Spec No 3:S245-57.
PMID: 22723532 DOI: 10.1259/bjr/54030257

The aim of this article is to provide a perspective on the relative importance and contribution of different imaging modalities in patients with valvular heart disease. Valvular heart disease is increasing in prevalence across Europe, at a time when the clinical ability of physicians to diagnose and assess severity is declining. Increasing reliance is placed on echocardiography, which is the mainstay of cardiac imaging in valvular heart disease. This article outlines the techniques used in this context and their limitations, identifying areas in which dynamic imaging with cardiovascular magnetic resonance and multislice CT are expanding.
Fulltext Characterization of flaxseed oil emulsions

Lee PE, Choo WS

J Food Sci Technol, 2015 Jul;52(7):4378-86.
PMID: 26139903 DOI: 10.1007/s13197-014-1495-3

The emulsifying capacity of surfactants (polysorbate 20, polysorbate 80 and soy lecithin) and proteins (soy protein isolate and whey protein isolate) in flaxseed oil was measured based on 1 % (w/w) of emulsifier. Surfactants showed significantly higher emulsifying capacity compared to the proteins (soy protein isolate and whey protein isolate) in flaxseed oil. The emulsion stability of the flaxseed oil emulsions with whey protein isolate (10 % w/w) prepared using a mixer was ranked in the following order: 1,000 rpm (58 min) ≈ 1,000 rpm (29 min) ≈ 2,000 rpm (35 min) >2,000 rpm (17.5 min). The emulsion stability of the flaxseed oil emulsions with whey protein isolate (10 % w/w) prepared using a homogenizer (Ultra Turrax) was independent of the speed and mixing time. The mean particle size of the flaxseed oil emulsions prepared using the two mixing devices ranged from 23.99 ± 1.34 μm to 47.22 ± 1.99 μm where else the particle size distribution and microstructure of the flaxseed oil emulsions demonstrated using microscopic imaging were quite similar. The flaxseed oil emulsions had a similar apparent viscosity and exhibited shear thinning (pseudoplastic) behavior. The flaxseed oil emulsions had L* value above 70 and was in the red-yellow color region (positive a* and b* values).
Antimicrobial betalains

Wijesinghe VN, Choo WS

J Appl Microbiol, 2022 Dec;133(6):3347-3367.
PMID: 36036373 DOI: 10.1111/jam.15798

Betalains are nitrogen-containing plant pigments that can be red-violet (betacyanins) or yellow-orange (betaxanthins), currently employed as natural colourants in the food and cosmetic sectors. Betalains exhibit antimicrobial activity against a broad spectrum of microbes including multidrug-resistant bacteria, as well as single-species and dual-species biofilm-producing bacteria, which is highly significant given the current antimicrobial resistance issue reported by The World Health Organization. Research demonstrating antiviral activity against dengue virus, in silico studies including SARS-CoV-2, and anti-fungal effects of betalains highlight the diversity of their antimicrobial properties. Though limited in vivo studies have been conducted, antimalarial and anti-infective activities of betacyanin have been observed in living infection models. Cellular mechanisms of antimicrobial activity of betalains are yet unknown; however existing research has laid the framework for a potentially novel antimicrobial agent. This review covers an overview of betalains as antimicrobial agents and discussions to fully exploit their potential as therapeutic agents to treat infectious diseases.
Betacyanins from Hylocereus polyrhizus: pectinase-assisted extraction and application as a natural food colourant in ice cream

Gengatharan A, Dykes G, Choo WS

J Food Sci Technol, 2021 Apr;58(4):1401-1410.
PMID: 33746268 DOI: 10.1007/s13197-020-04651-8

