Displaying publications 41 - 60 of 159 in total

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  1. Awang K, Abdullah Z, Mukhtar MR, Litaudon M, Jaafar FM, Hadi AH, et al.
    Nat Prod Res, 2009;23(7):652-8.
    PMID: 19401920 DOI: 10.1080/14786410802323743
    Dunaliine A (1), a new amino diketone, has been isolated from the leaves of Desmos dunalii together with four known dihydrochalcones: 2',4-dihydroxy-4',6'-dimethoxy-3',5'-dimethyldihydrochalcone (2), 2',4-dihydroxy-4',6'-dimethoxydihydrochalcone (3), 2',4-dihydroxy-4',5',6'-trimethoxydihydrochalcone (4) and 2',4-dihydroxy-5'-methyl-4',6'-dimethoxydihydrochalcone (5). The structures of these compounds were established notably by spectral analysis (1D- and 2D- (1)H, (13)C NMR), UV, IR and HRMS.
  2. Ee GC, Wen YP, Sukari MA, Go R, Lee HL
    Nat Prod Res, 2009;23(14):1322-9.
    PMID: 19735047 DOI: 10.1080/14786410902753138
    An investigation of Morinda citrifolia roots afforded a new anthraquinone, 2-ethoxy-1-hydroxyanthraquinone (1), along with five other known anthraquinones: 1-hydroxy-2-methylanthraquinone (2), damnacanthal (3), nordamnacanthal (4), 2-formyl-1-hydroxyanthraquinone (5) and morindone-6-methyl-ether (6). This is the first report on the isolation of morindone-6-methyl-ether (6) from this plant. The structures of these compounds were elucidated based on spectroscopic analyses such as NMR, MS and IR. Biological evaluation of five pure compounds and all the extracts against the larvae of Aedes aegypti indicated 1-hydroxy-2-methylanthraquinone (2) and damnacanthal (3) were the extracts to exhibit promising larvicidal activities.
  3. Rajudin E, Ahmad F, Sirat HM, Arbain D, Aboul-Enein HY
    Nat Prod Res, 2010 Mar;24(4):387-90.
    PMID: 20221945 DOI: 10.1080/14786410903421826
    Seven flavonoid compounds have been isolated from the aerial parts of tiger's betel (Piper porphyrophyllum), which were identified as 5,7-dimethoxyflavone, 4',5,7-trimethoxy-flavone, 3',4',5,7-tetramethoxyflavone, 4'-hydroxy-3',5,7-trimethoxyflavone, 5-hydroxy-3',4',7-trimethoxyflavone, 4',5-dihydroxy-3',7-dimethoxyflavone and 5-hydroxy-7-methoxyflavanone. The identification of all compounds was achieved by physical properties and spectroscopically. These data were also confirmed by comparison with previously reported spectral data. Flavonoid compounds with high content in P. porphyrophyllum can probably be used as a chemical marker for this Piper species.
  4. Hussain K, Ismail Z, Sadikun A, Ibrahim P
    Nat Prod Res, 2009;23(3):238-49.
    PMID: 19235024 DOI: 10.1080/14786410801987597
    Ethanol and aqueous extracts of the different parts of Piper sarmentosum were analysed by HPLC for marker compounds to standardise these extracts. The standardised extracts were investigated for antioxidant activity (beta-carotene linoleate model and DPPH model), anti-TB activity (microplate tetrazolium assay), and estimation of total phenolic and amide contents. The extracts of the different parts exhibited different antioxidant activity, phenolic and amide contents (p < 0.01). The ethanol extracts exhibited better antioxidant activity as compared to the aqueous extracts. The leaf ethanol extract was further investigated for dose response relationship and its EC(50) was found to be 38 microg mL(-1). All the extracts have exhibited anti-TB activity with MIC/MBC 12.5 microg mL(-1). The leaf methanol extract was fractionated and the ethyl acetate fraction exhibited anti-TB activity with MIC/MBC 3.12 microg mL(-1) while MIC/MBC of isoniazid (INH) was found to be 0.5 microg mL(-1). A positive correlation was found between antioxidant activity and total polyphenols, flavonoids and amides, in the beta-carotene linoleate model (p = 0.05) and in the DPPH model (p = 0.01). The analytical method was found to have linearity >0.9922, coefficient of variance <5% and accuracy 95.5 +/- 5 to 96.9 +/- 5. This plant possesses promising antioxidant as well as anti-TB properties.
