MyMedR

Displaying publications 141 - 160 of 296 in total

Abstract:

Sort:

Fulltext Giant Cell Tumour Around Knee Managed by Curettage and Zoledronic Acid with Structural Support by Fibula Cortical Struts

Singaravadivelu V, Kavinkumar V

Malays Orthop J, 2020 Nov;14(3):42-49.
PMID: 33403061 DOI: 10.5704/MOJ.2011.008

Introduction: Giant cell tumour (GCT) of the bone is a benign tumour with a high tendency to recur after surgery. This study aimed to analyse prospectively the rate of local recurrence following management of giant cell tumours by curettage, using intravenous zoledronic acid as an adjuvant, and fibular struts to support the empty cavity after curettage.
Materials and Methods: This study was carried out in ten cases of biopsy-proven GCTs: five males and five females, in the age group between 18 and 39 years. All patients were given three doses of zoledronic acid, one pre-operative and two post-operative. Extended curettage was done three weeks after the pre-operative dose of zoledronate. The cavity was left empty in all the cases. Fibular struts were used to support the cavity from collapse. Patients were followed-up for post-operative local recurrence. The functional status of the patients was assessed during each visit using the Musculoskeletal Tumour Society (MSTS) score.
Results: There were no recurrences at a follow-up of two years. All patients had a stable knee and were able to bear weight fully. The average knee flexion was 75º. The average MSTS score of the study was 92%.
Conclusion: Extended curettage using hydrogen peroxide, systemic zoledronic acid adjuvant and leaving the cavity empty without using cancellous bone graft did not lead to a recurrence of GCT. Non-vascularised fibular strut provided adequate support while the cavity left empty after curettage did not collapse and there was good knee function.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Effect of Non-hydrogen Peroxide on Antibacterial Activity of Malaysian Meliponini Honey against Staphylococcus aureus

Jibril FI, Mohd Hilmi AB, Aliyu S

J Pharm Bioallied Sci, 2020 Nov;12(Suppl 2):S831-S835.
PMID: 33828385 DOI: 10.4103/jpbs.JPBS_280_19

Introduction: Stingless bee is an insect that belongs to the family Apidae. Its name is based on its disability of stinging. It has a high product of Meliponini honey and propolis by which are commonly referred to as stingless bee honey and stingless bee propolis. Meliponini honey is one of the crucial natural sources and has the potential to kill infectious microorganisms. Previous studies have proved that the antibacterial activity of natural honey was an effect of hydrogen peroxide, a substance contained in the honey. However, these claims were contradicting with too many studies.
Objective: Therefore, this study aimed to identify the antibacterial activity of Malaysian Meliponini honey which contained non-hydrogen peroxide against Staphylococcus aureus, an opportunistic microbial.
Materials and Methods: Meliponini honey was used as an antibacterial agent for the treatment of S. aureus in agar well diffusion assay. An amplex red hydrogen peroxide kit was used to identify the hydrogen peroxide in the honey sample. Meanwhile, non-hydrogen peroxide activity was performed by using honey-catalase treated.
Results: For the first time, we found that hydrogen peroxide was absent in all Meliponini honey samples. Meliponini honey has higher antibacterial activity (13.30 ± 0.56mm) compared to Apis honey (9.03 ± 0.22mm) in agar well diffusion assay.
Discussion: Non-hydrogen peroxide in Meliponini honey is a bioactive compound and beneficial to kill the microbial infection.
Conclusion: Antibacterial activity of Malaysian Meliponini honey is directly contributed by non-hydrogen peroxide.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Pharmacokinetic evaluation, molecular docking and in vitro biological evaluation of 1, 3, 4-oxadiazole derivatives as potent antioxidants and STAT3 inhibitors

Khanam R, Hejazi II, Shahabuddin S, Bhat AR, Athar F

J Pharm Anal, 2019 Apr;9(2):133-141.
PMID: 31011470 DOI: 10.1016/j.jpha.2018.12.002

