Displaying all 14 publications

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  1. Phan CS, Vairappan CS
    Nat Prod Res, 2017 Apr;31(7):742-748.
    PMID: 27750446 DOI: 10.1080/14786419.2016.1241997
    Four new bicyclogermacrenes, capgermacrenes D (1) E (2) F (3) and G (4) were isolated from a population of Bornean soft coral Capnella imbricata. The structures of these metabolites were elucidated based on their nuclear magnetic resonance and high-resolution electrospray ionisation mass spectrometry spectral data. These compounds showed bacteriastatic and bacteriacidal activities against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.
  2. 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.
  3. 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).
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. Phan CS, Ng SY, Kim EA, Jeon YJ, Palaniveloo K, Vairappan CS
    Mar Drugs, 2015 May;13(5):3103-15.
    PMID: 25996100 DOI: 10.3390/md13053103
    Two new bicyclogermacrenes, capgermacrenes A (1) and B (2), were isolated with two known compounds, palustrol (3) and litseagermacrane (4), from a population of Bornean soft coral Capnella sp. The structures of these metabolites were elucidated based on spectroscopic data. Compound 1 was found to inhibit the accumulation of the LPS-induced pro-inflammatory IL-1b and NO production by down-regulating the expression of iNOS protein in RAW 264.7 macrophages.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
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