Further polycyclic quinones of Micromonospora sp.

The crude acetone extract of a marine Micromonospora sp. strain associated with Eudistoma vannnamei was fractioned with hexane and ethyl acetate. The crude extract and both soluble fractions were assayed against several bacteria strains. The new polycyclic quinones 12-hydroxy-9-propyltetracene-6,1-dione (1), 5,12-dihydroxy-4-methoxy-9-propyltetracene-5,12-dione (2), and  4,6-dihydroxy-3-methoxycarbonyl- methyl-6a-(oxobutyl)-5,12-anthraquinone (3), along with the known 4,6-dihydroxy-3-methoxycarbonyl-methyl-6a-(oxo-3-methyl-butyl)-5,12-anthraquinone (4) and 4,6-dihydroxy-3-methoxycarbonyl-methyl-6a-(oxopentyl)-5,12-anthraquinone (5) were isolated from the hexane-soluble fraction, while from the active ethyl acetate fraction were isolated the known 4,6,11-trihydroxy-9-propyltetracene-5,12-dione (6), 4-methoxy-9-propyltetracene-6,11-dione (7), 7,8,9,10-tetrahydro-9-hydroxy-4-methoxy-9-propyltetracene-6,11-dione (8), and 10b-carbomethoxy-7,8,9,10-tetrahydro-4,6,7a,9a,11-pentahydroxy-9-propyltetracene-5,12-dione (9). The structures of the new compounds were established by interpretation of HRMS and NMR techniques.  A study of molecular docking was performed with the compounds from the active ethyl acetate fraction to correlate tentatively with the antimicrobial activity.  Molecular docking, RMSD, RMSF, and MM-GBSA evaluations were performed to investigate the inhibitory activity of 6-8 against the protein PDB-codex 1MWT, being considered a promising target for studying drug development responsible for inhibiting replication of Staphylococcus aureus. Penicillin G was used as the standard inhibitory. Anthracyclinones 6-8 were the best hydrolase inhibitor with affinity energy -8.1 to -7.9 kcal/mol compared to penicillin G, which presented -6.9 kcal/mol.

Chromomycin A5 induces bona fide immunogenic cell death in melanoma.

Purpose: Some first-line cytotoxic chemotherapics, e.g. doxorubicin, paclitaxel and oxaliplatin, induce activation of the immune system through immunogenic cell death (ICD). Tumor cells undergoing ICD function as a vaccine, releasing damage-associated molecular patterns (DAMPs), which act as adjuvants, and neoantigens of the tumor are recognized as antigens. ICD induction is rare, however it yields better and long-lasting antitumor responses to chemotherapy. Advanced metastatic melanoma (AMM) is incurable for more than half of patients. The discovery of ICD inducers against AMM is an interesting drug discovery strategy with high translational potential. Here we evaluated ICD induction of four highly cytotoxic chromomycins A (CA5-8). Methods: ICD features and DAMPs were evaluated using several in vitro techniques with metastatic melanoma cell line (B16-F10) exposed to chromomcins A5-8 such as flow cytometry, western blot, RT-PCR and luminescence. Additionally in vivo vaccination assays with CA5-treated cells in a syngeneic murine model (C57Bl/6) were performed to confirm ICD evaluating the immune cells activation and their antitumor activity. Results: B16-F10 treated with CA5-8 and doxorubicin exhibited ICD features such as autophagy and apoptosis, externalization of calreticulin, and releasing of HMGB1. However, CA5-treated cells had the best profile, also inducing ATP release, ERp57 externalization, phosphorylation of eIF2α and altering expression of transcription of genes related to autophagy, endoplasmic reticulum stress, and apoptosis. Bona fide ICD induction by CA5 was confirmed by vaccination of C57BL/6 mice with CA5-treated cells which activated antigen-presenting cells and T lymphocytes and stimulated antitumor activity. Conclusion: CA5 induces bona fide immunogenic cell death on melanoma.

