Probing the acetylcholinesterase inhibitory activity of a novel Ru(II) polypyridyl complex and the supramolecular interaction by (STD)-NMR.

Currently, acetylcholinesterase (AChE) inhibitors are the only anti-Alzheimer drugs commercially available. Despite their wide use those drugs are all dose dependent and their effect last for no longer than two years, with several side effects. The search of novel acetylcholinesterase (AChE) inhibitors remains as the main scientific route. Here we describe the synthesis, characterization, biological activity and an NMR binding-target study of a novel cis-[Ru(Bpy)2(EtPy)2]2+, (RuEtPy), Bpy = 2,2'-bipyridine and EtPy = 4,2-Ethylamino-pyridine) as a potential AChE inhibitor. The classic Ellman's colorimetric assay suggests that the RuEtPy exhibits a high inhibitory activity, following a competitive mechanism, with a remarkable low inhibition constant (Ki ≈ 16.8 µM), together with a IC50 = 39 µM. Hence, we have studied the spatial interactions for this novel candidate towards the human acetylcholinesterase (hAChE) using saturation transfer difference (STD)-NMR, in order to describe the mechanism of the interaction. NMR binding-target results shows that the 4,2-Ethylamino-Pyridine group is spatially closer to hAChE surface chemical arrangement than 2,2' bipyridine counterpart, exerting an efficient intermolecular interaction, with a low dissociation constant (KD ≈ 55 µM), probing that 4,2-Ethylamino-pyridine motif plays a key role in the inhibitory action.

Green asymmetric synthesis of epoxypeptidomimetics and evaluation as human cathepsin K inhibitors.

Cathepsin K (CatK) is a cysteine protease known for its potent collagenolytic activity, being recognized as an important target to the development of therapies for the treatment of bone disorders. Epoxypeptidomimetics have been reported as potent inhibitors of cathepsins, thus in this work we present a green synthesis of new peptidomimetics by using a one-pot asymmetric epoxidation/Ugi multicomponent reaction. The compounds were evaluated against CatK showing selectivity when compared with cathepsin L, with an inhibition profile in the low micromolar IC50 range. Investigation of the mechanism of action carried out for compounds LSPN428 and LSPN694 suggested a mixed inhibition mode and docking studies allowed a better understanding about interactions of inhibitors with the enzyme.

Enhancing protein fold determination by exploring the complementary information of chemical cross-linking and coevolutionary signals.

Motivation: Elucidation of protein native states from amino acid sequences is a primary computational challenge. Modern computational and experimental methodologies, such as molecular coevolution and chemical cross-linking mass-spectrometry allowed protein structural characterization to previously intangible systems. Despite several independent successful examples, data from these distinct methodologies have not been systematically studied in conjunction. One challenge of structural inference using coevolution is that it is limited to sequence fragments within a conserved and unique domain for which sufficient sequence datasets are available. Therefore, coupling coevolutionary data with complimentary distance constraints from orthogonal sources can provide additional precision to structure prediction methodologies. Results: In this work, we present a methodology to combine residue interaction data obtained from coevolutionary information and cross-linking/mass spectrometry distance constraints in order to identify functional states of proteins. Using a combination of structure-based models (SBMs) with optimized Gaussian-like potentials, secondary structure estimation and simulated annealing molecular dynamics, we provide an automated methodology to integrate constraint data from diverse sources in order to elucidate the native conformation of full protein systems with distinct complexity and structural topologies. We show that cross-linking mass spectrometry constraints improve the structure predictions obtained from SBMs and coevolution signals, and that the constraints obtained by each method have a useful degree of complementarity that promotes enhanced fold estimates. Availability and implementation: Scripts and procedures to implement the methodology presented herein are available at https://github.com/mcubeg/DCAXL. Supplementary information: Supplementary data are available at Bioinformatics online.

Bioassay-guided evaluation of antinociceptive properties and chemical variability of the essential oil of Hyptis fruticosa.

The composition of three samples of essential oil (EO) extracted from the leaves and flowers of Hyptis fruticosa (Lamiaceae) were investigated by GC/MS and GC-FID. The variability of the constituents and biological activity were evaluated in the oil samples. Acetic acid-induced abdominal constrictions and formalin-induced pain tests in mice were used for screening the antinociceptive activity. The possible antagonism of the essential oils or morphine (MOR) antinociceptive effects by pretreatment with naloxone, showed no influence on the antinociceptive action of the oils in the acetic acid-induced writhing test. All examined oil samples presented antinociceptive activity. The oil sample obtained from the leaves collected during the vegetative growth stage, near São Cristóvão at Sítio Tujubeba exhibited the highest effect. The same oil sample had a main percentage of 1,8-cineole (18.70%). Nevertheless, the oil obtained from flowers collected at the same location, showed a significant difference (p < 0.05) in the response intensity in the first phase of paw licking (100 mg/kg) possibly due to the higher contents of α-pinene (20.51%) and ß-pinene (13.64%). The results provide evidence for the use of H. fruticosa by traditional medicine practitioners in the management of pain.

Essential oil composition and variability in Hyptis fruticosa

The composition of six samples of essential oil (EO) extracted from leaves, flowers and seeds of several plants of Hyptis fruticosa Salzm. ex Benth., Lamiaceae, was investigated by GC/MS and GC/FID. 1,8-Cineole, spathulenol, α-pinene, β-pinene were the major constituents. Ten constituents that have not been previously described in the composition of the oil of H. fruticosa were identified. Hydrocarbons sesquiterpenes represented the main group, followed by hydrocarbons monoterpenes. The results were submitted to Cluster Analysis which allowed three groups of EO to be distinguished with respect to the content of α-pinene/β-pinene, 1,8-cineole and spathulenol. Growth stages of the plants and geographical parameters seem to be important factors determining the variability of the oil. Sesquiterpenes were mainly produced in the seeds.

Chemical constituents and larvicidal activity of Hymenaea courbaril fruit peel.

The chemical compositions of the essential oils from the peel of ripe and unripe fruits of Hymenaea courbaril L., obtained by hydrodistillation, were analyzed by GC and GC-MS. The main constituents of the essential oil from the peel of the ripe fruits were the sesquiterpenes alpha-copaene (11.1%), spathulenol (10.1%) and beta-selinene (8.2%), while germacrene-D (31.9%), beta-caryophyllene (27.1%) and bicyclogermacrene (6.5%) were the major compounds in the oil from unripe fruits. The essential oils were tested against Aedes aegypti larvae and showed LC50 values of 14.8 +/- 0.4 microg/mL and 28.4 +/- 0.3 microg/mL for the ripe and unripe fruit peel oils, respectively. From the peel of the ripe fruits, the diterpenes zanzibaric acid and isoozic acid were isolated, along with the sesquiterpene caryolane-1,9beta-diol. To the best of our knowledge, this is the first report of this sesquiterpene in the genus. The structures of all compounds isolated were identified on the basis of their spectral data (IR, MS, 1D- and 2D-NMR) and by comparison with literature spectral data.