Displaying publications 1 - 20 of 34 in total

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  1. Asari MA, Abdullah MS, Abdullah S
    Malays J Med Sci, 2008 Jul;15(3):14-21.
    PMID: 22570585 MyJurnal
    Deltamethrin is a widely used insecticide belonging to the class of pyrethroid. Although the neurotoxicity of pyrethroids including deltamethrin is well established, it is still unclear whether exposure to deltamethrin during neonatal period has any deleterious effect on the survival of the Purkinje cells in the cerebellum. In the study, we investigated the total number of Purkinje cells in experimental rats exposed to deltamethrin using a stereological method, the fractionator. Deltamethrin in a dose of 1 mg/kg/day (corresponds to 20% of LD(50) ) was administered through oral gavage to male pups from 2(nd) to 5(th) postnatal day (PND). At PND 21 the animals were sacrificed and their cerebelli were removed. The cerebelli were systematically sampled using the fractionator method and stained with cresyl fast violet. The number of the Purkinje cells was counted for each cerebellum. The results showed that there was no significant difference in the total number of Purkinje cells in the deltamethrin-treated group as compared to the control animals. This suggests that deltamethrin exposure at the current dosage during the neonatal period do not have any significant effect on the survival of the Purkinje cells in the cerebellum.
    Matched MeSH terms: Oxazines
  2. Chuah, Y.J., Tan, Y.P., Abdullah, H.A.
    MyJurnal
    The crab carapace is a waste which cannot be decomposed. This waste was used to
    remove the Reactive Orange 16 (RO16) and Basic Blue 3 (BB3) from aqueous solution
    at different operational parameters such as pH, mass load, the concentrations of dye and
    the temperature. The crab collected was modified to obtain quaternized crab (QC) using
    (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution (C6H15Cl2NO, 65% w/w
    in water). The pH of the dyes solution was varied from pH 4 to 10. The highest adsorption
    percentage was achieved at pH 7 for both dyes. Increasing the QC mass for the adsorption
    process had granted an increase of dyes removal percentage. The highest adsorption
    percentage was achieved at 91.00% for RO16 and 29.40% for BB3 dyes with 7.5 g/L QC
    used. However, the adsorption capacity of QC decreased with higher QC mass because the
    dye molecules occupied on the surface and prevented other molecules to diffuse into the
    QC. At higher concentration beyond 20 mg/L and 10 mg/L of RO16 and BB3, respectively,
    the maximum adsorption was achieved at 2.5362 mg/g and 0.6812 mg/g. The adsorption of
    both dyes by QC was best fitted using Langmuir isotherm model, explaining the adsorption
    mainly occurred as a single layer on the surface of QC. Comparison to the results obtained
    from the kinetic models, the adsorption was
    chemisorption in nature. According to the
    thermodynamic studies, the adsorption of
    RO16 was an exothermic, while BB3 was
    an endorthermic process.
    Matched MeSH terms: Oxazines
  3. Nurita AT, Abu Hassan A
    Trop Biomed, 2010 Dec;27(3):559-65.
    PMID: 21399598 MyJurnal
    Two performance (efficacy and attractiveness) comparisons of neonicotinoid baits QuickBayt® (imidacloprid) and Agita® (thiamethoxam) against filth flies were conducted under field conditions to determine suitability for use outdoors. The first experiment compared bait performance and the second compared effects of different applications on QuickBayt® performance. Applications compared were: (i) scattered in petri dish (SPD); (ii) wet-down in petri dish (WPD); (iii) scattered on cardboard (SCB) and (iv) painted on cardboards (PCB). Efficacy and attractiveness were assessed based on knockdown percentage (KD%) and number of flies feeding on baits, respectively. The KD% of QuickBayt® (34% ± 3.0%) was not significantly higher than Agita® (29% ± 1.3%) (t-test, P>0.05). Agita® (101 ± 5.7 flies) was significantly more attractive to flies than QuickBayt® (76 ± 4.8 flies) and the sugar solution (49 ± 7.2) (one-way ANOVA, P<0.05). The PCB and SCB applications were significantly more attractive to filth flies than WPD and SPD (One-way ANOVA, P<0.05), however differences in KD% were not significantly different (One-way ANOVA, P>0.05). The two baits provided the same level of efficacy in a wide-open area against filth flies of various species. QuickBayt® was more versatile; efficacy was not significantly affected by different applications. Surface area and moisture affects attractiveness of the bait.
    Matched MeSH terms: Oxazines/pharmacology*; Oxazines/chemistry
  4. 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: Oxazines
  5. Far FE, Al-Obaidi MMJ, Desa MNM
    J Mycol Med, 2018 Sep;28(3):486-491.
    PMID: 29753721 DOI: 10.1016/j.mycmed.2018.04.007
    BACKGROUND: Malassezia furfur is lipodependent yeast like fungus that causes superficial mycoses such as pityriasis versicolor and dandruff. Nevertheless, there are no standard reference methods to perform susceptibility test of Malassezia species yet.

