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Structure-antioxidative activity relationships in benzylisoquinoline alkaloids
B K Cassels1, M Asencio, P Conget
1Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago.
Pharmacological Research
|February 1, 1995
Summary
Aporphines and benzyltetrahydroisoquinolines show antioxidative capacity, with aporphines being more potent. The study suggests the biphenyl system, not phenol groups, drives this antioxidant capacity in these compounds.
Area of Science:
- Biochemistry
- Pharmacology
- Neuroscience
Background:
- Aporphines and benzyltetrahydroisoquinolines are classes of alkaloids with potential biological activities.
- Understanding their antioxidative properties is crucial for potential therapeutic applications.
Purpose of the Study:
- To compare the antioxidative capacity (AC) of specific aporphines and benzyltetrahydroisoquinolines.
- To investigate the structural features contributing to the AC of these compounds.
Main Methods:
- Utilized a brain homogenate autoxidation model to assess antioxidant activity.
- Determined half-maximal inhibitory concentration (IC50) values for various compounds.
- Examined the effect of N-methylation on the protective effect of glaucine.
Main Results:
- Aporphines (boldine, glaucine, apomorphine) exhibited higher AC (IC50: 16-20 µM) than benzyltetrahydroisoquinolines (coclaurine: 131.7 µM, norarmepavine: 79.3 µM).
- Antioxidative capacity correlated with the presence of a biphenyl system rather than phenol groups.
- Non-phenolic glaucine showed significant protection against lysozyme inactivation (IC50: 12 µM), suggesting a benzylic hydrogen near a nitrogen lone pair is key.
Conclusions:
- The biphenyl system is a critical structural feature for the antioxidative capacity of these alkaloids.
- The presence of a benzylic hydrogen adjacent to a nitrogen atom enhances the protective effects of non-phenolic aporphines.