Displaying publications 61 - 80 of 166 in total

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  1. Fulltext Neonaucline, a new indole alkaloid from the leaves of Ochreinauclea maingayii (Hook. f.) Ridsd. (Rubiaceae)
    Muktar MR, Osman N, Awang K, Hazni H, Qureshi AK, Hadi AH, et al.
    Molecules, 2011 Dec 28;17(1):267-74.
    PMID: 22205092 DOI: 10.3390/molecules17010267
    A new indole alkaloid; neonaucline (1), along with six known compounds-Cadamine (2), naucledine (3), harmane, benzamide, cinnamide and blumenol A-were isolated from the leaves of Ochreinauclea maingayii (Rubiaceae). In addition to that of compound 1, (13)C-NMR data of cadamine (2) and naucledine (3) were also reported. Structural elucidations of these alkaloids were performed using spectroscopic methods especially 1D- and 2D-NMR, IR, UV and LCMS-IT-TOF. The excellent vasorelaxant activity on isolated rat aorta was observed for the alkaloids 1-3 after injection of each sample at 1 × 10(-5) M.
  2. Fulltext Cyclization vs. cyclization/dimerization in o-amidostilbene radical cation cascade reactions: the amide question
    Kee CH, Ariffin A, Awang K, Noorbatcha I, Takeya K, Morita H, et al.
    Molecules, 2011 Aug 25;16(9):7267-87.
    PMID: 21869754 DOI: 10.3390/molecules16097267
    The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl(3) promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline.
  3. 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.
  4. Fulltext The apoptotic effect of 1's-1'-acetoxychavicol acetate from Alpinia conchigera on human cancer cells
    Awang K, Azmi MN, Aun LI, Aziz AN, Ibrahim H, Nagoor NH
    Molecules, 2010 Nov;15(11):8048-59.
    PMID: 21063268 DOI: 10.3390/molecules15118048
    1'-(S)-1'-Acetoxychavicol acetate (ACA) isolated from the Malaysian ethno-medicinal plant Alpinia conchigera Griff. was investigated for its potential as an anticancer drug. In this communication, we describe the cytotoxic and apoptotic properties of ACA on five human tumour cell lines. Data from MTT cell viability assays indicated that ACA induced both time- and dose-dependent cytotoxicity on all tumour cell lines tested and had no adverse cytotoxic effects on normal cells. Total mortality of the entire tumour cell population was achieved within 30 hrs when treated with ACA at 40.0 µM concentration. Flow cytometric analysis for annexin-V and PI dual staining demonstrated that cell death occurred via apoptosis, followed by secondary necrosis. The apoptotic effects of ACA were confirmed via the DNA fragmentation assay, in which consistent laddering of genomic DNA was observed for all tumour cell lines after a 24 hrs post-treatment period at the IC(50) concentration of ACA. A cell cycle analysis using PI staining also demonstrated that ACA induced cell cycle arrest at the G(0)/G(1) phase, corresponding to oral tumour cell lines. In conclusion, ACA exhibits enormous potential for future development as a chemotherapeutic drug against various malignancies.
  5. Fulltext Anthraquinones with antiplasmodial activity from the roots of Rennellia elliptica Korth. (Rubiaceae)
    Osman CP, Ismail NH, Ahmad R, Ahmat N, Awang K, Jaafar FM
    Molecules, 2010;15(10):7218-26.
    PMID: 20966871 DOI: 10.3390/molecules15107218
    Dichloromethane root extract of Rennellia elliptica Korth. showed strong inhibition of Plasmodium falciparum growth in vitro with an IC₅₀ value of 4.04 µg/mL. A phytochemical study of the dichloromethane root extract has led to the isolation and characterization of a new anthraquinone, 1,2-dimethoxy-6-methyl-9,10-anthraquinone (1), and ten known anthraquinones: 1-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (2), nordamnacanthal (3), 2-formyl-3-hydroxy-9,10-anthraquinone (4), damnacanthal (5), lucidin-ω-methyl ether (6), 3-hydroxy-2-methyl-9,10-anthraquinone (7), rubiadin (8), 3-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (9), rubiadin-1-methyl ether (10) and 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone (11). Structural elucidation of all compounds was accomplished by modern spectroscopic methods, notably 1D and 2D NMR, IR, UV and HREIMS. The new anthraquinone 1, 2-formyl-3-hydroxy-9,10-anthraquinone (4) and 3-hydroxy-2-methyl-9,10-anthraquinone (7) possess strong antiplasmodial activity, with IC₅₀ values of 1.10, 0.63 and 0.34 µM, respectively.
