Support for Natural Small-Molecule Phenols as Anxiolytics.

Area of Science:

• Pharmacology
• Neuroscience
• Natural Products Chemistry

Background:

• Natural small-molecule phenols (NSMPs) exhibit diverse bioactivities.
• Anxiolytic properties of NSMPs are gaining scientific interest.
• This research investigates the general anxiolytic potential of NSMPs.

Purpose of the Study:

• To evaluate the anxiolytic activity of seven simple phenols in mice using the elevated plus maze (EPM) test.
• To determine the structural requirements for anxiolytic activity, focusing on the phenolic hydroxyl group.
• To explore the neuronal mechanisms underlying the anxiolytic effects in the hippocampus.

Main Methods:

• Elevated Plus Maze (EPM) test in mice and rats.
• Oral administration of phenols at varying doses (2.5-20 mg/kg).
• In vivo electrophysiological recordings of hippocampal neurons in rats.

Main Results:

• All seven tested phenols (phloroglucinol, eugenol, protocatechuic aldehyde, vanillin, thymol, ferulic acid, caffeic acid) exhibited anxiolytic activity in mice.
• The phenolic hydroxyl group in 4-hydroxycinnamic acid (4-OH CA) was crucial for anxiolytic effects, unlike 4-chlorocinnamic acid (4-Cl CA).
• Neuronal spike recordings indicated significant differences between 4-OH CA and 4-Cl CA in the hippocampal CA1 region.

Conclusions:

• NSMPs generally possess anxiolytic activity.
• The phenolic hydroxyl group is essential for the anxiolytic effects of certain NSMPs.
• The hippocampal CA1 region is implicated in the anxiolytic pathways of 4-OH CA, supporting phytotherapy applications.