1, 3, 4-Oxadiazole derivatives (4a-5f) were previously synthesized to investigate their anticancer properties. However, studies relating to their antioxidant potential and signal transducer and activator of transcription (STAT) inhibition have not been performed. We investigated previously synthesized 1, 3, 4-oxadiazole derivatives (4a-5f) for various radical scavenging properties using several in vitro antioxidant assays and also for direct inhibition of STAT3 through molecular docking. The data obtained from various antioxidant assays such as 2, 2,-diphenyl-1-picrylhydrazyl radical (DPPH), nitric oxide, hydrogen peroxide, and superoxide anion radical revealed that among all the derivatives, compound 5e displayed high antioxidant activities than the standard antioxidant L-ascorbic acid. Additionally, the total reduction assay and antioxidant capacity assay further confirmed the antioxidant potential of compound 5e. Furthermore, the molecular docking studies performed for all derivatives along with the standard inhibitor STX-0119 showed that binding energy released in direct binding with the SH2 domain of STAT3 was the highest for compound 5e (-9.91kcal/mol). Through virtual screening, compound 5e was found to exhibit optimum competency in inhibiting STAT3 activity. Compound 5e decreased the activation of STAT3 as observed with Western blot. In brief, compound 5e was identified as a potent antioxidant agent and STAT3 inhibitor and effective agent for cancer treatment.

Matched MeSH terms: Hydrogen Peroxide
Application of response surface methodology for the optimization of polycyclic aromatic hydrocarbons degradation from potable water using photo-Fenton oxidation process

Abd Manan TSB, Khan T, Sivapalan S, Jusoh H, Sapari N, Sarwono A, et al.

Sci Total Environ, 2019 May 15;665:196-212.
PMID: 30772550 DOI: 10.1016/j.scitotenv.2019.02.060

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds, composed of benzene rings. The objective of this research was to identify the optimum condition for the degradation of PAHs contaminated water using photo-Fenton oxidation process via response surface methodology (RSM). Aqueous solution was prepared and potable water samples were collected from water treatment plants in Perak Tengah, Perak, Malaysia in September 2016. The reaction time, pH, molarity of H2O2 and FeSO4 were analyzed followed by RSM using aqueous solution. A five level central composite design with quadratic model was used to evaluate the effects and interactions of these parameters. The response variable was the percentage of total organic carbon (TOC) removal. PAHs quantification was done using gas chromatography mass spectrometry analysis. The regression line fitted well with the data with R2 value of 0.9757. The lack of fit test gives the highest value of Sum of Squares (15,666.64) with probability F value 0.0001 showing significant quadratic model. The optimum conditions were established corresponding to the percentage of TOC removal. The PAHs removal efficiency for potable water samples ranged from 76.4% to 91% following the first order of kinetic rates with R2 values of >0.95. Conventional water treatment techniques are not effective for PAHs removal. Thus, advanced oxidation processes may be considered as an alternative to conventional water treatment techniques in Malaysia and other developing countries.

Matched MeSH terms: Hydrogen Peroxide
Effect of Chitosan Nanoparticle-Loaded Thymus serpyllum on Hydrogen Peroxide-Induced Bone Marrow Stromal Cell Damage

Baig S, Azizan AHS, Raghavendran HRB, Natarajan E, Naveen S, Murali MR, et al.

