mass spectral data were determined on a bruker bioapex 47e mass spectrometer operating in negative ion electrospray mode at the australian institute of marine science , cape ferguson . h nmr spectra were measured in cdcl3 at 300 mhz and c nmr spectra at 75.5 mhz on a varian mercury nmr using residual solvent peaks for calibration . grade silica gel 5 - 40 ( type 60 ) was used for column chromatography . hplc purification was carried out on a hewlett - packard c18 column ( 10  250 mm ) , monitored with a gbc diode array detector . the sponge dysidea herbacea was collected by hand using scuba ( from 11 m ) near pelorus island ( 18 34 s ; 146 29 e ) in the central section of the great barrier reef marine park , australia . the sample was frozen immediately after collection and kept frozen until used . a taxonomic sample ( registered sample no.g25097 ) is lodged with the museum of tropical queensland , flinders street , townsville , qld . the freeze - dried sponge ( 10.89 g ) was successively extracted with dichloromethane ( 3  100 ml ) . the solvent was removed on a rotary evaporator to afford a crude extract ( 0.448 g ) which was rapidly chromatographed on silica gel under vacuum using a stepwise gradient from hexane to dichloromethane to ethyl acetate . a mixture of the diphenyl ethers ( 1 and 2 ) ( 22.8 mg , 0.21% ) was eluted in the dichloromethane / hexane 1:9 and 1:4 fractions as a crystalline solid . this material was separated by reverse phase hplc by elution with acetonitrile/1% aqueous ammonium acetate ( 9:1 ) at a flow rate of 1.5 ml / min . the acetonitrile was removed from fractions that contained the metabolites 1 ( retention time 3.23 min ) and 2 ( retention time 2.85 min ) and each was transferred to a separating funnel and extracted with dichloromethane . removal of the dichloromethane solvent afforded the minor metabolite 1 and the major metabolite 2 in a ratio of 1:10 ( based on integrated peak areas ) . ir ( chloroform ) cm : 3515 , 3019 , 2927 , 2854 , 1727 , 1466 , 1392 , 1299 , 1257 , 1091 , 1043 , 932 , 871 , 807 . uv ( etoh ) nm : 211 (  27193 ) , 292 (  2379 ) , sh 317 (  1022 ) hresms ( negative ion mode ) for c12h4br3br2o2 [ m - h ] : calcd 578.6093 ; found 578.6097 . mass spectral data were determined on a bruker bioapex 47e mass spectrometer operating in negative ion electrospray mode at the australian institute of marine science , cape ferguson . h nmr spectra were measured in cdcl3 at 300 mhz and c nmr spectra at 75.5 mhz on a varian mercury nmr using residual solvent peaks for calibration . grade silica gel 5 - 40 ( type 60 ) was used for column chromatography . hplc purification was carried out on a hewlett - packard c18 column ( 10  250 mm ) , monitored with a gbc diode array detector . the sponge dysidea herbacea was collected by hand using scuba ( from 11 m ) near pelorus island ( 18 34 s ; 146 29 e ) in the central section of the great barrier reef marine park , australia . the sample was frozen immediately after collection and kept frozen until used . a taxonomic sample ( registered sample no.g25097 ) is lodged with the museum of tropical queensland , flinders street , townsville , qld . the freeze - dried sponge ( 10.89 g ) was successively extracted with dichloromethane ( 3  100 ml ) . the solvent was removed on a rotary evaporator to afford a crude extract ( 0.448 g ) which was rapidly chromatographed on silica gel under vacuum using a stepwise gradient from hexane to dichloromethane to ethyl acetate . a mixture of the diphenyl ethers ( 1 and 2 ) ( 22.8 mg , 0.21% ) was eluted in the dichloromethane / hexane 1:9 and 1:4 fractions as a crystalline solid . this material was separated by reverse phase hplc by elution with acetonitrile/1% aqueous ammonium acetate ( 9:1 ) at a flow rate of 1.5 ml / min . the acetonitrile was removed from fractions that contained the metabolites 1 ( retention time 3.23 min ) and 2 ( retention time 2.85 min ) and each was transferred to a separating funnel and extracted with dichloromethane . removal of the dichloromethane solvent afforded the minor metabolite 1 and the major metabolite 2 in a ratio of 1:10 ( based on integrated peak areas ) . ir ( chloroform ) cm : 3515 , 3019 , 2927 , 2854 , 1727 , 1466 , 1392 , 1299 , 1257 , 1091 , 1043 , 932 , 871 , 807 . uv ( etoh ) nm : 211 (  27193 ) , 292 (  2379 ) , sh 317 (  1022 ) hresms ( negative ion mode ) for c12h4br3br2o2 [ m - h ] : calcd 578.6093 ; found 578.6097 . ir ( chloroform ) cm : 3515 , 3019 , 2927 , 2854 , 1727 , 1466 , 1392 , 1299 , 1257 , 1091 , 1043 , 932 , 871 , 807 . uv ( etoh ) nm : 211 (  27193 ) , 292 (  2379 ) , sh 317 (  1022 ) hresms ( negative ion mode ) for c12h4br3br2o2 [ m - h ] : calcd 578.6093 ; found 578.6097 .
a pentabrominated phenolic diphenyl ether ( 1 ) that has not previously been reported from marine sources has been isolated from dysidea herbacea collected at pelorus island , great barrier reef , australia . 
 the structure was determined by comparison of nmr data with those of known structurally - related metabolites . 
 nmr spectral assignments for ( 1 ) are discussed in context with those of three previously reported isomeric pentabrominated phenolic diphenyl ethers .