Yuccalechins A–C from the Yucca schidigera Roezl ex Ortgies Bark: Elucidation of the Relative and Absolute Configurations of Three New Spirobiflavonoids and Their Cholinesterase Inhibitory Activities

Abstract

The ethyl acetate fraction of the methanolic extract of Yucca schidigera Roezl ex Ortgies bark exhibited moderate acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity (IC50 47.44 and 47.40 µg mL−1, respectively). Gel filtration on Sephadex LH-20 and further RP-C18 preparative HPLC of EtOAc fraction afforded 15 known and 3 new compounds, stereoisomers of larixinol. The structures of the isolated spirobiflavonoids 15, 26, and 29 were elucidated using 1D and 2D NMR and MS spectroscopic techniques. The relative configuration of isolated compounds was assigned based on coupling constants and ROESY (rotating-frame Overhauser spectroscopy) correlations along with applying the DP4+ probability method in case of ambiguous chiral centers. Determination of absolute configuration was performed by comparing calculated electronic circular dichroism (ECD) spectra with experimental ones. Compounds 26 and 29, obtained in sufficient amounts, were evaluated for activities against AChE and BChE, and they showed a weak inhibition only towards AChE (IC50 294.18 µM for 26, and 655.18 µM for 29). Furthermore, molecular docking simulations were performed to investigate the possible binding modes of 26 and 29 with AChE.

Neuroprotective Effect of Yucca schidigera Roezl ex Ortgies Bark Phenolic Fractions, Yuccaol B and Gloriosaol A on Scopolamine-Induced Memory Deficits in Zebrafish

“…Chemical characterization of YS unpur and YS pur phenolic fractions was performed using UHPLC-UV-MS analysis. Phenolic metabolites were identified from retention times and spectroscopic data (UV-Vis and mass spectrometry) of previously isolated YS standards [7,8]. The quantification of individual phenols was carried out by the external standard method, i.e., using trans-resveratrol and detection at 320 nm.…”

“…Ultrapure water was prepared using a Milli-Q water purification system (Millipore, Milford, MA, USA). Yuccaols A-E, Yuccalide A, gloriosaols A, C-E, and THMS were in-house prepared at the Department of Biochemistry and Crop Quality, IUNG [8]. Trans-resveratrol (Sigma Aldrich, Steinheim, Germany, >99% HPLC based) was used as a group standard for determination of yucca phenolics.…”

“…The plant material-Yucca schidigera Roezl ex Ortgies bark was purchased from a commercial source (Desert King Int., Chula Vista, CA, USA). The extraction of unpurified phenolic fraction and isolation procedures of single stilbenoids were described in detail in our previous work [8]. Briefly, the powdered material was extracted 3 times with a new portion of 100% MeOH in 15-fold excess, using an ultrasonic bath (Polsonic 33, Warsaw, Poland) for 20 min of each series.…”

“…YS bark is a byproduct that contains unique phenolic metabolites i.e., spiro-flavostilbenoids (biosynthesized from 2R-naringenin and trans-resveratrol (RV) or trans-3,3 ,5,5 -tetrahydroxy-4 -methoxystilbene (THMS)), which were previously only detected in the Yucca L. genus [7]. The spiro-compounds of YS include spiro-flavostilbenoids Yuccaols (Yus A-E), Yuccalide A (YueA), Gloriosaols (Glos A and C-E), and spiro-biflavonoids, namely Yuccalechins A-C [8]. Individual spiro-flavostilbenoids, RV, THMS, and the YS phenolic fraction were tested in vitro for their anti-inflammatory properties.…”

Qualitative and Quantitative Analysis of Secondary Metabolites in Morphological Parts of Paulownia Clon In Vitro 112® and Their Anticoagulant Properties in Whole Human Blood

“…The 1D and 2D NMR spectra of isolated compounds, including 1 H-, 13 C-DEPTQ (distortionless enhancement by polarization transfer with retention of quaternaries), selective TOCSY (total correlation spectroscopy), selective ROESY (rotation frame nuclear overhauser effect spectroscopy), 1 H-1 H-DQF-COSY (double-quantum filtered correlation spectroscopy), 1 H-13 C-HSQC (heteronuclear single quantum coherence) and 1 H-13 C-HMBC (heteronuclear multiple bond coherence) were recorded using an Avance III HD Ascend 500 MHz spectrometer (Bruker BioSpin, Rheinstetten, Germany) in deuterated methanol (MeOH-d4) at 30 °C. NMR spectra were calibrated to the signal of residual solvent: δ 3.31 for 1 H and 49.0 for 13 C [48,49].…”