Three new plakortides, 7,8-dihydroplakortide E (1), 2, and 10, along with known natural products 3, 4, spongosoritin A (5), 6-8, and plakortide P (9), were isolated from Brazilian specimens of Plakortis angulospiculatus. Compounds 2, 3, 5, and 7-9 displayed cytotoxic activities with IC50 values ranging from 0.2 to 10 μM. Compounds that contained a dihydrofuran ring were generally less active and displayed time dependence in their activity. The activities of compounds 2 and 7-9, carboxylic acids bearing a common six-membered endoperoxide, were higher overall than for compounds 3 and 5. The modes underlying the cytotoxic actions of plakortides 2, 3, 5, 7, and 9 were further investigated using HCT-116 cells. While dihydrofurans 3 and 5 induce a G0/G1 arrest, six-membered peroxides 2, 7, and 9 delivered a G2/M arrest and an accumulation of mitotic figures, indicating a distinctly different antimitotic response. Confocal analysis indicated that microtubules were not altered after treatment with 2, 7, or 9, therein suggesting that the mitotic arrest may be unrelated to cytoskeletal targets. Overall, we find that two related classes of natural products obtained from the same extract offer cytostatic activity, yet they do so through discrete pathways.

Marine natural products have emerged as an important source for drug development, notably in the field of anticancer therapy. Still, the limited effectiveness of current therapies for central nervous system tumors indicates the need to identify new therapeutic targets and also novel pharmacological agents. In this context, proteasome inhibitors are appearing as a promising new treatment for these diseases. Herein, cytotoxic extracts produced by four marine bacteria recovered from the Brazilian endemic ascidian Euherdmania sp. were screened to evaluate their potential as proteasome inhibitors. The extract from marine Streptomyces sp. BRA-346 was selected for further investigation due to the potent proteasome inhibitory activity it displayed. Bioassay-guided fractionation led to an enriched fraction (proteasome inhibition IC50 = 45 ng/mL), in which the presence of dihydroeponemycin (DHE), known for its proteasome inhibitory effect, and related compounds were annotated by mass spectrometry and further confirmed by comparison with DHE standard. Both DHE and the epoxyketone-containing fraction were evaluated in glioma cell lines, displaying high cytotoxicity in HOG and T98G cells (GI50 of 1.6 and 1.7 ng/mL for DHE, and 17.6 and 28.2 ng/mL for the BRA-346 fraction, respectively). Additional studies showed that the epoxyketone-containing fraction (at GI50 levels) led to an accumulation of ubiquitinated proteins and up-regulation of genes related to ER-stress response, suggesting treated cells are under proteasome inhibition. DHE induced similar effects in treated cells but at concentrations 25 times its GI50, suggesting that the other epoxyketone compounds in the bacteria extract derived fraction may contribute to enhance proteasome inhibition and further cellular effects in glioma cells. These findings revealed the molecular pathways modulated by this class of compounds in glioma cells and, moreover, reinforced the potential of this marine bacteria in producing a cocktail of structurally-related compounds that affect the viability of glioma cells.

Recebido em 17/8/12; aceito em 26/11/12; publicado na web em 6/3/13 FLAVONOIDS AND TERPENOIDS FROM Croton muscicarpa (Euphorbiaceae). A new sesquiterpene and twelve known compounds comprising eight flavonoids and four terpenoids, were isolated from the leaves, stems, roots and exudate of Croton muscicarpa Müll. Arg.. Their structures were identified as the terpenoids 6α-methoxy-cyperene, dammaradienol, squalene, acetyl aleuritolic acid and spathulenol, and as the flavonoids retusin, 3,7,4'-trimethoxy kaempferol, ombuine, pachipodol, kaempferol, casticin, 5-hydroxy-3,6,7,4'-tetramethoxyflavone and artemetin. All isolated compounds were characterized based on IR, MS, 1 H and 13 C NMR, including 2D analyses (COSY, HSQC, HMBC, NOESY) and comparison with data from the literature.