The effect of solvent, substrate-to-solvent ratio and concentration of pectinase on the extraction of betacyanins from the pulp of red pitahaya (Hylocereus polyrhizus) was evaluated with respect to yield, betacyanin content (BC) and total sugar content. The application of betacyanins from red pitahaya in ice cream was then evaluated by comparison to a commercial colourant, E-162. Without the use of pectinase, the highest yields (9.11 ± 0.35%) of betacyanins were obtained using 95% ethanol at a substrate-to-solvent ratio of 1:1. With the use of pectinase at a concentration of 1.5%, the highest yield (17.11-17.45%) of betacyanins were obtained using water as a solvent at a substrate-to-solvent ratio of 1:1 and 1:2. Pectinase treatment (1.5-2.5%) using water as a solvent yielded betacyanins with the highest BC (126.47-130.83 g kg-1) and lowest total sugar content (57.85-59.74 g kg-1). The BC and total colour changes were similar in ice cream containing betacyanins from red pitahaya and E-162 throughout the 21-days of frozen storage at -18 °C. Betacyanins from red pitahaya or E-162 enhanced the antioxidant properties of ice cream. The sensory evaluation of ice cream containing betacyanins from red pitahaya showed a better colour acceptability than E-162.
Extraction methods of butterfly pea (Clitoria ternatea) flower and biological activities of its phytochemicals

Jeyaraj EJ, Lim YY, Choo WS

J Food Sci Technol, 2021 Jun;58(6):2054-2067.
PMID: 33967304 DOI: 10.1007/s13197-020-04745-3

Clitoria ternatea or commonly known as 'Butterfly pea' has been used traditionally in Ayurvedic medicine in which various parts of the plants are used to treat health issues such as indigestion, constipation, arthritis, skin diseases, liver and intestinal problems. The flowers of C. ternatea are used worldwide as ornamental flowers and traditionally used as a food colorant. This paper reviews the recent advances in the extraction and biological activities of phytochemicals from C. ternatea flowers. The application of maceration or ultrasound assisted extraction greatly increased the yield (16-247% of increase) of phytochemicals from C. ternatea flowers. Various phytochemicals such as kaempferol, quercetin and myricetin glycosides as well as anthocyanins have been isolated from C. ternatea flowers. Clitoria ternatea flower extracts were found to possess antimicrobial, antioxidant, anti-inflammatory, cytotoxic and antidiabetic activities which are beneficial to human health. Clitoria ternatea flower is a promising candidate for functional food applications owing to its wide range of pharmacotherapeutic properties as well as its safety and effectiveness.
Radical scavenging activity of lipophilized products from transesterification of flaxseed oil with cinnamic acid or ferulic acid

Choo WS, Birch EJ, Stewart I

Lipids, 2009 Sep;44(9):807-15.
PMID: 19727883 DOI: 10.1007/s11745-009-3334-2

Lipase-catalyzed transesterification of flaxseed oil with cinnamic acid (CA) or ferulic acid (FA) using an immobilized lipase from Candida antarctica (E.C. 3.1.1.3) was conducted to evaluate whether the lipophilized products provided enhanced antioxidant activity in the oil. Lipase-catalyzed transesterification of flaxseed oil with CA or FA produced a variety of lipophilized products (identified using ESI-MS-MS) such as monocinnamoyl/feruloyl-diacylglycerol, dicinnamoyl-monoacylglycerol and monocinnamoyl-monoacylglycerol. The free radical scavenging activity of the lipophilized products of lipase-catalyzed transesterification of flaxseed oil with CA or FA toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) were both examined in ethanol and ethyl acetate. The polarity of the solvents proved important in determining the radical scavenging activity of the substrates. Unesterified FA showed the highest free radical scavenging activity among all substrates tested while CA had negligible activity. The esterification of CA or FA with flaxseed oil resulted in significant increase and decrease in the radical scavenging activity compared with the native phenolic acid, respectively. Based on the ratio of a substrate to DPPH. concentration, lipophilized FA was a much more efficient free radical scavenger compared to lipophilized CA and was able to provide enhanced antioxidant activity in the flaxseed oil. Lipophilized cinnamic acid did not provide enhanced radical scavenging activity in the flaxseed oil as the presence of natural hydrophilic antioxidants in the oil had much greater radical scavenging activity.
Fulltext Antioxidant, cytotoxic, and antibacterial activities of Clitoria ternatea flower extracts and anthocyanin-rich fraction