Stem Cells Int, 2019;2019:5142518.
PMID: 30956670 DOI: 10.1155/2019/5142518

We have determined the protective effects of Thymus serpyllum (TS) extract and nanoparticle-loaded TS on hydrogen peroxide-induced cell death of mesenchymal stromal cells (MSCs) in vitro. Gas chromatography-mass spectroscopy confirmed the spectrum of active components in the extract. Out of the three different extracts, the hexane extract showed significant free radical scavenging activity. Treatment of MSCs with H2O2 (hydrogen peroxide) significantly increased intracellular cell death; however, pretreatment with TS extract and nanoparticle-loaded TS (200 μg/ml) suppressed H2O2-induced elevation of Cyt-c and MMP13 and increased the survival rates of MSCs. H2O2-induced (0.1 mM) changes in cytokines were attenuated in the extract and nanoparticles by pretreatment and cotreatment at two time points (p < 0.05). H2O2 increased cell apoptosis. In contrast, treatment with nanoparticle-loaded TS suppressed the percentage of apoptosis considerably (p < 0.05). Therefore, TS may be considered as a potential candidate for enhancing the effectiveness of MSC transplantation in cell therapy.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Transcriptional regulation of Lonicera japonica Thunb. during flower development as revealed by comprehensive analysis of transcription factors

Wang T, Yang B, Guan Q, Chen X, Zhong Z, Huang W, et al.

BMC Plant Biol, 2019 May 14;19(1):198.
PMID: 31088368 DOI: 10.1186/s12870-019-1803-1

BACKGROUND: Lonicera japonica Thunb. flower has been used for the treatment of various diseases for a long time and attracted many studies on its potential effects. Transcription factors (TFs) regulate extensive biological processes during plant development. As the restricted reports of L. japonica on TFs, our work was carried out to better understand the TFs' regulatory roles under different developmental stages in L. japonica.
RESULTS: In this study, 1316 TFs belonging to 52 families were identified from the transcriptomic data, and corresponding expression profiles during the L. japonica flower development were comprehensively analyzed. 917 (69.68%) TFs were differentially expressed. TFs in bHLH, ERF, MYB, bZIP, and NAC families exhibited obviously altered expression during flower growth. Based on the analysis of differentially expressed TFs (DETFs), TFs in MYB, WRKY, NAC and LSD families that involved in phenylpropanoids biosynthesis, senescence processes and antioxidant activity were detected. The expression of MYB114 exhibited a positive correlation with the contents of luteoloside; Positive correlation was observed among the expression of MYC12, chalcone synthase (CHS) and flavonol synthase (FLS), while negative correlation was observed between the expression of MYB44 and the synthases; The expression of LSD1 was highly correlated with the expression of SOD and the total antioxidant capacity, while the expression of LOL1 and LOL2 exhibited a negative correlation with them; Many TFs in NAC and WRKY families may be potentially involved in the senescence process regulated by hormones and reactive oxygen species (ROS). The expression of NAC19, NAC29, and NAC53 exhibited a positive correlation with the contents of ABA and H2O2, while the expression of WRKY53, WRKY54, and WRKY70 exhibited a negative correlation with the contents of JA, SA and ABA.
CONCLUSIONS: Our study provided a comprehensive characterization of the expression profiles of TFs during the developmental stages of L. japonica. In addition, we detected the key TFs that may play significant roles in controlling active components biosynthesis, antioxidant activity and flower senescence in L. japonica, thereby providing valuable insights into the molecular networks underlying L. japonica flower development.

Matched MeSH terms: Hydrogen Peroxide
Electrocatalytic Reduction of Hydrogen Peroxide and Its Non-Enzymatic Electrochemical Detection Using Silver Nanoparticles Anchored on Reduced Graphene Oxide

Ikhsan NI, Rameshkumar P, Yusoff N, Huang NM

J Nanosci Nanotechnol, 2019 Nov 01;19(11):7054-7063.
PMID: 31039858 DOI: 10.1166/jnn.2019.16630

Silver-reduced graphene oxide (Ag-rGO) nanohybrid was synthesized by applying a slight modification to the Turkevich method using trisodium citrate as a reducing and stabilizing agent to catalyze the non-enzymatic electrochemical detection of hydrogen peroxide (H₂O₂). Spherical silver nanoparticles (AgNPs) with an average particle size of 2.2 nm surfaced on reduced graphene oxide (rGO) sheets. Cyclic voltammograms (CV) obtained from glassy carbon (GC) electrode coated with Ag-rGO nanohybrid (4 mM) exhibited a peak at an overpotential of -0.52 V, with a larger faradaic current for the reduction of H₂O₂. Using the modified electrode for the linear sweep voltammetry (LSV) detection of H₂O₂, the detection limit and sensitivity were determined to be 4.8 μM (S/N ═ 3) and 0.0262 μA μM-1, respectively. The sensor appeared selective and stable towards H₂O₂ in the presence of possible interference, and it also demonstrated good recoveries of H₂O₂ concentration in real water samples.

