Displaying publications 81 - 100 of 799 in total

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  1. Fulltext A novel cyclodione coumarin from the stem bark of Mesua beccariana
    Ee GC, Teh SS, Mah SH, Rahmani M, Taufiq-Yap YH, Awang K
    Molecules, 2011 Aug 25;16(9):7249-55.
    PMID: 21869752 DOI: 10.3390/molecules16097249
    Our ongoing investigations on the stem bark of Mesua beccariana afforded a novel cyclodione coumarin, beccamarin, together with two known xanthones, mesuarianone, mesuasinone, two anthraquinones, 4-methoxy-1,3,5-trihydroxy-anthraquinone and 2,5-dihydroxy-1,3,4-trimethoxyanthraquinone and one coumarin, mammea A/AB. The structures were elucidated by 1D and 2D NMR and MS techniques.
    Matched MeSH terms: Molecular Structure
  2. Fulltext Grandine A, a new proaporphine alkaloid from the bark of Phoebe grandis
    Mukhtar MR, Aziz AN, Thomas NF, Hadi AH, Litaudon M, Awang K
    Molecules, 2009;14(3):1227-33.
    PMID: 19325519 DOI: 10.3390/molecules14031227
    The stem bark of Phoebe grandis afforded one new oxoproaporphine; (-)-grandine A (1), along with six known isoquinoline alkaloids: (-)-8,9-dihydrolinearisine (2), boldine, norboldine, lauformine, scortechiniine A and scortechiniine B. In addition to that of the new compound, complete 1H- and 13C-NMR data of the tetrahydroproaporphine (-)-8,9-dihydrolinearisine (2) is also reported. The alkaloids' structures were elucidated primarily by means of high field 1D- and 2D-NMR and HRMS spectral data.
    Matched MeSH terms: Molecular Structure
  3. New proaporphines from the bark of Phoebe scortechinii
    Mukhtar MR, Hadi AH, Rondeau D, Richomme P, Litaudon M, Mustafa MR, et al.
    Nat Prod Res, 2008;22(11):921-6.
    PMID: 18629705 DOI: 10.1080/14786410701642821
    The phytochemical study of the bark of Malaysian Phoebe scortechinii (Lauraceae) has resulted in the isolation and identification of two new proaporphine alkaloids; (+)-scortechiniine A (1) and (+)-scortechiniine B (2) together with two known proaporphines; (-)-hexahydromecambrine A (3), (-)-norhexahydromecambrine A (4), and one aporphine; norboldine (5). Structural elucidations of these alkaloids were performed using spectroscopic methods especially 1D and 2D (1)H and (13)C NMR.
    Matched MeSH terms: Molecular Structure
  4. Venuloxanthone, a new pyranoxanthone from the stem bark of Calophyllum venulosum
    Bin Ismail AA, Ee GC, Bin Daud S, Teh SS, Hashim NM, Awang K
    J Asian Nat Prod Res, 2015;17(11):1104-8.
    PMID: 26023810 DOI: 10.1080/10286020.2015.1047353
    A new pyranoxanthone, venuloxanthone (1), was isolated from the stem bark of Calophyllum venulosum, together with three other xanthones, tovopyrifolin C (2), ananixanthone (3) and caloxanthone I (4), along with two common triterpenes, friedelin (5) and lupeol (6). The structures of these compounds were identified using several spectroscopic analyses which are NMR, GCMS and FTIR experiments.
    Matched MeSH terms: Molecular Structure
  5. Oppositinines A and B: new vasorelaxant beta-carboline alkaloids from Neisosperma oppositifolia
    Ahmad K, Thomas NF, Hadi AH, Mukhtar MR, Mohamad K, Nafiah MA, et al.
    Chem Pharm Bull (Tokyo), 2010 Aug;58(8):1085-7.
    PMID: 20686264
    A phytochemical study on the bark of Neisosperma oppositifolia (Apocynaceae) yielded two new beta-carboline indole alkaloids, oppositinines A (1) and B (2), together with five known alkaloids, isoreserpiline, isocarapanaubine, vobasine, 10-methoxydihydrocorynantheol-N-oxide, and ochropposinine oxindole. Structural elucidation of 1 and 2 was performed using 2D NMR methods. Oppositinines A (1) and B (2) showed potent vasorelaxant effects on the rat aorta.
