Abstract The extensive marine biodiversity has proved to be a promising source of substances with biomedical potential. In this study, the cytotoxicity of the Brazilian octocoral Phyllogorgia dilatata (Gorgoniidae) was evaluated against two tumor cell lines and three bacterial strains. The methanol/dichloromethane crude extract presented no antibacterial activity up to the highest concentration tested (512 µg/mL), however it revealed a noteworthy antiproliferative effect against HCT-116 (80%) and MCF-7 (54%) cell lines at 50 μg/mL. Therefore, guided by the cytotoxic activity, a multistep chemical fractionation of the extract provided the subfraction 5 (PDPH2-5) with IC50 values of 3.18 and 17.80 μg/mL against HCT-116 and MCF-7, respectively. The LC-HRMS/MS analysis of PDPH2-5 showed ions of m/z 219.1742 and 219.1743, characterized as (E,E) and (Z,E) germacrone, after a LC-DAD-SPE/NMR analysis of the hexanic fraction and comparisons of NMR data with the literature. Previously reported assessments to the cytotoxic activity of the (E,E)-diastereoisomer disclosed higher IC50 values than that obtained for the PDPH2-5 fraction, suggesting, herein, a potentiated effect of the diastereoisomeric mixture. Such remark encourage further bioactivity studies with stereoisomer mixtures and reduce the urge for compound isolation.

Chemical profiles of extracts of four species from Laurencia complex (Ceramiales, Rhodophyta) from different populations collected along Southeast Brazilian coast were assessed by High Performance Liquid Chromatography coupled with a Diode Array Detector in order to observe geographic chemical variability. Aiming to evaluate the impact of chemical diversity on potential pharmaceutical uses, the extracts were tested against the promastigote form of Leishmania amazonensis. The most active extracts were submitted to anti-amastigote and cytotoxicity assays. Principal Component Analysis of the chromatograms resulted in four major groups of chemical profiles according to the presence of leishmanicidal chamigranes (-)-elatol and obtusol. The existence of chemotypes, displaying variable pharmacological action, is proposed for the differences observed in L. dendroidea samples. Although all extracts were found active against promastigote form of L. amazonensis, their efficacy was remarkably different and not related to the variation of (-)-elatol and obtusol, which indicates the presence of additional compounds with antileishmanial activity. Moreover, the active extracts also displayed anti-amastigote activity and none of them were considered cytotoxic. The results highlight that the knowledge of chemical geographic variability can be valuable in the search of new antileishmanial compounds from marine sources.

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.

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.