2-Butenoic acid, 3-methyl-, 1-(1,4-dihydro-5,8-dihydroxy-1,4-dioxo-2-naphthalenyl)-4-methyl-3-pentenyl ester 5162-01-6 Arnebin 1 Arnebin I Crotonic acid, 3-methyl-, ester with 5,8-dihydroxy-2-(1-hydroxy-4-methyl-3-pentenyl)-1,4-naphthoquinone