Comparative Perturbation Effects Exerted by the Influenza A M2 WT Protein Inhibitors Amantadine and the Spiro[pyrrolidine-2,2′-adamantane] Variant AK13 to Membrane Bilayers Studied Using Biophysical Experiments and Molecular Dynamics Simulations

Abstract

Aminoadamantane drugs are lipophilic amines that block the membrane-embedded influenza A M2 WT (wild type) ion channel protein. The comparative effects of amantadine (Amt) and its synthetic spiro[pyrrolidine-2,2′-adamantane] (AK13) analogue in dimyristoylphosphatidylcholine (DMPC) bilayers were studied using a combination of experimental biophysical methods, differential scanning calorimetry (DSC), X-ray diffraction, solid-state NMR (ssNMR) spectroscopy, and molecular dynamics (MD) simulations. All three experimental methods pointed out that the two analogues perturbed drastically the DMPC bilayers with AK13 to be more effective at high concentrations. AK13 was tolerated in lipid bilayers at very high concentrations, while Amt was crystallized. This is an important consideration in the formulations of drugs as it designates a limitation of Amt incorporation. MD simulations verify provided details about the strong interactions of the drugs in the interface region between phosphoglycerol backbone and lipophilic segments. The two drugs form hydrogen bonding with both water and sn-2 carbonyls in their amine form or water and phosphate oxygens in their ammonium form. Such localization of the drugs explains the DMPC bilayers reorientation and their strong perturbing effect evidenced by all biophysical methodologies applied.

Influenza A M2 Spans the Membrane Bilayer, Perturbs its Organization and Differentiates the Effect of Amantadine and Spiro[pyrrolidine-2,2'-adamantane] AK13 on Lipids

“…According to 31 P NMR spectra, the ternary system DMPC + M2TM (x=0.03) + Amt (x=0.05) or AK13 (x=0.05) produced σ Ι -σ II values almost identical to those of DMPC + M2TM (x=0.03) at the gel phase indicating that Amt and AK13 at concentration x=0.05 do not perturb further the phosphate groups region in the presence of M2TM. This is consistent with results from our previous paper 29 showing that at these concentrations the drugs did not change σ II −σ I value compared to pure DMPC. Only when the concentration of the drug was x=0.08 in the DMPC + Aamt system did the σ Ι -σ II value increase by 4 ppm compared to the pure DMPC.…”

“…Only when the concentration of the drug was x=0.08 in the DMPC + Aamt system did the σ Ι -σ II value increase by 4 ppm compared to the pure DMPC. 29 As discussed previously in these two preparations the Aamt drug is inserted in the M2TM pore and the excess of molecules is distributed mainly in the bilayers. The observance of peaks with identical linewidths as those reported in our previous publication 29 where drugs perturbed DMPC bilayers not containing M2TM is an indication that Aamt drugs insert into and affect the lipid bilayer (see asterisks in Figure 6; Table 7).…”

“…19,[27][28] In a previous work, the effects of the M2 WT channel blockers Amt and AK13 on DMPC bilayers ( Figure 1) were compared using DSC, x-ray scattering, ssNMR spectroscopy, and MD simulations. 29 It was found that the two drugs localized in the polar head area of the DMPC bilayers, stabilized through hydrogen bonding with sn-2 carbonyls in their amine form, and phosphate oxygens in their ammonium form. Such localization of the drugs explain their strong perturbing effect evidenced by all biophysical methodologies applied, and may be involved in a step for their insertion into M2 protein pore and effecting its conformational plasticity.…”

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

“…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…”

Chimeric Stimuli-Responsive Liposomes as Nanocarriers for the Delivery of the Anti-Glioma Agent TRAM-34

“…In the case of DPPC, the main transition curve was influenced the least by the drug molecule, potentiating the absence of the drug molecule from the membrane interior or its distribution in a more homogeneous manner. However, in the case of the chimeric systems, the formation of a shoulder on the main transition, along with all other alterations, is an indication of the creation of drug-related domains [31]. After exposure to an acidic environment, the drug-loaded chimeric bilayer transitions exhibited no shoulders and the transition enthalpy ∆H m decreased, particularly for DPPC:PDMAEMA-b-PLMA 1 (Figure 3B).…”