148465-39-8 157976-68-6 21H,23H-Porphine-2,20-dicarboxylic acid, 18-(2-carboxyethyl)-12-ethenyl-7-ethyl-17,18-dihydro-3,8,13,17-tetramethyl-, cyclic 2,20-anhydride, (17S-trans)- 25465-77-4 PP-18 Purpurin 18 Purpurin-18