In vitro biocompatibility and wound healing properties of latex proteins dressing.

The chronification of ulcers or sores may result in a dramatic outcome such as amputation. Currently, the search for plant based treatments of various diseases/disorders, including complicated ones, is getting the attention of researchers worldwide. The soluble latex protein fraction (CpLP) obtained from Calotropis procera (Apocynaceae) was previously demonstrated to accelerate wound healing by topical application or when incorporated in a polyvinyl alcohol biomembrane (BioMemCpLP). Here, in vitro assays were performed to investigate and characterize the biocompatibility and bioactivity of latex proteins dressing. Macrophages (RAW 264.7), fibroblasts (L929) and keratinocytes (HaCaT) cell lines were used to evaluate the effect of CpLP. These cell lines were exposed to concentrations of CpLP comparable to those found in BioMemCpLP during 24-72 h. The cytotoxicity, proliferation, release of wound healing mediators (TGF-ß, VEGF, IL-10, IL-6, IL-1ß, TNF-α and NO) and migration of cells (E-cadherin and ß-catenin) incubated with CpLP was assessed and the cell adhesion to BioMemCpLP as well. The results showed that CpLP has no cytotoxic effects. It induced a suitable balance between pro- and anti-inflammatory mediators, enhanced proliferation and re-epithelialization in all cell lines, but the intensity of each effect was different at various doses in all cell strains. The BioMemCpLP stimulated cell adhesion to PVA substrate. The CpLP-PVA based biomembrane can be a good option for healing of different wounds.

Biopolymer production by halotolerant bacteria isolated from Caatinga biome.

Saline environments are extreme habitats with a high diversity of microorganisms source of a myriad of biomolecules. These microorganisms are assigned as extremophiles recognized to be producers of new natural compounds, which can be synthesized by helping to survive under harshness and extreme conditions. In Brazil, in the saline and semi-arid region of Areia Branca (Caatinga biome), halotolerant bacteria (able to growth at high NaCl concentrations) were isolated from rhizosphere of native plants Blutaparon portulacoides and Spergularia sp. and their biopolymer production was studied. A total of 25 bacterial isolates were identified at genus level based on 16S rRNA gene sequence analysis. Isolates were mainly Gram-positive bacteria from Bacillaceae, Staphylococcaceae, Microbacteriaceae, and Bacillales XII incertae sedis families, affiliates to Bacillus, Staphylococcus, Curtobacterium, and Exiguobacterium genera, respectively. One of the Gram-negative isolates was identified as member of the Pseudomonadaceae family, genus Pseudomonas. All the identified strains were halotolerant bacteria with optimum growth at 0.6-2.0 M salt concentrations. Assays for biopolymer production showed that the halotolerant strains are a rich source of compounds as polyhydroxyalkanoates (PHA), biodegradable biopolymer, such as poly(3-hydroxybutyrate) (PHB) produced from low-cost substrates, and exopolysaccharides (EPS), such as hyaluronic acid (HA), metabolite of great interest to the cosmetic and pharmaceutical industry. Also, eight bacterial EPS extracts showed immunostimulatory activity, promising results that can be used in biomedical applications. Overall, our findings demonstrate that these biomolecules can be produced in culture medium with 0.6-2.0 M NaCl concentrations, relevant feature to avoid costly production processes. This is the first report of biopolymer-producing bacteria from a saline region of Caatinga biome that showed important biological activities.

Secondary Metabolism in the Gill Microbiota of Shipworms (Teredinidae) as Revealed by Comparison of Metagenomes and Nearly Complete Symbiont Genomes.

