Brazoide E, a New Alkaloid and Other Compounds from Justicia wasshauseniana (Acanthaceae)

Abstract

A new alkaloid, named brazoide E (6), three known steroids (campesterol, β-sitosterol, stigmasterol), two glucosides (3-O-β-D-glucopyranosylsitosterol and 3-O-β-D-glucopyranosyl stigmasterol) and sucrose were isolated from the leaves and stems of Justicia wasshauseniana. Their structures were characterized using high-resolution electrospray ionization mass spectrometry (HRESIMS), nuclear magnetic resonance (1D and 2D NMR), and infrared (IR) spectroscopy. To reinforce the structural proposal, an acetylated derivative (6a) was obtained and its data compared to 6. Moreover, circular dichroism spectroscopy (CD) analysis was performed to determine the absolute stereochemistry, time-dependent density functional theory (TD-DFT) at the wB97X-D/def2-TZVP level, adopting functionals M06-2X and wB97X-D and base aug-cc-pVDZ, was employed to confirm the CD analysis.