Ion channel formation from a calix[4]arene amide that binds HCl

Mimicking the Shape and Function of the ClC Chloride Channel Selective Pore by Combining a Molecular Hourglass Shape with Anion-π Interactions

ClC is the main family of natural chloride channel proteins that transport Cl- across the cell membrane with high selectivity. The chloride transport and selectivity are determined by the hourglass-shaped pore and the filter located in the central and narrow region of the pore. Artificial unimolecular channel that mimics both the shape and function of the ClC selective pore is attractive, because it could provide simple molecular model to probe the intriguing mechanism and structure-function relevance of ClC. Here we elaborated upon the concept of molecular hourglass plus anion-π interactions for this purpose. The concept was validated by experimental results of molecular hourglasses using shape-persistent 1,3-alternate tetraoxacalix[2]arene[2]triazine as the central macrocyclic skeleton to control the conductance and selectivity, and anion-π interactions as the driving force to facilitate the chloride dehydration and movement along the channel.

Non-Covalently Stapled H+ /Cl- Ion Channels Activatable by Visible Light for Targeted Anticancer Therapy

The development of stimuli-responsive artificial H+ /Cl- ion channels, capable of specifically disturbing the intracellular ion homeostasis of cancer cells, presents an intriguing opportunity for achieving high selectivity in cancer therapy. Herein, we describe a novel family of non-covalently stapled self-assembled artificial channels activatable by biocompatible visible light at 442 nm, which enables the co-transport of H+ /Cl- across the membrane with H+ /Cl- transport selectivity of 6.0. Upon photoirradiation of the caged C4F-L for 10 min, 90 % of ion transport efficiency can be restored, giving rise to a 10.5-fold enhancement in cytotoxicity against human colorectal cancer cells (IC50 =8.5 μM). The mechanism underlying cancer cell death mediated by the H+ /Cl- channels involves the activation of the caspase 9 apoptosis pathway as well as the scarcely reported disruption of the autophagic processes. In the absence of photoirradiation, C4F-L exhibits minimal toxicity towards normal intestine cells, even at a concentration of 200 μM.

Supramolecular Barrel-Rosette Ion Channel Based on 3,5-Diaminobenzoic Acid for Cation-Anion Symport

The structural tropology and functions of natural cation-anion symporting channels have been continuously investigated due to their crucial role in regulating various physiological functions. To understand the physiological functions of the natural symporter channels, it is vital to develop small-molecule-based biomimicking systems that can provide mechanistic insights into the ion-binding sites and the ion-translocation pathways. Herein, we report a series of bis((R)-(-)-mandelic acid)-linked 3,5-diaminobenzoic acid based self-assembled ion channels with distinctive ion transport ability. Ion transport experiment across the lipid bilayer membrane revealed that compound 1 b exhibits the highest transport activity among the series, and it has interesting selective co-transporting functions, i.e., facilitates K+ /ClO4 - symport. Electrophysiology experiments confirmed the formation of supramolecular ion channels with an average diameter of 6.2±1 Å and single channel conductance of 57.3±1.9 pS. Selectivity studies of channel 1 b in a bilayer lipid membrane demonstrated a permeability ratio ofP C l - / P K + = 0 . 053 ± 0 . 02 ${{P}_{{Cl}^{-}}/{P}_{{K}^{+}}=0.053\pm 0.02}$ ,P C l O 4 - / P C l - = 2 . 1 ± 0 . 5 ${{P}_{{ClO}_{4}^{-}}/{P}_{{Cl}^{-}}=2.1\pm 0.5}$ , andP K + / P N a + = 1 . 5 ± 1 , ${{P}_{{K}^{+}}/{P}_{{Na}^{+}}=1.5\pm 1,}$ indicating the higher selectivity of the channel towards KClO4 over KCl salt. A hexameric assembly of a trimeric rosette of 1 b was subjected to molecular dynamics simulations with different salts to understand the supramolecular channel formation and ion selectivity pattern.

