Displaying publications 1 - 20 of 171 in total

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  1. Fulltext Chemical constituents of aglaia lanuginose
    Kamarulzaman, F. A., Mohamad, K., Awang, K., Lee, H. B.
    Pertanika Journal of Science & Technology, 2014;22(1):163-174.
    MyJurnal
    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. Fulltext Chemical compositions and termiticidal activities of the heartwood from Calophyllum inophyllum L
    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. Fulltext Insecticidal activity and the mechanism of action of three phenylpropanoids isolated from the roots of Piper sarmentosum Roxb
    Hematpoor A, Liew SY, Azirun MS, Awang K
    Sci Rep, 2017 10 03;7(1):12576.
    PMID: 28974710 DOI: 10.1038/s41598-017-12898-z
    Hexane, dichloromethane and methanol extracts of the roots of Piper sarmentosum Roxb. were screened for toxicity towards Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Plodia interpunctella (Hübner) and the hexane extract exhibited the highest mortality percentage. Bioassay-guided fractionation of the hexane extract resulted in the isolation of asaricin 1, isoasarone 2, and trans-asarone 3. Asaricin 1 and isoasarone 2 were the most toxic compounds to Sitophilus oryzae, Rhyzopertha dominica, and Plodia interpunctella. Sitophilus oryzae and Rhyzopertha dominica exposed to asaricin 1 and isoasarone 2 required the lowest median lethal time. Insecticidal activity of trans-asarone 3 showed consistent toxicity throughout the 60 days towards all three insects as compared to asaricin 1 and isoasarone 2. Asaricin 1 and isoasarone 2 at different doses significantly reduced oviposition and adult emergence of the three insects in treated rice. Trans-asarone 3 had lowest toxicity with highest LC and LT values in all tested insects relative to its mild oviposition inhibition and progeny activity. Moreover, asaricin 1 and isoasarone 2 significantly inhibited acetylcholinesterase in comparison with trans-asarone 3 and the control. Acetylcholinesterase inhibition of Rhyzopertha dominica and Plodia interpunctella by asaricin 1 and isoasarone 2 were lower than that of Sitophilus oryzae, which correlated with their higher resistance.
  4. Isolation of antioxidative compounds from Micromelum minutum guided by preparative thin layer chromatography-2,2-diphenyl-1-picrylhydrazyl (PTLC-DPPH) bioautography method
    Kassim NK, Lim PC, Ismail A, Awang K
    Food Chem, 2019 Jan 30;272:185-191.
    PMID: 30309531 DOI: 10.1016/j.foodchem.2018.08.045
    The application of preparative thin layer chromatography-2,2-diphenyl-1-picrylhydrazyl (PTLC-DPPH) bioautography technique successfully isolated a lignan sesamin (1), two prenylated coumarins (2 and 3) and a marmesin glycosides (4) from Micromelum minutum methanol bark extract. Compounds 2 and 3 were identified as new compounds whereas 1 and 4 were first isolated from Micromelum genus. Structural identification of all compounds were done by detailed spectroscopic analyses and comparison with literature data. Antioxidant capacities of extract, active fraction and compounds were measured based on DPPH free radical savenging activity, oxygen radical absorbance capacity (ORAC) and β-carotene bleaching. The DPPH activity of methanol extract and its fraction present the IC50 values of 54.3 and 168.9 µg/mL meanwhile the β-carotene bleaching results were 55.19% and 5.75% respectively. The ORAC measurements of M. minutum extract, compounds 2 and 4 showed potent antioxidant activity with the values of 5123, 5539 and 4031 µmol TE/g respectively.
