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Fulltext Extraneural metastasis of meningeal haemangiopericytoma to the liver

Yusoff AR, Mokhtar S, Raman K, Singh H, Shabery NAM

Turk J Gastroenterol, 2019 09;30(9):848-850.
PMID: 31530530 DOI: 10.5152/tjg.2019.18454
Antibacterial and antioxidant activity of naphthofuranquinones from the twigs of tropical mangrove Avicennia officinalis

Assaw S, Mohd Amir MIH, Khaw TT, Bakar K, Mohd Radzi SA, Mazlan NW

Nat Prod Res, 2020 Aug;34(16):2403-2406.
PMID: 30600710 DOI: 10.1080/14786419.2018.1538220

Mangrove plants are endowed with various biologically active compounds which have potent antibacterial and antioxidant properties. In present study, a bioactivity-guided fractionation for antibacterial and antioxidant active metabolites from the twigs of Avicennia officinalis collected from Kuala Selangor Nature Park, Selangor, Malaysia gave 13 major fractions. The antibacterial activity of A. officinalis fractions using well-diffusion showed strong selectivity on the Gram-positive bacteria (Staphylococcus epidermidis, S. aureus and Bacillus subtilis) with minimum inhibition concentration (MIC) values of 0.156-5.00 mg/mL. However, no antibacterial activities were observed on the Gram-negative bacteria (Vibrio cholera, Enterobacter cloacae and Escherichia coli). The active antibacterial fractions were further isolated using several chromatographic techniques to give two naphthofuranquinones, namely, avicenol C (1) and stenocarpoquinone B (2). Meanwhile, the antioxidant activity of A. officinalis fractions were evaluated using DPPH radical scavenging assay exhibited low antioxidant activities. Molecular structure of the naphthofuranquinones was elucidated using 1 D and 2 D NMR spectroscopy.
Fulltext Insight into Improved Thermostability of Cold-Adapted Staphylococcal Lipase by Glycine to Cysteine Mutation

Veno J, Rahman RNZRA, Masomian M, Ali MSM, Kamarudin NHA

Molecules, 2019 Aug 30;24(17).
PMID: 31480403 DOI: 10.3390/molecules24173169

Thermostability remains one of the most desirable traits in many lipases. Numerous studies have revealed promising strategies to improve thermostability and random mutagenesis often leads to unexpected yet interesting findings in engineering stability. Previously, the thermostability of C-terminal truncated cold-adapted lipase from Staphylococcus epidermidis AT2 (rT-M386) was markedly enhanced by directed evolution. The newly evolved mutant, G210C, demonstrated an optimal temperature shift from 25 to 45 °C and stability up to 50 °C. Interestingly, a cysteine residue was randomly introduced on the loop connecting the two lids and accounted for the only cysteine found in the lipase. We further investigated the structural and mechanistic insights that could possibly cause the significant temperature shift. Both rT-M386 and G210C were modeled and simulated at 25 °C and 50 °C. The results clearly portrayed the effect of cysteine substitution primarily on the lid stability. Comparative molecular dynamics simulation analysis revealed that G210C exhibited greater stability than the wild-type at high temperature simulation. The compactness of the G210C lipase structure increased at 50 °C and resulted in enhanced rigidity hence stability. This observation is supported by the improved and stronger non-covalent interactions formed in the protein structure. Our findings suggest that the introduction of a single cysteine residue at the lid region of cold-adapted lipase may result in unexpected increased in thermostability, thus this approach could serve as one of the thermostabilization strategies in engineering lipase stability.
Hearing status and behavioural patterns among school aged children with cleft lip and/or palate

Goh BS, Tang CL, Hashim ND, Annamalay T, Abd Rahman FN

Int J Pediatr Otorhinolaryngol, 2019 Mar;118:1-5.
PMID: 30578988 DOI: 10.1016/j.ijporl.2018.12.010