Matched MeSH terms: Hydrogen Peroxide
Controlled Synthesis of Well-Aligned and Highly Ordered TiO₂ Nanotubes Without Bundling for Enhanced Solar-Powered Photoelectrochemical Responses

Lai CW, Lau KS, Chou PM

J Nanosci Nanotechnol, 2019 Dec 01;19(12):7934-7942.
PMID: 31196312 DOI: 10.1166/jnn.2019.16777

Using solar-powered water electrolysis systems for hydrogen generation is a key decision for the development of a sustainable hydrogen economy. A facile approach is presented in the present investigation to improve the solar-powered photoelectrochemical performance of water electrolysis systems by synthesising well-aligned and highly ordered TiO₂ nanotube films without bundling through the electrochemical anodisation technique. Herein, geometrical calculations were conducted for all synthesised TiO₂ nanotubes, and determination of the aspect ratio (AR) and geometric surface area factor (G) was achieved. On the basis of the collected data, well-aligned TiO₂ nanotubes with an AR of approximately 60 and G of approximately 400 m² ·g-1 were successfully formed in an electrolyte mixture of ethylene glycol with 0.3 wt% NH4F and 5 wt% H₂O₂ at 40 V for 60 min. The nanotubes were subsequently annealed at 400 °C to form anatase-phase TiO₂ nanotube films. The resultant well-aligned and highly ordered TiO₂ nanotube films exhibited a photocurrent density of 1.5 mA · cm-2 due to a large number of photo-induced electrons moving along the tube axis and perpendicular to the Ti substrate, which greatly reduces interfacial recombination losses.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Ascorbate peroxidase activity of Aranda Broga Blue orchid protocorm-like bodies (plbs) in response to PVS2 cryopreservation method

Khor, Soo Ping, Rahmad Zakaria, Subramaniam, Sreeramanan

Trop Life Sci Res, 2016;27(11):139-143.
MyJurnal

Throughout the cryopreservation process, plants were exposed to a series of
abiotic stresses such as desiccation and osmotic pressure due to highly concentrated
vitrification solution. Abiotic stress stimulates the production of reactive oxygen species
(ROS) which include hydrogen peroxide, superoxide radicals, and singlet oxygen. Higher
production of ROS may lead to oxidative stress which contributes to the major injuries in
cryopreserved explants. Antioxidant enzymes in plant such as ascorbate peroxidase
(APX) can protect plants from cell damage by scavenging the free radicals. This study was
determined based on APX enzyme activity of Aranda Broga Blue orchid’s protocorm-like
bodies (PLBs) in response to PVS2 (Plant Vitrification Solution 2) cryopreservation
treatments at different stages. PLBs that were precultured at 0.25 M sucrose for 3 days
were subjected to vitrification cryopreservation method. Results obtained showed that the
highest APX activity was achieved at PVS2 cryoprotectant treatment prior liquid nitrogen
(LN) storage. This phenomenon indicating that accumulation of osmotic and dehydrating
stress throughout the cryopreservation treatment resulted in oxidative burst which in turn
leads to higher APX activity in order to control the excess production of ROS. To
conclude, PVS2 treatment was revealed as the most detrimental step throughout
cryopreservation treatment. Thus, this research also suggested that exogenous
antioxidant such as ascorbic acid can be added throughout cryopreservation procedure
especially at PVS2 treatment in the future experiments to aid in regrowth of cryopreserved
explants by reducing oxidative stress.