    Matched MeSH terms: Molecular Structure
  6. Natural cholinesterase inhibitors from Myristica cinnamomea King
    Abdul Wahab SM, Sivasothy Y, Liew SY, Litaudon M, Mohamad J, Awang K
    Bioorg Med Chem Lett, 2016 08 01;26(15):3785-92.
    PMID: 27236720 DOI: 10.1016/j.bmcl.2016.05.046
    A new acylphenol, malabaricone E (1) together with the known malabaricones A-C (2-4), maingayones A and B (5 and 6) and maingayic acid B (7) were isolated from the ethyl acetate extract of the fruits of Myristica cinnamomea King. Their structures were determined by 1D and 2D NMR techniques and LCMS-IT-TOF analysis. Compounds 3 (1.84±0.19 and 1.76±0.21μM, respectively) and 4 (1.94±0.27 and 2.80±0.49μM, respectively) were identified as dual inhibitors, with almost equal acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibiting potentials. The Lineweaver-Burk plots of compounds 3 and 4 indicated that they were mixed-mode inhibitors. Based on the molecular docking studies, compounds 3 and 4 interacted with the peripheral anionic site (PAS), the catalytic triad and the oxyanion hole of the AChE. As for the BChE, while compound 3 interacted with the PAS, the catalytic triad and the oxyanion hole, compound 4 only interacted with the catalytic triad and the oxyanion hole.
    Matched MeSH terms: Molecular Structure
  7. Phenylpropanoids isolated from Piper sarmentosum Roxb. induce apoptosis in breast cancer cells through reactive oxygen species and mitochondrial-dependent pathways
    Hematpoor A, Paydar M, Liew SY, Sivasothy Y, Mohebali N, Looi CY, et al.
    Chem Biol Interact, 2018 Jan 05;279:210-218.
    PMID: 29174417 DOI: 10.1016/j.cbi.2017.11.014
    The aim of the present study is to isolate bioactive compounds from the roots of Piper sarmentosum and examine the mechanism of action using human breast cancer cell line (MDA-MB-231). Bioassay guided-fractionation of methanolic extract led to the isolation of asaricin (1) and isoasarone (2). Asaricin (1) and isoasarone (2) had significant cytotoxicity towards MDA-MB-231. MCF-10A (human normal breast epithelial cells) cells are less sensitive than MDA-MB-231, but they respond to the treatment with the same unit of measurement. Both compounds increase reactive oxygen species (ROS), decrease mitochondrial membrane potential (MMP) and enhance cytochrome c release in treated MDA-MB-231 cells. Isoasarone (2) markedly elevated caspase -8 and -3/7 activities and caused a decline in nuclear NF-κB translocation, suggesting extrinsic, death receptor-linked apoptosis pathway. Quantitative PCR results of MDA-MB-231 treated with asaricin (1) and isoasarone (2) showed altered expression of Bcl-2: Bax level. The inhibitory potency of these isolates may support the therapeutic uses of these compounds in breast cancer.
    Matched MeSH terms: Molecular Structure
  8. Fulltext α-Amylase and dipeptidyl peptidase-4 (DPP-4) inhibitory effects of Melicope latifolia bark extracts and identification of bioactive constituents using in vitro and in silico approaches
    Quek A, Kassim NK, Lim PC, Tan DC, Mohammad Latif MA, Ismail A, et al.
    Pharm Biol, 2021 Dec;59(1):964-973.
    PMID: 34347568 DOI: 10.1080/13880209.2021.1948065
    CONTEXT: Melicope latifolia (DC.) T. G. Hartley (Rutaceae) was reported to contain various phytochemicals including coumarins, flavonoids, and acetophenones.

    OBJECTIVE: This study investigates the antidiabetic and antioxidant effects of M. latifolia bark extracts, fractions, and isolated constituents.

    MATERIALS AND METHODS: Melicope latifolia extracts (hexane, chloroform, and methanol), fractions, and isolated constituents with varying concentrations (0.078-10 mg/mL) were subjected to in vitro α-amylase and dipeptidyl peptidase-4 (DPP-4) inhibitory assay. Molecular docking was performed to study the binding mechanism of active compounds towards α-amylase and DPP-4 enzymes. The antioxidant activity of M. latifolia fractions and compounds were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and β-carotene bleaching assays.