    AIMS: Therefore, in this study, we evaluated the optimized culture medium for growth of this lipophilic yeast using modified leeming-Notman agar and colorimetric resazurin microtiter assay to assess antimycotic activity of fluconazole against M. furfur.

    RESULTS: The result showed that these assays were more adjustable for M. furfur with reliable and reproducible MIC end-point, by confirming antimycotic activity of fluconazole with MIC of 2μg/ml.

    CONCLUSION: We conclude that this method is considered as the rapid and effective susceptibility testing of M. furfur with fluconazole antifungal activity.

    Matched MeSH terms: Oxazines/chemistry*
  6. Barakat A, Al-Najjar HJ, Al-Majid AM, Soliman SM, Mabkhot YN, Shaik MR, et al.
    PMID: 25827772 DOI: 10.1016/j.saa.2015.03.016
    The synthesis and spectral characterization of the 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione;3 was reported. The solid state molecular structure of 3 was studied using X-ray crystallography. The relative stabilities of the seven possible isomers of 3 were calculated by DFT/B3LYP method using 6-311 G(d,p) basis set. The calculated total energies and thermodynamic parameters were used to predict the relative stabilities of these isomers. The effect of solvent polarity on the relative stability of these isomers was studied at the same level of theory using PCM. It was found that the keto form, (T0), is the most stable isomer both in the gaseous state and solution. In solution, the calculated total energies of all isomers are decreased indicating that all isomers are stabilized by the solvent effect. The vibrational spectra of the most stable isomer, 3(T0) are calculated using the same level of theory and the results are compared with the experimentally measured FTIR spectra. Good correlation was obtained between the experimental and calculated vibrational frequencies (R(2)=0.9992). The electronic spectra of 3(T0) in gas phase as well as in solutions were calculated using the TD-DFT method. All the predicted electronic transitions showed very little spectral shifts and increase in the intensity of absorption due to solvent effect. Also the (1)H- and (13)C-NMR chemical shifts of the stable isomer were calculated and the results were correlated with the experimental data. Good correlations between the experimental and calculated chemical shifts were obtained.
    Matched MeSH terms: Oxazines
  7. Karim MR, Zakaria Z, Hassan L, Ahmad NI, Faiz NM, Garba B
    J Glob Antimicrob Resist, 2021 09;26:154-156.
    PMID: 34118481 DOI: 10.1016/j.jgar.2021.05.012
    Matched MeSH terms: Oxazines
  8. Teo CL, Atta M, Bukhari A, Taisir M, Yusuf AM, Idris A
    Bioresour Technol, 2014 Jun;162:38-44.
    PMID: 24736210 DOI: 10.1016/j.biortech.2014.03.113
    Wavelength of light is a crucial factor which renders microalgae as the potential biodiesel. In this study, Tetraselmis sp. and Nannochloropsis sp. as famous targets were selected. The effect of different light wavelengths on growth rate and lipid production was studied. Microalgae were cultivated for 14 days as under blue, red, red-blue LED and white fluorescent light. The growth rate of microalgae was analyzed by spectrophotometer and cell counting while oil production under improved Nile red method. Optical density result showed the microalgae exhibited better growth curve under blue wavelength. Besides, Tetraselmis sp. and Nannochloropsis sp. under blue wavelength showed the higher growth rate (1.47 and 1.64 day(-1)) and oil production (102.954 and 702.366 a.u.). Gas chromatography analysis also showed that palmitic acid and stearic acid which were compulsory components for biodiesel contribute around 49-51% of total FAME from Nannochloropsis sp. and 81-83% of total FAME from Tetraselmis sp.
    Matched MeSH terms: Oxazines/metabolism
  9. Omotoso GO, Olajide OJ, Gbadamosi IT, Rasheed MA, Izuogu CT
    Malays J Med Sci, 2018 Mar;25(2):50-63.
    PMID: 30918455 DOI: 10.21315/mjms2018.25.2.6
    Background: This study explored the efficacy of kolaviron-a biflavonoid complex isolated from the seeds of Garcinia kola-in protecting against cuprizone (CPZ)-induced demyelination in both the prefrontal cortex and the hippocampus of Wistar rats.

