Marine Red Alga Laurencia Okamurai Research Articles

Cyclonerane sesquiterpenes and an isocoumarin derivative from the marine-alga-endophytic fungus Trichoderma citrinoviride A-WH-20-3

Two new cyclonerane sesquiterpenes, (10E)-isocyclonerotriol (1) and (10Z)-isocyclonerotriol (2), and one new isocoumarin derivative, trichophenol A (3), were isolated from Trichoderma citrinoviride A-WH-20-3, an endophyte from the marine red alga Laurencia okamurai. Their structures and relative configurations were assigned by spectroscopic techniques, highlighted by using Sarotti's DP4+ sheet to confirm the cyclopentane ring. The absolute configuration of 1 was established by comparison of experimental and calculated specific rotation data. Compounds 1 and 2 represent the first occurrence of ring-isomerized cycloneranes. Compound 3 is the first 3-phenylisocoumarin derivative from Trichoderma and features inhibition of several marine-derived bacteria and phytoplankton species.

Prenylated Phenol and Benzofuran Derivatives from Aspergillus terreus EN-539, an Endophytic Fungus Derived from Marine Red Alga Laurencia okamurai.

Three new prenylated phenol derivatives, terreprenphenols A–C (1–3), along with four known related compounds (4–7), were isolated from Aspergillus terreus EN-539, an endophytic fungus obtained from the marine red alga Laurencia okamurai. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, and optical rotation (OR). The corresponding relationship between absolute configuration and optical rotation for known compounds anodendroic acid (4) and asperterreusine C (5) was ambiguous in literature, and their absolute configurations were therefore discussed and confirmed for the first time by time-dependent density functional (TDDFT) ECD and OR calculations. Compounds 1–7 inhibited some common aquatic bacteria with MIC values ranging from 2 to 64 μg/mL.

Deoxytrichodermaerin, a harziane lactone from the marine algicolous fungus Trichoderma longibrachiatum A-WH-20-2

Three metabolites deoxytrichodermaerin (a new harziane lactone), harzianol A and harzianone were obtained from Trichoderma longibrachiatum A-WH-20-2, an endophyte from marine red alga Laurencia okamurai. Their structures and relative configurations were unequivocally assigned by spectroscopic techniques, and the absolute configuration of deoxytrichodermaerin was established by analysis of the ECD curve aided by quantum chemical calculations. Deoxytrichodermaerin represents the second harziane lactone with an ester linkage between C-10 and C-11. Harzianol A occurs as a natural product of Trichoderma for the first time. Harzianone has been previously discovered from T. longibrachiatum cf-11. These isolates exhibited potent inhibition of some marine plankton species.

A new dimeric sesquiterpene and other related derivatives from the marine red alga Laurencia okamurai

A new Bis-sesquiterpene, Nanji A (1), has been isolated together with 7 known compounds, debromolaurinterol (2), laurinterol (3), laurinterol acetate (4), isolaurinterol (5), 3α-hydroperoxy-3-epiaplysin (6), 3β-hydroperoxyaplysin (7), Laurokomurenene A (8), from the Nanji red alga Laurencia okamurai. The structure of 1 was elucidated on the basis of extensive spectroscopic analysis of its EIMS, 1D and 2D NMR data. Furthermore, the chemotaxonomic significance of these compounds was also summarized.

Antioxidant Hydroanthraquinones from the Marine Algal-Derived Endophytic Fungus Talaromyces islandicus EN-501.

Five new polyhydroxylated hydroanthraquinone derivatives, namely, 8-hydroxyconiothyrinone B (1), 8,11-dihydroxyconiothyrinone B (2), 4R,8-dihydroxyconiothyrinone B (3), 4S,8-dihydroxyconiothyrinone B (4), and 4S,8-dihydroxy-10-O-methyldendryol E (5), were isolated and identified from the culture extract of Talaromyces islandicus EN-501, an endophytic fungus obtained from the inner tissue of the marine red alga Laurencia okamurai. The structures of these compounds were established on the basis of detailed interpretation of their NMR and mass spectroscopic data, and the structures and absolute configurations of compounds 1 and 2 were confirmed by X-ray crystallographic analysis, while the absolute configurations of compounds 3-5 were determined by TDDFT calculations of the ECD spectra. The antimicrobial, antioxidant, and cytotoxic activities of compounds 1-5 were evaluated.

Two New Diphenylketones and a New Xanthone from Talaromyces islandicus EN-501, an Endophytic Fungus Derived from the Marine Red Alga Laurencia okamurai.