Shipworms play critical roles in recycling wood in the sea. Symbiotic bacteria supply enzymes that the organisms need for nutrition and wood degradation. Some of these bacteria have been grown in pure culture and have the capacity to make many secondary metabolites. However, little is known about whether such secondary metabolite pathways are represented in the symbiont communities within their hosts. In addition, little has been reported about the patterns of host-symbiont co-occurrence. Here, we collected shipworms from the United States, the Philippines, and Brazil and cultivated symbiotic bacteria from their gills. We analyzed sequences from 22 shipworm gill metagenomes from seven shipworm species and from 23 cultivated symbiont isolates. Using (meta)genome sequencing, we demonstrate that the cultivated isolates represent all the major bacterial symbiont species and strains in shipworm gills. We show that the bacterial symbionts are distributed among shipworm hosts in consistent, predictable patterns. The symbiotic bacteria harbor many gene cluster families (GCFs) for biosynthesis of bioactive secondary metabolites, only <5% of which match previously described biosynthetic pathways. Because we were able to cultivate the symbionts and to sequence their genomes, we can definitively enumerate the biosynthetic pathways in these symbiont communities, showing that ∼150 of ∼200 total biosynthetic gene clusters (BGCs) present in the animal gill metagenomes are represented in our culture collection. Shipworm symbionts occur in suites that differ predictably across a wide taxonomic and geographic range of host species and collectively constitute an immense resource for the discovery of new biosynthetic pathways corresponding to bioactive secondary metabolites.IMPORTANCE We define a system in which the major symbionts that are important to host biology and to the production of secondary metabolites can be cultivated. We show that symbiotic bacteria that are critical to host nutrition and lifestyle also have an immense capacity to produce a multitude of diverse and likely novel bioactive secondary metabolites that could lead to the discovery of drugs and that these pathways are found within shipworm gills. We propose that, by shaping associated microbial communities within the host, the compounds support the ability of shipworms to degrade wood in marine environments. Because these symbionts can be cultivated and genetically manipulated, they provide a powerful model for understanding how secondary metabolism impacts microbial symbiosis.

SN-38, the active metabolite of irinotecan, inhibits the acute inflammatory response by targeting toll-like receptor 4.

PURPOSE: Anticancer-drug efficacy seems to involve the direct interaction with host immune cells. Although topoisomerase I (Top I) inhibitors have been suggested to block LPS-evoked inflammation, the interaction between these drugs and toll-like receptor 4 (TLR4) is unaddressed. METHODS: SN-38, the active metabolite of the Top I inhibitor irinotecan, and TLR4 interaction was assessed using the in vitro luciferase nuclear factor-κB reporter assay, neutrophil migration to murine air-pouch, in silico simulation, and the thermal shift assay (TSA). Topotecan was used as a positive anti-inflammatory control. RESULTS: Non-cytotoxic concentrations of SN-38 attenuated LPS (a TLR4 agonist)-driven cell activation without affecting peptidoglycan (a TLR2 agonist)-activating response. Similarly, topotecan also prevented LPS-induced inflammation. Conversely, increasing concentrations of LPS reversed the SN-38 inhibitory effect. In addition, SN-38 abrogated LPS-dependent neutrophil migration and reduced TNF-α, IL-6, and keratinocyte chemoattractant levels in the air-pouch model, but failed to inhibit zymosan (a TLR2 agonist)-induced cell migration. A two-step molecular docking analysis indicated two potential binding sites for the SN-38 in the MD-2/TLR4 complex, the hydrophobic MD-2 pocket (binding energy of - 8.1 kcal/mol) and the rim of the same molecule (- 6.9 kcal/mol). The topotecan also bound to the MD-2 pocket. In addition, not only the lactone forms, but also the carboxylate conformations of both Top I inhibitors interacted with the MD-2 molecule. Furthermore, the TSA suggested the interaction of SN-38 with MD-2. CONCLUSIONS: Therefore, SN-38 inhibits acute inflammation by blocking LPS-driven TLR4 signaling. This mechanism seems to be shared by other Top I inhibitors.

Marine drugs for cancer: surfacing biotechnological innovations from the oceans.

