Figure 1. Structures and activity of HDAC inhibitors. (A) Structures of HDAC inhibitors: SAHA was chemically modified by replacing amino hydroxyl (NH-OH) with free selenium cyanide (SeCN) to create PCP-SeCN. B(PCP)-2Se is a dimer of PCP-SeCN lacking the –CN functional group. (B) PCP-SeCN and B(PCP)-2Se inhibited melanocytic and melanoma cell viability in a time dependent manner. WM35 and UACC 903 cells were treated with increasing concentrations of SAHA, PCP-SeCN or B(PCP)-2Se for 24, 48 or 72 h and cell viability measured using MTS and IC₅₀ values calculated using GraphPad Prism. Data represents average values of three independent experiments.