OBJECTIVE: There is a dearth of studies on long term hearing status and behavioural patterns among cleft lip and/or palate children after their primary lip and palate closure in Malaysia. This study describes the audiology status and behavioural patterns in a group of school aged children with cleft lip and/or palate.
METHOD: A cross sectional study was carried out where caretakers of cleft lip and/or palate were asked to complete the translated Malay language version of Strength Difficulties Questionnaire. The hearing status of the children was analyzed based on recent pure tone audiometric and tympanogram results. The patients' age, gender, type of cleft pathology, age of palatal surgery and behavioural patterns were examined for their potential relationship with hearing status.
RESULTS: A total of 74 children (148 ears) aged between 7 and 17 years with cleft lip and/or palate were recruited. The result showed 37 ears (25.0%) had hearing loss with majority suffered from mild conductive hearing loss. There were 16 ears (10.8%) that had persistent middle ear effusion. Hearing improvement occurred when palatal repair was performed at the age of less than 1 year old. (p = 0.015) There was no significant relationship between patients' gender, age, type of cleft and history of myringotomy with their hearing status. In terms of behavioural patterns, 16.3% were abnormal for total behavioural score, 39.2% for peer problem and 17.6% for conduct problem. For prosocial behaviour, 16.3% were rated low and very low. There was fair correlation between age and hyperactivity problems (r = 0.44). Patients' gender, type of cleft pathology, had been teased apart and hearing status was found not related to behavioural problems.
CONCLUSION: Cleft lip and/or palate patients have a good longterm hearing outcome. Majority had normal hearing and if there is hearing impairment, it is only a mild loss. Early palatal repair surgery before the age of 1 year can significantly reduce the risk of hearing loss. Cleft lip and/or palate patients experienced peer problems. There was no significant correlation between behavioural difficulty and hearing status among school-aged children with cleft lip and palate.
Fulltext Treatment of Wastewater Using Seaweed: A Review

Arumugam N, Chelliapan S, Kamyab H, Thirugnana S, Othman N, Nasri NS

Int J Environ Res Public Health, 2018 12 13;15(12).
PMID: 30551682 DOI: 10.3390/ijerph15122851

Inadequately treated or untreated wastewater greatly contribute to the release of unwanted toxic contaminants into water bodies. Some of these contaminants are persistent and bioaccumulative, becoming a great concern as they are released into the environment. Despite the abundance of wastewater treatment technologies, the adsorption method overall has proven to be an excellent way to treat wastewater from multiple industry sources. Because of its significant benefits, i.e., easy availability, handling, and higher efficiency with a low cost relative to other treatments, adsorption is opted as the best method to be used. However, biosorption using naturally found seaweeds has been proven to have promising results in removing pollutants, such as dyes from textile, paper, and the printing industry, nitrogen, and phosphorous and phenolic compounds, as well as heavy metals from various sources. Due to its ecofriendly nature together with the availability and inexpensiveness of raw materials, biosorption via seaweed has become an alternative to the existing technologies in removing these pollutants from wastewater effectively. In this article, the use of low-cost adsorbent (seaweed) for the removal of pollutants from wastewater has been reviewed. An extensive table summarises the applicability of seaweed in treating wastewater. Literature reported that the majority of research used simulated wastewater and minor attention has been given to biosorption using seaweed in the treatment of real wastewater.
Association of coronary artery calcium score with calcification and degree of stenosis: An autopsy study

Kaur M, Rahimi R, Razali F, Mohd Noor N, Omar E, Abdul Manaf Z, et al.

Malays J Pathol, 2019 Aug;41(2):177-183.
PMID: 31427553

INTRODUCTION: Coronary artery disease (CAD) is a known cause of major cardiovascular events and calcium score (CS) has been developed as a marker of coronary atherosclerosis. Yet, the relationship between post mortem computed tomography (PMCT) CS with histologically observed calcification and the severity of coronary artery stenosis has not been widely explored and is still unclear. This study aims to determine the association between coronary artery PMCT CS with histologically observed calcification and degree of stenosis of coronary arteries in post-mortem cases.
MATERIALS & METHODS: This was a cross-sectional study involving 101 subjects recruited from the National Institute of Forensic Medicine (IPFN) Hospital Kuala Lumpur (HKL) over a period of 15 months, from December 2012 until April 2014. PMCT CS of the coronary arteries was calculated using Agatston-Janowitz score. Histological presence of calcification was observed and the degree of stenosis was calculated using an image analysis technique.
RESULTS: PMCT CS increased with increasing severity of stenosis (p<0.001). PMCT CS showed a positive correlation with the presence of calcification (r=-0.82, p<0.001).
CONCLUSION: Calcium score is strongly associated with coronary artery calcification and the degree of luminal stenosis in post mortem subjects. Thus, PMCT may be useful as a non-invasive tool in diagnosing CAD in the event that an autopsy is not possible.
Conditioned media derived from mesenchymal stem cell cultures: The next generation for regenerative medicine

