Jakub Staroń

Encapsulation of curcumin in polyelectrolyte nanocapsules and their neuroprotective activity

Poor water solubility and low bioavailability of lipophilic drugs can be potentially improved with the use of delivery systems. In this study, encapsulation of nanoemulsion droplets was utilized to prepare curcumin nanocarriers. Nanosize droplets containing the drug were encapsulated in polyelectrolyte shells formed by the layer-by-layer (LbL) adsorption of biocompatible polyelectrolytes: poly-L-lysine (PLL) and poly-L-glutamic acid (PGA). The size of synthesized nanocapsules was around 100 nm. Their biocompatibility and neuroprotective effects were evaluated on the SH-SY5Y human neuroblastoma cell line using cell viability/toxicity assays (MTT reduction, LDH release). Statistically significant toxic effect was clearly observed for PLL coated nanocapsules (reduction in cell viability about 20%-60%), while nanocapsules with PLL/PGA coating did not evoke any detrimental effects on SH-SY5Y cells. Curcumin encapsulated in PLL/PGA showed similar neuroprotective activity against hydrogen peroxide (H2O2)-induced cell damage, as did 5 μM curcumin pre-dissolved in DMSO (about 16% of protection). Determination of concentration of curcumin in cell lysate confirmed that curcumin in nanocapsules has cell protective effect in lower concentrations (at least 20 times) than when given alone. Intracellular mechanisms of encapsulated curcumin-mediated protection engaged the prevention of the H2O2-induced decrease in mitochondrial membrane potential (MMP) but did not attenuate Reactive Oxygen Species (ROS) formation. The obtained results indicate the utility of PLL/PGA shell nanocapsules as a promising, alternative way of curcumin delivery for neuroprotective purposes with improved efficiency and reduced toxicity.

Rational design of 5-HT6R ligands using a bioisosteric strategy: synthesis, biological evaluation and molecular modelling

A bioisosteric strategy was successfully implemented with a screening protocol for new, potent 5-HT6R ligands. Initially, 2-[5-(4-methylpiperazin-1-yl)-2-nitrophenyl]-1,2,3,4-tetrahydroisoquinoline (9) was found in commercial databases using a bioisosteric query (screening 5-HT6R Ki = 128 nM). Then, the hit compound was bioisosterically modified (ring alteration) leading to a novel, high affinity (Ki = 6 nM) 5-HT6R ligand (10). Extensive docking studies followed by structural interaction fingerprint analysis supported by single-crystal X-ray structures of the investigated ligands suggest different binding modes with 5-HT6R models for compounds with varying activity. An alternative anchoring point for protonated amine (D7.36) that has not been previously reported was identified.

Lactose esters: synthesis and biotechnological applications

Abstract Biodegradable nonionic sugar esters-based surfactants have been gaining more and more attention in recent years due to their chemical plasticity that enables the various applications of these molecules. In this review, various synthesis methods and biotechnological implications of lactose esters (LEs) uses are considered. Several chemical and enzymatic approaches are described for the synthesis of LEs, together with their applications, i.e. function in detergents formulation and as additives that not only stabilize food products but also protect food from undesired microbial contamination. Further, this article discusses medical applications of LEs in cancer treatment, especially their uses as biosensors, halogenated anticancer drugs, and photosensitizing agents for photodynamic therapy of cancer and photodynamic inactivation of microorganisms.

Bioisosteric Matrices for Ligands of Serotonin Receptors

The concept of bioisosteric replacement matrices is applied to explore the chemical space of serotonin receptor ligands, aiming to determine the most efficient ways of manipulating the affinity for all 5‐HT receptor subtypes. Analysis of a collection of over 1 million bioisosteres of compounds with measured activity towards serotonin receptors revealed that an average of 31 % of the ligands for each target are mutual bioisosteres. In addition, the collected dataset allowed the development of bioisosteric matrices—qualitative and quantitative descriptions of the biological effects of each predefined type of bioisosteric substitution, providing favored paths of modifying the compounds. The concept exemplified here for serotonin receptor ligands can likely be more broadly applied to other target classes, thus representing a useful guide for medicinal chemists designing novel ligands.

