Displaying publications 1 - 20 of 21 in total

  1. Kamada T, Vairappan CS
    Nat Prod Commun, 2013 Mar;8(3):287-8.
    PMID: 23678792
    A Bomean red algal population of Laurencia similis Nam et Saito was analyzed for its secondary metabolite composition. Seven compounds were identified: ent-1(10)-aristolen-9beta-ol (1), (+)-aristolone (2), axinysone B (3), 9-aristolen-1alpha-ol (4), 2,3,5,6-tetrabromoindole (5), 1-methyl-2,3,5,6-tetrabromoindole (6), and 1-methyl-2,3,5-tribromoindole (7). Compound 1 was identified as a new optical isomer of 1(10)-aristolen-9beta-ol. Compounds 1, 4 and 5 exhibited good antibacterial activity against antibiotic resistant clinical bacteria and cytotoxic effects against selected cancer cell lines.
  2. Kamada T, Vairappan CS
    Molecules, 2012 Feb 21;17(2):2119-25.
    PMID: 22354189 DOI: 10.3390/molecules17022119
    Six populations of Laurencia nangii were found to produce three bromoallenes; dihydroitomanallene B (1), itomanallene B (2) and pannosallene (3). Prior to this report, L. nangii were only known to produce C(15)-acetogenins with acetylene functionality. This could be regarded as a new chemical race of L. nangii. The compound structures were elucidated on the basis of spectroscopic analysis and comparison with those previously reported in literature. Compound 1, dihydroitomanallene B, was isolated as a new compound representing a minor variation of itomanallene B (2).
  3. Kamada T, Vairappan CS
    Nat Prod Res, 2017 Feb;31(3):333-340.
    PMID: 27707003
    Two new non-halogenated sesquiterpenes, snakeol (1) and snakediol (2) were isolated together with 9 known sesquiterpenes such as (R,Z)-33-dimethyl-5-methylene-4-(3-methylpenta-24-dien-1-yl)cyclohex-1-ene (3), palisol (4), pacifigorgiol (5), palisadin D (6), palisadin A (7), palisadin B (8), 5-acetoxypalisadin B (9), debromolaurinterol (10) and α-bromocuparane (11) from the red algae Laurencia snackeyi. The structures of two new metabolites were determined from their spectroscopic data (IR, 1D and 2D NMR and MS). Compounds 1, 2, 10 and 11 showed strong antibacterial activity against selected human clinical bacterial pathogens.
  4. Ishii T, Kamada T, Vairappan CS
    J Asian Nat Prod Res, 2016 May;18(5):415-22.
    PMID: 26983053 DOI: 10.1080/10286020.2016.1145670
    Three new cembranoid diterpenes, 10-hydroxy-nephthenol acetate (1), 7,8-epoxy-10-hydroxy-nephthenol acetate (2), and 6-acetoxy-7,8-epoxy-10-hydroxy-nephthenol acetate (3), along with a known compound, 6-acetoxy-7,8-epoxy-nephthenol acetate (4), were isolated from the Bornean soft coral Nephthea sp. Antibacterial and anticancer activities were exhibited by compounds 1 and 2 against Staphylococcus aureus (ATCC 6538)/Escherichia coli (ATCC 13311) and Hela/MCF-7, respectively.
  5. Kamada T, Phan CS, Vairappan CS
    Nat Prod Res, 2019 Feb;33(4):464-471.
    PMID: 29092618 DOI: 10.1080/14786419.2017.1396593
    Three new halogenated tricyclic sesquiterpenes, omphalaurediol (1), rhodolaurenones B (2) and C (3) were isolated together with nine known haloganated sesquiterpenes such as rhodolaurenone A (4), rhodolaureol (5), isorhodolaureol (6), (-)-laurencenone D (7), elatol (8), (+)-deschloroelatol (9), cartilagineol (10), (+)-laurencenone B (11) and 2-chloro-3-hydroxy-α-chamigren-9-one (12) from a population of Bornean red algae Laurencia majuscula. The structures of three new metabolites were determined based on their spectroscopic data (IR, 1D and 2D NMR, and MS). These compounds showed antibacterial activity against three human pathogenic bacteria (Escherichia coli, Salmonella typhi and Vibrio cholera).