  6. Fulltext Alkaloids from Fissistigma latifolium (Dunal) Merr
    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.
  7. 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.
  8. Fulltext Deoxyelephantopin from Elephantopus scaber Inhibits HCT116 Human Colorectal Carcinoma Cell Growth through Apoptosis and Cell Cycle Arrest
    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.
  9. Fulltext Quorum Sensing Inhibitory Activity of Giganteone A from Myristica cinnamomea King against Escherichia coli Biosensors
    Sivasothy Y, Krishnan T, Chan KG, Abdul Wahab SM, Othman MA, Litaudon M, et al.
    Molecules, 2016 Mar 21;21(3):391.
    PMID: 27102164 DOI: 10.3390/molecules21030391
    Malabaricones A-C (1-3) and giganteone A (4) were isolated from the bark of Myristica cinnamomea King. Their structures were elucidated and characterized by means of NMR and MS spectral analyses. These isolates were evaluated for their anti-quorum sensing activity using quorum sensing biosensors, namely Escherichia coli [pSB401] and Escherichia coli [pSB1075], whereby the potential of giganteone A (4) as a suitable anti-quorum sensing agent was demonstrated.
  10. Fulltext Alkyl-Resorcinol Derivatives as Inhibitors of GDP-Mannose Pyrophosphorylase with Antileishmanial Activities
    Levaique H, Pamlard O, Apel C, Bignon J, Arriola M, Kuhner R, et al.
    Molecules, 2021 Mar 11;26(6).
    PMID: 33799883 DOI: 10.3390/molecules26061551
    Leishmaniasis is a vector-borne disease caused by the protozoan parasite Leishmania found in tropical and sub-tropical areas, affecting 12 million people around the world. Only few treatments are available against this disease and all of them present issues of toxicity and/or resistance. In this context, the development of new antileishmanial drugs specifically directed against a therapeutic target appears to be a promising strategy. The GDP-Mannose Pyrophosphorylase (GDP-MP) has been previously shown to be an attractive therapeutic target in Leishmania. In this study, a chemical library of 5000 compounds was screened on both L. infantum (LiGDP-MP) and human (hGDP-MP) GDP-MPs. From this screening, oncostemonol D was found to be active on both GDP-MPs at the micromolar level. Ten alkyl-resorcinol derivatives, of which oncostemonols E and J (2 and 3) were described for the first time from nature, were then evaluated on both enzymes as well as on L. infantum axenic and intramacrophage amastigotes. From this evaluation, compounds 1 and 3 inhibited both GDP-MPs at the micromolar level, and compound 9 displayed a three-times lower IC50 on LiGDP-MP, at 11 µM, than on hGDP-MP. As they displayed mild activities on the parasite, these compounds need to be further pharmacomodulated in order to improve their affinity and specificity to the target as well as their antileishmanial activity.
  11. Fulltext Cytotoxic Effects of Pinnatane A Extracted from Walsura pinnata (Meliaceae) on Human Liver Cancer Cells
    Zakaria N, Mahdzir MA, Yusoff M, Mohd Arshad N, Awang K, Nagoor NH
    Molecules, 2018 Oct 23;23(11).
    PMID: 30360475 DOI: 10.3390/molecules23112733
    BACKGROUND: Pinnatane A from the bark of Walsura pinnata was investigated for its anti-cancer properties by analyzing the cytotoxic activities and cell cycle arrest mechanism induced in two different liver cancer cell lines.

    METHODS: A 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to analyze the pinnatane A selectivity in inducing cell death in cancer and normal cells. Various biological assays were carried out to analyze the anti-cancer properties of pinnatane A, such as a live/dead assay for cell death microscopic visualization, cell cycle analysis using propidium iodide (PI) to identify the cell cycle arrest phase, annexin V-fluorescein isothiocyanate (annexin V-FITC)/PI flow cytometry assay to measure percentage of cell populations at different stages of apoptosis and necrosis, and DNA fragmentation assay to verify the late stage of apoptosis.

    RESULTS: The MTT assay identified pinnatane A prominent dose- and time-dependent cytotoxicity effects in Hep3B and HepG2 cells, with minimal effect on normal cells. The live/dead assay showed significant cell death, while cell cycle analysis showed arrest at the G₀/G₁ phase in both cell lines. Annexin V-FITC/PI flow cytometry and DNA fragmentation assays identified apoptotic cell death in Hep3B and necrotic cell death in HepG2 cell lines.

