Hydroxytakakiamide and Other Constituents from a Marine Sponge-Associated Fungus Aspergillus fischeri MMERU23, and Antinociceptive Activity of Ergosterol Acetate, Acetylaszonalenin and Helvolic Acid.

An unreported prenylated indole derivative hydroxytakakiamide (4) was isolated, together with the previously described ergosterol (1), ergosterol acetate (2), and (3R)-3-(1H-indol-3-ylmethyl)-3, 4-dihydro-1H-1,4-benzodiazepine-2,5-dione (3), from the column fractions of the crude ethyl acetate extract of the culture of a marine sponge-associated fungus, Aspergillus fischeri MMERU 23. The structure of 4 was elucidated by the interpretation of 1D and 2D NMR spectral data and high-resolution mass spectrum. The absolute configuration of the stereogenic carbon in 3 was proposed to be the same as those of the co-occurring congeners on the basis of their biogenetic consideration and was supported by the comparison of its sign of optical rotation with those of its steroisomers. The crude ethyl acetate extract and 2 were evaluated, together with acetylaszonalenin (5) and helvolic acid (6), which were previously isolated from the same extract, for the in vivo antinociceptive activity in the mice model. The crude ethyl acetate extract exhibited antinociceptive activity in the acetic acid-induced writhing and formalin tests, while 2, 5, and 6 displayed the effects in the late phase of the formalin test. On the other hand, neither the crude ethyl acetate extract nor 2, 5, and 6 affected the motor performance of mice in both open-field and rotarod tests. Additionally, docking studies of 2, 5, and 6 were performed with 5-lipoxygenase (5-LOX) and phosphodiesterase (PDE) enzymes, PDE4 and PDE7, which are directly related to pain and inflammatory processes. Molecular docking showed that 6 has low affinity energy to PDE4 and PDE7 targets while retaining high affinity to 5-LOX. On the other hand, while 2 did not display any hydrogen bond interactions in any of its complexes, it achieved overall better energy values than 6 on the three antinociceptive targets. On the other hand, 5 has the best energy profile of all the docked compounds and was able to reproduce the crystallographic interactions of the 5-LOX complex.

Drought response strategies of deciduous and evergreen woody species in a seasonally dry neotropical forest.

Deciduous and evergreen trees are usually considered the main coexisting functional groups in seasonally dry tropical forests (SDTF). We compared leaf and stem traits of 22 woody species in the Brazilian Caatinga to investigate whether deciduous (DC) and evergreen (EV) species have divergent water-use strategies. Our hypothesis was that DC trees compensate for their short leaf longevity by being less conservative in water use and showing higher variation in the seasonal water potential after leaf shedding. Evergreen species should exhibit a highly conservative water use strategy, which reduces variations in seasonal water potential and the negative effects of desiccation. Our leaf dynamics results indicate that the crown area of DC trees is more sensitive to air and soil drought, whereas EV trees are only sensitive to soil drought. Deciduous species exhibit differences in a set of leaf traits confirming their acquisitive strategy, which contrasts with evergreen species. However, when stomatal traits are considered, we found that DC and EV have similar stomatal regulation strategies (partially isohydric). We also found divergent physiological strategies within DC. For high wood density DC, the xylem water potential (Ψxylem) continued to drop during the dry season. We also found a negative linear relationship between leaf life span (LL) and the transpiration rate per unit of hydraulic conductivity (Λ), indicating that species with high LL are less vulnerable to hydraulic conductivity loss than early-deciduous species. Collectively, our results indicate divergence in the physiology of deciduous species, which suggests that categorizing species based solely on their leaf phenology may be an oversimplification.

Identification of new promising Plasmodium falciparum superoxide dismutase allosteric inhibitors through hierarchical pharmacophore-based virtual screening and molecular dynamics.

Malaria is the world's most widespread protozoan infection, being responsible for more than 445,000 annual deaths. Among the malaria parasites, Plasmodium falciparum is the most prevalent and lethal. In this context, the search for new antimalarial drugs is urgently needed. P. falciparum superoxide dismutase (PfSOD) is an important enzyme involved in the defense mechanism against oxidative stress. The goal of this study was to identify through hierarchical screening on pharmacophore models and molecular dynamics (MD), promising allosteric PfSOD inhibitors that do not show structural requirements for human inhibition. MD simulations of 1000 ps were performed on PfSOD using GROMACS 5.1.2. For this, the AMBER99SB-ILDN force field was adapted to describe the metal-containing system. The simulations indicated stability in the developed system. Therefore, a covariance matrix was generated, in which it was possible to identify residues with correlated and anticorrelated movements with the active site. These results were associated with the results found in the predictor of allosteric sites, AlloSitePro, which affirmed the ability of these residues to delimit an allosteric site. Then, after successive filtering of the Sigma-Aldrich® compounds database for HsSOD1 and PfSOD pharmacophores, 152 compounds were selected, also obeying Lipinski's rule of 5. Further filtering of those compounds based on molecular docking results, toxicity essays, availability, and price filtering led to the selection of a best compound, which was then submitted to MD simulations of 20,000 ps on the allosteric site. The study concludes that the ZINC00626080 compound could be assayed against SODs. Graphical Abstract Plasmodium falciparum superoxide dismutase.