In the present study, we investigated the antileishmanial activity of sesquiterpene elatol, the major constituent of the Brazilian red seaweed Laurencia dendroidea (Hudson) J.V. Lamouroux, against L. amazonensis. Elatol after 72 h of treatment, showed an IC50 of 4.0 μM and 0.45 μM for promastigote and intracellular amastigote forms of L. amazonensis, respectively. By scanning and transmission electron microscopy, parasites treated with elatol revealed notable changes compared with control cells, including: pronounced swelling of the mitochondrion; appearance of concentric membrane structures inside the organelle; destabilization of the plasma membrane; and formation of membrane structures, apparently an extension of the endoplasmic reticulum, which is suggestive of an autophagic process. A cytotoxicity assay showed that the action of the isolated compound is more specific for protozoa, and it is not toxic to macrophages. Our studies indicated that elatol is a potent antiproliferative agent against promastigote and intracellular amastigote forms, and may have important advantages for the development of new anti-leishamanial chemotherapies.

Chagas' disease is a debilitating but comparatively neglected illness that affects about 15 million people. There is an urgent need to develop new, more effective, and less-toxic compounds. In this study, we assessed the in vitro anti-trypanosomal activity of the sesquiterpene elatol from the Brazilian red seaweed Laurencia dendroidea. We used electron microscopy to evaluate the effect of elatol on the morphology and ultrastructure of the parasite. Elatol showed a dose-dependent effect against the epimastigote, trypomastigote, and amastigote forms, with IC50 values of 45.4, 1.38, and 1.01 microm, respectively. Observation of treated intracellular amastigotes by light microscopy demonstrated a total elimination of the infection at a dose of 3.0 microm. In addition, the compound did not affect the red blood cells, and the CC50 value for LLCMK2 cells was 27.0 microm. Transmission and scanning electron micrographs showed aberrant-shaped cells and breaks in the plasma membrane, prominent swollen mitochondria, and extensive formation of cytoplasmic vacuoles in all the forms. This is the first report of the anti-trypanosomal effect of the sesquiterpene elatol.

Dengue is a significant public health problem worldwide. Despite the important social and clinical impact, there is no vaccine or specific antiviral therapy for prevention and treatment of dengue virus (DENV) infection. Considering the above, drug discovery research for dengue is of utmost importance; in addition natural marine products provide diverse and novel chemical structures with potent biological activities that must be evaluated. In this study we propose a target-free approach for dengue drug discovery based on a novel, rapid, and economic in situ enzyme-linked immunosorbent assay and the screening of a panel of marine seaweed extracts. The in situ ELISA was standardized and validated for Huh7.5 cell line infected with all four serotypes of DENV, among them clinical isolates and a laboratory strain. Statistical analysis showed an average S/B of 7.2 and Z-factor of 0.62, demonstrating assay consistency and reliability. A panel of fifteen seaweed extracts was then screened at the maximum non-toxic dose previously determined by the MTT and Neutral Red cytotoxic assays. Eight seaweed extracts were able to reduce DENV infection of at least one serotype tested. Four extracts (Phaeophyta: Canistrocarpus cervicornis, Padina gymnospora; Rhodophyta: Palisada perforate; Chlorophyta: Caulerpa racemosa) were chosen for further evaluation, and time of addition studies point that they might act at an early stage of the viral infection cycle, such as binding or internalization.

Natural marine products have shown an interesting array of diverse and novel chemical structures with potent biological activities. Our study reports the antiproliferative assays of crude extracts, fraction and pure compound (4R,9S,14S)-4α-acetoxy-9β,14α-dihydroxydolast-1(15),7-diene (1) obtained from brown alga Canistrocarpus cervicornis showing the antileishmanial activity. We showed that 1 had a dose-dependent activity during 72 h of treatment, exhibiting IC50 of 2.0 μg/mL, 12.0 μg/mL, and 4.0 μg/mL for promastigote, axenic amastigote and intracellular amastigote forms of Leishmania amazonensis, respectively. A cytotoxicity assay showed that the action of the isolated compound 1 was 93.0 times less toxic to the macrophage than to the protozoan. Additionally, compound 1 induced ultrastructural changes, including extensive mitochondrial damage; decrease in Rh123 fluorescence, suggesting interference with the mitochondrial membrane potential; and lipid peroxidation in parasite cells. The use of 1 from C. cervicornis against L. amazonensis parasites might be of great interest as a future alternative to the development of new antileishmanial drugs.

