Caffeoyl phenylethanoid glycosides in Sanango racemosum and in the gesneriaceae

An investigation of Sanango racemosum for systematically useful glycosides has been performed. No iridoids could be detected, but reverse phase chromatography provided the caffeoyl phenylethanoid glycosides (CPGs) calceolarioside C and conandroside together with the new 2-(3,4-dihydroxyphenyl)ethyl 3-caffeoyl-β-allopyranoside which has been named sanangoside. The genus Sanango has previously been considered a member of Buddlejaceae, but recent work has shown that this is improbable. The presence of CPGs in S. racemosum combined with the lack of iridoid glucosides suggested a possible relationship with the Gesneriaceae. A survey of 20 species within this family showed that sanangoside was present in four species of subfamily Gesnerioideae and that all the investigated plants in the family contained CPGs, while no iridoids could be detected. The European genera Ramonda and Haberlea were characteristic by containing only the CPG-analogue myconoside, a dihydrocaffeoyl ester.