Chemistry of the Calceolaria genus. Structural and biological aspects

Aucochthonous species of the Calceolaria (Scrophulariaceae) genus are studi ed. From their apolar extracts 55 new diterpenes of six skeleton types, nap htoquinones and flavonoids have been isolated. Among the different diterpen es malonic substitutions and bis-diterpenes in which both units are joined by a malonic acid unit stand out. Pimaranes present C-9 epimerisation and, consequently, H-9 has the same orientation as Me-20. From C.sessilis naphth oquinones with anti-chagasic activity have been isolated; and the biotransf ormation of 2 alpha,19-dihydroxy-9-epi-entpimara-7,15-diene with Giberella fujikuroi produced 7 new diterpenes.