Jeyaraj EJ, Lim YY, Choo WS

Sci Rep, 2022 09 01;12(1):14890.
PMID: 36050436 DOI: 10.1038/s41598-022-19146-z

Clitoria ternatea flower is a traditional medicinal herb that has been used as a natural food colourant. As there are limited studies on investigating the bioactivities of the anthocyanin-rich fraction of Clitoria ternatea flower, this study aimed to determine an efficient column chromatography method to obtain the anthocyanin-rich fraction from this flower and characterise its composition, antioxidant, antibacterial, and cytotoxic activities. Amberlite XAD-16 column chromatography was more efficient in enriching the total anthocyanin content (TAC) of the fraction with the highest TAC to total phenolic content (TPC) ratio of 1:6 than that using C18-OPN. A total of 11 ternatin anthocyanins were characterised in the anthocyanin-rich fraction by LC-MS analysis. The antioxidant activity of the anthocyanin-rich fraction was more potent in the chemical-based assay with an IC50 value of 0.86 ± 0.07 mg/mL using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay than cellular antioxidant assay using RAW 264.7 macrophages. In vitro cytotoxicity assay using human embryonic kidney HEK-293 cell line showed the anthocyanin-rich fraction to be more toxic than the crude extracts. The anthocyanin-rich fraction had more potent antibacterial activity than the crude extracts against Bacillus cereus, Bacillus subtilis, and Escherichia coli. The anthocyanin-rich fraction of C. ternatea has the potential to be used and developed as a functional food ingredient or nutraceutical agent.
Fulltext Effect of hot water, ultrasound, microwave, and pectinase-assisted extraction of anthocyanins from black goji berry for food application

Vidana Gamage GC, Choo WS

Heliyon, 2023 Mar;9(3):e14426.
PMID: 36942215 DOI: 10.1016/j.heliyon.2023.e14426

Lycium ruthenicum, commonly known as black goji berry, is a rich anthocyanin source containing a high amount of monoacylated anthocyanins. This study investigates the effect of different extraction methods to extract anthocyanins from black goji berry for food application. Different hot water extraction conditions were applied to investigate the effect of specific substrate: solvent ratio (1:15 and 1:20 (w/v)), extraction time (30 and 60 min) and extraction temperature (40, 50 and 60 °C) on the extraction yield, total anthocyanin content (TAC) and the total phenolic content (TPC) of the anthocyanin extracts. Best hot water extraction conditions for obtaining an anthocyanin extract with high TAC (13.8 ± 1.14 mg CGE/g), TPC (69.7 ± 2.50 mg of GAE/g), and extraction yield (48.3 ± 3.25%) consuming less solvent, time and heat were substrate: solvent ratio of 1: 15 (w/v), extraction temperature of 50 °C, and extraction time of 30 min. The effect of pectinase, ultrasound, and microwave on hot water extraction of anthocyanins from black goji berry was investigated using the best conditions for hot water extraction. Pectinase-assisted extraction [1.5% (w/v) pectinase, substrate: solvent ratio of 1:15 (w/v) at 50 °C for 30 min] was the best extraction method to extract black goji berry anthocyanins demonstrating higher extraction yield, TAC, TPC, and the highest percentage of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside.
Biofilm formation by staphylococci in health-related environments and recent reports on their control using natural compounds

Yong YY, Dykes GA, Choo WS

Crit Rev Microbiol, 2019 Mar;45(2):201-222.
PMID: 30786799 DOI: 10.1080/1040841X.2019.1573802

Staphylococci are Gram-positive bacteria that are ubiquitous in the environment and able to form biofilms on a range of surfaces. They have been associated with a range of human health issues such as medical device-related infection, localized skin infection, or direct infection caused by toxin production. The extracellular material produced by these bacteria resists antibiotics and host defence mechanism which complicates the treatment process. The commonly reported Staphylococcus species are Staphylococcus aureus and S. epidermidis as they inhabit human bodies. However, the emergence of other staphylococci, such as S. haemolyticus, S. lugdunensis, S. saprophyticus, S. capitis, S. saccharolyticus, S. warneri, S. cohnii, and S. hominis, is also of concern and they have been associated with biofilm formation. This review critically assesses recent cases on the biofilm formation by S. aureus, S. epidermidis, and other staphylococci reported in health-related environments. The control of biofilm formation by staphylococci using natural compounds is specifically discussed as they represent potential anti-biofilm agents which may reduce the burden of antibiotic resistance.
Fulltext Fermentation of red pitahaya extracts using Lactobacillus spp. and Saccharomyces cerevisiae for reduction of sugar content and concentration of betacyanin content