This review will discuss the contributions of marine natural molecules, a source only recently found to have pharmaceutical prospects, to the development of anticancer drugs. Of the seven clinically utilized compounds with a marine origin, four are used for the treatment of cancer. The development of these drugs has afforded valuable knowledge and crucial insights to meet the most common challenges in this endeavor, such as toxicity and supply. In this context, the development of these compounds will be discussed herein to illustrate, with successful examples provided by cytarabine, trabectedin, eribulin and brentuximab vedotin, the steps involved in this process as well as the scientific advances and technological innovation potential associated with developing a new drug from marine resources.

Marine drugs for cancer: surfacing biotechnological innovations from the oceans

This review will discuss the contributions of marine natural molecules, a source only recently found to have pharmaceutical prospects, to the development of anticancer drugs. Of the seven clinically utilized compounds with a marine origin, four are used for the treatment of cancer. The development of these drugs has afforded valuable knowledge and crucial insights to meet the most common challenges in this endeavor, such as toxicity and supply. In this context, the development of these compounds will be discussed herein to illustrate, with successful examples provided by cytarabine, trabectedin, eribulin and brentuximab vedotin, the steps involved in this process as well as the scientific advances and technological innovation potential associated with developing a new drug from marine resources.

Chromomycin A2 induces autophagy in melanoma cells.

The present study highlights the biological effects of chromomycin A2 toward metastatic melanoma cells in culture. Besides chromomycin A2, chromomycin A3 and demethylchromomycin A2 were also identified from the extract derived from Streptomyces sp., recovered from Paracuru Beach, located in the northeast region of Brazil. The cytotoxic activity of chromomycin A2 was evaluated across a panel of human tumor cell lines, which found IC50 values in the nM-range for exposures of 48 and 72 h. MALME-3M, a metastatic melanoma cell line, showed the highest sensitivity to chromomycin A2 after 48h incubation, and was chosen as a model to investigate this potent cytotoxic effect. Treatment with chromomycin A2 at 30 nM reduced cell proliferation, but had no significant effect upon cell viability. Additionally, chromomycin A2 induced accumulation of cells in G0/G1 phase of the cell cycle, with consequent reduction of S and G2/M and unbalanced expression of cyclins. Chromomycin A2 treated cells depicted several cellular fragments resembling autophagosomes and increased expression of proteins LC3-A and LC3-B. Moreover, exposure to chromomycin A2 also induced the appearance of acidic vacuolar organelles in treated cells. These features combined are suggestive of the induction of autophagy promoted by chromomycin A2, a feature not previously described for chromomycins.

Structure elucidation and anticancer activity of 7-oxostaurosporine derivatives from the Brazilian endemic tunicate Eudistoma vannamei.

The present study reports the identification of two new staurosporine derivatives, 2-hydroxy-7-oxostaurosporine (1) and 3-hydroxy-7-oxostaurosporine (2), obtained from mid-polar fractions of an aqueous methanol extract of the tunicate Eudistoma vannamei, endemic to the northeast coast of Brazil. The mixture of 1 and 2 displayed IC50 values in the nM range and was up to 14 times more cytotoxic than staurosporine across a panel of tumor cell lines, as evaluated using the MTT assay.

Pro-apoptotic activity of lipidic α-amino acids isolated from Protopalythoa variabilis.

Lipidic α-amino acids (LAAs) have been described as non-natural amino acids with long saturated or unsaturated aliphatic chains. In the continuing prospect to discover anticancer agents from marine sources, we have obtained a mixture of two cytotoxic LAAs (1a and 1b) from the zoanthid Protopalythoa variabilis. The anti-proliferative potential of 14 synthetic LAAs and 1a/1b were evaluated on four tumor cell lines (HCT-8, SF-295, MDA-MB-435, and HL-60). Five of the synthetic LAAs showed high percentage of tumor cell inhibition, while 1a/1b completely inhibited tumor cell growth. Additionally, apoptotic effects of 1a/1b were studied on HL-60 cell line. 1a/1b-treated cells showed apoptosis morphology, loss of mitochondrial potential, and DNA fragmentation.