    RESULTS: Melicope latifolia chloroform extract showed the highest antidiabetic activity (α-amylase IC50: 1464.32 μg/mL; DPP-4 IC50: 221.58 μg/mL). Fractionation of chloroform extract yielded four major fractions (CF1-CF4) whereby CF3 showed the highest antidiabetic activity (α-amylase IC50: 397.68 μg/mL; DPP-4 IC50: 37.16 μg/mL) and resulted in β-sitosterol (1), halfordin (2), methyl p-coumarate (3), and protocatechuic acid (4). Isolation of compounds 2-4 from the species and their DPP-4 inhibitory were reported for the first time. Compound 2 showed the highest α-amylase (IC50: 197.53 μM) and β-carotene (88.48%) inhibition, and formed the highest number of molecular interactions with critical amino acid residues of α-amylase. The highest DPP-4 inhibition was exhibited by compound 3 (IC50: 911.44 μM).

    DISCUSSION AND CONCLUSIONS: The in vitro and in silico analyses indicated the potential of M. latifolia as an alternative source of α-amylase and DPP-4 inhibitors. Further pharmacological studies on the compounds are recommended.

    Matched MeSH terms: Molecular Structure
  9. Antiplasmodial and antioxidant isoquinoline alkaloids from Dehaasia longipedicellata
    Zahari A, Cheah FK, Mohamad J, Sulaiman SN, Litaudon M, Leong KH, et al.
    Planta Med, 2014 May;80(7):599-603.
    PMID: 24723007 DOI: 10.1055/s-0034-1368349
    The crude extract of the bark of Dehaasia longipedicellata exhibited antiplasmodial activity against the growth of Plasmodium falciparum K1 isolate (resistant strain). Phytochemical studies of the extract led to the isolation of six alkaloids: two morphinandienones, (+)-sebiferine (1) and (-)-milonine (2); two aporphines, (-)-boldine (3) and (-)-norboldine (4); one benzlyisoquinoline, (-)-reticuline (5); and one bisbenzylisoquinoline, (-)-O-O-dimethylgrisabine (6). Their structures were determined on the basis of 1D and 2D NMR, IR, UV, and LCMS spectroscopic techniques and upon comparison with literature values. Antiplasmodial activity was determined for all of the isolated compounds. They showed potent to moderate activity with IC50 values ranging from 0.031 to 30.40 µM. (-)-O-O-dimethylgrisabine (6) and (-)-milonine (2) were the two most potent compounds, with IC50 values of 0.031 and 0.097 µM, respectively, that were comparable to the standard, chloroquine (0.090 µM). The compounds were also assessed for their antioxidant activities with di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (IC50 = 18.40-107.31 µg/mL), reducing power (27.40-87.40 %), and metal chelating (IC50 = 64.30 to 257.22 µg/mL) having good to low activity. (-)-O-O-dimethylgrisabine (6) exhibited a potent antioxidant activity of 44.3 % reducing power, while di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium and metal chelating activities had IC50 values of 18.38 and 64.30 µg/mL, respectively. Thus it may be considered as a good reductant with the ability to chelate metal and prevent pro-oxidant activity. In addition to the antiplasmodial and antioxidant activities, the isolated compounds were also tested for their cytotoxicity against a few cancer and normal cell lines. (-)-Norboldine (4) exhibited potent cytotoxicity towards pancreatic cancer cell line BxPC-3 with an IC50 value of 27.060 ± 1.037 µM, and all alkaloids showed no toxicity towards the normal pancreatic cell line (hTERT-HPNE).
    Matched MeSH terms: Molecular Structure
  10. A new bis-labdanic diterpene from the rhizomes of Alpinia pahangensis
    Sivasothy Y, Ibrahim H, Paliany AS, Alias SA, Md Nor NR, Awang K
    Planta Med, 2013 Dec;79(18):1775-80.
    PMID: 24356874 DOI: 10.1055/s-0033-1351075
    The rhizomes of Alpinia pahangensis yielded a new bis-labdanic diterpene for which the name pahangensin C (1) was proposed along with twelve known analogues (2-13). The structure of 1 was elucidated via spectroscopic methods including 1D and 2D NMR techniques and LCMS-IT-TOF analysis. Compounds 2 and 12 were isolated for the first time from the genus Alpinia. This is the second occurrence of compounds 2 and 12 in the Zingiberaceae family. Selected analogues exhibited moderate to strong inhibitory activity against Staphylococcus aureus and Bacillus cereus.
