C[C@H]1CC[C@H]2C(=O)N3[C@@H](CC[C@H](C)[C@H]3c3cccc(N4CCCC4=O)c3)C(=O)N2[C@@H]1c1cccc(N2CCCC2=O)c1
Molecules with a polar surface area of greater than 140 angstroms squared (Å2) tend to be poor at permeating cell membranes. What's the psa of this molecule?