Newbouldiosides A-C, phenylethanoid triglycosides from Newbouldia laevis

Newbouldia laevis SEEM (Bignoniaceae) is a shrub or small tree distributed in the tropical rain forest and Savannah zones of Western Africa. The stem bark is traditionally used for the treatment of a variety of ailments including dysentery, rheumatoid arthritis, epilepsy and skin infections. Previous chemical studies have revealed the presence of furanonaphthoquinones, atraric acid and a benzofuran derivative [1].

Continued studies have led to the characterization of three new phenylethanoid glycosides, designated as newbouldioside A-C. In addition, a sodium salt of analogue B representing the first phenolate within this group was encountered. Newbouldioside C represents the first member possessing a linear glc-rha-api chain and a sinapoyl moiety. The structures of the newbouldiosides were elucidated by spectroscopic methods as ß-(3,4-dihydroxyphenyl)ethyl O-5-O-syringoyl-ß-D-apiofuranosyl-(1→2)-O-[α-L-rhamnopyranosyl-(1→3)]-ß-D-gluco-pyranoside, ß-(3,4-dihydroxyphenyl)ethyl O-5-O-syringoyl-ß-D-apiofuranosyl-(1→2)-O-[α-L-rhamnopyranosyl-(1→3)]-6-O-E-feruloyl-ß-D-glucopyranoside, and ß-(3,4-dihydroxyphenyl)ethyl O-3-O-E-feruloyl-ß-D-apiofuranosyl-(1→2)-O-α-L-rhamnopyranosyl-(1→2)-6-O-E-sinapoyl-ß-D-glucopyranoside, respectively.

Reference: 1. Gormann, R., Kaloga, M. et al. (2003), Phytochemistry 64: 583–587.