    CONCLUSIONS: Pinnatane A has the potential for further development as a chemotherapeutic agent prominently against human liver cells.

  12. Fulltext Cytotoxic and antioxidant compounds from the stem bark of Goniothalamus tapisoides Mat Salleh
    Kim RP, Bihud V, Bin Mohamad K, Leong KH, Bin Mohamad J, Bin Ahmad F, et al.
    Molecules, 2012 Dec 21;18(1):128-39.
    PMID: 23344192 DOI: 10.3390/molecules18010128
    Eleven compounds:goniomicin A (1), goniomicin B (2), goniomicin C (3), goniomicin D (4), tapisoidin (5), goniothalamin (6), 9-deoxygoniopypyrone (7), pterodondiol (8), liriodenine (9), benzamide (10) and cinnamic acid (11), were isolated from the stem bark of Goniothalamus tapisoides. All compounds were identified by spectroscopic analysis and, for known compounds, by comparison with published data. Goniothalamin (6) exhibited mild cytotoxic activity towards a colon cancer cell line (HT-29), with an IC(50)value of 64.17 ± 5.60 µM. Goniomicin B (2) give the highest antioxidant activity in the DPPH assay among all compounds tested, with an IC(50) of 0.207 µM.
  13. Fulltext (+)-Kunstlerone, a new antioxidant neolignan from the Leaves of Beilschmiedia kunstleri gamble
    Mollataghi A, Hadi AH, Awang K, Mohamad J, Litaudon M, Mukhtar MR
    Molecules, 2011 Aug 04;16(8):6582-90.
    PMID: 21818061 DOI: 10.3390/molecules16086582
    A new neolignan, 3,4-dimethoxy-3',4'-methylenedioxy-2,9-epoxy-6,7-cyclo-1,8-neolign-11-en-5(5H)-one, which has been named (+)-kunstlerone (1), together with six known alkaloids: (+)-norboldine (2), (+)-N-methylisococlaurine (3), (+)-cassythicine (4), (+)-laurotetanine (5), (+)-boldine (6) and (-)-pallidine (7), were isolated from the leaves of Beilschmiedia kunstleri. The structures were established through various spectroscopic methods notably 1D- and 2D-NMR, UV, IR and LCMS-IT-TOF. (+)- Kunstlerone (1) showed a strong antioxidant activity, with an SC(50) of 20.0 µg/mL.
  14. 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.
  15. Fulltext Antidiabetic and antioxidant properties of alkaloids from Catharanthus roseus (L.) G. Don
    Tiong SH, Looi CY, Hazni H, Arya A, Paydar M, Wong WF, et al.
    Molecules, 2013 Aug 15;18(8):9770-84.
    PMID: 23955322 DOI: 10.3390/molecules18089770
    Catharanthus roseus (L.) G. Don is a herbal plant traditionally used by local populations in India, South Africa, China and Malaysia to treat diabetes. The present study reports the in vitro antioxidant and antidiabetic activities of the major alkaloids isolated from Catharanthus roseus (L.) G. Don leaves extract. Four alkaloids--vindoline I, vindolidine II, vindolicine III and vindolinine IV--were isolated and identified from the dichloromethane extract (DE) of this plant's leaves. DE and compounds I-III were not cytotoxic towards pancreatic β-TC6 cells at the highest dosage tested (25.0 µg/mL). All four alkaloids induced relatively high glucose uptake in pancreatic β-TC6 or myoblast C2C12 cells, with III showing the highest activity. In addition, compounds II-IV demonstrated good protein tyrosine phosphatase-1B (PTP-1B) inhibition activity, implying their therapeutic potential against type 2 diabetes. III showed the highest antioxidant potential in ORAC and DPPH assays and it also alleviated H₂O₂-induced oxidative damage in β-TC6 cells at 12.5 µg/mL and 25.0 µg/mL.
  16. Fulltext Synthesis, crystal structure, DFT studies and evaluation of the antioxidant activity of 3,4-dimethoxybenzenamine schiff bases
    Aziz AN, Taha M, Ismail NH, Anouar el H, Yousuf S, Jamil W, et al.
    Molecules, 2014 Jun 19;19(6):8414-33.
