Displaying all 11 publications

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  1. 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).
    Matched MeSH terms: Laurencia/chemistry*
  2. 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.
    Matched MeSH terms: Laurencia/chemistry*
  3. 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.
    Matched MeSH terms: Laurencia/chemistry*
  4. 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.
    Matched MeSH terms: Laurencia/chemistry*
  5. Wijesinghe WA, Kim EA, Kang MC, Lee WW, Lee HS, Vairappan CS, et al.
    Environ Toxicol Pharmacol, 2014 Jan;37(1):110-7.
    PMID: 24317194 DOI: 10.1016/j.etap.2013.11.006
    5β-Hydroxypalisadin B, a halogenated secondary metabolite isolated from red seaweed Laurencia snackeyi was evaluated for its anti-inflammatory activity in lipopolysaccharide (LPS)-induced zebrafish embryo. Preliminary studies suggested the effective concentrations of the compound as 0.25, 0.5, 1 μg/mL for further in vivo experiments. 5β-Hydroxypalisadin B, exhibited profound protective effect in the zebrafish embryo as confirmed by survival rate, heart beat rate, and yolk sac edema size. The compound acts as an effective agent against reactive oxygen species (ROS) formation induced by LPS and tail cut. Moreover, 5β-hydroxypalisadin B effectively inhibited the LPS-induced nitric oxide (NO) production in zebrafish embryo. All the tested protective effects of 5β-hydroxypalisadin B were comparable to the well-known anti-inflammatory agent dexamethasone. According to the results obtained, 5β-hydroxypalisadin B isolated from red seaweed L. snackeyi could be considered as an effective anti-inflammatory agent which might be further developed as a functional ingredient.
    Matched MeSH terms: Laurencia/chemistry
  6. Vairappan CS, Suzuki M, Ishii T, Okino T, Abe T, Masuda M
    Phytochemistry, 2008 Oct;69(13):2490-4.
    PMID: 18718619 DOI: 10.1016/j.phytochem.2008.06.015
    During our studies on Malaysian Laurencia species, brominated metabolites, tiomanene, acetylmajapolene B, and acetylmajapolene A were isolated from an unrecorded species collected at Pulau Tioman, Pahang along with known majapolene B and majapolene A. Acetylmajapolene A was a mixture of diastereomers as in the case of majapolene A. Tiomanene may be a plausible precursor for acetylmajapolenes B and A. In addition, three known halogenated sesquiterpenes and two known halogenated C(15) acetogenins were found from other two unrecorded species collected at Pulau Karah, Terengganu and Pulau Nyireh, Terengganu, respectively. Some of these halogenated metabolites showed moderate antibacterial activity against some marine bacteria.
    Matched MeSH terms: Laurencia/chemistry*
  7. Oguri Y, Watanabe M, Ishikawa T, Kamada T, Vairappan CS, Matsuura H, et al.
    Mar Drugs, 2017 Aug 28;15(9).
    PMID: 28846653 DOI: 10.3390/md15090267
    Six new compounds, omaezol, intricatriol, hachijojimallenes A and B, debromoaplysinal, and 11,12-dihydro-3-hydroxyretinol have been isolated from four collections of Laurencia sp. These structures were determined by MS and NMR analyses. Their antifouling activities were evaluated together with eight previously known compounds isolated from the same samples. In particular, omaezol and hachijojimallene A showed potent activities (EC50 = 0.15-0.23 µg/mL) against larvae of the barnacle Amphibalanus amphitrite.
    Matched MeSH terms: Laurencia/chemistry*
  8. 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.
    Matched MeSH terms: Laurencia/chemistry*
  9. Vairappan CS, Ishii T, Lee TK, Suzuki M, Zhaoqi Z
    Mar Drugs, 2010;8(6):1743-9.
    PMID: 20631866 DOI: 10.3390/md8061743
    In our continuous interest to study the diversity of halogenated metabolites of Malaysian species of the red algal genus Laurencia, we examined the chemical composition of five populations of unrecorded Laurencia sp. A new brominated diterpene, 10-acetoxyangasiol (1), and four other known metabolites, aplysidiol (2), cupalaurenol (3), 1-methyl-2,3,5-tribromoindole (4), and chamigrane epoxide (5), were isolated and identified. Isolated metabolites exhibited potent antibacterial activities against clinical bacteria, Staphylococcus aureus, Staphylococcus sp., Streptococcus pyogenes, Salmonella sp. and Vibrio cholerae.
    Matched MeSH terms: Laurencia/chemistry*
  10. Vairappan CS
    Biomol. Eng., 2003 Jul;20(4-6):255-9.
    PMID: 12919806
    Red algae genus Laurencia (Rhodomelaceae, Ceramiales) are known to produce a wide range of chemically interesting secondary halogenated metabolites. This investigation delves upon extraction, isolation, structural elucidation and antibacterial activity of inherently available secondary metabolites of Laurencia majuscula Harvey collected from two locations in waters of Sabah, Malaysia. Two major halogenated compounds, identified as elatol (1) and iso-obtusol (2) were isolated. Structures of these compounds were determined from their spectroscopic data such as IR, 1H-NMR, 13C-NMR and optical rotation. Antibacterial bioassay against human pathogenic bacteria was conducted using disc diffusion (Kirby-Bauer) method. Elatol (1) inhibited six species of bacteria, with significant antibacterial activities against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp. while iso-obtusol (2) exhibited antibacterial activity against four bacterial species with significant activity against K. pneumonia and Salmonella sp. Elatol (1) showed equal and better antibacterial activity compared with tested commercial antibiotics while iso-obtusol (2) only equaled the potency of commercial antibiotics against K. pneumonia and Salmonella sp. Further tests conducted using dilution method showed both compounds as having bacteriostatic mode of action against the tested bacteria.
    Matched MeSH terms: Laurencia/chemistry
  11. 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).
    Matched MeSH terms: Laurencia/chemistry*
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