Stimulus-Controlled Anion Binding and Transport by Synthetic Receptors

Anionic species are omnipresent and involved in many important biological processes. A large number of artificial anion receptors has therefore been developed. Some of these are capable of mediating transmembrane transport. However, where transport proteins can respond to stimuli in their surroundings, creation of synthetic receptors with stimuli-responsive functions poses a major challenge. Herein, we give a full overview of the stimulus-controlled anion receptors that have been developed thus far, including their application in membrane transport. In addition to their potential operation as membrane carriers, the use of anion recognition motifs in forming responsive membrane-spanning channels is discussed. With this review article, we intend to increase interest in transmembrane transport among scientists working on host-guest complexes and dynamic functional systems in order to stimulate further developments.

Progress and prospects toward supramolecular bioactive ion transporters

The majority of cellular physiological processes depend on natural ion channels, which are pore-forming membrane-embedded proteins that let ions flow across the cell membranes selectively. This selective movement of ions across the membranes balances the osmolality within and outside the cell. However, mutations in the genes that encode essential membrane transport proteins or structural reorganisation of these proteins can cause life-threatening diseases like cystic fibrosis. Artificial ion transport systems have opened up a way to replace dysfunctional natural ion channels to cure such diseases through channel replacement therapy. Moreover, recent research has also demonstrated the ability of these systems to kill cancer cells, reigniting interest in the field among scientists. Our contributions to the recent progress in the design and development of artificial chloride ion transporters and their effect on biological systems have been discussed in this review. This review would provide current vistas and future directions toward the development of novel ion transporters with improved biocompatibility and desired anti-cancer properties. Additionally, it strongly emphasises stimuli-responsive ion transport systems, which are crucial for obtaining target-specificity and may speed up the application of these systems in clinical therapeutics.

Switchable Na+ and K+ selectivity in an amino acid functionalized 2D covalent organic framework membrane

Biological cell membranes can efficiently switch Na⁺/K⁺ selectivity in response to external stimuli, but achieving analogous functions in a single artificial membrane is challenging. Here, we report highly crystalline covalent organic framework (COF) membranes with well-defined nanochannels and coordinative sites (i. e., amino acid) that act as ion-selective switches to manipulate Na⁺ and K⁺ transport. The ion selectivity of the COF membrane is dynamic and can be switched between K⁺-selective and Na⁺-selective in a single membrane by applying a pH stimulus. The experimental results combined with molecular dynamics simulations reveal that the switchable Na⁺/K⁺ selectivity originates from the differentiated coordination interactions between ions and amino acids. Benefiting from the switchable Na⁺/K⁺ selectivity, we further demonstrate the membrane potential switches by varying electrolyte pH, miming the membrane polarity reversal during neural signal transduction in vivo, suggesting the great potential of these membranes for in vitro biomimetic applications.

Light-Driven Molecular Motors Boost the Selective Transport of Alkali Metal Ions through Phospholipid Bilayers

A hydrophobic light-driven rotary motor is functionalized with two 18-crown-6 macrocycles and incorporated into phospholipid bilayers. In the presence of this molecular construct, fluorescence assays and patch clamp experiments show the formation of selective alkali ion channels through the membrane. Further, they reveal a strongly accelerated ion transport mechanism under light irradiation. This increase of the fractional ion transport activity (up to 400%) is attributed to the out-of-equilibrium actuation dynamics of the light-driven rotary motors, which help to overcome the activation energy necessary to achieve translocation of alkali ions between macrocycles along the artificial channels.

A Pyridyl-Linked Benzimidazolyl Tautomer Facilitates Prodigious H+/Cl- Symport through a Cooperative Protonation and Chloride Ion Recognition

We report two pyridyl-linked benzimidazolyl hydrazones as HCl cotransporters that are 5 and 2 times superior to prodigiosin, a natural product whose transport efficiency has never been routed by synthetic molecules. These hydrazones provide a suitable HCl binding site through a cooperative protonation and chloride ion recognition. HCl transport by the most active compound induces lysosome deacidification. Viability assays confirmed that the compounds induce cytotoxicity toward human breast cancer MCF-7 cells but are relatively nontoxic toward noncancerous HEK293T cells.