Two new diphenylketones (1 and 2), a new xanthone (3), and a known xanthone analogue (4) were isolated and identified from Talaromyces islandicus EN-501, an endophytic fungus obtained from the fresh collected marine red alga Laurencia okamurai. Their structures were elucidated on the basis of NMR spectroscopic and X-ray crystallographic analysis. The joint isolation of benzophenones and xanthones from the same fungal strain supports the biogenesis of xanthones via a benzophenone intermediate. It is worth mentioning that xanthones 3 and 4 have a methyl group at C-6 and C-2, respectively, which is uncommon compared with typical xanthones usually having a methyl group at C-8. Compounds 1–4 exhibited potent antioxidative activities against DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) radicals with IC50 values ranging from 0.58 to 6.92 μg/mL, which are stronger than that of the positive controls BHT (butylated hydroxytoluene) and ascorbic acid. Compounds 1, 3, and 4 also showed inhibitory activities against several pathogenic bacteria.

Laurane-, Cyclolaurane-, and Cuparane-type Sesquiterpenes from the Marine Red Alga Laurencia okamurai

Chemical investigation of the secondary metabolites extracted from the marine red alga Laurencia okamurai has resulted in the isolation of one new (lauramurin, 1) and six known (2-7) sesquiterpenes. On the basis of the data obtained by our detailed spectroscopic analysis as well as by comparison with those reported, the structures of these compounds were elucidated as four laurane sesquiterpenes including lauramurin (1), laur-11-en-10-ol (2), aplysinol (3), and debromoaplysinol (4), two cyclolaurane sesquiterpenes laurequinone (5) and laurentristich-4-ol (6), and one cuparane ether sesquiterpene (7). The antibacterial activity against Staphylococcus aureus and brine shrimp (Artemia salina) lethality for the isolated compounds were evaluated. Compounds 2 and 5-7 displayed moderate lethality against brine shrimp.

Sesquiterpene and Acetogenin Derivatives from the Marine Red Alga Laurencia okamurai

In addition to 13 known compounds, four new bisabolane sesquiterpenes, okamurenes A–D (1–4), a new chamigrane derivative, okamurene E (5), and a new C12-acetogenin, okamuragenin (6), were isolated from the marine red alga Laurencia okamurai. The structures of these compounds were determined through detailed spectroscopic analyses. Of these, okamurenes A and B (1 and 2) are the first examples of bromobisabolane sesquiterpenes possessing a phenyl moiety among Laurencia-derived sesquiterpenes, while okamuragenin (6) was the first acetogenin aldehyde possessing a C12-carbon skeleton. Each of the isolated compounds was evaluated for the brine shrimp (Artemia salina) lethal assay and 7-hydroxylaurene displayed potent lethality with LD50 1.8 μM.

Sesquiterpenes and acetogenins from the marine red alga Laurencia okamurai

Three new halogenated sesquiterpenes, 10-bromo-7α,8α-expoxychamigr-1-en-3-ol (1), 10-bromo-β-chamigren-8-ol (2), and 10-bromo-3-chlorocupar-5-en-2-ol (3), one new C12-acetogenin, desepilaurallene (7), one new naturally occurring sesquiterpene, 7-hydroxylaurene acetate (4), two known sesquiterpenes, allolaurinterol acetate (5) and laurene (6), and one known C15-acetogenin, epilaurallene (8), were isolated from the marine red alga Laurencia okamurai collected from the coast of Rongcheng, China. The structures of these compounds were unambiguously established by 1D, 2D NMR and mass spectroscopic techniques. The bioassay results showed that 4, 5 exhibited potent antibacterial activity, and 1, 4, 5 were toxic to brine shrimp.

A new rearranged chamigrane sesquiterpene from Laurencia okamurai

A new rearranged chamigrane sesquiterpene, named laurenokamurin, was isolated from the marine red alga Laurencia okamurai. Its structure was determined on the basis of spectroscopic methods.

Two new halogenated chamigrane-type sesquiterpenes and other secondary metabolites from the marine red alga Laurencia okamurai and their chemotaxonomic significance

Two new halogenated chamigrane-type sesquiterpenes and other secondary metabolites from the marine red alga Laurencia okamurai and their chemotaxonomic significance

Isolation and structures of [formula omitted]-laurencenyne, a possible precursor of the C 15 halogenated cyclic ethers, and [formula omitted]-neolaurencenyne from [formula omitted

Isolation and structural elucidation of two new acetylenic polyenes, trans -laurencenyne 1 and trans -neolaurencenyne 2 from the marine red alga Laurencia okamurai were carried out, the former compound 1 very recently being proposed to be a biosynthetic precursor of the C 15 halogenated cyclic ethers, 7 and 8 .