Two new bromotyrosine derivatives, anomoian B (1) and aplyzanzine B (2), were isolated, respectively, from the organic extracts of a Verongida sponge belonging to the Hexadella genus and from a two-sponge association (Jaspis sp. and Bubaris sp.), both collected off the coast of Indonesia. The planar structure of 1 and 2 was determined by 1D and 2D NMR experiments and by high-resolution mass spectrometry, while their absolute stereochemistry was assigned by comparison with optical rotation values of known bromotyrosines and by chemical degradation. Both compounds showed moderate antiproliferative activity against a panel of different cancer cell lines. Their cytotoxic activity is facilitated through the induction of apoptosis, which is mediated neither by the generation of reactive oxygen species nor by the inhibition of histone deacetylases in these cell lines.
Environmental risk assessment is a key process for the authorization of pesticides, and is subjected to continuous challenges and updates. Current approaches are based on standard scenarios and independent substance-crop assessments. This arrangement does not address the complexity of agricultural ecosystems with mammals feeding on different crops. This work presents a simplified model for regulatory use addressing landscape variability, co-exposure to several pesticides, and predicting the effect on population abundance. The focus is on terrestrial vertebrates and the aim is the identification of the key risk drivers impacting on mid-term population dynamics. The model is parameterized for EU assessments according to the European Food Safety Authority (EFSA) Guidance Document, but can be adapted to other regulatory schemes. The conceptual approach includes two modules: (a) the species population dynamics, and (b) the population impact of pesticide exposure. Population dynamics is modelled through daily survival and seasonal reproductions rates; which are modified in case of pesticide exposure. All variables, parameters, and functions can be modified. The model has been calibrated with ecological data for wild rabbits and brown hares and tested for two herbicides, glyphosate and bromoxynil, using validated toxicity data extracted from EFSA assessments. Results demonstrate that the information available for a regulatory assessment, according to current EU information requirements, is sufficient for predicting the impact and possible consequences at population dynamic levels. The model confirms that agroecological parameters play a key role when assessing the effect of pesticide exposure on population abundance. The integration of laboratory toxicity studies with this simplified landscape model allows for the identification of conditions leading to population vulnerability or resilience. An Annex includes a detailed assessment of the model characteristics according to the EFSA scheme on Good Modelling Practice.
A new macrolide, enigmazole C (1), and two additional analogues, enigmazoles E (2) and D (3), were obtained from a new species of the Homophymia genus as part of an ongoing discovery program at PharmaMar to study cytotoxic substances from marine sources. The structures were fully characterized by cumulative analyses of NMR, IR, and MS spectra, along with density functional theory computational calculations. All three of the new compounds feature an unusual 2,3-dihydro-4H-pyran-4-one moiety, but only enigmazoles C (1) and D (3) showed cytotoxic activity in the micromolar range against A-549 (lung), HT-29 (colon), MDA-MB-231 (breast), and PSN-1 (pancreas) tumor cells.
A combination of configurational analysis based on coupling constants (JBCA) and Marfey's aminoacid derivatization allowed us to distinguish between the different possible diastereoisomers of threonines in cyclopeptides, when potentially some of the amino acids could be racemized/epimerized during the acid hydrolysis process. The strategy was applied to a new cyclic depsipeptide having an unusual chloropyrrol ring, gunungamide A (2), isolated from a marine sponge belonging to the genus Discodermia. Further validation of this approach was demonstrated with the peptide stellatolide (1), where epimerization of a threonine residue during hydrolysis in the Marfey's analysis resulted in a mistaken configuration. This approach can be extended to elucidate the absolute stereochemistry of peptides bearing amino acids with two or more contiguous chiral centers.