Related Experiment Video
Updated: Aug 9, 2026
HPLC Coupled with Chemical Fingerprinting for Multi-Pattern Recognition for Identifying the Authenticity of Clematidis Armandii Caulis
Published on: November 11, 2022
Structural elucidation of a tadalafil analogue found as an adulterant of a herbal product
Peng Zou1, Peiling Hou, Min-Yong Low
1Department of Pharmacy, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543.
Abstract:
A tadalafil analogue and hydroxyhomosildenafil were isolated from a herbal product marketed for erectile dysfunction. The structure of the tadalafil analogue was elucidated using LC-UV, high resolution MS, ESI-MS/MS, IR, and NMR. The compound was determined to be (6R,12aR)-2-amino-6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6] pyrido[3,4-b]indole-1,4-dione. This compound should be included as a target compound when screening for adulterants in herbal products. This is the first published paper on a tadalafil analogue and hydroxyhomosildenafil found as adulterants of a herbal product.
Related Concept Videos
01:19Pharmaceutical Alternatives: Excipients and Impurities-Related Therapeutic Nonequivalence
01:16Adrenergic Agonists: Chemistry and Structure-Activity Relationship
Aromatic ring substitutions: Substituting the aromatic ring with –OH groups at positions 3 and 4 yields catecholamines (e.g., epinephrine), which have a high affinity for adrenoceptors. Hydrogen bonding between –OH groups and receptors enhances adrenergic activity.
Separation of the aromatic...
01:28Treatment for Pulmonary Arterial Hypertension: Phosphodiesterase Inhibitors
Among the PDE5 inhibitors, sildenafil (Revatio) stands out as a competitive and selective inhibitor. It operates by elevating cellular levels of cGMP and augmenting signaling through the cGMP-PKG pathway, promoting vasodilation. Upon oral...