  5. 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.
  6. Awang K, Mukhtar MR, Mustafa MR, Litaudon M, Shaari K, Mohamad K, et al.
    Nat Prod Res, 2007 Jul 10;21(8):704-9.
    PMID: 17616898
    The leaves of the Phoebe scortechinii (Gamb.) Kochummen Comb. Nov. (Lauraceae), afforded one new proaporphine-tryptamine dimer; (-)-phoebescortechiniine (1), along with two known ones; phoebegrandine A and phoebegrandine B. The proaporphine, tetrahydropronuciferine (2), was isolated for the first time as a natural product. The alkaloids were elucidated primarily by means of high field NMR and HRMS.
  7. Ee GC, Daud S, Taufiq-Yap YH, Ismail NH, Rahmani M
    Nat Prod Res, 2006 Oct;20(12):1067-73.
    PMID: 17127660
    Studies on the stem of Garcinia mangostana have led to the isolation of one new xanthone mangosharin (1) (2,6-dihydroxy-8-methoxy-5-(3-methylbut-2-enyl)-xanthone) and six other prenylated xanthones, alpha-mangostin (2), beta-mangostin (3), garcinone D (4), 1,6-dihydroxy-3,7-dimethoxy-2-(3-methylbut-2-enyl)-xanthone (5), mangostanol (6) and 5,9-dihydroxy-8- methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)-2H,6H-pyrano-[3,2-b]-xanthene-6-one (7). The structures of these compounds were determined by spectroscopic methods such as 1H NMR, 13C NMR, mass spectrometry (MS) and by comparison with previous studies. All the crude extracts when screened for their larvicidal activities indicated very good toxicity against the larvae of Aedes aegypti. This article reports the isolation and identification of the above compounds as well as bioassay data for the crude extracts. These bioassay data have not been reported before.
  8. Taufiq-Yap YH, Peh TH, Ee GC, Rahmani M, Sukari MA, Ali AM, et al.
    Nat Prod Res, 2007 Jul 20;21(9):810-3.
    PMID: 17654285
    A new carbazole alkaloid, 3-carbomethoxy-2-hydroxy-7-methoxycarbazole, Clausine-TY (1), together with two known carbazole alkaloid, Clausine-H (2) and Clausine-B (3), were isolated from the ethyl acetate extract of the stem bark of the Malaysian Clausena excavata. The structures of these compounds were elucidated by spectroscopic analyses. The new carbazole alkaloid shows significant cytotoxicity against CEM-SS cell line.
  9. Ee GC, Kua AS, Lim CK, Jong V, Lee HL
    Nat Prod Res, 2006 May 10;20(5):485-91.
    PMID: 16644547
    In the authors' continuing search for new natural products, their recent studies on the roots of Calophyllum inophyllum (Guttiferae) have yielded a new prenylated pyranoxanthone, Inophyllin A together with the common triterpenes friedelin and stigmasterol. Structural elucidations of these compounds were achieved through (1)H, (13)C, DEPT, COSY, HSQC and HMBC experiments. The molecular mass was determined using MS techniques. The authors report here the isolation of and structural elucidation for Inophyllin A as well as its toxicity test result. The discovery of this new natural product from the unexploited Malaysian forest will certainly contribute to the search for potential natural larvicides.
  10. Shaari K, Safri S, Abas F, Lajis NH, Israf DA
    Nat Prod Res, 2006 May 10;20(5):415-9.
    PMID: 16644538
    The leaves of Melicope ptelefolia (Rutaceae) afforded a new acetophenone named 2,4,6-trihydroxy-3-geranylacetophenone. The structure of the compound was established by mass and NMR spectroscopy.
