Displaying publications 1 - 20 of 25 in total

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  1. Sim DS, Teoh WY, Sim KS, Lim SH, Thomas NF, Low YY, et al.
    J Nat Prod, 2016 Apr 22;79(4):1048-55.
    PMID: 26918761 DOI: 10.1021/acs.jnatprod.5b01117
    Six new bisindole alkaloids of the iboga-vobasine type, vobatensines A-F (1-6), in addition to four known bisindoles (8-11), were isolated from a stem bark extract of a Malayan Tabernaemontana corymbosa. The structures of these alkaloids were determined based on analysis of the spectroscopic data and in the case of vobatensines A (1), B (2), and 16'-decarbomethoxyvoacamine (8) also confirmed by partial syntheses. Nine of these alkaloids (1-5, 8-11) showed pronounced in vitro growth inhibitory activity against human KB, PC-3, LNCaP, HCT 116, HT-29, MCF7, MDA-MB-231, and A549 cancer cells.
    Matched MeSH terms: Tabernaemontana
  2. Zhong X, Li Y, Zhang J, Han FS
    Org. Lett., 2015 Feb 6;17(3):720-3.
    PMID: 25602274 DOI: 10.1021/ol503734x
    The synthesis of a pentacyclic indole compound corresponding to the core structure of the misassigned indole alkaloid, tronoharine (1), is presented. The key reactions were a formal [3 + 3] cycloaddition of an indol-2-yl carbinol with an azadiene for the construction of the 6/5/6/6 tetracyclic system containing an all-carbon quaternary center and an intramolecular substitution reaction of an amine and a triflate for the creation of the bridged azepine ring. In addition, some other interesting transformations discovered during the synthetic studies are also discussed.
    Matched MeSH terms: Tabernaemontana/chemistry
  3. Nge CE, Gan CY, Low YY, Thomas NF, Kam TS
    Org. Lett., 2013 Sep 20;15(18):4774-7.
    PMID: 23991636 DOI: 10.1021/ol4021404
    Two new indole alkaloids, voatinggine (1) and tabertinggine (2), which are characterized by previously unencountered natural product skeletons, were isolated from a Malayan Tabernaemontana species. The structures and absolute configuration of these alkaloids were determined using NMR and MS analysis, and X-ray diffraction analysis. A possible biogenetic pathway to these novel alkaloids from an iboga precursor, and via a common cleavamine-type intermediate, is presented.
    Matched MeSH terms: Tabernaemontana/chemistry*
  4. Lim KH, Sim KM, Tan GH, Kam TS
    Phytochemistry, 2009 Jun;70(9):1182-1186.
    PMID: 19643450 DOI: 10.1016/j.phytochem.2009.06.010
    Four tetracyclic oxindole alkaloids, 7(R)- and 7(S)-geissoschizol oxindole (1 and 2), 7(R),16(R)- and 7(S),16(R)-19(E)-isositsirikine oxindole (3 and 4), in addition to a taberpsychine derivative, N(4)-demethyltaberpsychine (5), were isolated from the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis.
    Matched MeSH terms: Tabernaemontana/chemistry*
  5. Kam TS, Pang HS, Lim TM
    Org Biomol Chem, 2003 Apr 21;1(8):1292-7.
    PMID: 12929658
    The ethanol extract of the leaves of Tabernaemontana divaricata (double flower variety) provided a total of 23 alkaloids, including the new aspidosperma alkaloids, taberhanine, voafinine, N-methylvoafinine, voafinidine, voalenine and the new bisindole alkaloid, conophyllinine in addition to the previously known, biologically active bisindole, conophylline and its congener, conofoline. The structures of the new alkaloids were established by spectroscopic methods. The preparation and characterization of the corresponding quinones of the biologically active bisindoles are also described in relation to a structure-activity study of these compounds with respect to their action in stimulating insulin expression.