    Methodology: Thirty rats were treated to receive 0.5 mL phosphate-buffered saline (group A, control), 0.5 mL corn oil (group B), 0.2% CPZ (group C), for 6 weeks, 0.2% CPZ for 3 weeks and then 200 mg/kg of Kv for 3 weeks (group D), or 200 mg/kg of Kv for 3 weeks followed by 0.2% CPZ for 3 weeks (group E). Rats were assessed for exploratory functions and anxiety-like behaviour before being euthanised and perfused transcardially with 4% paraformaldehyde. Prefrontal and hippocampal thin sections were stained in hematoxylin and eosin and cresyl fast violet stains.

    Results: CPZ-induced demyelination resulted in behavioural impairment as seen by reduced exploratory activities, rearing behaviour, stretch attend posture, center square entry, and anxiogenic characteristics. Degenerative changes including pyknosis, karyorrhexis, neuronal hypertrophy, and reduced Nissl integrity were also seen. Animals treated with Kv showed significant improvement in behavioural outcomes and a comparatively normal cytoarchitectural profile.

    Conclusion: Kv provides protective roles against CPZ-induced neurotoxicity through prevention of ribosomal protein degradation.

    Matched MeSH terms: Oxazines
  10. Ibrahim S, Sabudin S, Sahid S, Marzuke MA, Hussin ZH, Kader Bashah NS, et al.
    Saudi J Biol Sci, 2016 Jan;23(1):S56-63.
    PMID: 26858566 DOI: 10.1016/j.sjbs.2015.10.024
    Surface reactivity of bioactive ceramics contributes in accelerating bone healing by anchoring osteoblast cells and the connection of the surrounding bone tissues. The presence of silicon (Si) in many biocompatible and bioactive materials has been shown to improve osteoblast cell adhesion, proliferation and bone regeneration due to its role in the mineralisation process around implants. In this study, the effects of Si-biphasic calcium phosphate (Si-BCP) on bioactivity and adhesion of human osteoblast (hFOB) as an in vitro model have been investigated. Si-BCP was synthesised using calcium hydroxide (Ca(OH)2) and phosphoric acid (H3PO4) via wet synthesis technique at Ca/P ratio 1.60 of material precursors. SiO2 at 3 wt% based on total precursors was added into apatite slurry before proceeding with the spray drying process. Apatite powder derived from the spray drying process was pressed into discs with Ø 10 mm. Finally, the discs were sintered at atmospheric condition to obtain biphasic hydroxyapatite (HA) and tricalcium phosphate (TCP) peaks simultaneously and examined by XRD, AFM and SEM for its bioactivity evaluation. In vitro cell viability of L929 fibroblast and adhesion of hFOB cell were investigated via AlamarBlue® (AB) assay and SEM respectively. All results were compared with BCP without Si substitution. Results showed that the presence of Si affected the material's surface and morphology, cell proliferation and cell adhesion. AFM and SEM of Si-BCP revealed a rougher surface compared to BCP. Bioactivity in simulated body fluid (SBF) was characterised by pH, weight gain and apatite mineralisation on the sample surface whereby the changes in surface morphology were evaluated using SEM. Immersion in SBF up to 21 days indicated significant changes in pH, weight gain and apatite formation. Cell viability has demonstrated no cytotoxic effect and denoted that Si-BCP promoted good initial cell adhesion and proliferation. These results suggest that Si-BCP's surface roughness (164 nm) was significantly higher than BCP (88 nm), thus enhancing the adhesion and proliferation of the osteoblast.
    Matched MeSH terms: Oxazines
  11. Berahim Z, Moharamzadeh K, Rawlinson A, Jowett AK
    J. Periodontol., 2011 May;82(5):790-7.
    PMID: 21080786 DOI: 10.1902/jop.2010.100533
    Cell-based therapy using autologous cells has been suggested as a potential approach for periodontal tissue regeneration. Spheroid systems are a form of three-dimensional cell culture that promotes cell matrix interaction, which could recapitulate the aspect of cell homeostasis in vivo. The aim of this study is to assess the interaction of periodontal fibroblast spheroids with synthetic and collagen-based membranes that have been used in guided tissue regeneration.
    Matched MeSH terms: Oxazines
  12. Chong KF, Lee CY
    J Econ Entomol, 2009 Aug;102(4):1586-90.
    PMID: 19736772
    An evaluation of several insecticides, namely, 0.01% fipronil, 0.05% indoxacarb, and 2% boric acid in liquid bait formulations were carried out against field populations of the longlegged ant, Anoplolepis gracilipes (Fr. Smith) (Hymenoptera: Formicidae). The baits were formulated in brown cane sugar solution (50%, wt:wt) and placed in an experimental bait station. Each bait was evaluated against populations of A. gracilipes at four buildings. Fipronil, indoxacarb, and boric acid were effective against A. gracilipes, with > 90% reduction of workers within 3 d posttreatment. Total reduction (100%) was achieved within 7 d for fipronil, 14 d for indoxacarb, and 56 d for boric acid. The performance of fipronil and indoxacarb baits did not differ significantly (P > 0.05) in all postbaiting sampling intervals. Reduction of A. gracilipes resulted in an increase in other ant species [Monomorium pharaonis (L.), Monomorium floricola (Jerdon), Monomorium orientale Mayr, Monomorium destructor (Jerdon), Tapinoma indicum Forel, Pheidole sp., and Camponotus sp.] at the baited locations.
    Matched MeSH terms: Oxazines
  13. Teh CH, Nazni WA, Nurulhusna AH, Norazah A, Lee HL
    BMC Microbiol, 2017 Feb 16;17(1):36.
    PMID: 28209130 DOI: 10.1186/s12866-017-0936-3
    BACKGROUND: Antimicrobial resistance is currently a major global issue. As the rate of emergence of antimicrobial resistance has superseded the rate of discovery and introduction of new effective drugs, the medical arsenal now is experiencing shortage of effective drugs to combat diseases, particularly against diseases caused by the dreadful multidrug-resistant strains, such as the methicillin-resistant Staphylococcus aureus (MRSA). The ability of fly larvae to thrive in septic habitats has prompted us to determine the antibacterial activity and minimum inhibitory concentrations (MICs) of larval extract of flies, namely Lucilia cuprina, Sarcophaga peregrina and Musca domestica against 4 pathogenic bacteria [Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa and Escherichia coli] via a simple and sensitive antibacterial assay, resazurin-based turbidometric (TB) assay as well as to demonstrate the preliminary chemical profile of larval extracts using gas chromatography-mass spectrophotometry (GC-MS).