  5. Molecular Insight and Mode of Inhibition of α-Glucosidase and α-Amylase by Pahangensin A from Alpinia pahangensis Ridl
    Loo KY, Leong KH, Sivasothy Y, Ibrahim H, Awang K
    Chem Biodivers, 2019 Jun;16(6):e1900032.
    PMID: 30957403 DOI: 10.1002/cbdv.201900032
    The inhibition of carbohydrate-hydrolyzing enzymes in human digestive organs is crucial in controlling blood sugar levels, which is important in treating type 2 diabetes. In the current study, pahangensin A (1), a bis-labdanic diterpene characterized previously in the rhizomes of Alpinia pahangensis Ridl., was identified as an active dual inhibitor for α-amylase (IC50 =114.80 μm) and α-glucosidase (IC50 =153.87 μm). This is the first report on the dual α-amylase and α-glucosidase inhibitory activities of a bis-labdanic diterpene. The Lineweaver-Burk plots of compound 1 indicate that it is a mixed-type inhibitor with regard to both enzymes. Based on molecular docking studies, compound 1 docked in a non-active site of both enzymes. The dual inhibitory activity of compound 1 makes it a suitable natural alternative in the treatment of type 2 diabetes.
  6. Sesquiterpenes and alkaloids from Scorodocarpus borneensis
    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.
  7. An antimitotic and cytotoxic chalcone from Fissistigma lanuginosum
    Alias Y, Awang K, Hadi AH, Thoison O, Sévenet T, Païs M
    J Nat Prod, 1995 Aug;58(8):1160-6.
    PMID: 7595585
    Bioassay-guided fractionation of an ethyl acetate extract of Fissistigma lanuginosum led to the isolation of the known chalcone pedicin [1], which inhibited tubulin assembly into microtubules (IC50 value of 300 microM). From the same EtOAc fraction, two new condensed chalcones, fissistin [2] and isofissistin [3], which showed cytotoxicity against KB cells, were also obtained, together with the inactive dihydropedicin [4] and 6,7-dimethoxy-5,8-dihydroxyflavone [5]. In addition, the aminoquinones 6, 8, and 9 were isolated from the alkaloid extract. These compounds were artifacts, prepared by treatment of 1, 4, and 2, respectively, with NH4OH. The structures of the new compounds were elucidated by spectral methods, especially 2D nmr.
  8. Fulltext Suppression of microRNA-629 enhances sensitivity of cervical cancer cells to 1'S-1'-acetoxychavicol acetate via regulating RSU1
    Phuah NH, Azmi MN, Awang K, Nagoor NH
    Onco Targets Ther, 2017;10:1695-1705.
    PMID: 28356756 DOI: 10.2147/OTT.S117492
    BACKGROUND: Cervical cancer is the fourth most frequent malignancy affecting women worldwide, but drug resistance and toxicities remain a major challenge in chemotherapy. The use of natural compounds is promising because they are less toxic and able to target multiple signaling pathways. The 1'S-1'-acetoxychavicol acetate (ACA), a natural compound isolated from wild ginger Alpinia conchigera, induced cytotoxicity on various cancer cells including cervical cancer. MicroRNAs (miRNAs) are short noncoding RNAs that regulate numerous biological processes, such as apoptosis and chemosensitivity. Past studies reported that miR-629 is upregulated in many cancers, and its expression was altered in ACA-treated cervical cancer cells. However, the role of miR-629 in regulating sensitivity toward ACA or other anticancer agents has not been reported. Hence, this study aims to investigate the role of miR-629 in regulating response toward ACA on cervical cancer cells.