  11. Komala I, Rahmani M, Sukari MA, Mohd Ismail HB, Cheng Lian GE, Rahmat A
    Nat Prod Res, 2006 Apr;20(4):355-60.
    PMID: 16644530
    Investigation on the leaves of Melicope bonwickii (F.Muell.) T.Hartley (Rutaceae) afforded a new 7-(2'-hydroxy-3'-chloroprenyloxy)-4-methoxyfuroquinoline (1) together with the known 7-(2',3'-epoxyprenyloxy)-4-methoxyfuroquinoline (2), evellerine (3) kokusaginine (4) and an amide aurantiamide acetate (5). Compounds 1 and 2 showed significant activity against cervical cell lines (Hela).
  12. Awang K, Mukhtar MR, Hadi AH, Litaudon M, Latip J, Abdullah NR
    Nat Prod Res, 2006 May 20;20(6):567-72.
    PMID: 16835089
    The alkaloidal extract of the leaves of Phoebe grandis (nees) merr. have provided two new minor alkaloids; phoebegrandine D (1), a proaporphine-tryptamine dimer, and phoebegrandine E (2), an indoloquinolizidine. This is the first report on the occurrence of an indoloquinolizidine in the Phoebe species. The crude extract also exhibited antiplasmodial activity (IC50<8 microg mL-1). The structures of the novel compounds were elucidated by spectroscopic methods, notably 2D NMR and HRMS.
  13. Asmah Susidarti R, Rahmani M, Ismail HB, Sukari MA, Yun Hin TY, Ee Cheng Lian G, et al.
    Nat Prod Res, 2006 Feb;20(2):145-51.
    PMID: 16319008
    A new coumarin, 8,4''-dihydroxy-3'',4''-dihydrocapnolactone-2',3'-diol (1) and two known triterpenes, 5(6)-gluten-3-one (2) and 5(6)-gluten-3alpha-ol (3) were isolated from the leaves of Micromelum minutum (Rutaceae) collected from Sepilok, Sabah, Malaysia and their structures were characterized by spectroscopic methods.
  14. 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.
  15. Gomaa MN, Soliman K, Ayesh A, Abd El-Wahed A, Hamza Z, Mansour HM, et al.
    Nat Prod Res, 2016;30(6):729-34.
    PMID: 26186031 DOI: 10.1080/14786419.2015.1040991
    The marine soft corals Sarcophyton trocheliophorum crude extracts possessed antimicrobial activity towards pathogenic bacterial strains, i.e. Bacillus cereus, Salmonella typhi, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Bioassay-guided fractionation indicated that the antimicrobial effect was due to the presence of terpenoid bioactive derivatives. Further biological assays of the n-hexane fractions were carried out using turbidity assay, inhibition zone assay and minimum inhibitory concentration for investigating the growth-inhibition effect towards the Gram-positive and Gram-negative bacteria. The fractions were screened and the structure of the isolated compound was justified by interpretation of the spectroscopic data, mainly mass spectrometry (GC-MS). The structure was assigned as (5S)-3-[(3E,5S)-5-hydroxy-3-hepten-6-yn-1-yl]-5-methyl-2(5H)-furanone and was effective at concentrations as low as 0.20 mg/mL. The above findings, in the course of our ongoing research on marine products, may implicate that the profound anti-microbial activity of the S. trocheliophorum soft corals, inhabiting the red sea reefs, is attributed to the presence of growth-inhibiting secondary metabolites mainly terpenoids.
  16. Murugan K, Sanoopa CP, Madhiyazhagan P, Dinesh D, Subramaniam J, Panneerselvam C, et al.
    Nat Prod Res, 2016 Apr;30(7):826-33.
