Displaying publications 1 - 20 of 354 in total

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  1. Emerging supramolecular synthons: C-H···π(chelate) interactions in metal bis(1,1-dithiolates)
    Tiekink ER, Zukerman-Schpector J
    Chem Commun (Camb), 2011 Jun 21;47(23):6623-5.
    PMID: 21455512 DOI: 10.1039/c1cc11173f
    Crystal structures of transition and main group element 1,1-dithiolates are shown to be partially sustained by C-H···π(chelate) interactions. For the planar binary bisdithiocarbamates, C-H···π(MS(2)C) interactions lead to aggregation patterns ranging from a 0-D four molecule aggregate to a 3-D architecture but with the majority of structures featuring 1-D or 2-D supramolecular assemblies.
    Matched MeSH terms: Models, Molecular
  2. Fulltext Investigation of α-Glucosidase Inhibitory Metabolites from Tetracera scandens Leaves by GC-MS Metabolite Profiling and Docking Studies
    Nokhala A, Siddiqui MJ, Ahmed QU, Ahamad Bustamam MS, Zakaria AZA
    Biomolecules, 2020 02 12;10(2).
    PMID: 32059529 DOI: 10.3390/biom10020287
    Stone leaf (Tetracera scandens) is a Southeast Asian medicinal plant that has been traditionally used for the management of diabetes mellitus. The underlying mechanisms of the antidiabetic activity have not been fully explored yet. Hence, this study aimed to evaluate the α-glucosidase inhibitory potential of the hydromethanolic extracts of T. scandens leaves and to characterize the metabolites responsible for such activity through gas chromatography-mass spectrometry (GC-MS) metabolomics. Crude hydromethanolic extracts of different strengths were prepared and in vitro assayed for α-glucosidase inhibition. GC-MS analysis was further carried out and the mass spectral data were correlated to the corresponding α-glucosidase inhibitory IC50 values via an orthogonal partial least squares (OPLS) model. The 100%, 80%, 60% and 40% methanol extracts displayed potent α-glucosidase inhibitory potentials. Moreover, the established model identified 16 metabolites to be responsible for the α-glucosidase inhibitory activity of T. scandens. The putative α-glucosidase inhibitory metabolites showed moderate to high affinities (binding energies of -5.9 to -9.8 kcal/mol) upon docking into the active site of Saccharomyces cerevisiae isomaltase. To sum up, an OPLS model was developed as a rapid method to characterize the α-glucosidase inhibitory metabolites existing in the hydromethanolic extracts of T. scandens leaves based on GC-MS metabolite profiling.
    Matched MeSH terms: Models, Molecular
  3. Fulltext Functional characterization of sesquiterpene synthase from Polygonum minus
    Ee SF, Mohamed-Hussein ZA, Othman R, Shaharuddin NA, Ismail I, Zainal Z
    ScientificWorldJournal, 2014;2014:840592.
    PMID: 24678279 DOI: 10.1155/2014/840592
    Polygonum minus is an aromatic plant, which contains high abundance of terpenoids, especially the sesquiterpenes C15H24. Sesquiterpenes were believed to contribute to the many useful biological properties in plants. This study aimed to functionally characterize a full length sesquiterpene synthase gene from P. minus. P. minus sesquiterpene synthase (PmSTS) has a complete open reading frame (ORF) of 1689 base pairs encoding a 562 amino acid protein. Similar to other sesquiterpene synthases, PmSTS has two large domains: the N-terminal domain and the C-terminal metal-binding domain. It also consists of three conserved motifs: the DDXXD, NSE/DTE, and RXR. A three-dimensional protein model for PmSTS built clearly distinguished the two main domains, where conserved motifs were highlighted. We also constructed a phylogenetic tree, which showed that PmSTS belongs to the angiosperm sesquiterpene synthase subfamily Tps-a. To examine the function of PmSTS, we expressed this gene in Arabidopsis thaliana. Two transgenic lines, designated as OE3 and OE7, were further characterized, both molecularly and functionally. The transgenic plants demonstrated smaller basal rosette leaves, shorter and fewer flowering stems, and fewer seeds compared to wild type plants. Gas chromatography-mass spectrometry analysis of the transgenic plants showed that PmSTS was responsible for the production of β -sesquiphellandrene.
