New vasorelaxant indole alkaloids, villocarines A-D from Uncaria villosa.

• Main Authors: Matsuo, Hirotaka, Okamoto, Ryuichi, Zaima, Kazumasa, Hirasawa, Yusuke, Ismail, Intan Safinar, Lajis, Md. Nordin, Morita, Hiroshi
• Format: Article
• Language: English; English
• Published: Elsevier 2011
• Online Access: http://psasir.upm.edu.my/id/eprint/24848/1/New%20vasorelaxant%20indole%20alkaloids.pdf; http://psasir.upm.edu.my/id/eprint/24848/; http://www.elsevier.com/

Villocarines A–D (1–4), four new indole alkaloids have been isolated from the leaves of Uncaria villosa (Rubiaceae) and their structures were elucidated by 2D NMR methods and chemical correlations. Villocarine A (1) showed vasorelaxation activity against rat aortic ring and showed inhibition effect on vasocontraction of depolarized aorta with high concentration potassium, and also inhibition effect on phenylephrine (PE)-induced contraction in the presence of nicardipine in a Ca2+ concentration-dependent manner. The vasorelaxant effect by 1 might be attributed mainly to inhibition of calcium influx from extracellular space through voltage-dependent calcium channels (VDC) and/or receptor-operated Ca2+-channels (ROC), and also partly mediated through the increased release of NO from endothelial cells and opening of voltage-gated K+-channels.