Lik Tong Tan
Unknown Affiliation

Published : 4 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 4 Documents
Search

BIOMEDICAL POTENTIAL OF MARINE CYANOBACTERIA Lik Tong Tan
JOURNAL OF COASTAL DEVELOPMENT Vol 9, No 3 (2006): Volume 9, Number 3, Year 2006
Publisher : JOURNAL OF COASTAL DEVELOPMENT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (94.396 KB)

Abstract

Cyanobacteria, in particular those found living in the ocean, are emerging as an importantsource of unique bioactive secondary metabolites. A plethora of natural products, mostly nitrogencontainingmolecules, have been reported with majority belonging to the polyketide synthase (PKS)and/or non-ribosomal polypeptide synthetase (NRPS) structural class. Curacin A and the dolastatinsare examples of important marine cyanobacterial metabolites possessing exquisite anticancerproperties. Genetic studies on the biosynthetic capacity of these marine microalgae revealed manynovel biochemical features pertaining to the enzymology of secondary metabolism. Biodiscovery ofmarine cyanobacteria for new therapeutic agents as well as harnessing its biosynthetic gene clustersrepresent an exciting and fruitful area of research in marine biotechnology.
BIOMEDICAL POTENTIALS OF INTERTIDAL MARINE ORGANISMS FROM SINGAPORE Alfred Wai Ping Seng; Yan Zhi Ong; Wan Yen Lee; Peter Peng Foo Lee; Swee Cheng Lim; Koh Siang Tan; Lik Tong Tan
JOURNAL OF COASTAL DEVELOPMENT Vol 11, No 1 (2007): Volume 11, Number 1, Year 2007
Publisher : JOURNAL OF COASTAL DEVELOPMENT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1140.933 KB)

Abstract

As part of a pilot scale project on drug discovery from local marine organisms, 19 intertidal marine organisms from Singapore waters were collected and screened for the presence of biologically-active natural products.  These marine organisms were collected due to the ease of procurement and their relative abundance.  The organic extracts of these organisms were prepared and screened in the brine shrimp lethality (BSL), the cytotoxicity (MCF-7 and MOLT-4 cell lines), and the quorum sensing inhibition (QSI) assays.  Over 60% of the extracts gave significant biological activities in the BSL and the cytotoxicity (MOLT-4) assays when tested at 1000 ppm.  Three sponge extracts showed moderate antibacterial activity while a fraction obtained from the gross fractionation of the extract of the marine cyanobacterium, Lyngbya majuscula (PH2), exhibited anti quorum sensing activity in the QSI assay.  Lyngbya majuscula (PH2) also exhibited exceptional biological properties in the toxicity assays and its extract underwent further fractionation.  The 1H-NMR spectra of the bioactive chromatographic fractions derived from the microalgal extract indicated the presence of unique lipopeptides.  Data from this study provided rationale to initiate marine natural products research for drug discovery in Singapore.
DIVERSITY, DISTRIBUTION AND BIOLOGICAL ACTIVITY OF SOFT CORALS (OCTOCORALLIA, ALCYONACEA) IN SINGAPORE Beverly Pi Lee Goh; Grace Enhui Tan; Lik Tong Tan
JOURNAL OF COASTAL DEVELOPMENT Vol 12, No 2 (2009): Volume 12, Number 2, Year 2009
Publisher : JOURNAL OF COASTAL DEVELOPMENT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (241.673 KB)

Abstract

The Southern Islands of Singapore are known to contain coral reefs which are high in biodiversity. However, the diversity of soft corals had received little attention to date. This study was conducted to determine the soft coral diversity in Singapore reefs as well as to conduct preliminary bioactivity tests on the organic extracts from these soft corals. A 100-meter line transect was used to survey soft corals at a 3m depth at ten different sample sites. Sclerites from samples were used to identify the soft corals to the generic level. This study uncovered the following genera of soft corals: Carijoa spp., Cladiella spp., Sinularia spp., Lobophytum spp., Sarcophyton spp., Stereonephthya spp., and Nephthea spp. In addition, an unidentified genus of soft coral was observed at Kusu Island. Cladiella spp. yielded the highest number of colonies, and Sarcophyton spp. had the highest coverage in terms of total colony diameter. The brine shrimp (Artemia salina) toxicity assay was carried out to screen for toxicity of the soft coral extracts at concentrations of 10, 100, and 1000 ppm. Results showed high levels of toxicity in extracts of Sarcophyton spp. and Cladiella spp., indicating that these soft corals are potentially good sources of bioactive compounds for drug discovery.
CHEMICAL ECOLOGY OF MARINE CYANOBACTERIAL SECONDARY METABOLITES: A MINI-REVIEW Lik Tong Tan; Beverly Pi Lee Goh
JOURNAL OF COASTAL DEVELOPMENT Vol 13, No 1 (2009): Volume 13, Number 1, Year 2009
Publisher : JOURNAL OF COASTAL DEVELOPMENT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (78.02 KB)

Abstract

More than 300 nitrogen-containing secondary metabolites have been reported from the procaryotic marinecyanobacteria. A majority of these compounds are of the polypeptide or mixed polyketide-polypeptidestructural class and they are a potential source of novel pharmaceuticals. In spite of the chemical richnessof marine cyanobacteria, not much is known regarding their ecological functions. To date only a handful ofmarine cyanobacterial compounds have been examined for their involvement in predator-prey interactions.This mini-review surveys the various chemical ecology studies conducted on marine cyanobacterialcompounds. From these ecological studies, many marine cyanobacterial compounds are known to deterfeeding by several species of marine predators. Such chemical defense may be crucial in maintaining thepopulation of marine cyanobacterial bloom in nature. In addition, a series of ecological studies from ourlaboratory revealed the anti-settlement properties of a number of benthic marine cyanobacterialcompounds. These studies suggested marine cyanobacteria as a potential source of natural antifoulants forthe control of fouling organisms.