Low-basicity 5-HT 7 Receptor Agonists Synthesized Using the van Leusen Multicomponent Protocol

A series of 5-aryl-1-alkylimidazole derivatives was synthesized using the van Leusen multicomponent reaction. The chemotype is the first example of low-basicity scaffolds exhibiting high affinity for 5-HT7 receptor together with agonist function. The chosen lead compounds 3-(1-ethyl-1H-imidazol-5-yl)-5-iodo-1H-indole (AGH-107, 1o, Ki 5-HT7 = 6 nM, EC50 = 19 nM, 176-fold selectivity over 5-HT1AR) and 1e (5-methoxy analogue, Ki 5-HT7 = 30 nM, EC50 = 60 nM) exhibited high selectivity over related CNS targets, high metabolic stability and low toxicity in HEK-293 and HepG2 cell cultures. A rapid absorption to the blood, high blood-brain barrier permeation and a very high peak concentration in the brain (Cmax = 2723 ng/g) were found for 1o after i.p. (5 mg/kg) administration in mice. The compound was found active in novel object recognition test in mice, at 0.5, 1 and 5 mg/kg. Docking to 5-HT7R homology models indicated a plausible binding mode which explain the unusually high selectivity over the related CNS targets. Halogen bond formation between the most potent derivatives and the receptor is consistent with both the docking results and SAR. 5-Chlorine, bromine and iodine substitution resulted in a 13, 27 and 89-fold increase in binding affinities, respectively, and in enhanced 5-HT1AR selectivity.

Halogen bonding enhances activity in a series of dual 5-HT6/D2 ligands designed in a hybrid bioisostere generation/virtual screening protocol

A novel hybrid bioisostere generation/virtual screening method combined with narrowing of chemical space through similarity to compounds that are active at the second target was successfully applied for the development of structurally new dual 5-HT6/D2 receptor ligands. Consequently, a series of derivatives of the found hit 1d (N-[2-(dimethylamino)ethyl]-N-(2-phenylethyl)aniline) was synthesized. The most active 5-HT6/D2 ligands also showed affinity for 5-HT7R and 5-HT2AR. The para-chloroaniline derivative was identified as a potent dual 5-HT6/5-HT7 receptor antagonist (Ki = 24 nM and Kb = 30 nM, Ki = 4 nM and Kb = 1.4 nM, respectively). In the case of halogen-containing compounds, interesting structure–activity relationships were observed at 5-HT6, D2 and 5-HT7 receptors, and the ligand–receptor complexes were subsequently examined using a molecular modelling approach that combined quantum-polarized ligand docking (QPLD) and Molecular-Mechanics-Generalized-Born/Surface Area (MM/GBSA) free-energy calculation, which permitted the identification of putative halogen binding pockets.

5-HT1A receptor ligands and their therapeutic applications: review of new patents

ABSTRACT Introduction: 5-HT1AR was one of the first discovered serotonin receptors and is one of the most thoroughly studied. Dysfunctions associated with 5-HT1AR neurotransmission are linked to several psychiatric disorders, including anxiety, depression, and movement disorders. Areas covered: The current review covers patent literature published between January 2012 and May 2018. Queries were performed on Espacenet, SciFinder, clinicaltrials.gov, pharmacodia.com, and the websites of pharmaceutical companies. Expert opinion: Several novel therapeutic applications have been proposed for 5-HT1AR ligands, i.e. prostate cancer treatment, gastrointestinal and cardiopulmonary disorders, facilitation of urination and defecation, and L-DOPA-induced dyskinesia. Interestingly, no patent application has been filed by big pharma companies, while numerous researches are being conducted in smaller companies and academia.

Pyrano[2,3,4-cd]indole as a Scaffold for Selective Nonbasic 5-HT6R Ligands

In this letter, we report the synthesis of a pyrano[2,3,4-cd]indole chemical scaffold designed through a tandem bioisostere generation/virtual screening protocol in search of 5-HT6R ligands. The discovered chemical scaffold resulted in the design of highly active basic and nonbasic 5-HT6R ligands (5-HT6R Ki = 1 nM for basic compound 6b and 5-HT6R Ki = 4 nM for its neutral analog 7b). Additionally, molecular modeling suggested that the hydroxyl group of nonbasic ligands 7a-7d forms hydrogen bonds with aspartic acid D3×32 or D7.36×35.