    Matched MeSH terms: Molecular Structure
  11. Erythrocarpines IN, new limonoids from the barks of Chisocheton erythrocarpus and their neuroprotective effects against hydrogen peroxide in NG108-15 cells
    Ngadni MA, Chong SL, Kamarudin MNA, Hazni H, Litaudon M, Supratman U, et al.
    Fitoterapia, 2024 Mar;173:105765.
    PMID: 38042506 DOI: 10.1016/j.fitote.2023.105765
    A phytochemical study on the bark of Chisocheton erythrocarpus Hiern (Meliaceae) has led to the isolation of six new phragmalin-type limonoids named erythrocarpines I - N (1-6) along with one known limonoid, erythrocarpine F (7). Their structures were fully characterized by spectroscopic methods. The pre-treatment of NG108-15 cells with 1-5, 7 (2 h) demonstrated low to good protective effects against H2O2 exposure; 1 (83.77% ± 1.84 at 12.5 μM), 2 (69.07 ± 2.01 at 12.5 μM), 3 (80.38 ± 2.1 at 12.5 μM), 4 (62.33 ± 1.95 at 25 μM),5 (58.67 ± 1.85 at 50 μM) and 7 (66.07 ± 2.03 at 12.5 μM). Interestingly, 1 and 3 demonstrated comparable protective effects to positive control epigallocatechin gallate (EGCG) with similar cell viability capacity (≈ 80%), having achieved that at lower concentration (12.5 μM) than EGCG (50 μM). Collectively, the results suggested the promising use of 1 and 3 as potential neuroprotective agents against hydrogen peroxide-induced cytotoxicity in neuronal model.
    Matched MeSH terms: Molecular Structure
  12. Fulltext Regulation of apoptotic effects by erythrocarpine E, a cytotoxic limonoid from Chisocheton erythrocarpus in HSC-4 human oral cancer cells
    Nagoor NH, Shah Jehan Muttiah N, Lim CS, In LL, Mohamad K, Awang K
    PLoS One, 2011;6(8):e23661.
    PMID: 21858194 DOI: 10.1371/journal.pone.0023661
    The aim of this study was to determine the cytotoxic and apoptotic effects of erythrocarpine E (CEB4), a limonoid extracted from Chisocheton erythrocarpus on human oral squamous cell carcinoma. Based on preliminary dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, CEB4 treated HSC-4 cells demonstrated a cytotoxic effect and inhibited cell proliferation in a time and dose dependent manner with an IC(50) value of 4.0±1.9 µM within 24 h of treatment. CEB4 was also found to have minimal cytotoxic effects on the normal cell line, NHBE with cell viability levels maintained above 80% upon treatment. Annexin V-fluorescein isothiocyanate (FITC), poly-ADP ribose polymerase (PARP) cleavage and DNA fragmentation assay results showed that CEB4 induces apoptosis mediated cell death. Western blotting results demonstrated that the induction of apoptosis by CEB4 appeared to be mediated through regulation of the p53 signalling pathway as there was an increase in p53 phosphorylation levels. CEB4 was also found to up-regulate the pro-apoptotic protein, Bax, while down-regulating the anti-apoptotic protein, Bcl-2, suggesting the involvement of the intrinsic mitochondrial pathway. Reduced levels of initiator procaspase-9 and executioner caspase-3 zymogen were also observed following CEB4 exposure, hence indicating the involvement of cytochrome c mediated apoptosis. These results demonstrate the cytotoxic and apoptotic ability of erythrocarpine E, and suggest its potential development as a cancer chemopreventive agent.
    Matched MeSH terms: Molecular Structure
  13. Fulltext A Quantum Chemical and Statistical Study of Cytotoxic Activity of Compounds Isolated from Curcuma zedoaria
    Hamdi OA, Anouar el H, Shilpi JA, Trabolsy ZB, Zain SB, Zakaria NS, et al.
    Int J Mol Sci, 2015 Apr 27;16(5):9450-68.
