Bioactive C15 acetogenins from the red alga Laurencia obtusa.

The petroleum ether extract of the red alga Laurencia obtusa afforded three new C(15) acetogenins (cyclic ether enyne): (12Z)-cis-maneonene-D (1), (12E)-cis-maneonene-E (2), and (12Z)-trans-maneonene-C (3), along with one known cis-maneonene-A (4). Blood neutrophils were prepared, cultured, and incubated for 24, 48, and 72 h in medium with and without isolated compounds. Blood neutrophils were prepared, cultured, and incubated for 24, 48 and 72 h in medium with and without the isolated compounds.

Cytotoxic and protective DNA damage of three new diterpenoids from the brown alga Dictoyota dichotoma.

Three new diterpenes Amijiol acetate (3), dolabellane, Dolabellatrienol (4), and dolastane, Amijiol-7, 10-diacetate (9) were isolated together with the previously described Pachydictyol A (1), Isopachydictyol A (2), 8β-hydroxypachydictyol A (5), Amijiol (6), Isodictyohemiacetal (7) and Dictyol C (8) from the Red Sea brown alga Dictyota dichotoma var. implexa. The structures and relative stereochemistry of the new diterpenoids were proposed on the basis of their spectral data.