Gunawardena TNA, Rahman MT, Abdullah BJJ, Abu Kasim NH

J Tissue Eng Regen Med, 2019 04;13(4):569-586.
PMID: 30644175 DOI: 10.1002/term.2806

Recent studies suggest that the main driving force behind the therapeutic activity observed in mesenchymal stem cells (MSCs) are the paracrine factors secreted by these cells. These biomolecules also trigger antiapoptotic events to prevent further degeneration of the diseased organ through paracrine signalling mechanisms. In comparison with the normal physiological conditions, an increased paracrine gradient is observed within the peripheral system of diseased organs that enhances the migration of tissue-specific MSCs towards the site of infection or injury to promote healing. Thus, upon administration of conditioned media derived from mesenchymal stem cell cultures (MSC-CM) could contribute in maintaining the increased paracrine factor gradient between the diseased organ and the stem cell niche in order to speed up the process of recovery. Based on the principle of the paracrine signalling mechanism, MSC-CM, also referred as the secretome of the MSCs, is a rich source of the paracrine factors and are being studied extensively for a wide range of regenerative therapies such as myocardial infarction, stroke, bone regeneration, hair growth, and wound healing. This article highlights the current technological applications and advances of MSC-CM with the aim to appraise its future potential as a regenerative therapeutic agent.
Environmental Factors Associated with the Presence of Vibrionaceae in Tropical Cage-Cultured Marine Fishes

Mohamad N, Mustafa M, Amal MNA, Saad MZ, Md Yasin IS, Al-Saari N

J Aquat Anim Health, 2019 06;31(2):154-167.
PMID: 30653742 DOI: 10.1002/aah.10062

This study investigated the environmental factors associated with the presence of Vibrionaceae in economically important cage-cultured tropical marine fishes: the Asian Seabass Lates calcarifer, snapper Lutjanus sp., and hybrid grouper Epinephelus sp. Fish sampling was conducted at monthly intervals between December 2016 and August 2017. The body weight and length of individual fish were measured, and the skin, eye, liver, and kidney were sampled for bacterial isolation and identification. Water physicochemical parameters during the sampling activities were determined, and the enumeration of total Vibrionaceae count was also conducted from water and sediment samples. Nine species of Vibrio were identified, including V. alginolyticus, V. diabolicus, V. harveyi, V. campbellii, V. parahaemolyticus, V. rotiferianus, V. furnissii, V. fluvialis, and V. vulnificus. Photobacterium damselae subsp. damselae was also identified. A total of 73% of the isolated Vibrio belonged to the Harveyi clade, followed by the Vulnificus clade (5.5%) and Cholera clade (0.6%). Highest occurrence of Vibrio spp. and P. damselae subsp. damselae was found in hybrid grouper (72%), followed by Asian Seabass (48%) and snapper (36%). The associations of Vibrio spp. and P. damselae subsp. damselae with the host fish were not species specific. However, fish mortality and fish size showed strong associations with the presence of some Vibrio spp. On average, 60% of the infected cultured fish exhibited at least one clinical sign. Nevertheless, inconsistent associations were observed between the pathogens and water quality. The yearlong occurrence and abundance of Vibrionaceae in the environmental components indicate that they might serve as reservoirs of these pathogens.
Angiogenic effect of platelet-rich concentrates on dental pulp stem cells in inflamed microenvironment

Bindal P, Gnanasegaran N, Bindal U, Haque N, Ramasamy TS, Chai WL, et al.