    PMID: 25923077 DOI: 10.3390/ijms16059450
    A series of 21 compounds isolated from Curcuma zedoaria was subjected to cytotoxicity test against MCF7; Ca Ski; PC3 and HT-29 cancer cell lines; and a normal HUVEC cell line. To rationalize the structure-activity relationships of the isolated compounds; a set of electronic; steric and hydrophobic descriptors were calculated using density functional theory (DFT) method. Statistical analyses were carried out using simple and multiple linear regressions (SLR; MLR); principal component analysis (PCA); and hierarchical cluster analysis (HCA). SLR analyses showed that the cytotoxicity of the isolated compounds against a given cell line depend on certain descriptors; and the corresponding correlation coefficients (R2) vary from 0%-55%. MLR results revealed that the best models can be achieved with a limited number of specific descriptors applicable for compounds having a similar basic skeleton. Based on PCA; HCA and MLR analyses; active compounds were classified into subgroups; which was in agreement with the cell based cytotoxicity assay.
    Matched MeSH terms: Molecular Structure
  14. Simple, rapid and sensitive assay method for simultaneous quantification of urinary nicotine and cotinine using gas chromatography-mass spectrometry
    Man CN, Gam LH, Ismail S, Lajis R, Awang R
    J Chromatogr B Analyt Technol Biomed Life Sci, 2006 Dec 5;844(2):322-7.
    PMID: 16908224
    Nicotine is a major addictive compound in cigarette. Its smoke is rapidly and extensively metabolized to several metabolites in human. Cotinine as a major metabolite of nicotine is commonly used as a biomarker to determine active and passive smokers. Cotinine has a longer half-life ( approximately 20 h) compared to nicotine ( approximately 2h). A simple, sensitive, rapid and high throughput GC-MS method was developed for simultaneous quantification of urinary nicotine and cotinine in passive and active smokers. In the sample preparation method, the analytes and internal standard were first basified and followed by liquid-liquid extraction. Upon completion, anhydrous sodium sulphate was added to the solvent mixture to trap moistures. The clear extract obtained was directly injected into GC-MS, operating under selective ion monitoring (SIM) mode. Calibration curves in the range of 0.5-5000 ng/mL of the analytes in urine matrix were established with linear correlation coefficients (r(2)) greater than 0.997. The limit of detection for both nicotine and cotinine were 0.20 ng/mL. The mean recoveries for nicotine and cotinine were 93.0 and 100.4%, respectively. The within- and between-assay accuracies were between 2.1 and 7.9% for nicotine and between 0.7 and 11.1% for cotinine. Within- and between-assay precisions of 3.3-9.5% for nicotine and 3.4-9.8% for cotinine were also achieved. The method can be used in routine assessment and monitoring of active smoking and exposure to environmental tobacco smoke. The applicability of the assay was demonstrated in a small-scale comparison study between smokers and non-smokers.
    Matched MeSH terms: Molecular Structure
  15. Fulltext Role of Pyridine Nitrogen in Palladium-Catalyzed Imine Hydrolysis: A Case Study of (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine
    Ahmad G, Rasool N, Rizwan K, Altaf AA, Rashid U, Mahmood T, et al.
    Molecules, 2019 Jul 17;24(14).
    PMID: 31319634 DOI: 10.3390/molecules24142609
    In the present study, 4-methylpyridin-2-amine was reacted with 3-bromothiophene-2-carbaldehyde and the Schiff base (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine was obtained in a 79% yield. Coupling of the Schiff base with aryl/het-aryl boronic acids under Suzuki coupling reaction conditions, using Pd(PPh3)4 as catalyst, yielded products with the hydrolysis of the imine linkages (5a-5k, 6a-6h) in good to moderate yields. To gain mechanistic insight into the transition metal-catalyzed hydrolysis of the compounds, density functional theory (DFT) calculations were performed. The theoretical calculations strongly supported the experiment and provided an insight into the transition metal-catalyzed hydrolysis of imines.
    Matched MeSH terms: Molecular Structure
  16. High-dimensional QSAR modelling using penalized linear regression model with L1/2-norm
    Algamal ZY, Lee MH, Al-Fakih AM, Aziz M
    SAR QSAR Environ Res, 2016 Sep;27(9):703-19.