  6. Kamada T, Phan CS, Vairappan CS
    J Asian Nat Prod Res, 2019 Mar;21(3):241-247.
    PMID: 29281900 DOI: 10.1080/10286020.2017.1417265
    Two new halogenated nonterpenoids C15-acetogenins, nangallenes A-B (1-2), together with two known halogenated compounds itomanallene A (3) and 2,10-dibromo-3-chloro-α-chamigrene (4), were isolated and identified from the organic extract of the marine red alga Laurencia nangii Masuda collected from the coastal waters in Semporna, Borneo. Their structures were established by means of spectroscopic analysis including IR, high-resolution electrospray ionization mass spectrometry (HRESI-MS), and 1D and 2D NMR techniques. All these metabolites were submitted for the antifungal assay against four species of selected marine fungi. Compounds 1-4 showed potent activity against Haliphthoros sabahensis and Lagenidium thermophilum.
  7. Phan CS, Kamada T, Vairappan CS
    Nat Prod Res, 2020 Apr;34(7):1008-1013.
    PMID: 30600714 DOI: 10.1080/14786419.2018.1543681
    Two new C15-acetogenins, 4-epi-isolaurallene (1) and 4-epi-itomanallene A (2) were isolated from a population of marine red alga Laurencia nangii Masuda from Carrington Reef. The structures of these compounds were determined intensively by NMR and HRESIMS data. Their configurations were elucidated by detailed comparison of chemical shifts, germinal protons splitting and NOE correlations with known and synthesized analogues. In addition, antibacterial activities of these compounds were evaluated. These compounds would serve as diastereomeric models for future reference. Since the isolaurallene, neolaurallene, 9-acetoxy-1,10,12-tribromo-4,7:6,13-bisepoxypentadeca-1,2-diene, itomanallene A and laurendecumallene A were isolated, compounds 1 and 2 were the sixth example of C15-acetogenin with dioxabicyclo[7.3.0]dodecene skeleton.
  8. Ng SY, Kamada T, Suleiman M, Vairappan CS
    J Asian Nat Prod Res, 2016 Jul;18(7):690-6.
    PMID: 26828126 DOI: 10.1080/10286020.2015.1134503
    A new compound, chandonanol (1), along with four known compounds, chandonanthone (2), iso-chandonanthone (3), anastreptene (4), and (6R,7S)-sesquiphellandrene (5), was isolated from the MeOH extract of Bornean liverwort Chandonanthus hirtellus. The structure of the new metabolite was established by analyses of the spectroscopic data (1D NMR, 2D NMR, HRESIMS, and IR). These compounds were tested for their activity against antibiotic-resistant clinical strains. Chandonanol (1) exhibited potent bactericidal activity against Staphylococcus aureus and Escherichia coli.
  9. Azhar T, Kamada T, Lopez F, Harun R, Nor I, Lim A
    Med J Malaysia, 1991 Jun;46(2):123-8.
    PMID: 1839415
    One hundred patients with carcinoma of the cervix stages 1B to 4A were treated with intracavitary high dose rate radiation using a linear cobalt source. All cases have received external beam pelvic irradiation to 4500cGy mid plane in twenty fractions over four weeks. The results in terms of patient compliance and convenience were good while acute and late morbidities were comparable to standard Manchester technique of low dose rate intracavitary therapy as practised in the Institute of Radiotherapy and Oncology General Hospital Kuala Lumpur. The four year actuarial survival rate is 76% for stage II and 48% for stage III. All three stage IV patients died within 1 year. Four out of seven stage I patients are alive (minimum follow-up 18 months, longest 43 months). One died of systemic spread at 33 months while one is lost to follow up.
  10. Tani K, Kamada T, Phan CS, Vairappan CS
    Nat Prod Res, 2019 Dec;33(23):3343-3349.
    PMID: 29772929 DOI: 10.1080/14786419.2018.1475387
    Three new cembrane diterpenes, nephthecrassocolides A-B (1-2) and 6-acetoxy nephthenol acetate (3) along with three known compounds, 6-acetoxy-7,8-epoxy nephthenol acetate (4), epoxy nephthenol acetate (5) and nephthenol (6) were isolated from one population of Nephthea sp. Their structures were elucidated based on spectroscopic data analysis and the antifungal activities of compounds 1-6 were evaluated.
