Displaying publications 1 - 20 of 160 in total

  1. Kamarulzaman, F. A., Mohamad, K., Awang, K., Lee, H. B.
    Our continuing research on the Aglaia genus (family Meliaceace) has led us to this first study on the chemical constituents of Aglaia lanuginose (bark). The dichloromethane extract from the bark of Aglaia lanuginose showed cytotoxicity against HL-60 leukaemia cell line (45% inhibition) at 20 µg/ml and was prioritised for further investigation. Repeated chromatography of the dichloromethane extract yielded the known dammarane triterpenes which were identified as cabralealactone (1), methyl eichlerianate (2), cabraleone (3), ocotillone (4), eichleriatone (5), eichlerianic acid (6) and shoreic acid (7) together with the known sterols, sitosterol (9) and stigmasterol (10). Another isolated compound was the aromatic 4-hydroxycinnamyl-acetate (8), which has not been reported to be present in a plant from the Meliaceae family. The structures of all the compounds were elucidated on the basis of spectroscopic methods (IR, MS and NMR). Cytotoxicity testing of 1-10 showed activity only for mixtures of (3, 4), and (5, 6).
  2. Kadir R, Awang K, Khamaruddin Z, Soit Z
    An Acad Bras Cienc, 2015 Apr-Jun;87(2):743-51.
    PMID: 26131633 DOI: 10.1590/0001-3765201520140041
    Wood extractives from heartwood of Callophylum inophyllum (bintangor) were obtained by shaker method and analyzed for their constituents by gas chromatography-mass spectrometry (GC-MS). Ten compounds were identified by ethanol (EtOH) solvents, fourteen by methanol (MeOH) and only nine by petroleum ether (PETETHR). Major compounds were contributed by monoterpenes (75.11%, 53.75%) when extracted with EtOH and PETETHR solvents. The anti-termitic assay of the wood extracts was also investigated against Coptotermes curvignathus. The level of concentration for anti-termite activity may be an indication of the dose application of the wood extracts for new development of termiticide.
  3. Sivasothy Y, Loo KY, Leong KH, Litaudon M, Awang K
    Phytochemistry, 2016 Feb;122:265-269.
    PMID: 26712615 DOI: 10.1016/j.phytochem.2015.12.007
    A dimeric acylphenol and a potent α-glucosidase inhibitor, giganteone D (IC50 5.05μM), was isolated and characterized from the bark of Myristica cinnamomea King. The bark also yielded an acylphenol with an unprecedented skeleton for which the name cinnamomeone A (IC50 358.80μM) was proposed. Their structures were established by means of NMR and MS spectrometric analyses. The Lineweaver-Burk plot of giganteone D indicated that it was a mixed-type inhibitor. This is the first report on the α-glucosidase inhibiting potential of acylphenols.
  4. Ablat A, Mohamad J, Awang K, Shilpi JA, Arya A
    ScientificWorldJournal, 2014;2014:786130.
    PMID: 24688431 DOI: 10.1155/2014/786130
    The ethanol extract of B. javanica seed was fractionated with solvents of different polarities and tested for antioxidant activities by several assays including DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP), ferrous ion chelating activity (FCA), and nitric oxide radical scavenging activity (NORSA) along with their polyphenolic contents. Antidiabetic activity was evaluated both in vitro and in vivo using a glycogen phosphorylase α (GPα) inhibition assay and oral glucose tolerance test (OGTT) in nondiabetic rats. The ethyl acetate fraction (EAF), rich in tannin, exhibited the strongest antioxidant activities to DPPH, FRAP, and NORSA, except for FCA. The EAF also exerted a dose-depended inhibition of GPα (IC50 = 0.75 mg/ml). Further evaluation of hypoglycemic effect on OGGT indicated that rats treated with EAF (125 mg/kg bw) showed a 39.91% decrease (P < 0.05) in blood glucose levels at 30 min, and continuous fall (P < 0.05) of 28.89% and 20.29% was observed in the following hours (60 and 90 min) compared to the normal control during OGTT. The EAF was applied to polyamide column chromatography, and the resulting tannin-free fraction was tested for both GPα inhibition and antioxidant (DPPH only) activity. The GP α inhibitory activity was retained, while antioxidant activity was lost (4.6-fold) after tannin removal. These results concluded that the GPα inhibitory activity initially detected was primarily due to the compounds other than tannins, whereas antioxidant activity was mainly due to the tannins.