Clin Oral Investig, 2019 Oct;23(10):3821-3831.
PMID: 30687907 DOI: 10.1007/s00784-019-02811-5

OBJECTIVE: In this study, we aimed to determine the suitable concentrations of human platelet lysate (HPL) and platelet-rich plasma (PRP) for maintaining the in vitro proliferative and angiogenic potential of inflamed dental pulp stem cells.
MATERIALS AND METHODS: Lipopolysaccharide (LPS)-induced inflamed dental pulp-derived stem cells (iDPSCs) were treated with different concentrations of HPL and PRP (10% and 20%) followed by determination of viability using Alamar Blue assay. Expression of angiogenesis-, adhesion-, and inflammation-regulating genes was also analyzed using RT-qPCR array. Furthermore, expression of growth factors at protein level in the cell culture microenvironment was measured using multiplex assay.
RESULTS: Viability of iDPSCs was significantly (p
Fulltext Single Residue Substitution at N-Terminal Affects Temperature Stability and Activity of L2 Lipase

Bukhari N, Leow ATC, Abd Rahman RNZR, Mohd Shariff F

Molecules, 2020 Jul 28;25(15).
PMID: 32731608 DOI: 10.3390/molecules25153433

Rational design is widely employed in protein engineering to tailor wild-type enzymes for industrial applications. The typical target region for mutation is a functional region like the catalytic site to improve stability and activity. However, few have explored the role of other regions which, in principle, have no evident functionality such as the N-terminal region. In this study, stability prediction software was used to identify the critical point in the non-functional N-terminal region of L2 lipase and the effects of the substitution towards temperature stability and activity were determined. The results showed 3 mutant lipases: A8V, A8P and A8E with 29% better thermostability, 4 h increase in half-life and 6.6 °C higher thermal denaturation point, respectively. A8V showed 1.6-fold enhancement in activity compared to wild-type. To conclude, the improvement in temperature stability upon substitution showed that the N-terminal region plays a role in temperature stability and activity of L2 lipase.
Characterization of promoter of EgPAL1, a novel PAL gene from the oil palm Elaeis guineensis Jacq

Yusuf CYL, Abdullah JO, Shaharuddin NA, Abu Seman I, Abdullah MP

Plant Cell Rep, 2018 Feb;37(2):265-278.
PMID: 29090330 DOI: 10.1007/s00299-017-2228-7

KEY MESSAGE: The oil palm EgPAL1 gene promoter and its regulatory region were functional as a promoter in the heterologous system of Arabidopsis according to the cis-acting elements present in that region. The promoter was developmentally regulated, vascular tissue specific and responsive to water stress agents. Phenylalanine ammonia lyase (PAL, EC 4.3.1.24) is the key enzyme of the phenylpropanoid pathway which plays important roles in plant development and adaptation. To date, there is no report on the study of PAL from oil palm (Elaeis guineensis), an economically important oil crop. In this study, the 5' regulatory sequence of a highly divergent oil palm PAL gene (EgPAL1) was isolated and fused with GUS in Arabidopsis to create two transgenic plants carrying the minimal promoter with (2302 bp) and without its regulatory elements (139 bp). The regulatory sequence contained cis-acting elements known to be important for plant development and stress response including the AC-II element for lignin biosynthesis and several stress responsive elements. The promoter and its regulatory region were fully functional in Arabidopsis. Its activities were characterised by two common fundamental features of PAL which are responsive to plant internal developmental programme and external factors. The promoter was developmentally regulated in certain organs; highly active in young organs but less active or inactive in mature organs. The presence of the AC elements and global activity of the EgPAL1 promoter in all organs resembled the property of lignin-related genes. The existence of the MBS element and enhancement of the promoter activity by PEG reflected the behaviour of drought-responsive genes. Our findings provide a platform for evaluating oil palm gene promoters in the heterologous system of Arabidopsis and give insights into the activities of EgPAL1 promoter in oil palm.
Fulltext Effects of Lacto-Fermented Agricultural By-Products as a Natural Disinfectant against Post-Harvest Diseases of Mango (Mangifera indica L.)