    Matched MeSH terms: Models, Molecular
  4. Fulltext Development of drug delivery systems based on layered hydroxides for nanomedicine
    Barahuie F, Hussein MZ, Fakurazi S, Zainal Z
    Int J Mol Sci, 2014;15(5):7750-86.
    PMID: 24802876 DOI: 10.3390/ijms15057750
    Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.
    Matched MeSH terms: Models, Molecular
  5. Synthesis and antimicrobial properties of some new thiazolyl coumarin derivatives
    Arshad A, Osman H, Bagley MC, Lam CK, Mohamad S, Zahariluddin AS
    Eur J Med Chem, 2011 Sep;46(9):3788-94.
    PMID: 21712145 DOI: 10.1016/j.ejmech.2011.05.044
    Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10a-d and 15a-h, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans. The compounds 10c, 10d and 15e exhibited very good activities against all of the tested microbial strains.
    Matched MeSH terms: Models, Molecular
  6. Fulltext FKBP22 from the psychrophilic bacterium Shewanella sp. SIB1 selectively binds to the reduced state of insulin to prevent its aggregation
    Budiman C, Goh CKW, Arief II, Yusuf M
    Cell Stress Chaperones, 2021 Mar;26(2):377-386.
    PMID: 33247372 DOI: 10.1007/s12192-020-01183-0
    FKBP22 of a psychrophilic bacterium, Shewanella sp. SIB1 (SIB1 FKBP22), is a member of peptidyl-prolyl cis-trans isomerase (PPIase) and consists of N- and C-domains responsible for chaperone-like and PPIase catalytic activities, respectively. The chaperone-like activity of SIB1 FKBP22 was previously evidenced by its ability to prevent dithiothreitol (DTT)-induced insulin aggregation. Nevertheless, the mechanism by which this protein inhibits the aggregation remains unclear. To address this, the binding affinity of SIB1 FKBP22 to the native or reduced states of insulin was examined using surface plasmon resonance (SPR). The native and reduced states refer to insulin in the absence or DTT presence, respectively. The SPR sensorgram showed that SIB1 FKBP22 binds specifically to the reduced state of insulin, with a KD value of 37.31 ± 3.20 μM. This binding was facilitated by the N-domain, as indicated by the comparable KD values of the N-domain and SIB1 FKBP22. Meanwhile, the reduced state of insulin was found to have no affinity towards the C-domain. The KD value of SIB1 FKBP22 was slightly decreased by NaCl but was not severely affected by FK506, a specific FKBP inhibitor. Similarly, the prevention of DTT-induced aggregation by SIB1 FKBP22 was also modulated by the N-domain and was not affected by FK506. Further, the reduced and native states of insulin had no effect on the catalytic efficiency (kcat/KM) of SIB1 FKBP22 towards a peptide substrate. Nevertheless, the reduced state of insulin slightly reduced the catalytic efficiency towards refolding RNase T1, at up to 1.5-fold lower than in the absence of insulin. These results suggested that the binding event was mainly facilitated by hydrophobic interaction and was independent from its PPIase activity. Altogether, a possible mechanism by which SIB1 FKBP22 prevents DTT-induced insulin aggregation was proposed.
    Matched MeSH terms: Models, Molecular
  7. Fulltext Preparation and characterization of an anti-inflammatory agent based on a zinc-layered hydroxide-salicylate nanohybrid and its effect on viability of Vero-3 cells
    Ramli M, Hussein MZ, Yusoff K
    Int J Nanomedicine, 2013;8:297-306.