Calixarene-based artificial ionophores for chloride transport across natural liposomal bilayer: Synthesis, structure-function relationships, and computational study

An amphiphilic calix[6]arene, alone or complexed with an axle to form a pseudo-rotaxane, has been embedded into liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and the permeability of the membrane-doped liposomes towards Cl^- ions has been evaluated by using lucigenin as the fluorescent probe. The pseudo-rotaxane promotes transmembrane transport of Cl^- ions more than calix[6]arene does. Surprisingly, the quenching of lucigenin was very fast for liposomes doped with the positively charged axle alone. Molecular dynamics (MD) simulations and quantum-chemical calculations were also carried out for providing a semi-quantitative support to the experimental results.

Transmembrane Ion Channels Formed by a Star of David [2]Catenane and a Molecular Pentafoil Knot

A (Fe^II)₆-coordinated triply interlocked ("Star of David") [2]catenane (6₁² link) and a (Fe^II)₅-coordinated pentafoil (5₁) knot are found to selectively transport anions across phospholipid bilayers. Allostery, topology, and building block stoichiometry all play important roles in the efficacy of the ionophoric activity. Multiple Fe^II cation coordination by the interlocked molecules is crucial: the demetalated catenane exhibits no anion binding in solution nor any transmembrane ion transport properties. However, the topologically trivial, Lehn-type cyclic hexameric Fe^II helicates-which have similar anion binding affinities to the metalated Star of David catenane in solution-also display no ion transport properties. The unanticipated difference in behavior between the open- and closed-loop structures may arise from conformational restrictions in the linking groups that likely enhances the rigidity of the channel-forming topologically complex molecules. The (Fe^II)₆-coordinated Star of David catenane, derived from a hexameric cyclic helicate, is 2 orders of magnitude more potent in terms of ion transport than the (Fe^II)₅-coordinated pentafoil knot, derived from a cyclic pentamer of the same building block. The reduced efficacy is reminiscent of multisubunit protein ion channels assembled with incorrect monomer stoichiometries.

Organic-Inorganic Artificial Ion Channel Polyvinylidene Fluoride Membranes for Controllable Selectivity Transport of Alkali Metal Cations

In this article, organic-inorganic hybrid materials with different functional groups were used to form organic-inorganic hybrid dense membranes for selective separation of mono/divalent ions by blending these materials and polyvinylidene fluoride (PVDF) in dimethylacetamide with HCl as the catalyst. The membranes prepared by 3-(ureido benzene) propyltriethoxysilane (H1), 3-(ureido-4-methoxyphenyl) propyltriethoxysilane (H2), 3-(ureido-3-chloro-4-methoxyphenyl) propyltriethoxysilane (H3), 3-(ureidoindazolyl) propyltrieth-oxysilane (H4), or 3-(ureidopentanol) propyltriethoxysilane (H5) were labeled as HM1-HM5, respectively. The transport properties of different chlorides were tested. The effects of different anions on sodium cation transport were also tested. The results showed that HM1-HM4 could transport monovalent Li+, Na+, and K+ except Ca2+ and Mg2+, and the permeability of Li+, Na+, and K+ through the hybrid membranes followed the order of PNa+ > PK+ > PLi+. Moreover, membranes with different H2 content were also prepared due to HM2 having the best ion transport performance. The ion transport performance increased accordingly with the mass ratio of H2 to PVDF, and the permeability of Na+ was twice that of Li+ and K+ when the mass ratio was 15/10. Under this condition, it was also proved that NH4+ could not transport through the hybrid membrane with various selectivity for different anions as Cl- > NO3- > HCO3- > SO42-.

Advances in anion transport and supramolecular medicinal chemistry

Advances in anion transport by synthetic supramolecular systems are discussed in this article. Developments in the design of discrete molecular carriers for anions and supramolecular anion channels are reviewed followed by an overview of the use of these systems in biological systems as putative treatments for diseases such as cystic fibrosis and cancer.

Macrocyclic Transmembrane Anion Transporters via a One-Pot Condensation Reaction

Synthetic chloride transporters are potential therapeutic agents for cystic fibrosis and cancer. Reported herein are macrocyclic transmembrane chloride transporters prepared by a one-pot condensation reaction. The most efficient macrocycle possesses a fine balance of hydrophobicity for membrane permeation and hydrophilicity for ion recognition. The macrocycle transports chloride ions by forming channels in the membrane. Hydrogen bonds and anion-π interactions assist chloride transport.

