NOVEL HIGHLY SWEET SECODAMMARANE GLYCOSIDES FROM PTEROCARYA-PALIURUS

Two novel, potently sweet 3,4-secodammaranoid saponins designated pterocaryosides A (1) and B (2) have been isolated from the leaves and stems of the Chinese tree Pterocarya paliurus. The structures of these compounds were established as (23E)-(12R,20S)-12,20,25-trihydroxy-3,4-secodammara-4(28),23-dien-3-oic acid 12-O-beta-D-quinovopyranoside and (23E)-(12R,20S)-12,20,25-trihydroxy-3,4-secodammara-4(28),23-dien-3-oic acid 12-O-alpha-L-arabinopyranoside, on the basis of spectroscopic measurements, especially 1D and 2D NMR data. The methylated peracetates of pterocaryosides A and B were prepared and used for structural confirmation. Preliminary evaluations constituted by mouse acute toxicity and bacterial mutagenesis determinations supported the safety of 1 and 2, and subsequently the compounds were rated by a human taste panel as about 50 and 100 times sweeter than 2% sucrose, respectively.