Phenolic glycosides from Tabebuia argentea and Catalpa bignonioides Maryan Bruzual de Abreu a , Abeer Temraz b,c , Antonio Vassallo d , Alessandra Braca a, *, Nunziatina De Tommasi e a Dipartimento di Farmacia, Universita ` di Pisa, via Bonanno 33, 56126 Pisa, Italy b Faculty of Pharmacy, Al Azhar University, Nasr-City, 11371 Cairo, Egypt c Department of Pharmacognosy, Faculty of Pharmacy, Umm Al-Qura University, Makkah 21955, Saudi Arabia d Dipartimento di Scienze, Universita ` degli Studi della Basilicata, Viale dell’Ateneo Lucano 10, 85100 Potenza, Italy e Dipartimento di Farmacia, Universita ` di Salerno, via Ponte Don Melillo, 84084 Fisciano, Italy 1. Introduction Tabebuia argentea Britt. is a tree native of South America with wide distribution ranging from Venezuela to Argentina. In Northeastern Brazil it is known by the trivial names ‘‘craibeira’’, ‘‘paratudo’’, and ‘‘ipe ˆ-amarelo’’, and it is used in folk medicine as anti-inflammatory and against influenza (Agra, 1996). Further- more, T. argentea is also known as silver-trumpet tree, which owes its common name to the silver-gray cast of its evergreen leaves. The genus Tabebuia is a notable flowering tree; its stem bark is used in naval building construction, mainly because of the hardness and resistance of its wood. Catalpa bignonioides Walt., also known as American Catalpa, is a large ornamental shade tree, native to Gulf coast States of the USA, widely planted in urban areas as a street and lawn tree (Row, 2010). In addition to have sedative effect, the plant also is reported to have a mild narcotic action and it was therefore used in preparations with other herbs for the treatment of whooping chough, asthma, and spasmodic coughs in children (Felter and Lloyd, 1989). Several phytochemical studies revealed that the extracts from Bignoniaceae species contained secondary metabolites such as tannins, flavonoids, quinones, alkaloids, triterpenes, steroids, and iridoids (Choudhury et al., 2011; Cragg and Newman, 2005). As part of an ongoing program to search for bioactive compounds from Bignoniaceae family, we have carried out the chemical study on the leaves of T. argentea and petioles of C. bignonioides, resulting in the characterization of several iridoids that were evaluated for their Hsp90 inhibitory activity (Dal Piaz et al., 2013). In the current work we report the isolation and structural elucidation of one new lignan (1) and one new phenolic glycosides (2) (Fig. 1) on the basis of extensive spectroscopic and spectrometric analysis, including 2D NMR and ESI-MS spectra. Five known phenolic glycosides along with six flavonol glycosides were also isolated and characterized. 2. Results and discussion Compound 1 was obtained as yellow amorphous powder, showing a quasimolecular ion peak at m/z 879.2535 [M+Na] + in the positive mode HRESIMS. Other products ions detected in the ESIMS spectrum at m/z 717 [M + Na-162] + , 555 [M+Na-162-162] + , and 393 [M+Na-162-162-162] + were strongly suggestive of the presence of three hexose units. The 1 H NMR spectrum (Table 1) exhibited two doublets at d 5.27 and 4.73 (both, J = 4.5 Hz) characteristic of the H-7 and H-7 0 of sesamolinol-type lignans (Tan et al., 1998). The presence of two singlet signals for two methylenedioxy groups at d 5.93 and 5.95 and the five aromatic Phytochemistry Letters 7 (2014) 85–88 A R T I C L E I N F O Article history: Received 26 August 2013 Received in revised form 2 October 2013 Accepted 3 October 2013 Available online 22 October 2013 Keywords: Tabebuia argentea Catalpa bignonioides Bignoniaceae Phenolic glycosides Spectral analysis A B S T R A C T Phytochemical reinvestigation of Tabebuia argentea leaves and Catalpa bignonioides petioles extracts (Bignoniaceae) allowed to isolate two compounds not described before: one glycosylated lignan and one phenolic glycoside characterized as 5-hydroxysesamin 5-O-b-D-glucopyranosyl-(1 ! 2)-[b-D-gluco- pyranosyl-(1 ! 6)]-b-D-glucopyranoside (1) and 1-benzyl-[6-p-hydroxybenzoyl]-b-D-glucopyranosyl- (1 ! 3)-b-D-glucopyranoside (2), respectively. Their structural characterization was obtained on the basis of extensive NMR spectral studies. Five known phenolic glycosides along with six flavonol glycosides were also isolated and characterized. ß 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +39 050 2219688; fax: +39 050 2219660. E-mail address: alessandra.braca@farm.unipi.it (A. Braca). Contents lists available at ScienceDirect Phytochemistry Letters jo u rn al h om ep ag e: ww w.els evier.c o m/lo c ate/p hyt ol 1874-3900/$ – see front matter ß 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.phytol.2013.10.006