  5. Nasrullah AA, Zahari A, Mohamad J, Awang K
    Molecules, 2013 Jul 08;18(7):8009-17.
    PMID: 23884132 DOI: 10.3390/molecules18078009
    A dichloromethane extract of the stem bark of Cryptocarya nigra showed strong in vitro inhibition of Plasmodium falciparum growth, with an IC50 value of 2.82 μg/mL. The phytochemical study of this extract has led to the isolation and characterization of four known alkaloids: (+)-N-methylisococlaurine (1), atherosperminine (2), 2-hydroxyathersperminine (3), and noratherosperminine (4). Structural elucidation of all alkaloids was accomplished by means of high field 1D- and 2D-NMR, IR, UV and LCMS spectral data. The isolated extract constituents (+)-N-methylisococlaurine (1), atherosperminine (2) and 2-hydroxy-atherosperminine (3) showed strong antiplasmodial activity, with IC50 values of 5.40, 5.80 and 0.75 μM, respectively. In addition, (+)-N-methylisocolaurine (1) and atherosperminine (2) showed high antioxidant activity in a DPPH assay with IC50 values of 29.56 ug/mL and 54.53 ug/mL respectively. Compounds 1 and 2 also both showed high antioxidant activity in the FRAP assay, with percentages of 78.54 and 70.66 respectively and in the metal chelating assay, with IC50 values of 50.08 ug/mL and 42.87 ug/mL, respectively.
  6. Awang K, Abdullah NH, Hadi AH, Fong YS
    J. Biomed. Biotechnol., 2012;2012:876458.
    PMID: 22536026 DOI: 10.1155/2012/876458
    The dichloromethane (DCM) extract of Andrographis paniculata Nees was tested for cardiovascular activity. The extract significantly reduced coronary perfusion pressure by up to 24.5 ± 3.0 mm Hg at a 3 mg dose and also reduced heart rate by up to 49.5 ± 11.4 beats/minute at this dose. Five labdane diterpenes, 14-deoxy-12-hydroxyandrographolide (1), 14-deoxy-11,12-didehydroandrographolide (2), 14-deoxyandrographolide (3), andrographolide (4), and neoandrographolide (5), were isolated from the aerial parts of this medicinal plant. Bioassay-guided studies using animal model showed that compounds, (2) and (3) were responsible for the coronary vasodilatation. This study also showed that andrographolide (4), the major labdane diterpene in this plant, has minimal effects on the heart.
  7. Ambikabothy J, Ibrahim H, Ambu S, Chakravarthi S, Awang K, Vejayan J
    J Ethnopharmacol, 2011 Sep 1;137(1):257-62.
    PMID: 21640180 DOI: 10.1016/j.jep.2011.05.013
    Evaluations of the anti-snake venom efficacy of Mimosa pudica tannin isolate (MPT) obtained from root of the plant.
  8. Salim F, Ismail NH, Awang K, Ahmad R
    Molecules, 2011 Aug 04;16(8):6541-8.
    PMID: 21818057 DOI: 10.3390/molecules16086541
    Two new heteroyohimbine-type oxindole alkaloids, rauniticine-allo-oxindole B and rauniticinic-allo acid B, have been successfully isolated from the stems extract of Malaysian Uncaria longiflora var. pteropoda. The structures of the two new alkaloids were determined by spectroscopic analysis.
  9. Alias A, Hazni H, Jaafar FM, Awang K, Ismail NH
    Molecules, 2010 Jul;15(7):4583-8.
    PMID: 20657378 DOI: 10.3390/molecules15074583
    A phytochemical study of the bark of Fissistigma latifolium (Annonaceae) yielded a new aporphine alkaloid, (-)-N-methylguattescidine (1), and eight known alkaloids: liriodenine (2), oxoxylopine (3), (-)-asimilobine (4), dimethyltryptamine (5), (-)-remerine (6), (-)-anonaine (7), columbamine (8) and lysicamine (9). The compounds were isolated using various chromatographic methods and structural elucidation was accomplished by means of spectroscopic methods, notably 1D-NMR ((1)H, (13)C, DEPT), 2D-NMR (COSY, HMQC, HMBC), UV, IR and MS.