    PMID: 23345976 DOI: 10.2147/IJN.S38858
    A new organic-inorganic nanohybrid based on zinc-layered hydroxide intercalated with an anti-inflammatory agent was synthesized through direct reaction of salicylic acid at various concentrations with commercially available zinc oxide. The basal spacing of the pure phase nanohybrid was 15.73 Å, with the salicylate anions arranged in a monolayer form and an angle of 57 degrees between the zinc-layered hydroxide interlayers. Fourier transform infrared study further confirmed intercalation of salicylate into the interlayers of zinc-layered hydroxide. The loading of salicylate in the nanohybrid was estimated to be around 29.66%, and the nanohybrid exhibited the properties of a mesoporous-type material, with greatly enhanced thermal stability of the salicylate compared with its free counterpart. In vitro cytotoxicity assay revealed that free salicylic acid, pure zinc oxide, and the nanohybrid have a mild effect on viability of African green monkey kidney (Vero-3) cells.
    Matched MeSH terms: Models, Molecular
  8. Investigation of Melting Dynamics of Hafnium Clusters
    Ng WC, Lim TL, Yoon TL
    J Chem Inf Model, 2017 03 27;57(3):517-528.
    PMID: 28178783 DOI: 10.1021/acs.jcim.6b00553
    Melting dynamics of hafnium clusters are investigated using a novel approach based on the idea of the chemical similarity index. Ground state configurations of small hafnium clusters are first derived using Basin-Hopping and Genetic Algorithm in the parallel tempering mode, employing the COMB potential in the energy calculator. These assumed ground state structures are verified by using the Low Lying Structures (LLS) method. The melting process is carried out either by using the direct heating method or prolonged simulated annealing. The melting point is identified by a caloric curve. However, it is found that the global similarity index is much more superior in locating premelting and total melting points of hafnium clusters.
    Matched MeSH terms: Models, Molecular*
  9. Designing hypothesis of substituted benzoxazinones as HIV-1 reverse transcriptase inhibitors: QSAR approach
    Veerasamy R, Subramaniam DK, Chean OC, Ying NM
    J Enzyme Inhib Med Chem, 2012 Oct;27(5):693-707.
    PMID: 21961709 DOI: 10.3109/14756366.2011.608664
    A linear quantitative structure activity relationship (QSAR) model is presented for predicting human immunodeficiency virus-1 (HIV-1) reverse transcriptase enzyme inhibition. The 2D QSAR and 3D-QSAR models were developed by stepwise multiple linear regression, partial least square (PLS) regression and k-nearest neighbor-molecular field analysis, PLS regression, respectively using a database consisting of 33 recently discovered benzoxazinones. The primary findings of this study is that the number of hydrogen atoms, number of (-NH2) group connected with solitary single bond alters the inhibition of HIV-1 reverse transcriptase. Further, presence of electrostatic, hydrophobic and steric field descriptors significantly affects the ability of benzoxazinone derivatives to inhibit HIV-1 reverse transcriptase. The selected descriptors could serve as a primer for the design of novel and potent antagonists of HIV-1 reverse transcriptase.
    Matched MeSH terms: Models, Molecular
  10. Fulltext Novel variants in NUDT15 and thiopurine intolerance in children with acute lymphoblastic leukemia from diverse ancestry
    Moriyama T, Yang YL, Nishii R, Ariffin H, Liu C, Lin TN, et al.
    Blood, 2017 Sep 07;130(10):1209-1212.
    PMID: 28659275 DOI: 10.1182/blood-2017-05-782383
    Prolonged exposure to thiopurines (eg, mercaptopurine [MP]) is essential for curative therapy in acute lymphoblastic leukemia (ALL), but is also associated with frequent dose-limiting hematopoietic toxicities, which is partly explained by inherited genetic polymorphisms in drug metabolizing enzymes (eg, TPMT). Recently, our group and others identified germ line genetic variants in NUDT15 as another major cause of thiopurine-related myelosuppression, particularly in Asian and Hispanic people. In this article, we describe 3 novel NUDT15 coding variants (p.R34T, p.K35E, and p.G17_V18del) in 5 children with ALL enrolled in frontline protocols in Singapore, Taiwan, and at St. Jude Children's Research Hospital. Patients carrying these variants experienced significant toxicity and reduced tolerance to MP across treatment protocols. Functionally, all 3 variants led to partial to complete loss of NUDT15 nucleotide diphosphatase activity and negatively influenced protein stability. In particular, the p.G17_V18del variant protein showed extremely low thermostability and was completely void of catalytic activity, thus likely to confer a high risk of thiopurine intolerance. This in-frame deletion was only seen in African and European patients, and is the first NUDT15 risk variant identified in non-Asian, non-Hispanic populations. In conclusion, we discovered 3 novel loss-of-function variants in NUDT15 associated with MP toxicity, enabling more comprehensive pharmacogenetics-based thiopurine dose adjustments across diverse populations.
