To probe the conformational properties of a number of D-isomers (5a, 7a, 8a, 8c, 13c, 15c and 16c) of parent cyclic peptides p1 and p3, a series of all-atom MD simulations were performed in an aqueous solution. The initial spatial structures of the peptides were constructed with Maestro version 9.3.5. A number of independent MD runs, each lasting 500 ns, were conducted for each peptide, resulting in a cumulative simulation time of 2.0 μs (for 8a, 8c and 15c) and 4.0 μs (for 5a, 7a, 13c, 16c). The topology for the non-standard amino acid residue (Dip) had been previously generated 30 using a set of CHARMM36 force field parameters. The preparation and production stages of the MD process were consistent for all peptides and were described previously. In all calculations, the tip3p water model and 3D periodic boundary conditions were employed. To maintain the system electrically neutral, Cl counterions were introduced. A spherical cutoff function (12 Å) and the particle mesh Ewald (PME) algorithm (with a 12 Å cutoff) were used to treat van der Waals and electrostatic interactions, respectively. To enhance the conformational sampling, the constructed peptides were simulated at temperatures of 310 and 325 K. MD production runs (a half of runs at 325 K) were conducted in an NPT ensemble with an integration step of 2 fs.