Matched MeSH terms: Hydrogen Peroxide
Anti-aging Effects of Mangosteen Peel Extract and Its Phytochemical Compounds: Antioxidant Activity, Enzyme Inhibition and Molecular Docking Simulation

Widowati W, Ginting CN, Lister INE, Girsang E, Amalia A, Wibowo SHB, et al.

Trop Life Sci Res, 2020 Oct;31(3):127-144.
PMID: 33214860 DOI: 10.21315/tlsr2020.31.3.9

Skin aging is a complex natural process characterised by gradual diminishment of structural integrity and physiological imbalance of the skin tissue. Since the oxidative stress is tightly corelated to the skin aging process, the usage of antioxidant may serve as favourable strategies for slowing down the skin aging process. Mangosteen is an important fruit commodity and its extract had been extensively studied and revealing various biological activities. Present study aimed to assess the antioxidant and antiaging activity of mangosteen peel extract (MPE) and its phytochemical compounds. MPE and its compounds were subjected to ferric reducing antioxidant power (FRAP), hydroperoxide (H2O2) scavenging, anti-collagenase, anti-elastase, anti-hyaluronidase and anti-tyrosinase assay. MPE has the highest FRAP 116.31 ± 0.60 μM Fe(II) μg-1 extract, IC50 of MPE on H2O2 scavenging activity was 54.61 μg mL-1. MPE also has the highest anti elastase activity at IC50 7.40 μg mL-1. Alpha-mangostin showed potent anti-collagenase activity (IC50 9.75 μg mL-1). While gamma-mangostin showed potent anti-hyaluronidase (IC50 23.85 μg mL-1) and anti-tyrosinase (IC50 50.35 μg mL-1). MPE and its compounds were evaluated in vitro for antioxidant and antiaging activities. Current findings may provide scientific evidence for possible usage of mangosteen extract and its compounds as antioxidant and antiaging agent.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Cytotoxicity of snake venom enzymatic toxins: phospholipase A2 and l-amino acid oxidase

Hiu JJ, Yap MKK

Biochem Soc Trans, 2020 04 29;48(2):719-731.
PMID: 32267491 DOI: 10.1042/BST20200110

The phospholipase A2 (PLA2) and l-amino acid oxidase (LAAO) are two major enzymes found in the venoms from most snake species. These enzymes have been structurally and functionally characterised for their pharmacological activities. Both PLA2 and LAAO from different venoms demonstrate considerable cytotoxic effects on cancer cells via induction of apoptosis, cell cycle arrest and suppression of proliferation. These enzymes produce more pronounced cytotoxic effects in cancer cells than normal cells, thus they can be potential sources as chemotherapeutic agents. It is proposed that PLA2 and LAAO contribute to an elevated oxidative stress due to their catalytic actions, for instance, the ability of PLA2 to produce reactive oxygen species during lipolysis and formation of H2O2 from LAAO catalytic activity which consequently lead to cell death. Nonetheless, the cell-death signalling pathways associated with exposure to these enzymatic toxins are not fully elucidated yet. Here in this review, we will discuss the cytotoxic effects of PLA2 and LAAO in relationship to their catalytic mechanisms and the underlying mechanisms of cytotoxic actions.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Evaluation of closed vessel microwave digestion of fish muscle with various solvent combinations using fractional factorial design

Low, K.H., Zain, S.M., Abas, M.R., Ali Mohd, M.

ASM Science Journal, 2009;3(1):71-76.
MyJurnal

Fractional factorial design was utilized to evaluate the effect of combinations of nitric acid, hydrogen peroxide, hydrochloric acid and water for microwave digestion of fish muscle. Upon digestion, copper, iron and zinc were determined by flame atomic absorption spectroscopy. H2O2 and HCl volumes were found to be the most significant parameters which resulted in good metal recoveries. This is especially so for the effect of HCl on Fe recovery. The results indicated that the combination of 4 mL 65% HNO3, 2 mL 30% H2O2 and 2 mL 30% HCl gave the most satisfactory percentage recovery. There was good agreement between measured and certified values for all metals with respect to the DORM-3 fish protein.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Streptomyces antioxidans sp. nov., a Novel Mangrove Soil Actinobacterium with Antioxidative and Neuroprotective Potentials

Ser HL, Tan LT, Palanisamy UD, Abd Malek SN, Yin WF, Chan KG, et al.