    Matched MeSH terms: Tabernaemontana/chemistry*
  6. Nge CE, Sim KS, Lim SH, Thomas NF, Low YY, Kam TS
    J Nat Prod, 2016 10 28;79(10):2709-2717.
    PMID: 27759387
    Examination of the EtOH extract of the Malayan Tabernaemontana corymbosa resulted in the isolation of three new alkaloids, viz., cononuridine (1), an unusual hexacyclic, iboga-derived, monoterpenoid indole characterized by contraction of the tetrahydroazepine C-ring and incorporation of an additional isoxazolidine ring, taberisidine (2), a seco-corynanthean alkaloid, and conofolidine (3), an Aspidosperma-Aspidosperma bisindole that showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, and HCT 116 cells. The structures and absolute configurations of 1 and 3 and the absolute configuration of the novel pyridopyrimidine indole alkaloid vernavosine (4) were confirmed by X-ray diffraction analysis. A reasonable biosynthesis route to cononuridine starting from an iboga precursor is presented.
    Matched MeSH terms: Tabernaemontana/chemistry
  7. Nge CE, Gan CY, Lim KH, Ting KN, Low YY, Kam TS
    Org. Lett., 2014 Dec 19;16(24):6330-3.
    PMID: 25454201 DOI: 10.1021/ol503072g
    Two new indole alkaloids characterized by previously unencountered natural product skeletons, viz., criofolinine (1), incorporating a pyrroloazepine motif within a pentacyclic ring system, and vernavosine (2, isolated as its ethyl ether derivative 3, which on hydrolysis regenerated the putative precursor alkaloid 2), incorporating a pyridopyrimidine moiety embedded within a pentacyclic carbon framework, were isolated from a Malayan Tabernaemontana species. The structures and absolute configuration of these alkaloids were determined on the basis of NMR and MS analysis and confirmed by X-ray diffraction analysis.
    Matched MeSH terms: Tabernaemontana/chemistry*
  8. Lim KH, Hiraku O, Komiyama K, Kam TS
    J Nat Prod, 2008 Sep;71(9):1591-4.
    PMID: 18778099 DOI: 10.1021/np800435c
    Seven new indole alkaloids of the Aspidosperma type, jerantinines A-G (1-7), were isolated from a leaf extract of the Malayan Tabernaemontana corymbosa. The structures were established using NMR and MS analysis. Five of the alkaloids isolated and two derivatives (1-5, 8, 9) displayed pronounced in vitro cytotoxicity against human KB cells (IC50 < 1 microg/mL).
    Matched MeSH terms: Tabernaemontana/chemistry*
  9. Lim KH, Thomas NF, Abdullah Z, Kam TS
    Phytochemistry, 2009 Feb;70(3):424-9.
    PMID: 19217125 DOI: 10.1016/j.phytochem.2009.01.001
    Two seco-tabersonine alkaloids, jerantiphyllines A and B, in addition to a tabersonine hydroxyindolenine, jerantinine H, and a recently reported vincamine alkaloid 7, were isolated from the leaf extract of the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis. Biomimetic conversion of jerantinines A and E to their respective vincamine and 16-epivincamine derivatives were also carried out.
    Matched MeSH terms: Tabernaemontana/chemistry*
  10. Kam TS, Sim KM
    Phytochemistry, 2003 Jul;63(5):625-9.
    PMID: 12809725
    Four bisindole alkaloids, viz., 19'(S)-hydroxyconodurine, conodurinine, 19'(S)-hydroxyconoduramine, and 19'(S)-hydroxyervahanine A, in addition to conodurine and ervahanine A, were obtained from the leaf and stem-bark extracts of Tabernaemontana corymbosa. The structures of the new alkaloids were determined using NMR and MS analysis.
    Matched MeSH terms: Tabernaemontana/chemistry*
  11. Kam TS, Sim KM
    J Nat Prod, 2002 May;65(5):669-72.