Studies on the cytotoxic activity of synthetic 2H-azirine-2-azetidinone compounds.

2-azetidinones and 2H-azirines show antibacterial and cytotoxic activities, however the biological properties of molecules containing both 2H-azirine and 2-azetidinone functions in the same structure had never been evaluated before. In the present study, two 2H-azirine-2-azetidinones (1 and 2) and three 2H-azirines (3-5) were synthesized from 2-formyl-3-phenyl-2H-azirine-N-arylimines with diphenylketene. The compounds were assayed for antibacterial and cytotoxic activities. None of them showed antibacterial activity on the tested strains, but both 2H-azirine-2-azetidinones showed cytotoxicity against four tumor cell lines (HL-60, leukemia; HCT-8, colon cancer; MDA-MB-435, melanoma; and SF-295, CNS). The IC(50) values of 1 ranged from 1.1 to 10.5 microM and from 3.8 to 26.6 microM for 2. The mechanism of cell growth inhibition of 1 and 2 towards HL-60 cell line was also investigated. Membrane damage, cell viability, DNA synthesis inhibition and morphological changes were evaluated. The preliminary findings suggested that 1 and 2 induce apoptosis.

Estudo do potencial anticâncer de substâncias obtidas do zoantídeo protopalythoa variabilis Duerden, 1898 (cnidaria, anthozoa) encontrado no litoral cearense / Study of the potential anticancer substances obtained from zoanthid Protopalythoa variabilis Duerden, 1898 (cnidaria, anthozoa) found in Ceará

O câncer é um dos principais problemas mundiais de saúde e uma das causas mais importantes de morbidade e mortalidade em crianças e adultos. Apesar do sucesso no tratamento de diversos tipos de tumor, ainda não se chegou ao fármaco ideal e as terapias existentes nem sempre alcançam resultados satisfatórios além de induzir muitos efeitos colaterais. A pesquisa em produtos naturais marinhos (PNM), embora recente, tem revelado uma enorme diversidade de estruturas químicas, muitas vezes inéditas e com potente atividade biológica. Moléculas citotóxicas, com potencial aplicação na quimioterapia do câncer, são frequentemente isoladas dos organismos marinhos e dos quatro fármacos oriundos de PNM comercializados atualmente, dois são utilizados na quimioterapia do câncer. Além dos metabólicos secundários, o estudo de polissacarídeos modificadores da resposta biológica para imunoterapia adjuvante também vem surgindo como uma área bastante promissora. Os cnidários juntamente com esponjas, ascídias, moluscos e algas compõem o grupo de representantes marinhos quimicamente mais prolíficos. O zoantídeo Protopalythoa variabilis (Cnidaria, Anthozoa) é encontrado no litoral do mundo inteiro, porém o seu potencial farmacológico nunca foi investigado anteriormente. O potencial antitumoral de substâncias obtidas do P. variabilis encontrado no litoral cearense foi avaliado neste trabalho. O fracionamento guiado pela citotoxicidade de 4 linhagens de células tumorais (HL-60, leucemia; HTC-8, cólon; SF-295, sistema nervoso central e MDA-MB-435, melanoma) do extrato hidroalcoólico bruto (EHB) rendeu uma mistura de α-aminoácidos lipídicos (1a/1b) inéditos a partir da fração hexano e 5 frações (AcOEt-P-1-5) contendo sinais compatíveis com esteróides...

Antileukemic effects of Didemnum psammatodes (Tunicata: Ascidiacea) constituents.