Switchable foldamer ion channels with antibacterial activity

Synthetic ion channels may have applications in treating channelopathies and as new classes of antibiotics, particularly if ion flow through the channels can be controlled. Here we describe triazole-capped octameric α-aminoisobutyric acid (Aib) foldamers that "switch on" ion channel activity in phospholipid bilayers upon copper(ii) chloride addition; activity is "switched off" upon copper(ii) extraction. X-ray crystallography showed that CuCl₂ complexation gave chloro-bridged foldamer dimers, with hydrogen bonds between dimers producing channels within the crystal structure. These interactions suggest a pathway for foldamer self-assembly into membrane ion channels. The copper(ii)-foldamer complexes showed antibacterial activity against B. megaterium strain DSM319 that was similar to the peptaibol antibiotic alamethicin, but with 90% lower hemolytic activity.

Polyhydrazide-Based Organic Nanotubes as Efficient and Selective Artificial Iodide Channels

Reported herein is a series of pore-containing polymeric nanotubes based on a hydrogen-bonded hydrazide backbone. Nanotubes of suitable lengths, possessing a hollow cavity of about a 6.5 Å diameter, mediate highly efficient transport of diverse types of anions, rather than cations, across lipid membranes. The reported polymer channel, having an average molecular weight of 18.2 kDa and 3.6 nm in helical height, exhibits the highest anion-transport activities for iodide (EC50 =0.042 μm or 0.028 mol % relative to lipid), whcih is transported 10 times more efficiently than chlorides (EC50 =0.47 μm). Notably, even in cholesterol-rich environment, iodide transport activity remains high with an EC50 of 0.37 μm. Molecular dynamics simulation studies confirm that the channel is highly selective for anions and that such anion selectivity arises from a positive electrostatic potential of the central lumen rendered by the interior-pointing methyl groups.

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

The intramolecular cyclization of a C-3-tetrasubstituted furanoid sugar amino acid-derived linear tetrapeptide afforded an oxazolone pseudo-peptide with the formation of an oxazole ring at the C-terminus. A conformational study of the oxazolone pseudo-peptide showed intramolecular C=O···HN(II) hydrogen bonding in a seven-membered ring leading to a γ-turn conformation. This fact was supported by a solution-state NMR and molecular modeling studies. The oxazolone pseudotetrapeptide was found to be a better Cl⁻-selective transporter for which an anion–anion antiport mechanism was established.

Anion Transporters Based on Noncovalent Balance including Anion-π, Hydrogen, and Halogen Bonding

Anion transmembrane transport mediated by novel noncovalent interactions is of central interest in supramolecular chemistry. In this work, a series of oxacalix[2]arene[2]triazine-derived transporters 1 and 2 bearing anion-π-, hydrogen-, and halogen-bonding sites in rational proximity were designed and synthesized by a one-pot strategy starting from gallic acid ester derivatives and mono- or di-halogen-substituted triazines. ¹H NMR titrations demonstrated efficient binding of 1 and 2 toward Cl^- and Br^- in solution, giving association constants in the range of 10²-10⁴ M^-1. Cooperation of anion-π, hydrogen, and halogen bonding was revealed as a driving force for anion binding by single-crystal structures of two complexes and density functional theory calculations. Fluorescence assays indicated that compounds 1 are efficient chloride transporters with effective concentrations (EC₅₀) falling in the range of 3.1-7.4 μM and following an order of 1a > 1b > 1c > 1d. The contribution of halogen bonding and cooperative noncovalent bonds to ion transport was then discussed. Significantly, transporters 1 exhibit high anticancer activity. In the presence of 1 and KCl (60 mM), the cell survival of HCT116 reduces to 11.9-24.9% with IC₅₀ values in the range of 52.3-66.4 μM.