  10. Awang K, Yusoff M, Mohamad K, Chong SL, Ng SW
    PMID: 21583968 DOI: 10.1107/S1600536809015086
    3-Oxoolean-1-en-28-oic acid, isolated from the bark of Walsura pinnata Hassk, crystallized from n-hexane as an n-hexane 0.25-solvent 0.25-hydrate, C(30)H(46)O(3)·0.25C(6)H(14)·0.25H(2)O. There are two independent mol-ecules in the asymmetric unit of the title compound. The three six-membered cyclo-hexane rings in each mol-ecule adopt chair conformations and the carboxyl substituent occupies an axial/equatorial position. The two independent mol-ecules are linked by a pair of O-H(carbox-yl)⋯O hydrogen bonds into a dimer. The n-hexane mol-ecule is disordered about a twofold rotation axis and the water mol-ecule lies on a twofold rotation axis. In addition, the cyclo-hexone carbonyl group of one of the independent mol-ecules is disordered over two sites with occupancies of 0.75 and 0.25.
  11. Mohamad K, Yusoff M, Awang K, Ahmad K, Ng SW
    PMID: 21583174 DOI: 10.1107/S1600536809015955
    In the mol-ecule of pinnatane A, C(30)H(48)O(3), isolated from the bark of Walsura pinnata Hassk, the four cyclo-hexane rings adopt chair conformations; the carboxyl and hydr-oxy substituents occupy axial positions. The cyclo-hexene ring is envelope-shaped. Adjacent mol-ecules are linked by O-H⋯O hydrogen bonds into a chain running along the c axis.
  12. Ahmad K, Thomas NF, Nafiah MA, Awang K, Ng SW
    PMID: 21583151 DOI: 10.1107/S1600536809017401
    In the title compound, C(17)H(17)NO(2), the phenyl-ene rings are bent with respect to the carbon-carbon double bond [dihedral angle between rings = 39.6 (1)°]. The acetamido group is twisted out of the plane of the aromatic ring [dihedral angle = 44.2 (1)°] in order to form an N-H⋯O hydrogen bond to the acetamido group of an adjacent mol-ecule, generating a zigzag chain running along the c axis.
  13. Ahmad K, Thomas NF, Din MF, Awang K, Ng SW
    PMID: 21583150 DOI: 10.1107/S1600536809017395
    In the title compound, C(17)H(17)NO(2), the phenyl-ene rings are nearly coplanar [dihedral angle 7.3 (1)°]. The acetamido group is twisted out of the plane of the aromatic ring in order to form an N-H⋯O hydrogen bond to the acetamido group of an adjacent mol-ecule, generating a helical chain running along the b axis.
  14. Chan G, Awang K, A Hadi AH, Ng SW
    PMID: 21202956 DOI: 10.1107/S1600536808018151
    The title compound, C(30)H(34)O(5), crystallizes with two symmetry-independent mol-ecules in the asymmetric unit. In the crystal structure, the two independent mol-ecules are disposed about a pseudo-center of inversion. An intra-molecular O-H⋯O hydrogen bond is observed in each independent mol-ecule. The crystal structure is stabilized by C-H⋯O hydrogen bonds.
  15. Othman R, Ibrahim H, Mohd MA, Mustafa MR, Awang K
    Phytomedicine, 2006 Jan;13(1-2):61-6.
    PMID: 16360934
    Bioassay-guided fractionation was performed on a crude dichloromethane extract of Kaempferia galanga L. using chromatography techniques. Screening of the extract for biological activity started with the brine shrimp lethality bioassay, followed by the study of its antihypertensive activity on anaesthetized rats, which involved monitoring of the extract's effect on mean arterial blood pressure. The components of the fractions obtained from the separation procedures were analyzed using gas chromatography (GC). The yield of the CH(2)Cl(2) extract was 0.29% of the crude plant extract. Analysis of the data for brine shrimp lethality test using the Finney computer program showed that this extract exhibited potent bioactivity with an ED(50) value of 7.92+/-0.13 microgml(-1). Intravenous administration of the extract induced a dose-related reduction of basal mean arterial pressure (MAP) (130+/-5 mmHg) in the anaesthetized rat, with maximal effects seen after 5-10 min of injection. The gas chromatogram showed that the common compound in the active fractions obtained from the bioassay-guided fractionation of the CH(2)Cl(2) extract was ethyl cinnamate. This vasorelaxant active compound, ethyl cinnamate, was isolated as a colorless oil. Ethyl p-methoxycinnamic acid was also isolated as white needles but did not exhibit any relaxant effect on the precontracted thoracic rat aorta.