Gengatharan A, Dykes GA, Choo WS

J Food Sci Technol, 2021 Sep;58(9):3611-3621.
PMID: 34366478 DOI: 10.1007/s13197-021-05116-2

A study was conducted to concentrate the betacyanin in red pitahaya extracts by removing the coexisting sugars by fermentation. Four lactic acid bacteria (Lactobacillus acidophilus, L. casei, L. rhamnosus and L. plantarum) and a yeast species (Saccharomyces cerevisiae) were screened to determine their efficiency to reduce sugar content in red pitahaya extracts for concentration of their betacyanin content. A reduction of sugar content (19.8-56.4%) and increase in the yield of betacyanins were observed in all extracts as compared to the control, which was not innoculated with any microorganisms after 1 day of fermentation. The lowest total sugar content (26.40 g/L) was observed in extracts fermented by S. cerevisiae. Extracts fermented by S. cerevisiae also showed greater numbers of microbial cells (10.75 log CFU/mL) and a lower pH value (3.54) compared to those (6.89-8.48 log CFU/mL and pH 4.64-5.42) of the Lactobacillus spp. after 1 day of fermentation. An optimization step using response surface methodology (RSM) was then conducted using S. cerevisiae. Temperature, time and agitation speed were found to have a significant effect on the total sugar content and BC of concentrated betacyanins from red pitahaya, while the yield of betacyanins was significantly influenced by temperature and agitation speed.
SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05116-2.
Anti-Amyloid β Aggregation Activity and Cell Viability Effect of Betacyanins from Red Pitahaya (Hylocereus polyrhizus) for Alzheimer's Disease

Thwe PN, Yeong KY, Choo WS

Plant Foods Hum Nutr, 2023 Sep;78(3):613-619.
PMID: 37466824 DOI: 10.1007/s11130-023-01081-7

Betacyanin-rich extract from red beet (Beta vulgaris) was recently reported to inhibit amyloid β (Aβ) aggregation, a main pathological event in Alzheimer's disease. However, the anti-Aβ aggregation effect of individual betacyanin isolates has not been reported before. This study investigated the anti-Aβ aggregation activity and cytotoxicity of betacyanins from red pitahaya or red dragon fruit (Hylocereus polyrhizus). Betacyanin fraction (IC50 = 16.02 ± 1.15 µg/mL) and individual betacyanin isolates exhibited anti-Aβ aggregation activity in a concentration-dependent manner using a thioflavin T fluorescence assay. The highest to lowest IC50 was in the order of betanin (426.30 ± 29.55 µM), phyllocactin (175.22 ± 1.52 µM), and hylocerenin (131.73 ± 5.58 µM), following a trend of increase in functional groups of carboxyl, hydroxyl, and/or carbonyl. Further, the betacyanin fraction of 135.78 µg/mL and below, which were concentrations with an anti-Aβ aggregation effect, were validated as non-neurotoxic based on an in vitro cytotoxicity assay using human neuroblastoma (SH-SY5Y) cells. These findings highlight the potential neuroprotective activity of betacyanins for Alzheimer's disease.
Fulltext Awareness of diastolic heart failure as a disease entity among Malaysian doctors -- a questionnaire survey from three general hospitals

Choo WS, Loh LC, Goh TH, Omar I

Med J Malaysia, 2011 Oct;66(4):350-2.
PMID: 22299556

The concept of diastolic heart failure (DHF) is not new. However awareness and understanding on this subject may remains uncertain among medical practitioners. We wished to examine the extent of awareness of such entity among doctors in Malaysia. A questionnaire was designed and distributed randomly during hospital Continuous Professional Development (CPD/CME) sessions and also in the respective outpatient departments (OPD) between July to October 2008. This cross-sectional survey in three urban-based general hospitals showed that there are a significant proportion of doctors who are lack of understanding and awareness of diastolic heart failure.