    Matched MeSH terms: Models, Molecular
  11. Synthesis, X-ray, NMR, FT-IR, UV/vis, DFT and TD-DFT studies of N-(4-chlorobutanoyl)-N'-(2-, 3- and 4-methylphenyl)thiourea derivatives
    Abosadiya HM, Anouar el H, Hasbullah SA, Yamin BM
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Jun 5;144:115-24.
    PMID: 25748989 DOI: 10.1016/j.saa.2015.01.092
    A new isomers of thiourea derivatives, namely N-(4-chlorobutanoyl)-N'-(2-methylphenyl)-thiourea (1a), N-(4-chlorobutanoyl)-N'-(3-methylphenyl)thiourea (1b) and N-(4-chlorobutanoyl)-N'-(4-methylphenyl)thiourea (1c) have been synthesized by refluxing mixture of equimolar amounts of 4-chlorobutanoylisothiocyanate with 2, 3 or 4-toluidine, respectively. The three isomers were characterized by spectroscopic (UV/vis, FT-IR and NMR) and X-ray crystallography techniques. To investigate the isomerization effect on spectroscopic data, DFT and TD-DFT calculations have been carried out using five hybrid functionals (B3LYP, B3P86, CAM-B3LYP, M06-2X and PBE0) to predict UV/vis absorption bands (n→π∗ and π→π∗), (1)H and (13)C NMR chemical shifts, FT-IR vibration modes and X-ray parameters (bonds, bond angles and torsion angles) for 1a, 1b and 1c isomers. The results showed that the isomerization effect is significant on λ(MAX) absorption bands, while for IR and NMR the effect is negligible. In accordance with previous studies, B3LYP, B3P86 and PBE0 gave the most reliable to predict the excitation energies of thiourea derivatives.
    Matched MeSH terms: Models, Molecular*
  12. Synthesis, antibacterial activity and cytotoxicity of new fused pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c][1,2,4]triazine derivatives from new 5-aminopyrazoles
    Al-Adiwish WM, Tahir MI, Siti-Noor-Adnalizawati A, Hashim SF, Ibrahim N, Yaacob WA
    Eur J Med Chem, 2013 Jun;64:464-76.
    PMID: 23669354 DOI: 10.1016/j.ejmech.2013.04.029
    New 5-aminopyrazoles 2a-c were prepared in high yields from the reaction of known α,α-dicyanoketene-N,S-acetals 1a-c with hydrazine hydrate under reflux in ethanol. These compounds were utilized as intermediates to synthesize pyrazolo[1,5-a]-pyrimidines 3a-c, 4a-d, 5a-c, and 6a-c, as well as pyrazolo[5,1-c][1,2,4]triazines 7a-c and 8a-c, by the reaction of 2-[bis(methylthio)methylene]malononitrile, α,α-dicyanoketene-N,S-acetals 1a-b, acetylacetone, acetoacetanilide as well as acetylacetone, and malononitrile, respectively. Furthermore, cyclization of 2a-c with pentan-2,5-dione yielded the corresponding 5-pyrrolylpyrazoles 9a-c. Moreover, fusion of 2a-c with acetic anhydride resulted in the corresponding 1-acetyl-1H-pyrazoles 10a-c. The antibacterial activity and cytotoxicity against Vero cells of several selected compounds are also reported.
    Matched MeSH terms: Models, Molecular
  13. Ethyl (6aRS,8RS,12bRS)-6-oxo-8-phenyl-6a,7,8,12b-tetrahydro-6H-benzo[b]naphtho[1,2-d]pyran-6a-carboxylate
    Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Feb;58(Pt 2):o57-8.