Ranjith FH, Muhialdin BJ, Yusof NL, Mohammed NK, Miskandar MH, Hussin ASM

Plants (Basel), 2021 Feb 03;10(2).
PMID: 33546183 DOI: 10.3390/plants10020285

BACKGROUND: the antagonism activity of lactic acid bacteria metabolites has the potential to prevent fungal growth on mango.
METHODS: the potential of developing natural disinfectant while using watermelon rinds (WR), pineapple (PP), orange peels (OP), palm kernel cake (PKC), and rice bran (RB), via lacto-fermentation was investigated. The obtained lactic acid bacteria (LAB) metabolites were then employed and the in vitro antifungal activity toward five spoilage fungi of mango was tested through liquid and solid systems. Besides, the effect of the produced disinfectant on the fungal growth inhibition and quality of mango was investigated.
RESULTS: the strains Lactobacillus plantarum ATCC8014 and Lactobacillus fermentum ATCC9338 growing in the substrates PKC and PP exhibited significantly higher in vitro antifungal activity against Colletotrichum gloeosporioides and Botryodiplodia theobromae as compared to other tested LAB strains and substrates. The in-situ results demonstrated that mango samples that were treated with the disinfectant produced from PKC fermented with L. plantarum and L. fermentum had the lowest disease incidence and disease severity index after 16 days shelf life, as well as the lowest conidial concentration. Furthermore, PKC that was fermented by L. fermentum highly maintained the quality of the mango.
CONCLUSIONS: lactic acid fermentation of PKC by L. fermentum demonstrated a high potential for use as a natural disinfectant to control C. gloeosporioides and B. theobromae on mango.
Fulltext Phytochemical and In Vitro Genotoxicity Studies of Standardized Ficus deltoidea var. kunstleri Aqueous Extract

Muhammad H, Omar MH, Rasid ENI, Suhaimi SN, Mohkiar FH, Siu LM, et al.

Plants (Basel), 2021 Feb 11;10(2).
PMID: 33670296 DOI: 10.3390/plants10020343

The present study was carried out to assess the genotoxicity potential of Ficus deltoidea var. kunstleri aqueous extract (FDAE) using standard in vitro assays. The DNA damage of V79B cells was measured using the alkaline comet assay treated at 0.1 mg/mL (IC10) and 0.3 mg/mL (IC25) of FDAE together with positive and negative controls. For in vitro micronucleus assay, the V79B cells were treated with FDAE at five different concentrations (5, 2.5, 1.25, 0.625, and 0.3125 mg/mL) with and without S9 mixture. The bacteria reverse mutation assay of FDAE was performed on Salmonella typhimurium strains TA98, 100, 1535, 1537, and Escherichia coli strain WP2uvrA using pre-incubation method in the presence or in the absence of an extrinsic metabolic system (S9 mixture). FDAE at 0.1 and 0.3 mg/mL significantly increased DNA damage in both comet tail and tail moment (p < 0.05). No significant changes were detected in the number of micronucleated cell when compared to control. Tested at the doses up to 5000 µg/plate, the FDAE did not increase the number of revertant colonies for all strains. In conclusion, further investigation needs to be conducted in animal model to confirm the non-genotoxicity activities of FDAE.
Fulltext Effect of Temperature, Water Activity and Carbon Dioxide on Fungal Growth and Mycotoxin Production of Acclimatised Isolates of Fusarium verticillioides and F. graminearum

Peter Mshelia L, Selamat J, Iskandar Putra Samsudin N, Rafii MY, Abdul Mutalib NA, Nordin N, et al.