    PMID: 24950444 DOI: 10.3390/molecules19068414
    Schiff bases of 3,4-dimethoxybenzenamine 1-25 were synthesized and evaluated for their antioxidant activity. All the synthesized compounds were characterized by various spectroscopic techniques. In addition, the characterizations of compounds 13, 15 and 16 were supported by crystal X-ray determinations and their geometrical parameters were compared with theoretical DFT calculations at the B3LYP level of theory. Furthermore, the X-ray crystal data of two non-crystalline compounds 8 and 18 were theoretically calculated and compared with the practical values of compounds 13, 15, 16 and found a good agreement. The compounds showed good DPPH scavenging activity ranging from 10.12 to 84.34 μM where compounds 1-4 and 6 showed stronger activity than the standard n-propyl gallate. For the superoxide anion radical assay, compounds 1-3 showed better activity than the standard.
  17. Acridone alkaloids from Glycosmis chlorosperma as DYRK1A inhibitors
    Beniddir MA, Le Borgne E, Iorga BI, Loaëc N, Lozach O, Meijer L, et al.
    J Nat Prod, 2014 May 23;77(5):1117-22.
    PMID: 24798019 DOI: 10.1021/np400856h
    Two new acridone alkaloids, chlorospermines A and B (1 and 2), were isolated from the stem bark of Glycosmis chlorosperma, together with the known atalaphyllidine (3) and acrifoline (4), by means of bioguided isolation using an in vitro enzyme assay against DYRK1A. Acrifoline (4) and to a lesser extent chlorospermine B (2) and atalaphyllidine (3) showed significant inhibiting activity on DYRK1A with IC50's of 0.075, 5.7, and 2.2 μM, respectively. Their selectivity profile was evaluated against a panel of various kinases, and molecular docking calculations provided structural details for the interaction between these compounds and DYRK1A.
  18. Chisomicines A-C, limonoids from Chisocheton ceramicus
    Najmuldeen IA, Hadi AH, Awang K, Mohamad K, Ketuly KA, Mukhtar MR, et al.
    J Nat Prod, 2011 May 27;74(5):1313-7.
    PMID: 21428417 DOI: 10.1021/np200013g
    Three new limonoids, chisomicines A-C (1-3), have been isolated from the bark of Chisocheton ceramicus. Their structures were determined by 2D NMR, CD spectroscopic methods, and X-ray analysis. Chisomicine A (1) exhibited NO production inhibitory activity in J774.1 cells stimulated by LPS dose-dependently at high cell viability.
  19. Malabaricone C from Myristica cinnamomea exhibits anti-quorum sensing activity
    Chong YM, Yin WF, Ho CY, Mustafa MR, Hadi AH, Awang K, et al.
    J Nat Prod, 2011 Oct 28;74(10):2261-4.
    PMID: 21910441 DOI: 10.1021/np100872k
    A methanol-soluble extract of the bark of Myristica cinnamomea was found to exhibit anti-quorum sensing activity, and subsequent bioassay-guided isolation led to the identification of the active compound malabaricone C (1). Compound 1 inhibited violacein production by Chromobacterium violaceum CV026 when grown in the presence of a cognate signaling molecule, N-3-oxohexanoyl-homoserine lactone. Furthermore, 1 inhibited the quorum sensing-regulated pyocyanin production and biofilm formation in Pseudomonas aeruginosa PAO1. These results suggest that the anti-quorum sensing activity of 1 and related molecules should be investigated further.
  20. Rearranged diterpenoids from the biotransformation of ent-trachyloban-18-oic acid by Rhizopus arrhizus
    Leverrier A, Martin MT, Servy C, Ouazzani J, Retailleau P, Awang K, et al.
    J Nat Prod, 2010 Jun 25;73(6):1121-5.
    PMID: 20481544 DOI: 10.1021/np100145n
    In our search for inhibitors of the antiapoptotic protein Bcl-xL, investigation of Xylopia caudata afforded a new diterpenoid, ent-trachyloban-4beta-ol (2), and five known ent-trachylobane or ent-atisane compounds. Only ent-trachyloban-18-oic acid (1) exhibited weak binding activity to Bcl-xL. These compounds exhibited cytotoxicity against KB and HCT-116 cell lines with IC(50) values between 10 and 30 microM. Bioconversion of compound 1 by Rhizopus arrhizus afforded new hydroxylated metabolites (3-7) of the ent-trachylobane and ent-kaurene type and compound 8, with a rearranged pentacyclic carbon framework that was named rhizopene. Compounds 3-8 were noncytotoxic to the two cancer cell lines, and compounds 3 and 5 exhibited only weak binding affinity for Bcl-xL.
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