Chemical investigation of the methanolic extract of the ascidian Didemnum psammatodes has led to the identification of fourteen known compounds: three methyl esters (methyl myristate, methyl palmitate and methyl stearate), four steroids (cholesterol, campesterol, stigmasterol and beta-sitosterol), two fatty acids (palmitic acid and stearic acid), three glyceryl ethers {(1,2-propanediol, 3-(heptadecyloxy), batyl alcohol and 1,2-propanediol, 3-[(methyloctadecyl)oxy]} and two nucleosides (thymidine and 2'-deoxyguanosine). Their structures were proposed by NMR and comparison with literature data and GC analysis in comparison with authentic sample. The cytotoxic activity of these compounds was evaluated against human leukemia cell line panel using the MTT assay. The mixture of the three methyl esters was the most active group of compounds, showing antiproliferative and cytotoxic effects. Further studies on their mode of action suggest that these activities are connected with inhibition of DNA synthesis and induction of both necrosis and apoptosis.

Antimitotic properties of pterocarpans isolated from Platymiscium floribundum on sea urchin eggs.

This study reports the antimitotic effects on sea urchin eggs of five known pterocarpans: (+)-3,10-dihydroxy-9-methoxypterocarpan, (+)-3,9-dimethoxypterocarpan [(+)-homopterocarpin], (+)-2,3,9-trimethoxypterocarpan, (+)-3,4-dihydroxy-9-methoxypterocarpan [(+)-vesticarpan] and (+)-3-hydroxy-9-methoxypterocarpan [(+)-medicarpin], isolated from the trunk of Platymiscium floribundum, a native tree from Brazil. All tested compounds showed strong activity in this assay, with 2,3,9-trimethoxypterocarpan being the most active (log IC50 of -8.10 +/- 0.02; -7.91 +/- 0.01; -7.97 +/- 0.02 M for first and third cleavages, and blastulae stages, respectively). These data suggest that the 2-methoxy substituent can be an important pharmacophoric unit.

Studies of the anticancer potential of plants used in Bangladeshi folk medicine.

The present study evaluated the anticancer potential of 11 plants used in Bangladeshi folk medicine. The extracts were tested for cytotoxicity using the brine shrimp lethality assay, sea urchin eggs assay, hemolysis assay and MTT assay using tumor cell lines. The extract of Oroxylum indicum showed the highest toxicity on all tumor cell lines tested, with an IC(50) of 19.6 microg/ml for CEM, 14.2 microg/ml for HL-60, 17.2 microg/ml for B-16 and 32.5 microg/ml for HCT-8. On the sea urchin eggs, it inhibited the progression of cell cycle since the frist cleavage (IC(50)=13.5 microg/ml). The extract of Aegle marmelos exhibited toxicity on all used assays, but in a lower potency than Oroxylum indicum. In conclusion, among all tested extracts, only the extracts of Oroxylum indicum, Moringa oleifera and Aegles marmelos could be considered as potential sources of anticancer compounds. Further studies are necessary for chemical characterization of the active principles and more extensive biological evaluations.

A cytotoxic meroterpenoid benzoquinone from roots of Cordia globosa.

(1a S*,1b S*,7a S*,8a S*)-4,5-Dimethoxy-1a,7a-dimethyl-1,1a,1b,2,7, 7a,8,8a-octahydrocyclopropa cyclopenta[1,2-b]naphthalene-3,6-dione (1), a new meroterpenoid benzoquinone, and microphyllaquinone (2), a known naphthoquinone, have been isolated from roots of Cordia globosa. Both structure determinations were performed by conventional spectroscopic methods, including inverse detection NMR techniques, and by comparison with data from the literature for related compounds. Compound 1 displayed considerable cytotoxic activity against several cancer cell lines with IC50 values in the range of 1.2 to 5.0 microg/mL. The cytotoxic activity seemed to be related to DNA synthesis inhibition, as revealed by the reduction of 5-bromo-2'-deoxyuridine incorporation, and apoptosis induction, as indicated by the acridine orange/ethidium bromide assay and morphological changes after 24 h of incubation on leukemic cells.