    PMID: 11828107
    In the title compound, C(26)H(22)O(4), the pyranone ring adopts a twisted boat conformation, while the cyclohexane ring is close to an envelope conformation. The dihedral angle between the mean planes of the coumarin and naphthalene systems is 78.8(1) degree. The attached phenyl ring is in an equatorial position with respect to the cyclohexane ring.
    Matched MeSH terms: Models, Molecular
  14. 1,1'-diacetyl-3-hydroxy-2,2',3,3'-tetrahydro-3,3'-bi(1H-indole)-2,2'-dione
    Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Jan;58(Pt 1):o24-5.
    PMID: 11781485
    In the title compound, C20H16N2O5, both of the 1-acetylisatin (1-acetyl-1H-indole-2,3-dione) moieties are planar and form a dihedral angle of 74.1 (1) degrees. Weak intermolecular hydrogen bonds and C-H...pi interactions stabilize the packing in the crystal.
    Matched MeSH terms: Models, Molecular
  15. Fulltext Cinnamomum cassia Suppresses Caspase-9 through Stimulation of AKT1 in MCF-7 Cells but Not in MDA-MB-231 Cells
    Rad SK, Kanthimathi MS, Abd Malek SN, Lee GS, Looi CY, Wong WF
    PLoS One, 2015;10(12):e0145216.
    PMID: 26700476 DOI: 10.1371/journal.pone.0145216
    BACKGROUND: Cinnamomum cassia bark is a popular culinary spice used for flavoring and in traditional medicine. C. cassia extract (CE) induces apoptosis in many cell lines. In the present study, particular differences in the mechanism of the anti-proliferative property of C. cassia on two breast cancer cell lines, MCF-7 and MDA-MB-231, were elucidated.

    METHODOLOGY/PRINCIPAL FINDINGS: The hexane extract of C. cassia demonstrated high anti-proliferative activity against MCF-7 and MDA-MB-231 cells (IC50, 34 ± 3.52 and 32.42 ± 0.37 μg/ml, respectively). Oxidative stress due to disruption of antioxidant enzyme (SOD, GPx and CAT) activity is suggested as the probable cause for apoptosis initiation. Though the main apoptosis pathway in both cell lines was found to be through caspase-8 activation, caspase-9 was also activated in MDA-MB-231 cells but suppressed in MCF-7 cells. Gene expression studies revealed that AKT1, the caspase-9 suppressor, was up-regulated in MCF-7 cells while down-regulated in MDA-MB-231 cells. Although, AKT1 protein expression in both cell lines was down-regulated, a steady increase in MCF-7 cells was observed after a sharp decrease of suppression of AKT1. Trans-cinnamaldehyde and coumarin were isolated and identified and found to be mainly responsible for the observed anti-proliferative activity of CE (Cinnamomum cassia).

    CONCLUSION: Activation of caspase-8 is reported for the first time to be involved as the main apoptosis pathway in breast cancer cell lines upon treatment with C. cassia. The double effects of C. cassia on AKT1 gene expression in MCF-7 cells is reported for the first time in this study.

    Matched MeSH terms: Models, Molecular
  16. Fulltext The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus
    Ishak IH, Riveron JM, Ibrahim SS, Stott R, Longbottom J, Irving H, et al.
    Sci Rep, 2016 Apr 20;6:24707.
    PMID: 27094778 DOI: 10.1038/srep24707
    Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.
    Matched MeSH terms: Models, Molecular
  17. Computational evaluation of unsaturated carbonitriles as neutral receptor model for beryllium(II) recognition
    Rosli AN, Ahmad MR, Alias Y, Zain SM, Lee VS, Woi PM
    J Mol Model, 2014 Dec;20(12):2533.