  16. Mukhtar MR, Hadi AH, Litaudon M, Awang K
    Fitoterapia, 2004 Dec;75(7-8):792-4.
    PMID: 15567268
    Five morphinoid alkaloids have been isolated from Dehaasia longipedicellata, namely (-) pallidine, a new alkaloid (+) pallidinine (1), (+)-milonine, (-) 8,14-dehydrosalutaridine and (-) sinoacutine.
  17. Sianturi J, Harneti D, Darwati, Mayanti T, Supratman U, Awang K
    Nat Prod Res, 2016 Oct;30(19):2204-8.
    PMID: 26985634 DOI: 10.1080/14786419.2016.1160233
    New (-)-5',6-dimethoxyisolariciresinol-(3″,4″-dimethoxy)-3α-O-β-d-glucopyranoside compound was isolated from the methanol extract of the bark of Aglaia eximia (Meliaceae). The chemical structure of the new compound were elucidated on the basis of spectroscopic data including, UV, IR, HR-ESI-TOFMS, 1D-NMR, 2D-NMR and comparison with those related compounds previously reported.
  18. Chan CK, Chan G, Awang K, Abdul Kadir H
    Molecules, 2016 Mar 21;21(3):385.
    PMID: 27007366 DOI: 10.3390/molecules21030385
    Deoxyelephantopin (DET), one of the major sesquiterpene lactones derived from Elephantopus scaber was reported to possess numerous pharmacological functions. This study aimed to assess the apoptosis inducing effects and cell cycle arrest by DET followed by elucidation of the mechanisms underlying cell death in HCT116 cells. The anticancer activity of DET was evaluated by a MTT assay. Morphological and biochemical changes were detected by Hoescht 33342/PI and Annexin V/PI staining. The results revealed that DET and isodeoxyelephantopin (isoDET) could be isolated from the ethyl acetate fraction of E. scaber leaves via a bioassay-guided approach. DET induced significant dose- and time-dependent growth inhibition of HCT116 cells. Characteristics of apoptosis including nuclear morphological changes and externalization of phosphatidylserine were observed. DET also significantly resulted in the activation of caspase-3 and PARP cleavage. Additionally, DET induced cell cycle arrest at the S phase along with dose-dependent upregulation of p21 and phosphorylated p53 protein expression. DET dose-dependently downregulated cyclin D1, A2, B1, E2, CDK4 and CDK2 protein expression. In conclusion, our data showed that DET induced apoptosis and cell cycle arrest in HCT116 colorectal carcinoma, suggesting that DET has potential as an anticancer agent for colorectal carcinoma.
  19. Wiart C, Martin MT, Awang K, Hue N, Serani L, Laprévote O, et al.
    Phytochemistry, 2001 Oct;58(4):653-6.
    PMID: 11576617
    A new sesquiterpene, scodopin, and a mixture of three tryptamine-type alkaloids, scorodocarpines A-C, were isolated from the fruits of Scorodocarpus borneensis, together with a known hemisynthetic sesquiterpene, cadalene-beta-carboxylic acid, which was isolated from the bark. The structures of the new compounds were elucidated by interpretation of spectral data, especially tandem mass spectrometry for the alkaloid mixture.
  20. Mohamad K, Martin MT, Najdar H, Gaspard C, Sévenet T, Awang K, et al.
    J Nat Prod, 1999 Jun;62(6):868-72.
    PMID: 10395505
    Nine 3,4-secoapotirucallanes, argentinic acids A-I, were isolated from the bark of Aglaia argentea and transformed to their methyl esters 1-9. The structures were determined by spectral and chemical means. Compounds 1-8 showed moderate cytotoxic activity against KB cells (IC50 1.0-3.5 microg/mL).
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