Chemistry of the Calceolaria genus. Structural and biological aspects

Aucochthonous species of the Calceolaria (Scrophulariaceae) genus are studied. From their apolar extracts 55 new diterpenes of six skeleton types, naphtoquinones and flavonoids have been isolated. Among the different diterpenes 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 naphthoquinones with anti-chagasic activity have been isolated; and the biotransformation of 2 alpha,19-dihydroxy-9-epi-entpimara-7,15-diene with Giberella fujikuroi produced 7 new diterpenes.