Study site: Hospital Pulau Pinang, Georgetown, Pulau Pinang, Hospital Tuanku Ja’afar Seremban, Bukit Rasah, Seremban, Hospital Ampuan Najihah Kuala Pilah, Negeri Sembilan.
Fulltext Thixotropic Supramolecular Pectin-Poly(Ethylene Glycol) Methacrylate (PEGMA) Hydrogels

Chan SY, Choo WS, Young DJ, Loh XJ

Polymers (Basel), 2016 Nov 18;8(11).
PMID: 30974681 DOI: 10.3390/polym8110404

Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-d-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent this problem, cerium-initiated radical polymerization was utilized to graft methoxy-poly(ethylene glycol) methacrylate (mPEGMA) onto pectin in water. The copolymers were characterized by ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and used in the formation of supramolecular hydrogels through the addition of α-cyclodextrin (α-CD) to induce crosslinking. These hydrogels possessed thixotropic properties; shear-thinning to liquid upon agitation but settling into gels at rest. In contrast to most of the other hydrogels produced through the use of poly(ethylene glycol) (PEG)-grafted polymers, the pectin-PEGMA/α-CD hydrogels were unaffected by temperature changes.
Comparative Study of Betacyanin Profile and Antimicrobial Activity of Red Pitahaya (Hylocereus polyrhizus) and Red Spinach (Amaranthus dubius)

Yong YY, Dykes G, Lee SM, Choo WS

Plant Foods Hum Nutr, 2017 Mar;72(1):41-47.
PMID: 27917454 DOI: 10.1007/s11130-016-0586-x

Betacyanins are reddish to violet pigments that can be found in red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius). This study investigated the impact of sub-fractionation (solvent partitioning) on betacyanin content in both plants. Characterization of betacyanins and evaluation of their antimicrobial activities were also carried out. Betanin was found in both plants. In addition, isobetanin, phyllocactin and hylocerenin were found in red pitahaya whereas amaranthine and decarboxy-amaranthine were found in red spinach. Sub-fractionated red pitahaya and red spinach had 23.5 and 121.5 % more betacyanin content, respectively, than those without sub-fractionation. Sub-fractionation increased the betanin and decarboxy-amaranthine content in red pitahaya and red spinach, respectively. The betacyanin fraction from red spinach (minimum inhibitory concentration [MIC] values: 0.78-3.13 mg/mL) demonstrated a better antimicrobial activity profile than that of red pitahaya (MIC values: 3.13-6.25 mg/mL) against nine Gram-positive bacterial strains. Similarly, the red spinach fraction (MIC values: 1.56-3.13 mg/mL) was more active than the red pitahaya fraction (MIC values: 3.13-6.25 mg/mL) against five Gram-negative bacterial strains. This could be because of a higher amount of betacyanin, particularly amaranthine in the red spinach.
Pectin as a rheology modifier: Origin, structure, commercial production and rheology

Chan SY, Choo WS, Young DJ, Loh XJ

Carbohydr Polym, 2017 Apr 01;161:118-139.
PMID: 28189220 DOI: 10.1016/j.carbpol.2016.12.033

Pectins are a diverse family of biopolymers with an anionic polysaccharide backbone of α-1,4-linked d-galacturonic acids in common. They have been widely used as emulsifiers, gelling agents, glazing agents, stabilizers, and/or thickeners in food, pharmaceutical, personal care and polymer products. Commercial pectin is classified as high methoxy pectin (HMP) with a degree of methylation (DM) >50% and low methoxy pectin (LMP) with a DM <50%. Amidated low methoxy pectins (ALMP) can be obtained through aminolysis of HMP. Gelation of HMP occurs by cross-linking through hydrogen bonds and hydrophobic forces between the methyl groups, assisted by a high co-solute concentration and low pH. In contrast, gelation of LMP occurs by the formation of ionic linkages via calcium bridges between two carboxyl groups from two different chains in close proximity, known as the 'egg-box' model. Pectin gels exhibit Newtonian behaviour at low shear rates and shear-thinning behaviour when the shear rate is increased. An overview of pectin from its origin to its physicochemical properties is presented in this review.
Enzymatic synthesis of quercetin oleate esters using Candida antarctica lipase B

Saik AY, Lim YY, Stanslas J, Choo WS

Biotechnol Lett, 2017 Feb;39(2):297-304.
PMID: 27812823 DOI: 10.1007/s10529-016-2246-5