Toxins (Basel), 2020 07 28;12(8).
PMID: 32731333 DOI: 10.3390/toxins12080478

Climate change is primarily manifested by elevated temperature and carbon dioxide (CO2) levels and is projected to provide suitable cultivation grounds for pests and pathogens in the otherwise unsuitable regions. The impacts of climate change have been predicted in many parts of the world, which could threaten global food safety and food security. The aim of the present work was therefore to examine the interacting effects of water activity (aw) (0.92, 0.95, 0.98 aw), CO2 (400, 800, 1200 ppm) and temperature (30, 35 °C and 30, 33 °C for Fusarium verticillioides and F. graminearum, respectively) on fungal growth and mycotoxin production of acclimatised isolates of F. verticillioides and F. graminearum isolated from maize. To determine fungal growth, the colony diameters were measured on days 1, 3, 5, and 7. The mycotoxins produced were quantified using a quadrupole-time-of-flight mass spectrometer (QTOF-MS) combined with ultra-high-performance liquid chromatography (UHPLC) system. For F. verticillioides, the optimum conditions for growth of fumonisin B1 (FB1), and fumonisin B2 (FB2) were 30 °C + 0.98 aw + 400 ppm CO2. These conditions were also optimum for F. graminearum growth, and zearalenone (ZEA) and deoxynivalenol (DON) production. Since 30 °C and 400 ppm CO2 were the baseline treatments, it was hence concluded that the elevated temperature and CO2 levels tested did not seem to significantly impact fungal growth and mycotoxin production of acclimatised Fusarium isolates. To the best of our knowledge thus far, the present work described for the first time the effects of simulated climate change conditions on fungal growth and mycotoxin production of acclimatised isolates of F. verticillioides and F. graminearum.
Fulltext The Role of Surface Exposed Lysine in Conformational Stability and Functional Properties of Lipase from Staphylococcus Family

Ahmad NN, Ahmad Kamarudin NH, Leow ATC, Rahman RNZRA

Molecules, 2020 Aug 25;25(17).
PMID: 32854267 DOI: 10.3390/molecules25173858

Surface charge residues have been recognized as one of the stability determinants in protein. In this study, we sought to compare and analyse the stability and conformational dynamics of staphylococcal lipase mutants with surface lysine mutation using computational and experimental methods. Three highly mutable and exposed lysine residues (Lys91, Lys177, Lys325) were targeted to generate six mutant lipases in silico. The model structures were simulated in water environment at 25 °C. Our simulations showed that the stability was compromised when Lys177 was substituted while mutation at position 91 and 325 improved the stability. To illustrate the putative alterations of enzyme stability in the stabilising mutants, we characterized single mutant K325G and double mutant K91A/K325G. Both mutants showed a 5 °C change in optimal temperature compared to their wild type. Single mutant K325G rendered a longer half-life at 25 °C (T1/2 = 21 h) while double mutant K91A/K325G retained only 40% of relative activity after 12 h incubation. The optimal pH for mutant K325G was shifted from 8 to 9 and similar substrate preference was observed for the wild type and two mutants. Our findings indicate that surface lysine mutation alters the enzymatic behaviour and, thus, rationalizes the functional effects of surface exposed lysine in conformational stability and activity of this lipase.
Phylogeography of the Japanese scad, Decapterus maruadsi (Teleostei; Carangidae) across the Central Indo-West Pacific: evidence of strong regional structure and cryptic diversity

Jamaludin NA, Mohd-Arshaad W, Mohd Akib NA, Zainal Abidin DH, Nghia NV, Nor SM

Mitochondrial DNA A DNA Mapp Seq Anal, 2020 10;31(7):298-310.
PMID: 32744461 DOI: 10.1080/24701394.2020.1799996

The Japanese scad Decapterus maruadsi (Carangidae) is an economically important marine species in Asia but its exploitation shows signs of overfishing. To document its stock structure, a population genetic and phylogeographic study of several populations of this species from the central part of the Indo-West Pacific region was conducted using the mitochondrial cytochrome b gene. Genetic homogeneity within the Sundaland region's population, including Rosario (the Philippines) and Ranong (Andaman Sea) populations was revealed with low nucleotide diversity (π = 0.001-0.003) but high haplotype diversity (h = 0.503-0.822). In contrast, a clear genetic structure was observed between this group and the northern Vietnam populations as revealed by FST, AMOVA and SAMOVA, while the central Vietnam population of Khanh Hoa is an admixed group between the two differentiated regional populations. The neutrality and mismatch distribution analyses supported a demographic expansion of D. maruadsi in between last Pleistocene to early Holocene period which influenced present day distribution pattern. Contemporary factors such as oceanic currents and different life history traits are also believed to play significant roles in the observed population structure and biogeographical pattern. Based on these results, recommendations on how stocks of the Japanese scad should be managed are offered.
Fulltext Antiamoebic activity of plant-based natural products and their conjugated silver nanoparticles against Acanthamoeba castellanii (ATCC 50492)

Anwar A, Ting ELS, Anwar A, Ain NU, Faizi S, Shah MR, et al.