    PMID: 27628959 DOI: 10.1080/1062936X.2016.1228696
    In high-dimensional quantitative structure-activity relationship (QSAR) modelling, penalization methods have been a popular choice to simultaneously address molecular descriptor selection and QSAR model estimation. In this study, a penalized linear regression model with L1/2-norm is proposed. Furthermore, the local linear approximation algorithm is utilized to avoid the non-convexity of the proposed method. The potential applicability of the proposed method is tested on several benchmark data sets. Compared with other commonly used penalized methods, the proposed method can not only obtain the best predictive ability, but also provide an easily interpretable QSAR model. In addition, it is noteworthy that the results obtained in terms of applicability domain and Y-randomization test provide an efficient and a robust QSAR model. It is evident from the results that the proposed method may possibly be a promising penalized method in the field of computational chemistry research, especially when the number of molecular descriptors exceeds the number of compounds.
    Matched MeSH terms: Molecular Structure
  17. A penalized quantitative structure-property relationship study on melting point of energetic carbocyclic nitroaromatic compounds using adaptive bridge penalty
    Al-Fakih AM, Algamal ZY, Lee MH, Aziz M
    SAR QSAR Environ Res, 2018 May;29(5):339-353.
    PMID: 29493376 DOI: 10.1080/1062936X.2018.1439531
    A penalized quantitative structure-property relationship (QSPR) model with adaptive bridge penalty for predicting the melting points of 92 energetic carbocyclic nitroaromatic compounds is proposed. To ensure the consistency of the descriptor selection of the proposed penalized adaptive bridge (PBridge), we proposed a ridge estimator ([Formula: see text]) as an initial weight in the adaptive bridge penalty. The Bayesian information criterion was applied to ensure the accurate selection of the tuning parameter ([Formula: see text]). The PBridge based model was internally and externally validated based on [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], the Y-randomization test, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and the applicability domain. The validation results indicate that the model is robust and not due to chance correlation. The descriptor selection and prediction performance of PBridge for the training dataset outperforms the other methods used. PBridge shows the highest [Formula: see text] of 0.959, [Formula: see text] of 0.953, [Formula: see text] of 0.949 and [Formula: see text] of 0.959, and the lowest [Formula: see text] and [Formula: see text]. For the test dataset, PBridge shows a higher [Formula: see text] of 0.945 and [Formula: see text] of 0.948, and a lower [Formula: see text] and [Formula: see text], indicating its better prediction performance. The results clearly reveal that the proposed PBridge is useful for constructing reliable and robust QSPRs for predicting melting points prior to synthesizing new organic compounds.
    Matched MeSH terms: Molecular Structure
  18. Synthesis, biological evaluation, and molecular modelling of novel quinoxaline-isoxazole hybrid as anti-hyperglycemic
    Phongphane L, Mohd Radzuan SN, Abu Bakar MH, Che Omar MT, Supratman U, Harneti D, et al.
    Comput Biol Chem, 2023 Oct;106:107938.
    PMID: 37542847 DOI: 10.1016/j.compbiolchem.2023.107938
    In our effort to develop potent anti-hyperglycemic compounds with inhibitory activity against α-amylase and α-glucosidase, a series of novel quinoxaline-isoxazole moieties were synthesized. The novel quinoxaline-isoxazole derivatives were assessed in vitro for their anti-hyperglycemic activities on α-amylase and α-glucosidase inhibitions. The results revealed promising IC50 values compared to acarbose as a positive control for α-amylase and α-glucosidase. Among them, N-Ethyl-7-chloro-3-((3-phenylisoxazol-5-yl)methoxy)quinoxalin-2-amine 5b showed dual inhibitory with IC50 of 24.0 µM for α-amylase and 41.7 µM for α-glucosidase. In addition, N-Ethyl-7-methoxy-3-((3-(2-chlorophenyl)isoxazol-5-yl)methoxy)quinoxalin-2-amine 5j also had dual bioactivities against α-amylase and α-glucosidase with IC50 of 17.0 and 40.1 µM, respectively. Nevertheless, two more compounds N-Ethyl-7-cyano-3-((3-phenylisoxazol-5-yl)methoxy)quinoxaline-2-amine 5e showed strong mono-inhibition for α-glucosidase with IC50 of 16.6 µM followed by N-Ethyl-7-methoxy-3-((3-phenylisoxazol-5-yl)methoxy)quinoxalin-2-amine 5 f with IC50 of 18.6 µM. The molecular docking study for α-glucosidase inhibitor provided the binding energy ranging from 8.3 to 9.1 kcal/mol and α-amylase inhibitor showed the binding energy score at 8.4 and 8.5 kcal/mol. The dual inhibitions nature of 5b and 5j were further analyzed and confirmed via molecular dynamics including the stability of the compound, interaction energy, binding free energy, and the interaction residue analysis using the MM-GBSA approach. The results showed that compound 5j was the most potent compound. Lastly, the drug-likeness properties were also evaluated with all synthesized compounds 5a-5j and the results reveal that all potent compounds meet Lipinski's rules of five.
