Mechanism of action involved in the anxiolytic-like effects of Hibalactone isolated from Hydrocotyle umbellata L.

Background and aim: Hibalactone (HB) is a lignan related to the anxiolytic-like effects of Hydrocotyle umbellata L. However, there is a need to understand better the mechanism of action of this lignan to support the ethnopharmacological uses of the species. This work aimed to evaluate by in vivo and in silico analysis the mechanism of action of HB involved in its anxiolytic-like effects. Experimental procedure: The effects of HB in mice were evaluated on light-dark box (LDB) and elevated plus maze (EPM) tests. The participation of 5-HT1A receptor and the benzodiazepine site of GABAA receptor was evaluated to investigate the possible mechanism of action. In silico tools were used to better elucidate the anxiolytic-like effects of HB. Results: Oral treatment with HB at a dose of 33 mg/kg showed an anxiolytic-like effect in the LDB and EPM tests. Besides that, the treatment altered the ethological parameters, frequency of head dips, and stretched-attend postures (SAP), important to better describe the anxiolytic profile of HB. Pretreatment with flumazenil (2 mg/kg) reverted the anxiolytic-like effect of HB on LDB and EPM tests. On the other hand, pretreatment with NAN-190 (0.5 mg/kg) not reverted the activity observed. In silico predictions revealed the potential of HB to increase GABAergic neurotransmission. Pharmacophore modelling and docking simulations showed that HB might interact with the α1ß2γ2 GABAA receptor. Conclusion: Together, the results presented herein suggest that activation of the benzodiazepine site of the GABAA receptor contributes to the anxiolytic-like effect of HB.

Search for Potential Inducible Nitric Oxide Synthase Inhibitors with Favorable ADMET Profiles for the Therapy of Helicobacter pylori Infections.

BACKGROUND: Helicobacter pylori is a gram-negative bacterium related to chronic gastritis, peptic ulcer and gastric carcinoma. During its infection process, promotes excessive inflammatory response, increasing the release of reactive species and inducing the production of pro-inflammatory mediators. Inducible Nitric Oxide Synthase (iNOS) plays a crucial role in the gastric carcinogenesis process and a key mediator of inflammation and host defense systems, which is expressed in macrophages induced by inflammatory stimuli. In chronic diseases such as Helicobacter pylori infections, the overproduction of NO due to the prolonged induction of iNOS is of major concern. OBJECTIVES: In this sense, the search for potential iNOS inhibitors is a valuable strategy in the overall process of Helicobacter pylori pathogeny. METHODS: In silico techniques were applied in the search of interesting compounds against Inducible Nitric Oxide Synthase enzyme in a chemical space of natural products and derivatives from the Analyticon Discovery databases. RESULTS: The five compounds with the best iNOS inhibition profile were selected for activity and toxicity predictions. Compound 9 (CAS 88198-99-6) displayed significant potential for iNOS inhibition, forming hydrogen bonds with residues from the active site and an ionic interaction with heme. This compound also displayed good bioavailability and absence of toxicity/or from its probable metabolites. CONCLUSION: The top-ranked compounds from the virtual screening workflow show promising results regarding the iNOS inhibition profile. The results evidenced the importance of the ionic bonding during docking selection, playing a crucial role in binding and positioning during ligand-target selection for iNOS.

Cubebin and derivatives as inhibitors of mitochondrial complex I. Proposed interaction with subunit B8.

The effects on mitochondrial respiration and complex I NADH oxidase activity of cubebin and derivatives were evaluated. The compounds inhibited the state 3 glutamate/malate-supported respiration of hamster liver mitochondria with IC(50) values ranging from 12.16 to 83.96 microM. NADH oxidase reaction was evaluated in submitochondrial particles. The compounds also inhibited this activity, showing the same order of potency observed for effects on state 3 respiration, as well as a tendency towards a non-competitive type of inhibition (K(I) values ranging from 0.62 to 16.1 microM). A potential binding mode of these compounds with complex I subunit B8, assessed by docking calculations, is proposed.