Search Results (6)

Non-alcoholic fatty liver disease (NAFLD), which starts with liver steatosis, is a growing worldwide epidemic responsible for chronic liver diseases. Among its risk factors, exposure to environmental contaminants, such as endocrine disrupting compounds (EDC), has been recently emphasized. Given this important public health concern, regulation agencies need novel simple and fast biological tests to evaluate chemical risks. In this context, we developed a new in vivo bioassay called StAZ (Steatogenic Assay on Zebrafish) using an alternative model to animal experimentation, the zebrafish larva, to screen EDCs for their steatogenic properties. Taking advantage of the transparency of zebrafish larvae, we established a method based on fluorescent staining with Nile red to estimate liver lipid content. Following testing of known steatogenic molecules, 10 EDCs suspected to induce metabolic disorders were screened and DDE, the main metabolite of the insecticide DDT, was identified as a potent inducer of steatosis. To confirm this and optimize the assay, we used it in a transgenic zebrafish line expressing a blue fluorescent liver protein reporter. To obtain insight into DDE’s effect, the expression of several genes related to steatosis was analyzed; an up-regulation of scd1 expression, probably relying on PXR activation, was found, partly responsible for both membrane remodeling and steatosis. Full article

Environmental and lifestyle adaptations over the last decades have contributed to enhanced man´s longevity, however it also paved the ground for different diseases to unfold. Today one of the main public health challenges is obesity and its related metabolic dysfunctions. In recent years, the pharmacological options are reported as being insufficient, therefore, the discovery and pharmacological development of new therapeutic approaches are required to overcome this epidemic. Vitamin K are a fat-soluble family of compounds implicated in a number of essential biological functions. Vitamin K1 and K2 are two naturally occurring compounds, while vitamin K3 is the most common synthetic form. A bioactivity-guided approach was used with the Nile red fat metabolism assay in zebrafish larvae to successfully isolate an analog of vitamin K1 for the first time from Tychonema sp. LEGE 07196. The structure confirmation was based on NMR spectroscopy and mass spectrometry. This analog was first isolated in 1965 from the cyanobacteria Synechococcus elongatus, but little is known on its bioactivity. The anti-obesity effects of all vitamin K forms, including the K1-analog, were studied. The compounds did not cause any general toxicity or malformations and showed significant neutral lipid-reducing activity after 48 h of exposure. The different vitamin forms displayed different levels of activity which shows the importance of the naphthoquinone ring, as well as the impact of the saturation and polarity of the aliphatic side-chain for the structure–activity relationship. Metabolomics approaches were employed to establish the distinct bioavailability and biotransformation of the different forms of vitamins in the organisms. The metabolite profiling was achieved using different databases and MetaboAnalyst was used for associated analysis. The organism has a clear preference to transform the various vitamins into K1 and K1-analog forms, regardless of the supplementation, and each exposed vitamin significatively altered the expression of different metabolites indicating that different metabolic targets are involved. This work is ongoing, and the final aim is to understand the effects of vitamin K family on obesity and related co-morbidities, which could lay the ground to develop a future nutraceutical with lipid reduction activity. Full article

The previously reported 1-(2,4-dihydroxy-5-methylphenyl)ethan-1-one (1), (1’Z)-2-(1’,5’-dimethylhexa-1’,4’-dieny1)-5-methylbenzene-1,4-diol (2), and 1,8-epoxy-1(6),2,4,7,10-bisaborapentaen-4-ol (5) together with four new structures of aromatic bisabolane-related compounds (3, 4, 6, 7) were isolated from the marine sponge Myrmekioderma sp. Compounds 1, 2, and 5 were identified based on spectral data available in the literature. The structures of the four new compounds were experimentally established by 1D and 2D-NMR and (−)-HRESIMS spectral analysis. Cytotoxic and lipid-reducing activities of the isolated compounds were evaluated. None of the isolated compounds were active against the tested cancer cell lines; however, lipid-reducing activity was found for compounds 2–5 and 7 in the zebrafish Nile red fat metabolism assay. This class of compounds should be further explored for their suitability as possible agents for the treatment of lipid metabolic disorders and obesity. Full article