  11. Phan CS, Kamada T, Kobayashi K, Hamada T, Vairappan CS
    Nat Prod Res, 2018 Jan;32(2):202-207.
    PMID: 28691521 DOI: 10.1080/14786419.2017.1346638
    A new xenicane diterpenoid, 15-deoxy-isoxeniolide-A (1) along with four known compounds 9-deoxy-isoxeniolide-A (2), isoxeniolide-A (3), xeniolide-A (4) and coraxeniolide-B (5) were isolated from the Bornean soft coral Xenia sp. The structures of these metabolites were elucidated on the basis of spectral analysis, NMR and HRESIMS. Compound 5 showed cytotoxic activity against ATL cell line, S1T.
  12. Ng SY, Kamada T, Suleiman M, Vairappan CS
    Nat Prod Res, 2018 Aug;32(15):1832-1837.
    PMID: 29156972 DOI: 10.1080/14786419.2017.1405409
    The Bornean liverwort Gottschelia schizopleura was investigated phytochemically for the first time. Two new and four previously known clerodane-type diterpenoids were isolated from the MeOH extract of G. schizopleura through a series of chromatographic techniques. The structures of the new metabolites were established by analyses of their spectroscopic data (1D NMR, 2D NMR, HRESIMS and IR). All the isolated compounds 1-6 were tested against human promyelocytic leukaemia (HL-60), human colon adenocarcinoma (HT-29) and Mus musculus skin melanoma (B16-F10). Compound 1 and 2 showed active inhibition against HL-60 and B16-F10 cells.
  13. Phan CS, Kamada T, Ishii T, Hamada T, Vairappan CS
    Nat Prod Res, 2019 Mar;33(6):808-813.
    PMID: 29202596 DOI: 10.1080/14786419.2017.1410812
    One new compound, 12-epi-9-deacetoxyxenicin (1) along with a hydroperoxide product, 12-epi-9-deacetoxy-8-hydroperoxyxenicin (2) and two known sesquiterpenoids (3-4) were isolated from a population of Bornean soft coral Xenia sp. The structures of these secondary metabolites were elucidated based on their spectroscopic data. Compounds 1 and 2 showed cytotoxic activity against ATL cell line, S1T. In addition, compound 3 exhibited hyphal inhibition of Lagenidium thermophilum.
  14. Ng SY, Kamada T, Suleiman M, Vairappan CS
    Nat Prod Commun, 2016 Aug;11(8):1071-1072.
    PMID: 30725558
    A new compound, schistochilic acid D (1) and two known compounds (2 and 3) were isolated from MeOH extract of Bornean liverwort. Schistochila acuininata collected from Mount Trus Madi, Sabah. The structure of the new metabolite was established based on spectroscopic (ID NMR, 2D NMR, and IR). and HRESIMS data. In addition, another population of S. acuminata collected from Mount Alab (Sabah) yielded four known compounds, 2, 3, 4 and 5. These compounds were tested for their biological potential against the B 16-Fl0 cell line. Compounds 4 and 5 exhibited weak cytotoxic activity.
  15. Hatai K, Kamada T, Lau LM, Kulip J, Phan CS, Vairappan CS
    Biocontrol Sci, 2018;23(1):35-39.
    PMID: 29576593 DOI: 10.4265/bio.23.35
     The antifungal activity of two Bornean medicinal wild gingers Plagiostachys megacarpa and Zingiber phillippsiae were examined against Lagenidium thermophilum. The most active extract was P. megacarpa at concentration of 320 µg/mL inhibiting both hyphal growth and zoospore production of L. thermophilum in 24 h. Toxicity tests were conducted using mud crab (Scylla tranquebarica) larva. Bath treatment of P. megacarpa at concentrations of 320 and 640 µg/mL for 24 h were highly effective against hyphae and zoospores of the strain and it is non-toxic to mud crab larva. Therefore, crude extracts P. megacarpa may be used as alternative treatment for marine Oomycete infection of mud crab.
  16. Shamsudin KJ, Phan CS, Kulip J, Hatai K, Vairappan CS, Kamada T
    J Asian Nat Prod Res, 2019 May;21(5):435-441.