Front Microbiol, 2016;7:899.
PMID: 27379040 DOI: 10.3389/fmicb.2016.00899

A novel strain, Streptomyces antioxidans MUSC 164(T) was recovered from mangrove forest soil located at Tanjung Lumpur, Malaysia. The Gram-positive bacterium forms yellowish-white aerial and brilliant greenish yellow substrate mycelium on ISP 2 agar. A polyphasic approach was used to determine the taxonomy status of strain MUSC 164(T). The strain showed a spectrum of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The cell wall peptidoglycan was determined to contain LL-diaminopimelic acid. The predominant menaquinones were identified as MK-9(H6) and MK-9(H8), while the identified polar lipids consisted of aminolipid, diphosphatidylglycerol, glycolipid, hydroxyphosphatidylethanolamine, phospholipid, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol and lipid. The cell wall sugars consist of galactose, glucose and ribose. The predominant cellular fatty acids (>10.0%) were identified as iso-C15: 0 (34.8%) and anteiso-C15: 0(14.0%). Phylogenetic analysis identified that closely related strains for MUSC 164(T) as Streptomyces javensis NBRC 100777(T) (99.6% sequence similarity), Streptomyces yogyakartensis NBRC 100779(T) (99.6%) and Streptomyces violaceusniger NBRC 13459(T) (99.6%). The DNA-DNA relatedness values between MUSC 164(T) and closely related type strains ranged from 23.8 ± 0.3% to 53.1 ± 4.3%. BOX-PCR fingerprints comparison showed that MUSC 164(T) exhibits a unique DNA profile, with DNA G + C content determined to be 71.6 mol%. Based on the polyphasic study of MUSC 164(T), it is concluded that this strain represents a novel species, for which the name Streptomyces antioxidans sp. nov. is proposed. The type strain is MUSC 164(T) (=DSM 101523(T) = MCCC 1K01590(T)). The extract of MUSC 164(T) showed potent antioxidative and neuroprotective activities against hydrogen peroxide. The chemical analysis of the extract revealed that the strain produces pyrazines and phenolic-related compounds that could explain for the observed bioactivities.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Synthesis of epoxidized palm oil-based trimethylolpropane ester by in situ epoxidation method

Ferra Naidir, Robiah Yunus, Tinia Idaty Mohd. Ghazi, Irmawati Ramli

Pertanika Journal of Science & Technology, 2012;20(2):331-337.
MyJurnal

Palm oil-based Trimethylolpropane ester (TMP ester), with an iodine value of 66.4 g/100g, was epoxidizedto produce epoxidized TMP esters. In situ epoxidation method was used with peracetic acid to eliminatefatty acid double bonds in palm oil-based TMP ester and change it into oxirane ring. This was done toimprove the oxidative stability of trimethylolpropane ester which is a key concern limiting the usefulservice life in lubricants. The epoxidation was performed by reacting acetic acid as active oxygen carrierwith concentrated hydrogen peroxide as oxygen donor and a small amount of homogeneous catalyst(sulphuric acid). The effects of various parameters on the rate of epoxidation (such as the ratio of moleacetic acid to ethylenic unsaturation, hydrogen peroxide to ethylenic unsaturation and acetic acid moleratio, and amount of catalyst) were studied. The rate of oxidation was investigated by the percentageof oxirane oxygen analysis and iodine value.

