Investigation of the bioactive crude extracts from two populations of the red alga Laurencia dendroidea from the southeastern Brazilian coast led to the identification of five sesquiterpenes: (+)-obtusane (1), a triquinane derivative (2), (-)-elatol (3), obtusol (4), and cartilagineol (5). An antileishmanial bioassay against Leishmania amazonensis was conducted for crude lipophilic extracts and for sesquiterpenes 2, 3, and 4. Compounds 3 and 4 displayed in vitro and in vivo leishmanicidal activity and very low cytotoxicity.

Abstract:Two new chamigrane sesquiterpenes 1-2 and three known compounds 3-5 were isolated from a lipophilic extract of the red alga Laurencia dendroidea collected from the OPEN ACCESSMolecules 2014, 19 3182 Southeastern Brazilian coast. Dendroidone (1) and dendroidiol (2) were isolated from samples collected at Biscaia Inlet, Angra dos Reis, Rio de Janeiro and at Manguinhos Beach, Serra, Espírito Santo, respectively. Debromoelatol (3), obtusane (4) and (1S*,2S*,3S*,5S*,8S*,9S*)-2,3,5,9-tetramethyltricyclo[6.3.0.0 1.5 ]undecan-2-ol (5) were obtained from specimens collected at Vermelha Beach, Parati, Rio de Janeiro. The structures of new compounds were elucidated by extensive NMR ( 1 H-, 13 C-, COSY, HSQC, HMBC and NOESY) and high resolution mass spectrometry analysis. Additionally, the absolute configuration of compound 2 was assigned by X-ray analysis. Full spectroscopic data is described for the first time for compound 3. Anti-inflammatory and antimycobacterial activities of compounds 2-5 were evaluated. Compounds 3-5 inhibited the release of inflammatory mediator NO while TNF-α levels were only affected by 3. All compounds tested displayed moderate antimycobacterial action.

RESUMO:As algas vermelhas do gênero Laurencia são conhecidas como uma riquíssima fonte de metabólitos secundários. As principais classes químicas já isoladas são terpenos -sesquiterpenos, diterpenos, triterpenos -e acetogeninas. Estudos apontam que estas substâncias apresentam importantes atividades biológicas, principalmente citotóxica e antibacteriana. Existem ainda alguns poucos trabalhos com informações sobre atividade antiparasitária, antiviral e antifúngica dos metabólitos de Laurencia. O forte perfil bioativo observado em alguns estudos sugere que alguns destes metabólitos podem ser futuramente utilizados como fármacos ou como protótipos de novos agentes antitumorais e antibacterianos. Muitos dos metabólitos de Laurencia ainda não foram avaliados sob o ponto de vista farmacológico, o que representa um grande potencial a ser explorado por diversos campos da farmacologia.Unitermos: macroalgas, Ceramiales, Rhodomelaceae, produtos naturais.ABSTRACT: "Biological activity of the secondary metabolite from marine algae of the genus Laurencia." The red alga of the genus Laurencia is known as an endless source of metabolites. The main substances produced are sesquiterpenes, diterpenes, triterpenes and acetogenins. Many studies reveal that these metabolites are active, especially cytotoxic and antibacterial. There are few other studies that describe the antiparasital, antifungal and antiviral actions of the metabolites produced by the alga of the genus Laurencia. The results observed in some studies suggest that these metabolites may be used in the future as drugs or lead compounds as antitumoral and/or antibacterial agents. Many metabolites have not been submitted to pharmacological studies which still represents an area to be explored.

Red algae of the genus Laurencia J. V. Lamouroux are found in tropical and subtropical regions throughout the world and are an extremely rich source of active secondary metabolites with diverse structural features. In the present study, 6 sesquiterpenes (obtusol, (-)-elatol, dendoidiol, debrome-elatol, triquinane, and obtusane) isolated from Laurencia dendroidea were investigated for their cytotoxicity, using 4 cancer cell lines (U937, Jurkat, B16F10, and Colo-205). Among all sesquiterpenes tested, obtusol and (-)-elatol showed a promising activity in the treatment of Colo-205 strain, with IC of 1.2 ± 1.4 and 2.5 ± 1.3 μg/ml, respectively. In addition, fluorescence microscopy results indicated that, at 100 μg/ml, obtusol induced apoptosis at 79% and (-)-elatol at 95%. Activation of Caspases 2, 4, 6, and 8 showed to be involved in (-)-elatol activity and only Caspase 6 in obtusol activity. These data demonstrated the effective apoptosis-inducing activity of the sesquiterpene (-)-elatol and obtusol in the treatment of Colo-205 strain. Therefore, more studies should be done so that the sesquiterpenes (-)-elatol and obtusol might become promising chemotherapy.

Background:Red algae of the genus Laurencia J. V. Lamouroux are a rich source of secondary metabolites with important pharmacological activities such as anti-tumoral, anti-inflammatory, anti-fungal, anti-viral, anti-leishmanial, anti-helminthic, anti-malarial, anti-trypanosomal, anti-microbial as well as anti-bacterial against Mycobacterium tuberculosis.Objective:In the present study, we evaluated the inhibition of nitric oxide (NO) and tumor necrosis factor-α production and the anti-mycobacterial activity of crude extracts from the red Alga Laurencia dendroidea (from the South-Eastern coast of Brazil). Halogenated sesquiterpenes elatol (1), obtusol (2) and cartilagineol (3), previously isolated from this Alga by our group, were also studied.Materials and Methods:The lipopolysaccharide-activated macrophage cells (RAW 264.7) were used as inflammation model. Cytotoxic effect was determined using a commercial lactate dehydrogenase (LDH) kit and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The growing Mycobacterium inhibition was verified against Mycobacterium bovis Bacillus Calmette–Guérin and M. tuberculosis H37 Rv strains.Results:The crude extract from Alga collected at Angra dos Reis, RJ, Brazil, was the most active inhibitor of both mycobacterial growth (half maximal inhibitory concentration [IC50] 8.7 ± 1.4 μg/mL) and NO production by activated macrophages (IC50 5.3 ± 1.3 μg/mL). The assays with isolated compounds revealed the anti-mycobacterial activity of obtusol (2), whereas (-)-elatol (1) inhibited the release of inflammatory mediators, especially NO. To our knowledge, this is the first report describing an anti-mycobacterial effect of L. dendroidea extract and demonstrating the association of this activity with obtusol (2).Conclusion:The described effects of active compounds from L. dendroidea are promising for the control of inflammation in infectious diseases and specifically, against mycobacterial infections associated with exacerbated inflammation.SUMMARY Inflammation is strongly involved in the pathogenesis of most infectious diseases, including TB. The treatment of TB is based on the use of anti mycobacterial drugs, however the most severe forms of TB, require additional anti inflammatory therapy to prevent excessive inflammation. A combination of these properties in one compound could provide additional therapeutic benefits. In this work, we studied L. dendroidea extracts and purified compounds and demonstrated that the LDA extract and (-)-elatol (1) were potent in inhibiting NO production by macrophages through the specific inhibition of iNOS expression. The LDA and LDM extracts and obtusol (2) were active against virulent strain of M. tuberculosis. This is the first report demonstrating that the anti-inflammatory activities of L. dendroidea were associated with the presence of (-)-elatol (1), whereas anti-mycobacterial activities of L. dendroidea extracts were associated with obtusol (2).