    RESULTS: The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml(-1). Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica.

    CONCLUSION: The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.

    Matched MeSH terms: Oxazines/chemistry*
  14. Rajakumar MK, Ngeow YF, Khor BS, Lim KF
    Sex Transm Dis, 1988 1 1;15(1):25-6.
    PMID: 3162781
    Forty-three patients with uncomplicated gonorrhea were treated with 400 mg of ofloxacin. All had cultures negative for Neisseria gonorrhoeae at follow-up within two weeks of treatment. Minimal side effects were reported. Ofloxacin appears to be satisfactory as a single-dose oral drug for the treatment of gonococcal urethritis, including those cases caused by penicillinase-producing strains of N. gonorrhoeae.
    Matched MeSH terms: Oxazines/administration & dosage; Oxazines/therapeutic use*
  15. Mohd Zain N.S., Tajudin S.S., Mohd Noor S.N.F., Mohamad H.
    MyJurnal
    Thisstudy aim tocharacterize melt-derivedbioactive glass and to determinethe bioactive glass (BG) suitability for dental usagethrough proliferative activity assessment of stem cells from human exfoliated deciduous teeth (SHED)when exposed to bioactive glass conditioned medium. Bioglass 45S5 in mole percentages (46.13% SiO2, 26.91% CaO, 24.35% Na2O and 2.60% P2O5)was synthesizedthrough melt-derived and characterized usingX-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR)to confirm and identify its properties.SHEDwere used to evaluate the biocompatibility of 45S5 by exposing the cells to various concentration of BG-conditioned medium (1-10 mg/ml) using alamarBlue assay. The BG produced has an amorphous structureas shown by XRD analysis. TheSi-O-Si bending, asymmetric Si-O stretching and asymmetricSi-O-Si stretchingbands were observed in the BG structure supporting the presenceof silicate network. For alamarBlue assay, SHED cultured in BG-conditioned medium showed high proliferation rate when subjected to minimal powder content in the DMEM cell culture medium.Hence, it can be concluded that SHED cultured in lower powder content of the BG-conditioned media showedhigh proliferative activity suggesting the potential of the BG for dental usage.
    Matched MeSH terms: Oxazines
  16. Mohd Izham NZ, Yusoff HM, Ul Haq Bhat I, Endo T, Fukumura H, Kwon E, et al.
    Data Brief, 2020 Jun;30:105568.
    PMID: 32368595 DOI: 10.1016/j.dib.2020.105568
    The structural investigation of synthesized compounds can be carried out by various spectroscopic techniques. It is an important prospect in order to elucidate the structure of the desired products before being further utilized. The preparation of new p-nitro stilbene Schiff base derivatives as an electrochemical DNA potential spacer was synthesized using (E)-4-(4-nitrostyryl)aniline from Heck reaction with aldehydes in ethanolic solution. The data presented here in this article contains FTIR, UV-Vis and 1H and 13C NMR of (E)-4-(4-nitrostyryl)aniline and nitrostyryl aniline derivatives.
    Matched MeSH terms: Oxazines
  17. Musa M, Mohd Ali K, Kannan TP, Azlina A, Omar NS, Chatterji A, et al.
    Cell J, 2015;17(2):253-63.
    PMID: 26199904
    OBJECTIVE: Perivitelline fluid (PVF) of the horseshoe crab embryo has been reported to possess an important role during embryogenesis by promoting cell proliferation. This study aims to evaluate the effect of PVF on the proliferation, chromosome aberration (CA) and mutagenicity of the dental pulp stem cells (DPSCs).

