A significant number of halogenated low molecular weight metabolites have exhibited an impressive array of biological properties ranging from antimicrobial to insecticidal activities. Studies on the natural products chemistry of the red seaweeds were recently stimulated by the discovery of the acyclic monoterpene halomon, which exhibits selective antitumor activity in the National Cancer Institute's human tumor and disease oriented in vitro screen.The present review is a taxonomy based compilation of the available literature on the halogenated volatile metabolites (C 1 -C 10 ) produced by red seaweeds, with a short description of the reported ecological and pharmaceutical activities. The review begins with a presentation of simple halogenated hydrocarbons and phenols, showing their wide occurrence in rhodophyta, along with a description of simple halogenated lipids in some of the most frequently investigated red algae species and finally focuses on the chemical composition of individual red algae species.

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Neorogioltriol is a tricyclic brominated diterpenoid isolated from the organic extract of the red algae Laurencia glandulifera. In the present study, the anti-inflammatory effects of neorogioltriol were evaluated both in vivo using carrageenan-induced paw edema and in vitro on lipopolysaccharide (LPS)-treated Raw264.7 macrophages. The in vivo study demonstrated that the administration of 1 mg/kg of neorogioltriol resulted in the significant reduction of carregeenan-induced rat edema. In vitro, our results show that neorogioltriol treatment decreased the luciferase activity in LPS-stimulated Raw264.7 cells, stably transfected with the NF-κB-dependent luciferase reporter. This effect on NF-κB activation is not mediated through MAPK pathways. The inhibition of NF-κB activity correlates with decreased levels of LPS-induced tumor necrosis factor-alpha (TNFα) present in neorogioltriol treated supernatant cell culture. Further analyses indicated that this product also significantly inhibited the release of nitric oxide and the expression of cyclooxygenase-2 (COX-2) in LPS-stimulated Raw264.7 cells. These latter effects could only be observed for neorogioltriol concentrations below 62.5 μM. To our knowledge, this is the first report describing a molecule derived from Laurencia glandulifera with anti-inflammatory activity both in vivo and in vitro. The effect demonstrated in vitro may be explained by the inhibition of the LPS-induced NF-κB activation and TNFα production. NO release and COX-2 expression may reinforce this effect.

Terpenes U 0200 New Cytotoxic Sesquiterpenes from the Red Algae Laurencia obtusa and Laurencia microcladia. -(KLADI, M.; XENAKI, H.; VAGIAS, C.; PAPAZAFIRI, P.; ROUSSIS*, V.; Tetrahedron 62 (2006) 1, 182-189; Div. Pharmacogn. Chem. Nat. Prod., Sch. Pharm., Univ. Athens, GR-15771 Athens, Greece; Eng.) -Nuesgen 21-178