Chemotherapy Based on Supramolecular Chemistry: A Promising Strategy in Cancer Therapy

Chemotherapeutic agents are considered one of the strategies in treating cancer. However, their use is faced by many challenges, such as poor water solubility leading to poor bioavailability and non-selective targeting of cancerous cells leading to diminished therapeutic actions and systemic adverse effects. Many approaches were adopted to overcome these drawbacks and to achieve the targeted delivery of the chemotherapeutic agents to the cancerous cells while minimizing adverse effects. Recently, supramolecular systems such as macrocycles have gained attention in the field of cancer therapy for being able to encapsulate different anticancer drugs via either host-guest complexation or self-assembly leading to a myriad of advantages. This review highlights the most recent studies concerned with the design of such novel systems for cancer therapy.

Synthesis and biological evaluation of aza-crown ether–squaramide conjugates as anion/cation symporters

Aim: Anion/cation symport across cellular membranes may lead to cell apoptosis and be developed as a strategy for new anticancer drug discovery. Methodology: Four aza-crown ether–squaramide conjugates were synthesized and characterized. Their anion recognition, anion/cation symport, cytotoxicity and probable mechanism of action were investigated in details. Conclusion: These conjugates are able to form ion-pairing complexes with chloride anions and facilitate the transmembrane transport of anions via an anion/cation symport process. They can disrupt the cellular homeostasis of chloride anions and sodium cations and induce the basification of acidic organelles in live cells. These conjugates exhibit moderate cytotoxicity toward the tested cancer cells and trigger cell apoptosis by mediating the influx of chloride anions and sodium cations into live cells.

Embedding calix[4]resorcinarenes in liposomes: Experimental and computational investigation of the effect of resorcinarene inclusion on liposome properties and stability

Two calix[4]resorcinarenes, which differ in the length of the alkyl chain on the methylene bridge between the aromatic rings, have been embedded in unilamellar liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine in three host/guest ratios, following two different procedures. The effect of the insertion of the guests has been evaluated through the measurements of the viscosity and the kinetic stability of the liposomal systems by means of the fluorescent probes pyrene and 5(6)-carboxyfluorescein. The presence of the guests reduces the viscosity of the liposomes, suggesting a modification of the bilayer structure. However, this does not affect liposome stability. A calix[4]resorcinarene cavitand with a more rigid conformation compared to the parent resorcinarene, has been also synthetized and embedded in liposomes. The free energy of the insertion of the substrates in the lipid bilayer has been evaluated through Molecular Dynamics simulations.

Artificial K+ Channels Formed by Pillararene-Cyclodextrin Hybrid Molecules: Tuning Cation Selectivity and Generating Membrane Potential

A class of artificial K⁺ channels formed by pillararene-cyclodextrin hybrid molecules have been designed and synthesized. These channels efficiently inserted into lipid bilayers and displayed high selectivity for K⁺ over Na⁺ in fluorescence and electrophysiological experiments. The cation transport selectivity of the artificial channels is tunable by varying the length of the linkers between pillararene and cyclodexrin. The shortest channel showed specific transmembrane transport preference for K⁺ over all alkali metal ions (selective sequence: K⁺ > Cs⁺ > Rb⁺ > Na⁺ > Li⁺ ), and is rarely observed for artificial K⁺ channels. The high selectivity of this artificial channel for K⁺ over Na⁺ ensures specific transmembrane translocation of K⁺ , and generated stable membrane potential across lipid bilayers.

Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

A reversible ion transportation switch of ON–OFF–ON type by a ligand-gated calix[6]arene channel

Calix[6]arene (CX6) was found to be an efficient ion transmembrane channel, which could be blocked by methylene blue (MB) through host–guest interactions.