    PMID: 26284510 DOI: 10.1080/14786419.2015.1074230
    Aedes aegypti is a primary vector of dengue, a mosquito-borne viral disease infecting 50-100 million people every year. Here, we biosynthesised mosquitocidal silver nanoparticles (AgNP) using the aqueous leaf extract of Crotalaria verrucosa. The green synthesis of AgNP was studied by UV-vis spectroscopy, SEM, EDX and FTIR. C. verrucosa-synthesised AgNPs were toxic against A. aegypti larvae and pupae. LC50 of AgNP ranged from 3.496 ppm (I instar larvae) to 17.700 ppm (pupae). Furthermore, we evaluated the predatory efficiency of dragonfly nymphs, Brachydiplax sobrina, against II and III instar larvae of A. aegypti in an aquatic environment contaminated with ultra-low doses of AgNP. Under standard laboratory conditions, predation after 24 h was 87.5% (II) and 54.7% (III). In an AgNP-contaminated environment, predation was 91 and 75.5%, respectively. Overall, C. verrucosa-synthesised AgNP could be employed at ultra-low doses to reduce larval population of dengue vectors enhancing predation rates of dragonfly nymphs.
  17. Yap AC, Chan KG, Sim KS, Choo YM
    Nat Prod Res, 2016 Apr;30(7):783-8.
    PMID: 26252083 DOI: 10.1080/14786419.2015.1065492
    Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.
  18. Jamila N, Khan N, Khan I, Khan AA, Khan SN
    Nat Prod Res, 2016 Jun;30(12):1388-97.
    PMID: 26158779 DOI: 10.1080/14786419.2015.1060594
    The dichloromethane bark extract of Garcinia hombroniana yielded one new cycloartane triterpene; (22Z,24E)-3β-hydroxycycloart-14,22,24-trien-26-oic acid (1) together with five known compounds: garcihombronane G (2), garcihombronane J (3), 3β acetoxy-9α-hydroxy-17,14-friedolanostan-14,24-dien-26-oic acid (4), (22Z, 24E)-3β, 9α-dihydroxy-17,14-friedolanostan-14,22,24-trien-26-oic acid (5) and 3β, 23α-dihydroxy-17,14-friedolanostan-8,14,24-trien-26-oic acid (6). Their structures were established by the spectral techniques of NMR and ESI-MS. These compounds together with some previously isolated compounds; garcihombronane B (7), garcihombronane D (8) 2,3',4,5'-tetrahydroxy-6-methoxybenzophenone (9), volkensiflavone (10), 4''-O-methyll-volkensiflavone (11), volkensiflavone-7-O-glucopyranoside (12), volkensiflavone-7-O-rhamnopyranoside (13), Morelloflavone (14), 3''-O-methyl-morelloflavone (15) and morelloflavone-7-O-glucopyranoside (16) were evaluated for cholinesterase enzymes inhibitory activities using acetylcholinesterase and butyrylcholinesterase. In these activities, compounds 1-9 showed good dual inhibition on both the enzymes while compounds 10-16 did not reasonably contribute to both the cholinesterases inhibitory effects.
  19. Chong FC, Gwee XF
    Nat Prod Res, 2015;29(15):1485-7.
    PMID: 25836369 DOI: 10.1080/14786419.2015.1027892
    The ultrasonic extraction (UE) method of anthocyanin from Clitoria ternatea flowers using response surface methodology (RSM) was performed in this study. By using RSM, the objective is to optimise the extraction yield of anthocyanin from C. ternatea which is influenced by various factors, including the extraction temperature, time, ratio of solvent to solid and ultrasonic power. The empirical model was investigated by performing first-level optimisation in a two-level factorial design with Design Expert 7 software. In comparison with the conventional solvent extraction, UE showed a 246.48% better extraction yield and produced an anthocyanin extract with a radical scavenging activity of 68.48% at the optimised factors of 50°C, 150 min, 15 mL/g and 240 W.
  20. Ramli I, Kamarulzaman NH, Shaari K, Ee GC
    Nat Prod Res, 2004 Aug;18(4):289-94.
    PMID: 15214478
    Leaf extracts of Melicope lunu-ankenda were chemically studied and found to contain mixtures of hydrocarbons and squalene, fatty acids and esters. A geranylated coumaric acid was isolated as the major compound. The crude dichloromethane and methanol extracts of the leaves were found to be strongly larvicidal with LC50 values below 20 microg mL(-1). This is a first isolation of p-O-geranylcoumaric acid from this plant.
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