Cooperative Effects of an Antifungal Moiety and DMSO on Pore Formation over Lipid Membranes Revealed by Free Energy Calculations

Abstract

Itraconazole is a triazole drug widely used in the treatment of fungal infections, and it is in clinical trials for treatment of several cancers. However, the drug suffers from poor solubility, while experiments have shown that itraconazole delivery in liposome nanocarriers improves both circulation half-life and tissue distribution. The drug release mechanism from the nanocarrier is still unknown, and it depends on several factors including membrane stability against defect formation. In this work, we used molecular dynamics simulations and potential of mean force (PMF) calculations to quantify the influence of itraconazole on pore formation over lipid membranes, and we compared the effect by itraconazole with a pore-stabilizing effect by the organic solvent dimethyl sulfoxide (DMSO). According to the PMFs, both itraconazole and DMSO greatly reduce the free energy of pore formation, by up to ∼20 kJ mol −1 . However, whereas large concentrations of itraconazole of 8 mol% (relative to lipid) were required, only small concentrations of few mol% DMSO (relative to water) were sufficient to stabilize pores.In addition, itraconazole and DMSO facilitate pore formation by different mechanisms.Whereas itraconazole predominantly aids the formation of a partial defect with a locally thinned membrane, DMSO mainly stabilizes a transmembrane water needle by shielding it from the hydrophobic core. Notably, the two distinct mechanisms act cooperatively upon adding both itraconazole and DMSO to the membrane, as revealed by an additional reduction of the pore free energy. Overall, our simulations reveal molecular mechanisms and free energies of membrane pore formation by small molecules.We suggest that the stabilization of a locally thinned membrane as well as the shielding of a transmembrane water needle from the hydrophobic membrane core may be general mechanism by which amphiphilic molecules facilitate pore formation over lipid membranes at sufficient concentration.

Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design

“…The free energy barrier is reduced when a larger number of peptides is present in the bilayer and almost disappears, i.e., is close to 0 kJ/mol, when six peptides are present in the membrane. Atomistic MD simulation studies have also found that synthetic polycations [834], itraconazole [258], and DMSO [258] induce a decrease in the free energy barrier against pore nucleation. [832].…”

“…Levofloxacin [236][237][238], Clarithromycin [236], Isoniazid N -acylated derivatives [239], Rifampicin [234,240], Mangostin [241], Trimethoprim [242], Negamycin [243] Potential antibiotic Kanamycin A [133], nTZDpa and its derivatives [244], Cholic acid derived amphiphiles [245], γ-terpineol [246], Bithionol [247] Antimicrobial compound Chlorhexidine [248][249][250], Triclosan [251], Octenidine [250] Antiparasitic Praziquantel [252] Antiviral drugs Darunavir [253], Amantadine [254][255][256], Spiro[pyrrolidine-2,2 -adamantane] [254,255], 20,30-dideoxyadenosine (Didanosine) [242], Saffron [257] Antifungal drug Itraconazole, [184,186,187,258], Nystatin [259], Amphotericin B [260] Rheumatoid arthritis Lapatinib [213] Nonsteroidal antiinflammatory drugs, inhibitor of cyclooxygenase-1 and -2…”

“…It is worth noting that the results of calculations of the free energy of pore formation are strongly dependent on the force field used [258,835]; other methodological issues related to the simulation of membrane active peptides are (1) the size of the simulation box, (2) electrostatic interaction treatment, (3) initial conditions, and (4) the simulation protocol used [836].…”

Cardiolipin prevents pore formation in phosphatidylglycerol bacterial membrane models

“…The steps during pore formation mediated by the insertion and aggregation of peptides were described by unbiased molecular dynamics (MD) simulations [27][28][29]. The energetic cost of formation of pores has also been quantified in allatom MD simulations [30,31], for distinct lipid types [32] and also in the presence of solutes [33][34][35], as well as in coarse-grain simulations [36]. These simulations revealed the existence of metastable states during pore formation, which were tightly linked to the hydrophilic head-hydrophobic tail volume ratio [32].…”

Computational and Experimental Advances in Biomembranes: Resolving Their Complexity

“…Understanding the mechanism of translocation and binding of a variety of drugs, transfection reagents, and antifungal/ antimicrobial compounds also remains a hot topic, 17,18 with additional complexity arising from the presence of certain lipids, 19 synergetic effects, 20 and modulation of pH. 21,22 Apart from these more applied studies, this Virtual Special Issue includes exciting contributions aimed at increasing our understanding of fundamental physical mechanisms that govern membrane behavior.…”