    Matched MeSH terms: Molecular Structure
  19. Chemodiverse monoterpene indole alkaloids from Kopsia teoi, inhibitory potential against α-amylase, and their molecular docking studies
    Muhammad MT, Beniddir MA, Phongphane L, Abu Bakar MH, Hussin MH, Awang K, et al.
    Fitoterapia, 2024 Apr;174:105873.
    PMID: 38417682 DOI: 10.1016/j.fitote.2024.105873
    Diabetes mellitus stands as a metabolic ailment marked by heightened blood glucose levels due to inadequate insulin secretion. The primary aims of this investigative inquiry encompassed the isolation of phytochemical components from the bark of Kopsia teoi, followed by the assessment of their α-amylase inhibition. The phytochemical composition of the K. teoi culminated in the discovery of a pair of new indole alkaloids; which are 16-epi-deacetylakuammiline N(4)-methylene chloride (akuammiline) (1), and N(1)-methoxycarbonyl-11-methoxy-12-hydroxy-Δ14-17-kopsinine (aspidofractinine) (2), together with five known compounds i.e. kopsiloscine G (aspidofractinine) (3), akuammidine (sarpagine) (4), leuconolam (aspidosperma) (5), N-methoxycarbonyl-12-methoxy-Δ16, 17-kopsinine (aspidofractinine) (6), and kopsininate (aspidofractinine) (7). All compounds were determined via spectroscopic analyses. The in vitro evaluation against α-amylase showed good inhibitory activities for compounds 5-7 with the inhibitory concentration (IC50) values of 21.7 ± 1.2, 34.1 ± 0.1, and 30.0 ± 0.8 μM, respectively compared with the reference acarbose (IC50 = 34.4 ± 0.1 μM). The molecular docking outputs underscored the binding interactions of compounds 5-7 ranging from -8.1 to -8.8 kcal/mol with the binding sites of α-amylase. Consequently, the outcomes highlighted the anti-hyperglycemic attributes of isolates from K. teoi.
    Matched MeSH terms: Molecular Structure
  20. Iron incorporated heterogeneous catalyst from rice husk ash
    Adam F, Kandasamy K, Balakrishnan S
    J Colloid Interface Sci, 2006 Dec 1;304(1):137-43.
    PMID: 16996077
    Silica supported iron catalyst was prepared from rice husk ash (RHA) via the sol-gel technique using an aqueous solution of iron(III) salt in 3.0 M HNO3. The sample was dried at 110 degrees C and labeled as RHA-Fe. A sample of RHA-Fe was calcined at 700 degrees C for 5 h and labeled as RHA-Fe700. X-ray diffraction spectrogram showed that both RHA-Fe and RHA-Fe700 were amorphous. The SEM/EDX results showed that the metal was present as agglomerates and the Fe ions were not homogeneously distributed in RHA-Fe but RHA-Fe700 was shown to be homogeneous. The specific surface areas for RHA-Fe and RHA-Fe700 were determined by BET nitrogen adsorption studies and found to be 87.4 and 55.8 m(2) g(-1), respectively. Both catalysts showed high activity in the reaction between toluene and benzyl chloride. The mono-substituted benzyltoluene was the major product and both catalysts yielded more than 92% of the product. The GC showed that both the ortho- and para-substituted monoisomers were present in about equal quantities. The minor products consisting of 16 di-substituted isomers were also observed in the GC-MS spectra of both catalytic products. The catalyst was found to be reusable without loss of activity and with no leaching of the metal.
    Matched MeSH terms: Molecular Structure
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