This review discusses the isolation, structural elucidation, and biological activities of halogenated indole alkaloids obtained from marine invertebrates. Meridianins and related compounds (variolins, psammopemmins, and aplicyanins), as well as aplysinopsins and leptoclinidamines, are focused on. A compilation of the 13C-NMR spectral data of these selected natural indole alkaloids is also provided.

Miconia langsdorffii Cogn. (Melastomataceae), Roupala montana Aubl. (Proteaceae), Struthanthus syringifolius (Mart.) (Loranthaceae), and Schefflera vinosa (Cham. & Schltdl.) Frodin (Araliaceae) are plant species from the Brazilian Cerrado whose schistosomicidal potential has not yet been described. The crude extracts, fractions, the triterpenes betulin, oleanolic acid, ursolic acid and the flavonoids quercetin 3-O-β-D-rhamnoside, quercetin 3-O-β-D-glucoside, quercetin 3-O-β-D-glucopyranosyl-(1-2)-α-L-rhamnopyranoside and isorhamnetin 3-O-β-D-glucopyranosyl-(1-2)-α-L-rhamnopyranoside were evaluated in vitro against Schistosoma mansoni adult worms and the bioactive n-hexane fractions of the mentioned species were also analyzed by GC-MS. Betulin was able to cause worm death percentage values of 25% after 120 h (at 100 μM), and 25% and 50% after 24 and 120 h (at 200 μM), respectively; besides the flavonoid quercetin 3-O-β-D-rhamnoside promoted 25% of death of the parasites at 100 μM. Farther the flavonoids quercetin 3-O-β-D-glucoside and quercetin 3-O-β-D-rhamnoside at 100 μM exhibited significantly reduction in motor activity, 75% and 87.5%, respectively. Biological results indicated that crude extracts of R. montana, S. vinosa, and M. langsdorffii and some n-hexane and EtOAc fractions of this species were able to induce worm death to some extent. The results suggest that lupane-type triterpenes and flavonoid monoglycosides should be considered for further antiparasites studies.

The aim of this study was to examine the cytotoxic and genotoxic potential of a hydroethanolic extract of Schefflera vinosa (SV), a plant with schistosomicidal activity, as well as its influence on DNA damage induced by different mutagens, methyl methane sulfonate (MMS) and hydrogen peroxide (HO), in V79 cells and Swiss mice. Schefflera vinosa extract produced cytotoxicity at concentrations of 312.5 µg/ml or higher using the XTT cell proliferation assay kit. Treatment of V79 cell cultures with the highest SV concentration tested (150 µg/ml) significantly increased the frequency of micronuclei (MN) compared to controls. All SV concentrations significantly reduced the frequency of MN induced by hydrogen peroxide in V79 cell cultures. Further, SV was able to scavenge free radicals in the DPPH assay. In the in vivo test system, treatment with the highest dose tested (1,000 mg/kg body weight) induced a significant rise in frequency of DNA damage using the comet assay. However, animals treated with different doses of SV demonstrated absence of genotoxicity in the bone marrow MN test. For assessment of modulatory effects, the lower concentration of SV (250 mg/kg body weight) administered to MMS-treated mice significantly reduced frequency of DNA damage compared to the positive control (MMS alone). In contrast, the highest concentration tested (1,000 mg/kg body weight) significantly increased the rate of MN induced by MMS. The lack of genotoxic damage at biologically relevant SV concentrations, as well as the SV-mediated antigenotoxic and antioxidant activities, indicate the potential therapeutic usefulness of this plant extract. These activities may be attributed, at least in part, to the flavonoid quercitrin, its major component.

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O presente estudo teve como objetivo reisolar, identificar e investigar o potencial antifitopatogênico de uma série de metabólitos secundários obtidos de duas fontes botânicas diversas. Do extrato acetônico de Usnea steineri , foram obtidos ácido úsnico e ácido difractáico. A partir do extrato de Rosmarinus officinalis , o ácido rosmarínico foi reisolado. A identificação de todas as substâncias foi realizada com base em dados obtidos de 1 H RMN, 13 C RMN e/ou comparação com padrões autênticos. Nos testes de atividade antimicrobiana contra nove bactérias fitopatogênicas, o ácido úsnico se mostrou promissor, sendo que os melhores resultados obtidos foram contra as bactérias Xanthomonas axonopodis e Xanthomonas campestriscom MIC de 3,12 µg/mL e 6,25 µg/mL, respectivamente. Nos estudos de sobrevivência realizados com o ácido úsnico contra Xanthomonas axonopodis constatou-se que na concentração de 3,12 µg/mL somente após 48 horas, o ácido úsnico foi bactericida para as espécies estudadas. Os resultados da avaliação da atividade citotóxica do ácido úsnico em células GM7492A (fibroblastos humanos) revelaram que não houve diferenças significativas entre as culturas tratadas com ácido úsnico (15,6 µg/ml a 2000,0 µg/ml) e o controle negativo, apresentando ausência citotóxica efeitos nas concentrações testadas. Diante dos resultados, pode-se concluir que o ácido úsnico é um composto promissor para o desenvolvimento de um novo bactericida para o controle de alguns fitopatógenos.