    PMID: 25433601 DOI: 10.1007/s00894-014-2533-9
    Design of neutral receptor molecules (ionophores) for beryllium(II) using unsaturated carbonitrile models has been carried out via density functional theory, G3, and G4 calculations. The first part of this work focuses on gas phase binding energies between beryllium(II) and 2-cyano butadiene (2-CN BD), 3-cyano propene (3-CN P), and simpler models with two separate fragments; acrylonitrile and ethylene. Interactions between beryllium(II) and cyano nitrogen and terminal olefin in the models have been examined in terms of geometrical changes, distribution of charge over the entire π-system, and rehybridization of vinyl carbon orbitals. NMR shieldings and vibrational frequencies probed charge centers and strength of interactions. The six-membered cyclic complexes have planar structures with the rehybridized carbon slightly out of plane (16° in 2-CN BD). G3 results show that in 2-CN BD complex participation of vinyl carbon further stabilizes the cyclic adduct by 16.3 kcal mol(-1), whereas, in simpler models, interaction between beryllium(II) and acetonitrile is favorable by 46.4 kcal mol(-1) compared with that of ethylene. The terminal vinyl carbon in 2-CN BD rehybridizes to sp (3) with an increase of 7 % of s character to allow interaction with beryllium(II). G4 calculations show that the Be(II) and 2-CN BD complex is more strongly bound than those with Mg(II) and Ca(II) by 98.5 and 139.2 kcal mol(-1) (-1), respectively. QST2 method shows that the cyclic and acyclic forms of Be(II)-2-CN BD complexes are separated by 12.3 kcal mol(-1) barrier height. Overlap population analysis reveals that Ca(II) can be discriminated based on its tendency to form ionic interaction with the receptor models.
    Matched MeSH terms: Models, Molecular*
  18. Cytotoxic Aporphines from Artabotrys crassifolius
    Kwan TK, Shipton F, Azman NS, Hossan S, Jin KT, Wiart C
    Nat Prod Commun, 2016 Mar;11(3):389-92.
    PMID: 27169188
    Artabotrys crassifolius Hook. f. & Thomson is a medicinal plant used in Malaysia. The cytotoxic effects of the hexane, chloroform and ethanol extracts of the leaves and bark were examined in vitro against MCF-7, MDA-468 and HCT-116 cells. The chloroform extract of the bark inhibited the growth of all cell lines with GI₅₀ values ranging from 4.2 µg/mL to 9.4 µg/mL. Silica gel column chromatography of this extract yielded artabotrine, liridine, atherospermidine and lysicamine. Artabotrine and lysicamine inhibited the growth of HCT-116 and MCF-7 cells with GI₅₀ values ranging from 3.3 µM to 3.9 µM. These alkaloids were not toxic to human embryonic kidney cells (HEK297) up to a concentration of 50 µg/mL.
    Matched MeSH terms: Models, Molecular
  19. 2beta-Hydroxy-4'-demethyldesoxy-podophyllotoxin
    Du Boulay D, Shaari K, Skelton BW, Waterman PG, White AH
    Acta Crystallogr C, 2000 Feb;56 ( Pt 2):199-200.
    PMID: 10777886
    Matched MeSH terms: Models, Molecular
  20. Fulltext Antioxidant activity of hispidin oligomers from medicinal fungi: a DFT study
    El Hassane A, Shah SA, Hassan NB, El Moussaoui N, Ahmad R, Zulkefeli M, et al.
    Molecules, 2014;19(3):3489-507.
    PMID: 24662069 DOI: 10.3390/molecules19033489
    Hispidin oligomers are styrylpyrone pigments isolated from the medicinal fungi Inonotus xeranticus and Phellinus linteus. They exhibit diverse biological activities and strong free radical scavenging activity. To rationalize the antioxidant activity of a series of four hispidin oligomers and determine the favored mechanism involved in free radical scavenging, DFT calculations were carried out at the B3P86/6-31+G (d, p) level of theory in gas and solvent. The results showed that bond dissociation enthalpies of OH groups of hispidin oligomers (ArOH) and spin density delocalization of related radicals (ArO•) are the appropriate parameters to clarify the differences between the observed antioxidant activities for the four oligomers. The effect of the number of hydroxyl groups and presence of a catechol moiety conjugated to a double bond on the antioxidant activity were determined. Thermodynamic and kinetic studies showed that the PC-ET mechanism is the main mechanism involved in free radical scavenging. The spin density distribution over phenoxyl radicals allows a better understanding of the hispidin oligomers formation.
    Matched MeSH terms: Models, Molecular
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