Chin-Soon Phan

Capgermacrenes D-G, new sesquiterpenoids from a Bornean soft coral, Capnella imbricata

Abstract 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.

15-deoxy-isoxeniolide-A, new diterpenoid from a bornean soft coral, Xenia sp.

Abstract 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-Epi-9-deacetoxyxenicin, new cytotoxic diterpenoid from a Bornean soft coral, Xenia sp.

Abstract 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.

New cembrane-type diterpenoids from Bornean soft coral Nephthea sp. with antifungal activity against Lagenidium thermophilum

Abstract 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.

Bioactive Cembranoids from the Soft Coral Genus Sinularia sp. in Borneo

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.

Leucoxenols A and B, two new phenolics from Bornean medicinal plant Syzygium leucoxylon

Abstract 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.

Halogenated chamigrane sesquiterpenes from Bornean Laurencia majuscula

The red alga genus Laurencia (Rhodomelaceae, Ceramiales) is known to produce and contain a rich diversity of halogenated secondary metabolites. These compounds are dominated by two major biosynthetic groups: terpenes (sesquiterpenes, diterpenes, and triterpenes) and C15-acetogenins. In the course of our investigation on red algae genus Laurencia from North Borneo Island, three new halogenated chamigranes, 7-aldehydelaurencenone B (1), 2-chloro-3-methoxy-α-chamigren-9-one (2), and laureborneone (3) along with five known halogenated derivatives such as [1(15)Z,2Z,4R,8S,9R]-8,15-dibromochamigra-1(15),2,11(12)-trien-9-ol (4), [1(15)E,2Z,4R,8S,9R]-8,15-dibromochamigra-1(15),2,11(12)-trien-9-ol (5), ma’ilion (6), laurencenone B (7), and 2-chloro-3-hydroxy-α-chamigren-9-one (8) were isolated from Laurencia majuscula. The structures of these compounds were determined based on spectroscopic data which consisted of infrared (FT-IR), H1-NMR, C13-NMR, H1-H1-COSY, HSQC, HMBC, and NOESY. In addition, high-resolution electrospray ionization mass spectrometry (HRESIMS) was done to calculate their molecular formula and unsaturation index. The anticancer potentials of these compounds were tested against three cancer cell lines, and their IC50 values were determined.

Paralemnolins V and W, New Nardosinane-Type Sesquiterpenoids from a Bornean Soft Coral, Lemnalia sp.

Two new nardosinane-type sesquiterpenoids, paralemnolin V (1) and paralemnolin W (2), along with five known sesquiterpenoids (3–7), were isolated from a population of Bornean soft coral Lemnalia sp. The structures of these metabolites were elucidated based on their NMR and HR-ESI-MS spectral data. These compounds were subjected to antibacterial and antifungal tests against eight bacterial and seven fungal strains.

In vitro Inhibitory Effects of Two Bornean Medicinal Wild Gingers against Pathogenic Lagenidium thermophilum Infected Mud Crab Scylla tranquebarica

　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.

New anti-bacterial halogenated tricyclic sesquiterpenes from Bornean Laurencia majuscula (Harvey) Lucas

Abstract 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).