Anion-Transport Mechanism of a Triazole-Bearing Derivative of Prodigiosine: A Candidate for Cystic Fibrosis Therapy

Cystic fibrosis (CF) is a genetic lethal disease, originated from the defective function of the CFTR protein, a chloride and bicarbonate permeable transmembrane channel. CF mutations affect CFTR protein through a variety of molecular mechanisms which result in different functional defects. Current therapeutic approaches are targeted to specific groups of patients that share a common functional defect. We seek to develop an innovative therapeutic approach for the treatment of CF using anionophores, small molecules that facilitate the transmembrane transport of anions. We have characterized the anion transport mechanism of a synthetic molecule based on the structure of prodigiosine, a red pigment produced by bacteria. Anionophore-driven chloride efflux from large unilamellar vesicles is consistent with activity of an uniporter carrier that facilitates the transport of anions through lipid membranes down the electrochemical gradient. There are no evidences of transport coupling with protons. The selectivity sequence of the prodigiosin inspired EH160 ionophore is formate > acetate > nitrate > chloride > bicarbonate. Sulfate, phosphate, aspartate, isothionate, and gluconate are not significantly transported by these anionophores. Protonation at acidic pH is important for the transport capacity of the anionophore. This prodigiosin derived ionophore induces anion transport in living cells. Its low toxicity and capacity to transport chloride and bicarbonate, when applied at low concentration, constitute a promising starting point for the development of drug candidates for CF therapy.

A halogen bond-mediated highly active artificial chloride channel with high anticancer activity

Chloride-selective transmembrane carriers or channels might have possible uses in treating channelopathies or cancers. While chloride carriers have been extensively investigated, the corresponding chloride channels have remained limitedly studied. Moreover, all hitherto reported channel systems lack clearly definable and readily modifiable positions in their structures for the reliable construction and combinatorial optimization of their ion transport properties. As a result, the existing channels are limited by their large molecular weight, weak activity or low anion selectivity. In this report, we describe a readily accessible and robust monopeptide-based scaffold for the reliable construction of halogen bond-mediated artificial anion channels via directional assembly of electron-deficient iodine atoms, which create a transmembrane pathway for facilitating anion transport. The high intrinsic modularity of the backbone of the scaffold, which enables the rapid and combinatorial optimization of the transport activity and selectivity of channels, effectively delivers a highly active chloride channel A10. Such high activity in chloride transport subsequently leads to an excellent IC50 value of 20 μM toward inhibiting the growth of human breast cancer cells (BT-474), an anticancer activity that is even higher than that of the well-known anticancer agent cisplatin.

Hybrid multicyclophanes based on thiacalix[4]arene and pillar[5]arene: synthesis and influence on the formation of polyaniline

A series of new tetrakispillar[5]thiacalix[4]arenes was synthesized. Supramolecular assistance of the multicyclophanes in oxidative polymerization of aniline was studied.

Bypassing CFTR dysfunction in cystic fibrosis with alternative pathways for anion transport

One therapeutic strategy for cystic fibrosis (CF) seeks to restore anion transport to affected epithelia by targeting other apical membrane Cl^- channels to bypass dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl^- channel. The properties and regulation of the Ca²⁺-activated Cl^- channel TMEM16A argue that long-acting small molecules which target directly TMEM16A are required to overcome CFTR loss. Through genetic studies of lung diseases, SLC26A9, a member of the solute carrier 26 family of anion transporters, has emerged as a promising target to bypass CFTR dysfunction. An alternative strategy to circumvent CFTR dysfunction is to deliver to CF epithelia artificial anion transporters that shuttle Cl^- across the apical membrane. Recently, powerful, non-toxic, biologically-active artificial anion transporters have emerged.

Synthesis and comprehensive structural and physicochemical characterization of dutasteride hydrochloride hydrate solvates

Four crystalline dutasteride hydrochloride hydrate solvates containing respectively methanol, ethanol, acetone and acetonitrile molecules were obtained. All samples were characterized by extensive spectroscopic analysis with infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and ¹H as well as ¹³C NMR techniques. For three solvates, i.e. methanol, ethanol and acetone solvates, the single crystal X-ray diffraction (SCXRD) experiments were possible, and their respective crystal and molecular structures were determined. The present study allowed to unambiguously establish the molecular composition of solvates as consisting of a dutasteride : hydrogen chloride : water : solvent in a molar ratio of 1:1:1:1 and confirm that they are isostructural. Beyond providing the full spectroscopic characteristic of the compounds, the results obtained have also allowed clarifying of some appearing inconsistencies in published literature regarding the appropriate attribution of IR absorption bands to the relevant molecular vibrations.