    METHODS: The miR-629 expression following transfection with miR-629 hairpin inhibitor and hairpin inhibitor negative control was measured using quantitative real-time polymerase chain reaction (RT-qPCR). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to investigate sensitivity toward ACA. Apoptosis was detected using Annexin V/propidium iodide and Caspase 3/7 assays. The gene target for miR-629 was identified using miRNA target prediction programs, luciferase reporter assay and Western blots. Gene overexpression studies were performed to evaluate its role in regulating response toward ACA.

    RESULTS: Transfection with miR-629 hairpin inhibitor downregulated its expression in both cervical cancer cell lines. Suppression of miR-629 increased sensitivity toward ACA by reducing cell proliferation and inducing apoptosis. Luciferase reporter assay confirmed RSU1 as a direct target of miR-629. Overexpression of miR-629 decreased RSU1 protein expression, while inhibition of miR-629 increased RSU1 protein expression. Overexpression of RSU1 augmented antiproliferative and apoptosis-inducing effects of ACA.

    CONCLUSION: Our findings showed that combination of ACA with miR-629 and RSU1 may provide a potential strategy in treating cervical cancer.

  9. Fulltext Down-Regulation of MicroRNA-210 Confers Sensitivity towards 1'S-1'-Acetoxychavicol Acetate (ACA) in Cervical Cancer Cells by Targeting SMAD4
    Phuah NH, Azmi MN, Awang K, Nagoor NH
    Mol Cells, 2017 Apr;40(4):291-298.
    PMID: 28401751 DOI: 10.14348/molcells.2017.2285
    MicroRNAs (miRNAs) are short non-coding RNAs that regulate genes posttranscriptionally. Past studies have reported that miR-210 is up-regulated in many cancers including cervical cancer, and plays a pleiotropic role in carcinogenesis. However, its role in regulating response towards anti-cancer agents has not been fully elucidated. We have previously reported that the natural compound 1'S-1'-acetoxychavicol acetate (ACA) is able to induce cytotoxicity in various cancer cells including cervical cancer cells. Hence, this study aims to investigate the mechanistic role of miR-210 in regulating response towards ACA in cervical cancer cells. In the present study, we found that ACA down-regulated miR-210 expression in cervical cancer cells, and suppression of miR-210 expression enhanced sensitivity towards ACA by inhibiting cell proliferation and promoting apoptosis. Western blot analysis showed increased expression of mothers against decapentaplegic homolog 4 (SMAD4), which was predicted as a target of miR-210 by target prediction programs, following treatment with ACA. Luciferase reporter assay confirmed that miR-210 binds to sequences in 3'UTR of SMAD4. Furthermore, decreased in SMAD4 protein expression was observed when miR-210 was overexpressed. Conversely, SMAD4 protein expression increased when miR-210 expression was suppressed. Lastly, we demonstrated that overexpression of SMAD4 augmented the anti-proliferative and apoptosis-inducing effects of ACA. Taken together, our results demonstrated that down-regulation of miR-210 conferred sensitivity towards ACA in cervical cancer cells by targeting SMAD4. These findings suggest that combination of miRNAs and natural compounds could provide new strategies in treating cervical cancer.
  10. Cytotoxic 3,4-secoapotirucallanes from Aaglaia argentea bark
    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).
  11. Fulltext Cardiovascular activity of labdane diterpenes from Andrographis paniculata in isolated rat hearts
    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.
  12. Fulltext Evaluation of antidiabetic and antioxidant properties of Brucea javanica seed
    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.
  13. Fulltext 3-Oxoolean-1-en-28-oic acid-n-hexa-ne-water (4/1/1) from the bark of Walsura pinnata Hassk
    Awang K, Yusoff M, Mohamad K, Chong SL, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2009;65(Pt 5):o1166.
    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.
  14. Fulltext Pinnatane A from the bark of Walsura pinnata Hassk
    Mohamad K, Yusoff M, Awang K, Ahmad K, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2009;65(Pt 6):o1317.
    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.
  15. Fulltext N'-{2-[2-(3-Methoxyphenyl)ethenyl]phenyl}acetamide
    Ahmad K, Thomas NF, Nafiah MA, Awang K, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2009;65(Pt 6):o1290.
    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.
  16. Fulltext N'-{2-[2-(4-Methoxyphenyl)ethenyl]phenyl}acetamide
    Ahmad K, Thomas NF, Din MF, Awang K, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2009;65(Pt 6):o1289.
    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.
  17. Bioassay-guided isolation of a vasorelaxant active compound from Kaempferia galanga L
    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.
  18. Fulltext 6-[(E)-3,7-Dimethyl-octa-2,6-dien-yl]-5,7-dihydr-oxy-8-(2-methyl-butano-yl)-4-phenyl-2H-chromen-2-one from Mesua kunstleri King (Kosterm)
    Chan G, Awang K, A Hadi AH, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2008;64(Pt 7):o1332.
    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.
  19. Efficacy evaluations of Mimosa pudica tannin isolate (MPT) for its anti-ophidian properties
    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.
  20. Fulltext Rauniticine-allo-oxindole B and rauniticinic-allo acid B, new heteroyohimbine-type oxindole alkaloids from the stems of Malaysian Uncaria longiflora var. pteropoda
    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.
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