Three new irregular abietane-type diterpenes were isolated from the root of Salvia dichroantha. It was revealed by spectroscopic methods and chemical reaction that these compounds have a unique structure which contains a rearranged abietane skeleton. They were named dichroanal A and B and dichroanone and shown to be rel-(4aS,9R,9aS)-8-formyl-1,2,3,4,4a,9a-hexahydro-5,6,9-trihydroxy-7-isopropyl-1,1,4a-trimethylfluorene; 4aS*-8-formyl-2,3,4,4a-tetrahydro-5,6-dihydroxy-7-isopropyl-1,1,4a-trimethyl-1H-fluorene and 4aS*-2,3,4,4a-tetrahydro-6-hydroxy-7-isopropyl-1,1,4a-trimethyl-5,8(1H)-fluorenedione, respectively. Salvia tomentosa was found to contain seven known abietane-type diterpenes. (C) 1998 Elsevier Science Ltd. All rights reserved.