1 SS9 5-[(3-aminopropyl)amino]pentane-1-thiol 1.000 2 SPD Spermidine 0.750 3 SR0 N~1~-(3-azaniumylpropyl)butane-1,4-diaminium 0.750 4 OKP {5-[(3-aminopropyl)amino]pentyl}boronic acid 0.714