KCNA3 and multiple sclerosis: Interestingly, the highly potent and selective Kv1.3 inhibitor 5-(4-phenoxybutoxy)psoralen (PAP-1), which is a derivative of 5-methoxypsoralen—isolated from Ruta graveolens (Common Rue) after a tea made from this plant was reported to be beneficial in multiple sclerosis—is also thought to inhibit Kv1.3 in a use-dependent manner, binding preferentially to and stabilizing the C-type inactivated state of Kv1.3 to inhibit the channel75.