OBJECTIVES: To investigate the lipase-catalyzed acylation of quercetin with oleic acid using Candida antarctica lipase B.
RESULTS: Three acylated analogues were produced: quercetin 4'-oleate (C33H42O8), quercetin 3',4'-dioleate (C51H74O9) and quercetin 7,3',4'-trioleate (C69H106O10). Their identities were confirmed with UPLC-ESI-MS and (1)H NMR analyses. The effects of temperature, duration and molar ratio of substrates on the bioconversion yields varied across conditions. The regioselectivity of the acylated quercetin analogues was affected by the molar ratio of substrates. TLC showed the acylated analogues had higher lipophilicity (152% increase) compared to quercetin. Partition coefficient (log P) of quercetin 4'-oleate was higher than those of quercetin and oleic acid. Quercetin 4'-oleate was also stable over 28 days of storage.
CONCLUSIONS: Quercetin oleate esters with enhanced lipophilicity can be produced via lipase-catalyzed reaction using C. antarctica lipase B to be used in topical applications.
Biofilm inhibiting activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms

Yong YY, Dykes G, Lee SM, Choo WS

J Appl Microbiol, 2019 Jan;126(1):68-78.
PMID: 30153380 DOI: 10.1111/jam.14091

AIMS: To investigate the biofilm inhibitory activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms.
METHODS AND RESULTS: The pulp of red pitahaya and the leaves of red spinach were extracted using methanol followed by subfractionation to obtain betacyanin fraction. The anti-biofilm activity was examined using broth microdilution assay on polystyrene surfaces and expressed as minimum biofilm inhibitory concentration (MBIC). The betacyanin fraction from red spinach showed better anti-biofilm activity (MBIC: 0·313-1·25 mg ml-1 ) against five Staph. aureus strains while the betacyanin fraction from red pitahaya showed better anti-biofilm activity (MBIC: 0·313-0·625 mg ml-1 ) against four P. aeruginosa strains. Both betacyanin fraction significantly reduced hydrophobicity of Staph. aureus and P. aeruginosa strains. Numbers of Staph. aureus and P. aeruginosa attached to polystyrene were also reduced without affecting their cell viability.
CONCLUSION: Betacyanins can act as anti-biofilm agents against the initial step of biofilm formation, particularly on a hydrophobic surface like polystyrene.
SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to investigate the use of betacyanin as a biofilm inhibitory agent. Betacyanin could potentially be used to reduce the risk of biofilm-associated infections.
Betacyanin-inhibited biofilm formation of co-culture of Staphylococcus aureus and Pseudomonas aeruginosa on different polymer surfaces

Yong YY, Ong MWK, Dykes G, Choo WS

FEMS Microbiol Lett, 2021 01 26;368(1).
PMID: 33338235 DOI: 10.1093/femsle/fnaa214

Staphylococcus aureus and Pseudomonas aeruginosa are bacteria that cause biofilm-associated infections. The aim of this study was to determine the activity of combined betacyanin fractions from Amaranthus dubius (red spinach) and Hylocereus polyrhizus (red pitahaya) against biofilms formed by co-culture of S. aureus and P. aeruginosa on different polymer surfaces. Various formulations containing different concentrations of the betacyanin fractions were investigated for biofilm-inhibiting activity on polystyrene surfaces using crystal violet assay and scanning electron microscopy. A combination of each betacyanin fraction (0.625 mg mL-1) reduced biofilm formation of five S. aureus strains and four P. aeruginosa strains from optical density values of 1.24-3.84 and 1.25-3.52 to 0.81-2.63 and 0.80-1.71, respectively. These combined fractions also significantly inhibited dual-species biofilms by 2.30 and reduced 1.0-1.3 log CFU cm-2 bacterial attachment on polymer surfaces such as polyvinyl chloride, polyethylene, polypropylene and silicone rubber. This study demonstrated an increase in biofilm-inhibiting activity against biofilms formed by two species using combined fractions than that by using single fractions. Betacyanins found in different plants could collectively be used to potentially decrease the risk of biofilm-associated infections caused by these bacteria on hydrophobic polymers.

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