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This manuscript describes the evaluation of anti-infective potential in vitro of organic extracts from nine sponges, one ascidian, two octocorals, one bryozoan, and 27 seaweed species collected along the Brazilian coast. Antimicrobial activity was tested against Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922) and Candida albicans (ATCC 10231) by the disk diffusion method. Antiprotozoal activity was evaluated against Leishmania braziliensis (MHOM/BR/96/LSC96-H3) promastigotes and Trypanosoma cruzi (MHOM/BR/00/Y) epimastigotes by MTT assay. Activity against intracellular amastigotes of T. cruzi and L. brasiliensis in murine macrophages was also evaluated. Antiviral activity was tested against Herpes Simplex Virus type 1 (HSV-1, KOS strain) by the plaque number reduction assay (IC50). Cytotoxicity on VERO cells was evaluated by the MTT assay (CC50). The results were expressed as SI = CC50/IC50. The most promising antimicrobial results were obtained against S. aureus and C. albicans with Dragmacidon reticulatum. Among the seaweeds, only Osmundaria obtusiloba showed moderate activity against P. aeruginosa. Concerning antiprotozoal activity, Bugula neritina, Carijoa riseii, Dragmaxia anomala and Haliclona (Halichoclona) sp. showed the most interesting results, mainly against extracellular promastigote forms of L. braziliensis (66, 35.9, 97.2, and 43.6% inhibition, respectively). Moreover, six species of seaweeds Anadyomene saldanhae, Caulerpa cupressoides, Canistrocarpus cervicornis, Dictyota sp., Ochtodes secundiramea, and Padina sp. showed promising results against L. braziliensis (87.9, 51.7, 85.9, 93.3, 99.7, and 80.9% inhibition, respectively), and only Dictyota sp. was effective against T. cruzi (60.4% inhibition). Finally, the antiherpes activity was also evaluated, with Haliclona (Halichoclona) sp. and Petromica citrina showing the best results (SI = 11.9 and SI > 5, respectively). All the active extracts deserve special attention in further studies to chemically characterize the bioactive compounds, and to perform more refined biological assays.

This paper reports the antifouling properties of the dichloromethane crude extract (DC) and 3 pure compounds isolated from the Brazilian brown seaweed Canistrocarpus cervicornis against establishment of the mussel Perna perna. DC extract showed a strong inhibition activity against byssal threads. Two natural dolastanes and one seco-dolastane diterpene, namely (4R, 9S, 14S)-4α-acetoxy-9β,14α-dihydroxydolast-1(15),7-diene (1), (4R,7R,14S)-4α,7α-diacetoxy-14-hydroxydolast-1(15),8-diene (2) and isolinearol (3), were isolated from DC extract. Dolastane (1) inhibited 60% of byssal fixation, while compound 2 and the seco-dolastane (3) strongly inhibited (82%) the establishment of P. perna. This is the first report of this type of chemical skeleton in three powerful compounds that could be further explored for the development of antifouling technology.

Aqueous extract of Indigofera suffruticosa leaves obtained by infusion was used to evaluate the oviposition, its effect on development of eggs and larvae, and morphological changes in larvae of Aedes aegypti. The bioassays were carried out with aqueous extract in different concentrations on eggs, larvae, and female mosquitoes, and the morphological changes were observed in midgut of larvae. The extract showed repellent activity on A. aegypti mosquitoes, reducing significantly the egg laying by females with control substrate (343 (185–406)) compared with the treated substrate (88 (13–210)). No eclosion of A. aegypti eggs at different concentrations studied was observed. The controleclodedin 35%. At concentration of 250 μg/mL, 93.3% of larvae remained in the second instar of development and at concentrations of 500, 750, and 1000 μg/mL the inhibitory effect was lower with percentages of 20%, 53.3%, and 46.6%, respectively. Morphological changes like disruption on the peritrophic envelope (PE), discontinued underlying epithelium, increased gut lumen, and segments with hypertrophic aspects were observed in anterior region of medium midgut of larvae of A. aegypti. The results showed repellent activity, specific embryotoxicity, and general growth retardation in A. aegypti by medium containing aqueous extract of I. suffruticosa leaves.