Related Experiment Video
Updated: Jun 20, 2026

Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
Structure-activity relationship study on alpha1 adrenergic receptor antagonists from beer
Toshiyuki Wakimoto1, Makoto Nitta, Kana Kasahara
1School of Pharmaceutical Sciences, University of Shizuoka and Global COE Program, 52-1 Yada, Suruga-ku, Shizuoka-shi, Shizuoka 422-8526, Japan. wakimoto@u-shizuoka-ken.ac.jp
Researchers determined the absolute stereochemistry of hordatine A and aperidine from beer. The (2R,3R)-hordatine A enantiomer showed the most potent alpha1A adrenoceptor antagonist activity.
Area of Science:
- Natural Product Chemistry
- Pharmacology
- Organic Synthesis
Background:
- Hordatine A and aperidine, found in beer, interact with muscarinic M3 and alpha1A adrenoceptors.
- Previous studies determined relative structures but not absolute stereochemistry.
Purpose of the Study:
- Elucidate the absolute stereochemistry of natural hordatine A and aperidine.
- Investigate structure-activity relationships for alpha1A adrenoceptor antagonism.
Main Methods:
- Synthesis of hordatine A and aperidine enantiomers from optically pure precursors.
- Chiral column High-Performance Liquid Chromatography (HPLC) analysis.
- Structure-activity relationship (SAR) studies with related synthetic compounds.
Main Results:
- Absolute stereochemistry of natural hordatine A identified as (2S,3S).
- Stereochemistry of aperidine determined as (2R,3S) via isomerization.
- (2R,3R)-hordatine A exhibited the highest potency as an alpha1A adrenoceptor antagonist.
- A synthetic derivative, (2R,3R)-methyl benzofurancarboxylate, showed superior antagonist activity.
Conclusions:
- Established the absolute stereochemistry of hordatine A and aperidine.
- Identified specific enantiomers with significant alpha1A adrenoceptor antagonist properties.
- Highlighted potential for synthetic analogs with enhanced pharmacological activity.
More Related Videos
Related Concept Videos
Adrenergic 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...
Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers
Nonselective α-blockers: Nonselective α-blockers contain haloalkylamine or imidazoline moieties. Phenoxybenzamine, with a haloalkylamine...
Adrenergic Receptors: ɑ Subtype
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase C—inositol-1,4,5-trisphosphate...
Structure-Activity Relationships and Drug Design
SAR studies the intricate relationship between a drug's chemical structure and biological activity. It focuses on understanding how modifications to a drug's structure can influence its...
Adrenergic Antagonists: Pharmacological Actions of ɑ-Receptor Blockers
α1-blockers: These drugs inhibit α1-adrenoceptors on smooth muscle cells, resulting in vasodilation. This vasodilation lowers blood pressure, making α1-blockers valuable in treating hypertension. Additionally, α1-blockers effectively address urinary obstruction...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...