Obesity is a complex disease resulting in several metabolic co-morbidities and is increasing at epidemic rates. The marine environment is an interesting resource of novel compounds and in particular cyanobacteria are well known for their capacity to produce novel secondary metabolites. In this work, we explored the potential of cyanobacteria for the production of compounds with relevant activities towards metabolic diseases using a blend of target-based, phenotypic and zebrafish assays as whole small animal models. A total of 46 cyanobacterial strains were grown and biomass fractionated, yielding in total 263 fractions. Bioactivities related to metabolic function were tested in different in vitro and in vivo models. Studying adipogenic and thermogenic gene expression in brown adipocytes, lipid metabolism and glucose uptake in hepatocytes, as well as lipid metabolism in zebrafish larvae, we identified 66 (25%) active fractions. This together with metabolite profiling and the evaluation of toxicity allowed the identification of 18 (7%) fractions with promising bioactivity towards different aspects of metabolic disease. Among those, we identified several known compounds, such as eryloside T, leptosin F, pheophorbide A, phaeophytin A, chlorophyll A, present as minor peaks. Those compounds were previously not described to have bioactivities in metabolic regulation, and both known or unknown compounds could be responsible for such effects. In summary, we find that cyanobacteria hold a huge repertoire of molecules with specific bioactivities towards metabolic diseases, which needs to be explored in the future. Full article

Marine organisms, particularly cyanobacteria, are important resources for the production of bioactive secondary metabolites for the treatment of human diseases. In this study, a bioassay-guided approach was used to discover metabolites with lipid-reducing activity. Two chlorophyll derivatives were successfully isolated, the previously described 13²-hydroxy-pheophytin a (1) and the new compound 13²-hydroxy-pheofarnesin a (2). The structure elucidation of the new compound 2 was established based on one- and two-dimensional (1D and 2D) NMR spectroscopy and mass spectrometry. Compounds 1 and 2 showed significant neutral lipid-reducing activity in the zebrafish Nile red fat metabolism assay after 48 h of exposure with a half maximal effective concentration (EC₅₀) of 8.9 ± 0.4 µM for 1 and 15.5 ± 1.3 µM for 2. Both compounds additionally reduced neutral lipid accumulation in 3T3-L1 multicellular spheroids of murine preadipocytes. Molecular profiling of mRNA expression of some target genes was evaluated for the higher potent compound 1, which indicated altered peroxisome proliferator activated receptor gamma (PPARγ) mRNA expression. Lipolysis was not affected. Different food materials (Spirulina, Chlorella, spinach, and cabbage) were evaluated for the presence of 1, and the cyanobacterium Spirulina, with GRAS (generally regarded as safe) status for human consumption, contained high amounts of 1. In summary, known and novel chlorophyll derivatives were discovered from marine cyanobacteria with relevant lipid-reducing activities, which in the future may be developed into nutraceuticals. Full article

A new ergosterol analog, talarosterone (1) and a new bis-anthraquinone derivative (3) were isolated, together with ten known compounds including palmitic acid, ergosta-4,6,8(14),22-tetraen-3-one, ergosterol-5,8-endoperoxide, cyathisterone (2), emodin (4a), questinol (4b), citreorosein (4c), fallacinol (4d), rheoemodin (4e) and secalonic acid A (5), from the ethyl acetate extract of the culture of the marine sponge-associated fungus Talaromyces stipitatus KUFA 0207. The structures of the new compounds were established based on extensive 1D and 2D spectral analysis, and in the case of talarosterone (1), the absolute configurations of its stereogenic carbons were determined by X-ray crystallographic analysis. The structure and stereochemistry of cyathisterone (2) was also confirmed by X-ray analysis. The anthraquinones 4a–e and secalonic acid A (5) were tested for their anti-obesity activity using the zebrafish Nile red assay. Only citreorosein (4c) and questinol (4b) exhibited significant anti-obesity activity, while emodin (4a) and secalonic acid A (5) caused toxicity (death) for all exposed zebrafish larvae after 24 h. Full article