    MATERIALS AND METHODS: This is an in vitro experimental study. PVF samples were collected from horseshoe crabs from beaches in Malaysia and the crude extract was prepared. DPSCs were treated with different concentrations of PVF crude extract in an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay (cytotoxicity test). We choose two inhibitory concentrations (IC50 and IC25) and two PVF concentrations which produced more cell viability compared to a negative control (100%) for further tests. Quantitative analysis of the proliferation activity of PVF was studied using the AlamarBlue®assay for 10 days. Population doubling times (PDTs) of the treatment groups were calculated from this assay. Genotoxicity was evaluated based on the CA and Ames tests. Statistical analysis was carried out using independent t test to calculate significant differences in the PDT and mitotic indices in the CA test between the treatment and negative control groups. Significant differences in the data were P<0.05.

    RESULTS: A total of four PVF concentrations retrieved from the MTT assay were 26.887 mg/ml (IC50), 14.093 mg/ml (IC25), 0.278 mg/ml (102% cell viability) and 0.019 mg/ml (102.5% cell viability). According to the AlamarBlue®assay, these PVF groups produced comparable proliferation activities compared to the negative (untreated) control. PDTs between PVF groups and the negative control were insignificantly different (P>0.05). No significant aberrations in chromosomes were observed in the PVF groups and the Ames test on the PVF showed the absence of significant positive results.

    CONCLUSION: PVF from horseshoe crabs produced insignificant proliferative activity on treated DPSCs. The PVF was non-genotoxic based on the CA and Ames tests.