    PMID: 29502443 DOI: 10.1080/10286020.2018.1440391
    The medicinal plant, Syzygium leucoxylon or commonly known as Obah found in North Borneo was considered as traditional medicine by local committee. Two new phenolics, leucoxenols A (1) and B (2) were isolated and identified as major secondary metabolites from the leaves of S. leucoxylon. Their chemical structures were elucidated based on spectroscopic data such as NMR and HRESIMS. Furthermore, these compounds were active against selected strains of fungi.
  17. Kamada T, Kang MC, Phan CS, Zanil II, Jeon YJ, Vairappan CS
    Mar Drugs, 2018 Mar 21;16(4).
    PMID: 29561805 DOI: 10.3390/md16040099
    Soft corals are known to be prolific producers of a wide spectrum of biologically active cembranoids. One new cembranoid, sinularolide F (2), along with three known compounds, cembranolide (1), (E,E,E)-6,10,14-trimethyl-3-methylene-cis-3α,4,5,8,9,12,13,15α-octahydrocyclo tetradeca[β]furan-2(3H)-one (3), and denticulatolide (4), were isolated from the Bornean soft coral Sinularia sp. Compounds 2 and 4 showed potential anti-inflammatory activities against lipopolysaccharide-stimulated RAW 264.7 with IC50 values less than 6.25 µg/mL and anticancer activity against HL60 cell lines. The compounds' mechanisms of action were investigated via the Western blot evaluation of their protein markers. These activities could be attributed to the presence of tertiary methyl at C-8 and the compounds' 3D configurations.
  18. Kamada T, Johanis ML, Ng SY, Phan CS, Suleiman M, Vairappan CS
    Nat Prod Bioprospect, 2020 Feb;10(1):51-56.
    PMID: 32062804 DOI: 10.1007/s13659-020-00232-6
    New bioactive 13-epi-neoverrucosane diterpenoid, 5β-acetoxy-13-epi-neoverrucosanic acid (1) along with three known secondary metabolites, 13-epi-neoverrucosan-5β-ol (2), chelodane (3) and (E)-β-farnesene (4) were isolated from the MeOH extract of east Malaysia's liverwort Pleurozia subinflata. The chemical structure of new compound was elucidated by the analyses of its spectroscopic data (FTIR, NMR and HR-ESI-MS). These epi-neoverrucosane-type compounds seem to be notable chemosystematic markers for P. subinflata in Borneo. Compound 3 was widespread in marine sponges however this is the first record for 3 to be found in liverwort. These metabolites were tested for their antifungal potentials against selected fungi from the marine environment. Compound 1 exhibited effective antifungal activity against Lagenidium thermophilum.
  19. Kamada T, Phan CS, Tin HS, Vairappan CS, Muhammad TST
    Nat Prod Commun, 2016 Aug;11(8):1077-1078.
    PMID: 30725560
    One new cembrane diterpene, 16-hydroxycembra-1,3,7,11-tetraene (1), along with three known compounds, 15-hydroxycembra-1,3,7,11-tetraene (2), sarcophine (3) and sarcophytoxide (4) were isolated from Sarcophyton sp. collected from Karah Island, Terengganu, West Malaysia. Their structures were elucidated based on spectroscopic data. Activities of these compounds against antibacterial resistant clinical bacteria are reported. Only 1 exhibited inhibition against Staphylococcus aureus.
  20. Ng SY, Phan CS, Ishii T, Kamada T, Hamada T, Vairappan CS
    Molecules, 2020 Nov 18;25(22).
    PMID: 33217924 DOI: 10.3390/molecules25225386
    Members of the marine soft coral genus Xenia are rich in a diversity of diterpenes. A total of 199 terpenes consisting of 14 sesquiterpenes, 180 diterpenes, and 5 steroids have been reported to date. Xenicane diterpenes were reported to be the most common chemical skeleton biosynthesized by members of this genus. Most of the literature reported the chemical diversity of Xenia collected from the coral reefs in the South China Sea and the coastal waters of Taiwan. Although there was a brief review on the terpenoids of Xenia in 2015, the present review is a comprehensive overview of the structural diversity of secondary metabolites isolated from soft coral genus Xenia and their potent biological activity as reported between 1977 to 2019.
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