    PMID: 12027738
    Five new indole alkaloids of the ibogan type (1-5), in addition to 12 other known iboga alkaloids, were obtained from the leaf and stem-bark extract of the Malayan species Tabernaemontana corymbosa, viz., 19(S)-hydroxyibogamine (1), 19-epi-isovoacristine (2), isovoacryptine (3), 3R/S-ethoxyheyneanine (4), and 3R/S-ethoxy-19-epi-heyneanine (5). The structures were determined using NMR and MS analysis and comparison with known related compounds.
    Matched MeSH terms: Tabernaemontana/chemistry*
  12. Kam TS, Sim KM, Pang HS
    J Nat Prod, 2003 Jan;66(1):11-6.
    PMID: 12542336
    Ten new bisindole alkaloids of the vobasinyl-ibogan type, viz., conodiparines A-F (1-6), conodutarines A and B (7, 8), and cononitarines A and B (9, 10), were obtained from the leaf extract of the Malayan species Tabernaemontana corymbosa. The structures were determined using NMR and MS analysis.
    Matched MeSH terms: Tabernaemontana/chemistry*
  13. Sim DS, Navanesan S, Sim KS, Gurusamy S, Lim SH, Low YY, et al.
    J Nat Prod, 2019 04 26;82(4):850-858.
    PMID: 30869890 DOI: 10.1021/acs.jnatprod.8b00919
    Examination of the EtOH extract of the leaves of the Malayan Tabernaemontana corymbosa resulted in the isolation of four new (1-4) and two known bisindole alkaloids (5, 6) of the Aspidosperma- Aspidosperma type. The structures of these alkaloids were determined based on analysis of the spectroscopic data (NMR and HRESIMS). X-ray diffraction analyses of the related bisindole alkaloids conophylline (5) and conophyllinine (6) established the absolute configurations. Treatment of the bisindole alkaloid conophylline (5) with benzeneselenic anhydride gave, in addition to the known bisindole polyervinine (7) previously isolated from another Malayan Tabernaemontana, another bisindole product, 8, an isolable tautomer of 7. X-ray diffraction analyses yielded the absolute configurations of both bisindoles and in addition showed that polyervinine (7) exists primarily as the neutral dione structure. The bisindoles (1-8) and the related conophylline-type bisindoles (9-13) showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, A549, HT-29, and HCT 116 cells, with IC50 values for the active compounds in the 0.01-5 μM range.
    Matched MeSH terms: Tabernaemontana/chemistry*
  14. Kam TS, Pang HS, Choo YM, Komiyama K
    Chem Biodivers, 2004 Apr;1(4):646-56.
    PMID: 17191876
    Six new indole alkaloids, viz., (3S)-3-cyanocoronaridine (2), (3S)-3-cyanoisovoacangine (3), conolobine A (5), conolobine B (6), conolidine (7), and (3R/3S)-3-ethoxyvoacangine (8), in addition to 36 known ones, were obtained from the stem-bark extract of the Malayan Tabernaemontana divaricata. The structures were determined by NMR and MS analysis. The CN-substituted alkaloids showed appreciable cytotoxicity towards the KB human oral epidermoid carcinoma cell-line.
    Matched MeSH terms: Tabernaemontana*
  15. Mohamad S, Ismail NN, Parumasivam T, Ibrahim P, Osman H, A Wahab H
    BMC Complement Altern Med, 2018 Jan 08;18(1):5.
    PMID: 29310671 DOI: 10.1186/s12906-017-2077-5
    BACKGROUND: Costus speciosus, Cymbopogon citratus, and Tabernaemontana coronaria are herbal plants traditionally used as remedies for symptoms of tuberculosis (TB) including cough. The aims of the present study were to evaluate the in vitro anti-TB activity of different solvent partitions of these plants, to identify the phytochemical compounds, and to assess the effects of the most active partitions on the growth kinetics and cellular integrity of the tubercle organism.

