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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The red algal genus Laurencia is a prolific producer of halogenated secondary metabolites. A new tricyclic dibrominated diterpenoid, neoiriepentaol (1) and chlorinated C15-acetogenin, nangenyne (2), along with two known terpenoids, neoirietetraol (3) and dactyloxene A (4), were isolated from methanol crude extract of red alga Laurencia nangii. The structures were established based on one- and two-dimensional nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR), and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. These compounds were screened against seven species of marine fungi. Compounds 1-3 exhibited activity against Lagenidium thermophilum and Haliphthoros sabahensis. Potent activity was showed by 1 with L. thermophilum hyphal inhibition at MIC value of 12.5 μg mL−1 and hyphal motility was observed at 50 μg mL−1 within 24 h. [ABSTRACT FROM AUTHOR]

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 C15-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).

The chemical investigation of an ethyl acetate extract (EtOAc) obtained from Laurencia obtusa, collected in Corsica, allowed for the identification of three new compounds (1, 2, and 4) and six known compounds. Compounds 1 to 4 were isolated and fully characterized by a detailed spectroscopic analysis. Compounds 1 and 2 are two C15-acetogenins sharing the same ring system: a tetrahydropyran linked by a methylene to a tetrahydrofuran ring. Compound 1 exhibits a bromoallene unit whereas compound 2 possesses an uncommon α-bromo-α,β-unsaturated aldehyde terminal unit. Compound 4 is the first diterpene exhibiting a 19(4 → 3)abeo-labdane skeleton isolated from a Laurencia species. Isolation of concinndiol (compound 3) together with compound 4 suggests a common biosynthetic origin. Additionally, five known compounds, namely sagonenyne, laurene, α-bromocuparene, microcladallene A, and β-snyderol were identified in chromatographic fractions by NMR analysis using a computerized method that was developed in our laboratory.

Seven parguerane diterpenes: 15-bromo-2,7,19-triacetoxyparguer-9(11)-en-16-ol (1), 15-bromo-2,7,16,19-tetraacetoxyparguer-9(11)-ene (2), 15-bromo-2,19-diacetoxyparguer-9(11)-en-7,16-diol (3), 15-bromo-2,16,19-triacetoxyparguer-9(11)-en-7-ol (4), 15-bromo-2,16-diacetoxyparguer-9(11)-en-7-ol (5), 15-bromoparguer-9(11)-en-16-ol (6), 15-bromoparguer-7-en-16-ol (7), two polyether triterpenes: thyrsiferol (8) and thyrsiferyl 23-acetate (9), and one C15-acetogenin, neolaurallene (10), were isolated from a sample of marine red alga Laurencia saitoi collected off the coast of Yantai. Their structures were established by detailed NMR spectroscopic analysis and comparison with literature data.

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 C15-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). [ABSTRACT FROM AUTHOR]

Specimens of the cosmopolitan sea hare Aplysia parvula , collected in the Tsistsikamma National Park on the south-east coast of South Africa yielded the new dibromo-C15-acetogenin, (3 Z )-bromofucin ( 1 ). Standard spectroscopic methods were used to establish the structure of this compound. [ABSTRACT FROM AUTHOR]

Two new C 15 -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 C 15 -acetogenin with dioxabicyclo[7.3.0]dodecene skeleton.

The chemical investigation of an ethyl acetate extract (EtOAc) obtained from Laurencia obtusa, collected in Corsica, allowed for the identification of three new compounds (1, 2, and 4) and six known compounds. Compounds 1 to 4 were isolated and fully characterized by a detailed spectroscopic analysis. Compounds 1 and 2 are two C15-acetogenins sharing the same ring system: a tetrahydropyran linked by a methylene to a tetrahydrofuran ring. Compound 1 exhibits a bromoallene unit whereas compound 2 possesses an uncommon α-bromo-α,β-unsaturated aldehyde terminal unit. Compound 4 is the first diterpene exhibiting a 19(4 → 3)abeo-labdane skeleton isolated from a Laurencia species. Isolation of concinndiol (compound 3) together with compound 4 suggests a common biosynthetic origin. Additionally, five known compounds, namely sagonenyne, laurene, α-bromocuparene, microcladallene A, and β-snyderol were identified in chromatographic fractions by NMR analysis using a computerized method that was developed in our laboratory. [ABSTRACT FROM AUTHOR]