Phenolic extractives with chemotaxonomic significance from the bark of Paulownia tomentosa var. tomentosa

Chemotaxonomy, also known as chemosystematics, can be regarded as a hybrid science which can classify plants based on their unique extractives (secondary metabolites). In this work, we investigated the chemotaxonomic marks of Paulownia species by studying the extractives of Paulownia tomentosa (Thunb.) Steud. var. tomentosa, a hardwood species widely used in Chinese medicine and pulping industries. Nine phenolic extractives, including two flavonoids (naringenin (1), and quercetin (2)), two phenolic acids (cinnamic acid (3), and gallic acid (4)), and five phenylpropanoid glycosides (cistanoside F (5), acteoside (6), isoacteoside (7), campneoside II (8), and isocampneoside II (9)), were isolated from the n-BuOH soluble fraction of P. tomentosa var. tomentosa bark, by repeated sephadex LH-20 open column chromatography coupled by Thin Layer Chromatography detection. The structures of the phenolic extractives were elucidated and characterized on the basis of their spectroscopical data and physiochemical properties. This was the first time to report the nine extractives from P. tomentosa var. tomentosa bark. Our chemotaxonomic analysis demonstrated that phenylpropanoid glycosides in P. tomentosa var. tomentosa were interesting and phenylpropanoid glycosides may possibly be considered as a useful chemotaxonomic marker within the species of Paulownia.