    METHODS: The in vitro anti-TB activity of different solvent partitions of the plant materials was determined against M. tuberculosis H37Rv using a tetrazolium colorimetric microdilution assay. The phytochemical compounds in the most active partition of each plant were identified using gas chromatography-mass spectrometry (GC-MS) analysis. The effects of these partitions on the growth kinetics of the mycobacteria were evaluated over 7-day treatment period in a batch culture system. Their effects on the mycobacterial cellular integrity were observed under a scanning electron microscope (SEM).

    RESULTS: The respective n-hexane partition of C. speciosus, C. citratus, and T. coronaria exhibited the highest anti-TB activity with minimum inhibitory concentrations (MICs) of 100-200 μg/mL and minimum bactericidal concentration (MBC) of 200 μg/mL. GC-MS phytochemical analysis of these active partitions revealed that majority of the identified compounds belonged to lipophilic fatty acid groups. The active partitions of C. speciosus and T. coronaria exhibited high cidal activity in relation to time, killing more than 99% of the cell population. SEM observations showed that these active plant partitions caused multiple structural changes indicating massive cellular damages.

    CONCLUSIONS: The n-hexane partition of the plant materials exhibited promising in vitro anti-TB activity against M. tuberculosis H37Rv. Their anti-TB activity was supported by their destructive effects on the integrity of the mycobacterial cellular structure.

    Matched MeSH terms: Tabernaemontana/chemistry*
  16. Abubakar IB, Lim KH, Kam TS, Loh HS
    J Ethnopharmacol, 2016 May 26;184:107-18.
    PMID: 26947901 DOI: 10.1016/j.jep.2016.03.004
    The genus Tabernaemontana has widespread distribution throughout tropical and subtropical parts of the world, i.e. Africa, Asia and America which has long been used for treatments of different disease conditions including tumours, wounds, syphilis, stomach ache and headache. Some Tabernaemontana species are used for treatment of piles, spleen and abdominal tumours in India. In particular, the leaf of Tabernaemontana corymbosa is used for treatment of tumours in Bangladesh. Parts of the plant or whole plants are used as decoctions, steam bath, powder and ointments.
    Matched MeSH terms: Tabernaemontana
  17. Heida Nadia Zulkefli, Jamaludin Mohamad, Nurhayati Zainal Abidin
    Sains Malaysiana, 2013;42:697-706.
    Tinospora crispa and Tabernaemontana corymbosa have been used traditionally to treat fever, diabetes, rheumatism and sinusitis. The objective of this study was to evaluate the antioxidant activity of Tinospora crispa and Tabernaemontana corymbosa. The presence of apigenin and magnoflorine was detected using LCMS/MS in Tinospora crispa (Patawali) whereas appararicine, voafinine, conodusarine, conodurine, voacamine and voacangine were detected in Tabernaemontana corymbosa (Susur kelapa) methanol extract. The stem extract of Tinospora crispa showed high antioxidant activity in the following order: DPPH radical scavenging, reducing power and metal chelating assay (98.8%, 0.957, 81.97%) than Tabernaemontana corymbosa of leaves (90.04%, 0.652, 69.64%), stem (82.78%, 0.819, 36.70%) and root extracts (63.25%, 0.469, 51.56%), respectively. The high antioxidant activity in the stem extract of Tinospora crispa is due to the presence of apigenin and magnoflorine. The high antioxidant activity in Tabernaemontana corymbosa extract is due to its high phenol contents. There were significant linear positive correlation (r=0.788, p<0.001, r2=0.621) between the total phenolic content and DPPH free radical scavenging assay in the crude extracts of Tinospora crispa and Tabernaemontana corymbosa. Meanwhile, a significant moderate positive correlation was observed between the total phenolic content and ferric reducing power assay (r= 0.556, p<0.05, r2= 0.309). However, there was no significant difference in the correlation coefficient of total phenolic content and metal chelating assay.
    Matched MeSH terms: Tabernaemontana
  18. Abubakar IB, Loh HS
    J Pharm Pharmacol, 2016 Apr;68(4):423-32.
