Rhynchines A–E: Ca<sub>v</sub>3.1 Calcium Channel Blockers from <i>Uncaria rhynchophylla</i>
Haofeng Zhou, Wenyan Li, Li‐Yan Peng, Xiao‐Nian Li, Zhili Zuo, Qin‐Shi Zhao
Abstract
Rhynchines A–E (1–5), five new indole alkaloids with an unprecedented skeleton, were isolated from Uncaria rhynchophylla. The new skeleton was characterized by an indole moiety and a 2-oxa-8-azatricyclo[6,5,01,5,01,8]tridecane core, forming a unique 6/5/7/5/5 ring system. Their structures were determined by nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, infrared spectroscopy, and calculated electronic circular dichroism (ECD) and were confirmed by X-ray crystallography. Interestingly, 1 and 2 showed strong inhibitory activities against the Cav3.1 calcium channel with IC50 values of 6.86 and 10.41 μM.
Topics & Concepts
ChemistryMoietyCircular dichroismIndole testStereochemistryCalcium channelElectrospray ionizationRing (chemistry)Mass spectrometryNuclear magnetic resonance spectroscopyCalciumOrganic chemistryChromatographyAlkaloids: synthesis and pharmacologyTraditional and Medicinal Uses of AnnonaceaeBerberine and alkaloids research