Matched MeSH terms: Hydrogen Peroxide
Neurotoxicity and neuroprotective effects of polyimides (P1) and polyphenylenevinylene (PPV) against hydrogen peroxide (H2O2)

Norfaezah Mazalan, Mazatulikhma Mat Zain, Nor Saliyana Jumali, Norhanim Mohalid, Zurina Shameri, Ahmad Sazali Hamzah

Scientific Research Journal, 2011;8(2):33-47.
MyJurnal

Recently, research and development in the field of drug delivery systems (DDS) facilitating site-specific therapy has reached significant progression. DDS based on polymer micelles, coated micro- and nanoparticles, and various prodrug systems including water-soluble polymer have been prepared and extensively studied as novel drugs designed for cancer chemotherapy and brain delivery. Since polymers are going to be used in human, this study has the interest of testing two types of polymer, polyimides (PI) and polyphenylenevinylene (PPV) on neuronal cells. The objective of this study was to determine the possible neurotoxicity and potential neuroprotective effects of PI and PPV towards SH-SY5Y neuronal cells challenged by hydrogen peroxide (1120) as an oxidant. Cells were pretreated with either PI or PPV for 1 hour followed by incubation for 24 hour with 100 ,uM of 11201. MTS • assay was used to assess cell viability. Results show that PI and PPV are not harmful within the concentration up to 10 pM and 100 pM, respectively. However, PI and PPV do not protect neuronal cells against toxicity induced by H2O, or further up the cell death.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Response of Streptococcus Zooepidemicus to oxidative stress in hyaluronic acid fermentation

Mashitah, M.D., Masitah, H., Ramachandran, K.B.

Pertanika Journal of Science & Technology, 2009;17(1):-.
MyJurnal

Streptococcus zooepidemicus (SZ) is an aerotolerant bacteria and its ability to survive under reactive oxidant raises the question of the existence of a defense system against oxidative stress. As a characteristic of lactic acid bacteria, Streptococcus lacks an ordinary anti-oxidative stress enzyme, catalases and an electron transport chain. Whether this bacterium resists oxidative stress prior to an exposure to a higher level of an oxidizing agent H2O2 in hyaluronic acid fermentation is not known. This paper describes that Streptococcus cells, once treated with lower concentrations of H2O2 (i.e. 0.25, 0.50 and 1.0 mM) at least, were prepared for a subsequent higher concentrations of H2O2 such as 20.5 and 100 mM. At low concentrations (i.e. 0.25, 0.50 and 1.0 mM), H2O2 was found to act as a stimulant for HA synthesis, but it became toxic if presented at a very high level (100 mM H2O2). The highest HA yield to glucose consumed (YHAtotal/glu) was 0.017 gg-1 for the cells pre-treated with 0 mM of H2O2, and then exposed to 20.5 mM H2O2. Thus, this implied that this bacteria might possess a defense mechanism against oxidative stress and that this system was inducible.

Matched MeSH terms: Hydrogen Peroxide
Fulltext A simple design for microwave assisted digestion vessel with low reagent consumption suitable for food and environmental samples

Gholami M, Behkami S, Zain SM, Bakirdere S

Sci Rep, 2016 11 17;6:37186.
PMID: 27853264 DOI: 10.1038/srep37186

The objective of this work is to prepare a cost-effective, low reagent consumption and high performance polytetrafluoroethylene (PTFE) vessel that is capable to work in domestic microwave for digesting food and environmental samples. The designed vessel has a relatively thicker wall compared to that of commercial vessels. In this design, eight vessels are placed in an acrylonitrile butadiene styrene (ABS) holder to keep them safe and stable. This vessel needs only 2.0 mL of HNO3 and 1.0 mL H2O2 to digest 100 mg of biological sample. The performance of this design is then evaluated with an ICP-MS instrument in the analysis of the several NIST standard reference material of milk 1849a, rice flour 1568b, spinach leave 1570a and Peach Leaves 1547 in a domestic microwave oven with inverter technology. Outstanding agreement to (SRM) values are observed by using the suggested power to time microwave program, which simulates the reflux action occurring in this closed vessel. Taking into account the high cost of commercial microwave vessels and the volume of chemicals needed for various experiments (8-10 mL), this simple vessel is cost effective and suitable for digesting food and environmental samples.