    PMID: 26887962 DOI: 10.1111/jphp.12523
    OBJECTIVES: Tabernaemontana is a genus from the plant family, Apocynaceae with vast medicinal application and widespread distribution in the tropics and subtropics of Africa, Americas and Asia. The objective of this study is to critically evaluate the ethnobotany, medicinal uses, pharmacology and phytochemistry of the species, Tabernaemontana corymbosa (Roxb. ex Wall.) and provide information on the potential future application of alkaloids isolated from different parts of the plant.

    KEY FINDINGS: T. corymbosa (Roxb. ex Wall.) parts are used as poultice, boiled juice, decoctions and infusions for treatment against ulceration, fracture, post-natal recovery, syphilis, fever, tumours and orchitis in Malaysia, China, Thailand and Bangladesh. Studies recorded alkaloids as the predominant phytochemicals in addition to phenols, saponins and sterols with vast bioactivities such as antimicrobial, analgesic, anthelmintic, vasorelaxation, antiviral and cytotoxicity.

    SUMMARY: An evaluation of scientific data and traditional medicine revealed the medicinal uses of different parts of T. corymbosa (Roxb. ex Wall.) across Asia. Future studies exploring the structure-bioactivity relationship of alkaloids such as jerantinine and vincamajicine among others could potentially improve the future application towards reversing anticancer drug resistance.

    Matched MeSH terms: Tabernaemontana/chemistry*
  19. Sim DS, Chong KW, Nge CE, Low YY, Sim KS, Kam TS
    J Nat Prod, 2014 Nov 26;77(11):2504-12.
    PMID: 25333996 DOI: 10.1021/np500589u
    Seven new indole alkaloids (1-7) comprising four vobasine, two tacaman, and one corynanthe-tryptamine bisindole alkaloid were isolated from the stem-bark extract of a Malayan Tabernaemontana. Two of the new vobasine alkaloids (1, 3), as well as 16-epivobasine (15) and 16-epivobasenal (17), showed appreciable cytotoxicity toward KB cells (IC50 ca. 5 μg/mL). The structure of the known Tabernaemontana alkaloid tronoharine (8) was revised based on newly acquired NMR data, as well as X-ray diffraction analysis.
    Matched MeSH terms: Tabernaemontana/chemistry*
  20. Ali Khan MS, Mat Jais AM, Afreen A
    Biomed Res Int, 2013;2013:185476.
    PMID: 24350249 DOI: 10.1155/2013/185476
    The present study was conducted to evaluate the antiulcerogenic effect and recognize the basic mechanism of action of Tabernaemontana divaricata (L.) R. Br. flowers. T. divaricata flower methanolic extract (TDFME) was screened for antiulcer activity versus aspirin and ethanol induced gastric ulcers at three doses--125, 250, and 500 mg/kg--orally using misoprostol as a standard. Besides histopathological examination, seven parameters, that is, ulcer index, total protein, nonprotein sulphhydryls, mucin, catalase, malondialdehyde, and superoxide dismutase levels, were estimated. In addition to HPLC profiling, GC-MS analysis and electrospray ionization--high resolution mass spectral (ESI-HRMS) analysis of crude TDFME were carried out in an attempt to identify known phytochemicals present in the extract on the basis of m/z value. The results revealed a significant increase in the levels of catalase, superoxide dismutase, mucin, and nonprotein sulphhydryls, while they revealed a reduction in ulcer index, the levels of total protein, and malondialdehyde. Histopathological observations also demonstrated the protective effect. Though all the doses of TDFME exhibited gastroprotective function, higher doses were found to be more effective. Mass spectral analysis gave a few characteristic m/z values suggesting the presence of a few known indole alkaloids, while HPLC profiling highlighted the complexity of the extract. TDFME was found to exhibit its gastroprotective effect through antioxidant mechanism and by enhancing the production of gastric mucous.
    Matched MeSH terms: Tabernaemontana/chemistry*
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