    Matched MeSH terms: Oxazines
  18. Woon KL, Yi CL, Pan KC, Etherington MK, Wu CC, Wong KT, et al.
    J Phys Chem C Nanomater Interfaces, 2019 May 16;123(19):12400-12410.
    PMID: 32952765 DOI: 10.1021/acs.jpcc.9b01900
    Understanding the excited-state dynamics and conformational relaxation in thermally activated delayed fluorescence (TADF) molecules, including conformations that potentially support intramolecular through-space charge transfer, can open new avenues for TADF molecular design as well as elucidate complex photophysical pathways in structurally complex molecules. Emissive molecules comprising a donor (triphenylamine, TPA) and an acceptor (triphenyltriazine, TRZ) bridged by a second donor (9,9-dimethyl-9-10-dihydroacridin, DMAC, or phenoxazine, PXZ) are synthesized and characterized. In solution, the flexibility of the sp3-hybridized carbon atom in DMAC of DMAC-TPA-TRZ, compared to the rigid PXZ, allows significant conformational reorganization, giving rise to multiple charge-transfer excited states. As a result of such a reorganization, the TRZ and TPA moieties become cofacially aligned, driven by a strong dipole-dipole attraction between the TPA and TRZ units, forming a weakly charge-transfer dimer state, in stark contrast to the case of PXZ-TPA-TRZ where the rigid PXZ bridge only supports a single PXZ-TRZ charge transfer (CT) state. The low-energy TPA-TRZ dimer is found to have a high-energy dimer local triplet state, which quenches delayed emission because the resultant singlet CT local triplet energy gap is too large to mediate efficient reverse intersystem crossing. However, organic light-emitting diodes using PXZ-TPA-TRZ as an emitting dopant resulted in external quantum efficiency as high as 22%, more than two times higher than that of DMAC-TPA-TRZ-based device, showing the impact that such intramolecular reorganization and donor-acceptor dimerization have on TADF performance.
    Matched MeSH terms: Oxazines
  19. Schönrath I, Tsvetkov VB, Zatsepin TS, Aralov AV, Müller J
    J Biol Inorg Chem, 2019 08;24(5):693-702.
    PMID: 31263954 DOI: 10.1007/s00775-019-01682-1
    1,3-Diaza-2-oxophenoxazine (X) has been introduced as a ligand in silver(I)-mediated base pairing in a parallel DNA duplex. This fluorescent cytosine analog is capable of forming stabilizing X-Ag(I)-X and X-Ag(I)-C base pairs in DNA duplexes, as confirmed by temperature-dependent UV spectroscopy and luminescence spectroscopy. DFT calculations of the silver(I)-mediated base pairs suggest the presence of a synergistic hydrogen bond. Molecular dynamics (MD) simulations of entire DNA duplexes nicely underline the geometrical flexibility of these base pairs, with the synergistic hydrogen bond facing either the major or the minor groove. Upon silver(I) binding to the X:X or X:C base pairs, the luminescence emission maximum experiences a red shift from 448 to 460 nm upon excitation at 370 nm. Importantly, the luminescence of the 1,3-diaza-2-oxophenoxazine ligand is not quenched significantly upon binding a silver(I) ion. In fact, the luminescence intensity even increases upon formation of a X-Ag(I)-C base pair, which is expected to be beneficial for the development of biosensors. As a consequence, the silver(I)-mediated phenoxazinone base pairs represent the first strongly fluorescent metal-mediated base pairs.
    Matched MeSH terms: Oxazines/chemistry*
  20. Chaudhary S, Nair AB, Shah J, Gorain B, Jacob S, Shah H, et al.
    AAPS PharmSciTech, 2021 Apr 09;22(3):127.
    PMID: 33835317 DOI: 10.1208/s12249-021-01995-y
    Being a candidate of BCS class II, dolutegravir (DTG), a recently approved antiretroviral drug, possesses solubility issues. The current research was aimed to improve the solubility of the DTG and thereby enhance its efficacy using the solid dispersion technique. In due course, the miscibility study of the drug was performed with different polymers, where Poloxamer 407 (P407) was found suitable to move forward. The solid dispersion of DTG and P407 was formulated using solvent evaporation technique with a 1:1 proportion of drug and polymer, where the solid-state characterization was performed using differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray diffraction. No physicochemical interaction was found between the DTG and P407 in the fabricated solid dispersion; however, crystalline state of the drug was changed to amorphous as evident from the X-ray diffractogram. A rapid release of DTG was observed from the solid dispersion (>95%), which is highly significant (p<0.05) as compared to pure drug (11.40%), physical mixture (20.07%) and marketed preparation of DTG (35.30%). The drug release from the formulated solid dispersion followed Weibull model kinetics. Finally, the rapid drug release from the solid dispersion formulation revealed increased Cmax (14.56 μg/mL) when compared to the physical mixture (4.12 μg/mL) and pure drug (3.45 μg/mL). This was further reflected by improved bioavailability of DTG (AUC: 105.99±10.07 μg/h/mL) in the experimental Wistar rats when compared to the AUC of animals administered with physical mixture (54.45±6.58 μg/h/mL) and pure drug (49.27±6.16 μg/h/mL). Therefore, it could be concluded that the dissolution profile and simultaneously the bioavailability of DTG could be enhanced by means of the solid dispersion platform using the hydrophilic polymer, P407, which could be projected towards improved efficacy of the drug in HIV/AIDS.
    Matched MeSH terms: Oxazines/administration & dosage*; Oxazines/pharmacokinetics*; Oxazines/therapeutic use
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