Recebido em 7/6/10; aceito em 11/8/10; publicado na web em 26/11/10 ANTIFUNGAL GLYCOALKALOIDS, FLAVONOIDS AND OTHER CHEMICAL CONSTITUENTS OF Solanum asperum Rich (Solanaceae). Two glycoalkaloids: solamargine and solasonine; three flavonoids: tiliroside, 7-O-α-L-ramnopyranosyl-kaempferol and, in addition to the tripeptide Leu-Ile-Val, the aminoacid proline and the eicosanoic acid were isolated from Solanum asperum (Solanaceae). The structures of all compounds were determined by interpretation of their spectra (IR, MS, 1 H and 13 C NMR) and comparison with the literature data. All compounds, except the glycoalkaloids, are being reported for the first time for S. asperum. Solasonine showed strong activity (MIC < 0.24 mg/mL) against four filamentous fungi species of the genera Microsporum and Trichophyton.Keywords: Solanum asperum; antifungal glycoalkaloids; flavonoids. INTRODUÇÃOA família Solanaceae é representada por aproximadamente 2000 espécies distribuídas em 95 gêneros, sendo o taxon Solanum o mais representativo, com aproximadamente 1500 espécies e 5000 epítetos. As plantas que representam este gênero estão distribuídas preferencialmente nas áreas tropicais e subtropicais do planeta, sendo a América do Sul, o centro de maior diversidade e distribuição. 1 Uma grande fração do total de espécies descritas pode ser encontrada no Brasil, particularmente, na região Nordeste, onde são catalogadas cerca de 350 espécies. 2 Várias plantas deste gênero são popularmente conhecidas como "jurubebas", muitas das quais são largamente utilizadas na medicina popular, especialmente no tratamento de doenças da pele ou doenças relacionadas ao fígado e baço. 3,4 As plantas do gênero Solanum destacam-se pela capacidade de biossintetizar esteroides e alcaloides, livres ou na forma de heterosídeos, metabólitos secundários estruturalmente diversificados e complexos. 5,6 Estes compostos, em geral, são de interesse terapêutico, visto que apresentam um grande leque de atividades, como citotóxica, 5 anticâncer, 7 anti-inflamatória, 8 antiulcerogênica 9 e moluscicida. 10 Além disso, são também responsáveis pela resistência natural das espécies em seu ecossistema. 11 Compostos fenólicos, principalmente flavonas e flavonóis, incluindo seus heterosídeos, são também identificados com frequência em espécies de Solanum. 1,12 Como parte de um estudo multidisciplinar, cujo objetivo é investigar plantas da família Solanaceae, na busca por compostos bioativos, especialmente com atividade anticâncer, já foram isoladas várias lactonas esteroidais. 13,14 Neste trabalho é relatado o resultado obtido com a prospecção química de Solanum asperum Rich, popularmente conhecido como "coça-coça" ou "russara". As plantas desta espécie apresentam porte arbustivo e todas as suas partes são pulverulentas, isto é, ricas em pelos urticantes que se desprendem facilmente e que, em contato com a pele, provocam intensa coceira, daí o nome popular. Concomitante ao estudo químico foi ainda investigado o potencial antifúngico de algumas das substâncias isoladas.

The present study evaluated the effect of supplementing in vitro culture medium with J. insularis compared to FSH on isolated secondary follicles and in vitro maturation of oocytes from those follicles. Secondary follicles were isolated from sheep ovaries and individually cultured for 18 days in α-MEM+ (Control), α-MEM+ supplemented with 100 ng/mL recombinant bovine follicle stimulating hormone (FSH) or with 0.3, 1.25, or 2.5 mg/mL of J. insularis extract (JI0.3, JI1.25, and JI2.5, respectively). Culture medium collected every 2 days was used to measure ROS levels. At the end of the culture period, cumulus oocytes complex (COCs) were collected and matured in vitro. Follicular walls were used for mRNA quantitation. JI0.3 led to a higher (P < 0.05) percentages of intact follicles than other groups after 18 days of culture. While follicular diameter remained unchanged from Day 6 onwards with JI0.3 and FSH, percentages of antral cavity formation were higher (P < 0.05) with JI0.3 at Day 6 than in all other treatments. No differences were observed between controls and treatment groups regarding ROS levels and mRNA expression of genes. Viability of resulting oocytes was higher (P < 0.05) in JI0.3 compared to FSH. Interestingly, in control experiment, supplementation of maturation medium with JI0.3 led to higher (P < 0.05) percentages of metaphase II compared to controls. Although more validations will be needed, it seems that this natural extract could be used as a cheap and easily available alternative to commercial FSH.

Three new solanidane alkaloids bearing a 22,23-epoxy ring (1-3) and four known compounds were isolated from leaves of Solanum campaniforme. The structures were determined using spectroscopic techniques, including 1D and 2D NMR, and HRESIMS experiments. The antiophidic activity of the alkaloids was tested against Bothrops pauloensis venom. Compounds 1-3 completely inhibited myotoxicity without inhibiting phospholipase A2 activity of the venom, while hemorrhage and skin necrosis were significantly reduced in the presence of alkaloids 1 and 2.

A new polycyclic antibiotic, pradimicin-IRD, was isolated from actinobacteria Amycolatopsis sp. IRD-009 recovered from soil of Brazilian rainforest undergoing restoration area. This molecule is the major compound produced in solid culture media. The new compound was detected by a focused method of precursor ion (high-performance liquid chromatography coupled to tandem mass spectrometer) developed previously to identify unusual aminoglycosyl sugar moieties. The compound was isolated and its structure was, therefore, elucidated by high-resolution mass spectrometry, and 1D and 2D nuclear magnetic resonance experiments. Pradimicin-IRD displayed potential antimicrobial activity against Streptococcus agalactiae (MIC 3.1 μg/mL), Pseudomonas aeruginosa (MIC 3.1 μg/mL) and Staphylococcus aureus (MIC 3.1 μg/mL), and also cytotoxicity against tumour and non-tumour cell lines with IC values ranging from 0.8 μM in HCT-116 colon carcinoma cells to 2.7 μM in MM 200 melanoma cells. Particularly, these biological properties are described for the first time for this chemical class.

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