Matched MeSH terms: Hydrogen Peroxide
Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution

Matsuguma Y, Takada H, Kumata H, Kanke H, Sakurai S, Suzuki T, et al.

Arch Environ Contam Toxicol, 2017 Aug;73(2):230-239.
PMID: 28534067 DOI: 10.1007/s00244-017-0414-9

Microplastics (<5 mm) were extracted from sediment cores collected in Japan, Thailand, Malaysia, and South Africa by density separation after hydrogen peroxide treatment to remove biofilms were and identified using FTIR. Carbonyl and vinyl indices were used to avoid counting biopolymers as plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm-1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

Matched MeSH terms: Hydrogen Peroxide
Fulltext Effect of microwave heating with different exposure times on the degradation of corn oil

Abbas Ali, Hadi Mesran, M., Nik Mahmood, N.A., Abd Latip, R.

International Food Research Journal, 2016;23(2):842-848.
MyJurnal

In the present work, the influence of microwave power and heating times on the quality
degradation of corn oil was evaluated. Microwave heating test was carried out using a domestic
microwave oven for different periods at low- and medium-power settings for the corn oil sample.
The changes in physicochemical characteristics related to oil degradation of the samples during
heating were determined by standard methods. In this study, refractive index, free fatty acid
content, peroxide value, p-anisidine value, TOTOX value, viscosity and total polar compound
of the oils all increased with increasing heating power and time of exposure. In GLC analysis,
the percentage of linoleic acid tended to decrease, whereas the percentage of palmitic, stearic
and oleic acids increased. The C18:2/C16:0 ratio decreased in all oil samples with increasing
heating times. Exposing the corn oil to various microwave power settings and heating periods
caused the formation of hydroperoxides and secondary oxidation products. The heating reduced
the various tocopherol isomers in corn oil and highest reduction was detected in γ-tocopherol.
Longer microwave heating times resulted in a greater degree of oil deterioration. Microwave
heating caused the formation of comparatively lower amounts of some degradative products in
the oil samples heated at low-power setting compared to medium-power setting. The present
analysis indicated that oil quality was affected by both microwave power and heating time.

Matched MeSH terms: Hydrogen Peroxide
Flavonoids of Piper sarmentosum and its cytoprotective effects against oxidative stress

Ugusman A, Zakaria Z, Hui CK, Nordin NA, Mahdy ZA

EXCLI J, 2012;11:705-714.
PMID: 27847456

Abnormalities in endothelial cell structure and function may lead to diseases such as thrombosis and atherosclerosis. Oxidative stress plays an important role in the pathogenesis of various cardiovascular diseases including atherosclerosis. Previous studies have shown a relationship between a diet rich in flavonoid and a reduced incidence of cardiovascular diseases. Piper sarmentosum (PS) is a plant with high flavonoid content and it possesses antioxidant and anti-atherosclerotic activities. Therefore this study aimed to investigate the flavonoids present in aqueous extract of PS (AEPS) and its cytoprotective effects in oxidative stress-induced human umbilical vein endothelial cells (HUVEC). AEPS contained high total phenolic content (91.02 ± 0.02 mg QE/g DM) and total flavonoid content (48.57 ± 0.03 mg GAE/g DM). Screening using high performance liquid chromatography (HPLC) technique showed the presence of rutin and vitexin as the main flavonoids in AEPS. HUVEC were exposed to 180 µM H2O2 and treated with various concentrations of rutin or vitexin (10 to 400 µM) for 24 hours. Both rutin and vitexin at the concentration of 150-400 µM significantly increased the viability of H2O2-induced HUVEC as denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Therefore rutin and vitexin as the main flavonoids present in PS may be involved in the protective effects of PS against oxidative stress.

Matched MeSH terms: Hydrogen Peroxide

Filters

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

External Links