AMB Express, 2020 Feb 03;10(1):24.
PMID: 32016777 DOI: 10.1186/s13568-020-0960-9

Acanthamoeba spp. are the causative agent of Acanthamoeba keratitis and granulomatous amoebic encephalitis (GAE). The current options to treat Acanthamoeba infections have limited success. Silver nanoparticles show antimicrobial effects and enhance the efficacy of their payload at the specific biological targets. Natural folk plants have been widely used for treating diseases as the phytochemicals from several plants have been shown to exhibit amoebicidal effects. Herein, we used natural products of plant or commercial sources including quercetin (QT), kolavenic acid (PGEA) isolated from plant extracts of Polyalthia longifolia var pendula and crude plant methanolic extract of Caesalpinia pulcherrima (CPFLM) as antiacanthamoebic agents. Furthermore, these plant-based materials were conjugated with silver nanoparticles (AgNPs) to determine the effects of the natural compounds and their nanoconjugates against a clinical isolate of A. castellanii from a keratitis patient (ATCC 50492) belonging to the T4 genotype. The compounds were conjugated with AgNPs and characterized by using ultraviolet visible spectrophotometry and atomic force microscopy. Quercetin coated silver nanoparticles (QT-AgNPs) showed characteristic surface plasmon resonance band at 443 nm and the average size distribution was found to be around 45 nm. The natural compounds alone and their nanoconjugates were tested for the viability of amoebae, encystation and excystation activity against A. castellanii. The natural compounds showed significant growth inhibition of A. castellanii while QT-AgNPs specifically exhibited enhanced antiamoebic effects as well as interrupted the encystation and excystation activity of the amoebae. Interestingly, these compounds and nanoconjugates did not exhibit in vitro cytotoxic effects against human cells. Plant-based compounds and extracts could be an interesting strategy in development of alternative therapeutics against Acanthamoeba infections.
Optimized lipase-catalyzed synthesis of adipate ester in a solvent-free system

Chaibakhsh N, Abdul Rahman MB, Abd-Aziz S, Basri M, Salleh AB, Abdul Rahman RN

J Ind Microbiol Biotechnol, 2009 Sep;36(9):1149-55.
PMID: 19479288 DOI: 10.1007/s10295-009-0596-x

Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM) approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme. A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60 degrees C, reaction time of 438 min, and agitation speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester.
Cloning, extracellular expression and characterization of a predominant beta-CGTase from Bacillus sp. G1 in E. coli

Ong RM, Goh KM, Mahadi NM, Hassan O, Rahman RN, Illias RM

J Ind Microbiol Biotechnol, 2008 Dec;35(12):1705-14.
PMID: 18726621 DOI: 10.1007/s10295-008-0462-2

The cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) gene from Bacillus sp. G1 was successfully isolated and cloned into Escherichia coli. Analysis of the nucleotide sequence revealed the presence of an open reading frame of 2,109 bp and encoded a 674 amino acid protein. Purified CGTase exhibited a molecular weight of 75 kDa and had optimum activity at pH 6 and 60 degrees C. Heterologous recombinant protein expression in E. coli is commonly problematic causing intracellular localization and formation of inactive inclusion bodies. This paper shows that the majority of CGTase was secreted into the medium due to the signal peptide of Bacillus sp. G1 that also works well in E. coli, leading to easier purification steps. When reacted with starch, CGTase G1 produced 90% beta-cyclodextrin (CD) and 10% gamma-CD. This enzyme also preferred the economical tapioca starch as a substrate, based on kinetics studies. Therefore, CGTase G1 could potentially serve as an industrial enzyme for the production of beta-CD.
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.

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