New cytotoxic sesquiterpenes from the red algae Laurencia obtusa and Laurencia microcladia

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

“…from the Gulf of California 113 and from Australia. 114 Eudesmane sesquiterpenes of Rhodomelace origin display a 1-bromo substituent, with 129 and 130 containing a Cl-atom at C 6 and C 7 , respectively, while 1-bromo-6,8-cyclo-4-eudesmanol (135), isolated from L. microcladia collected in the Bay of Calenzana, Elba Island, 117 125,126,130,131,137,139,140 sesquiterpenes were identified from the algal family Rhodomelaceae ( Figure 9 and Supporting Information Table S4). These molecules are generally constituted by a substituted aromatic/phenyl group connecting a 1,2,3-trisubstituted cyclopentane moiety, with only one exception, compound 163, as a nonaromatic triene obtained from a Spanish specimen of L. pinnatif ida.…”

“…162 Following extensive analyses of NOESY correlations, the stereochemistry of 219 was revised in a recent report, which also described the structures of four similar compounds 220− 223 from L. obtusa collected at Milos Island in the Aegean Sea, Greece. 163 L. obtusa (Serifos Island in the central Aegean Sea, Greece) was the source of the sesquiterpene 8-bromo-9,11-cyclo-4-perforen-3-one (224), 140 while L. tenera (Townsville region of the Great Barrier Reef, Australia) produced 2-epiperforatone (225) 164 and tenerol acetate (226). 165 The structure of 2-epi-perforatone (225) was determined by single-crystal X-ray diffraction.…”

“…165 The structure of 2-epi-perforatone (225) was determined by single-crystal X-ray diffraction. 164 Perforenone B (227) 162 and perforenol (228) 166 isolated from L. perforata and perforenol B (229) 140 isolated from L. obtusa were three halosesquiterpenes with a new carbon skeleton (perforane), which might be derived from perforatone 219 by cleavage of the C 1 −C 9 bond ( Figure 14 and Supporting Information Table S6). L. perforata was also the source of another bromochlorosesquiterpene, perforene (230), 167 possesses another new carbon skeleton (friedoperforane) that might be derived from the bromocarbenium ion of the corresponding chamigrene sesquiterpenes through a stereospecific pathway.…”

“…103 Especially potent activity was observed against HT-29 cells, with IC 50 's ranging from 0.025 to 0.5 μg/mL (Table 6). 103 Representatives of two structurally related classes of halosesquiterpenes, lauranes 144, 166, 140 activity against several tumor cell lines, and were found to display a wide range of potency levels. 109,137,140 Analysis of the data indicated that, for laurane and cuparane sesquiterpenes, neither the cyclopropyl ring nor the trisubstituted double bond are essential for cytotoxicity.…”

Natural Sesquiterpenoids

“…These algae had been collected from the coastal rocks of Serifos in the Aegean Sea. 114 Another species of this genus, Laurencia okamurai, 115 contains a new laurane derivative, 3b-hydroxyaplysin 138, and two novel rearranged sesquiterpenes, laurokamurene A 139 and laurokamurene B 140. The structure of the laurokamurene A was identical to a metabolite which had been obtained from Laurencia microcladia (see our last review 116 ).…”