Anti-inflammatory Limonoids From Cortex Dictamni.

Area of Science:

• Natural Product Chemistry
• Pharmacology
• Medicinal Chemistry

Background:

• The root bark of *Dictamnus dasycarpus* (*Cortex Dictamni*) is a traditional remedy known for its anti-inflammatory properties.
• Limonoids are a class of compounds found in this plant, suspected to be responsible for its therapeutic effects.

Purpose of the Study:

• To isolate and characterize novel anti-inflammatory limonoids from *Cortex Dictamni*.
• To evaluate the anti-inflammatory potential of these isolated compounds.

Main Methods:

• Isolation of limonoids using various chromatographic techniques.
• Structure elucidation employing extensive spectroscopic methods and Electronic Circular Dichroism (ECD) data analysis.
• In vitro anti-inflammatory activity assessment in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cell lines.

Main Results:

• Six new limonoids (dictamlimonol A, dictamlimonoside B, dictamlimonols C-F) and seven known limonoids were successfully isolated.
• Compound 1, dictamlimonol A, represents the first naturally occurring 7,19-epoxy limonoid.
• Compounds 5, 7-11, and 13 inhibited LPS-induced nitric oxide (NO) production.
• Dictamlimonol D (5), fraxinellone (11), and dasylactone A (13) significantly reduced the protein expression of IL-6, TNF-α, iNOS, NF-κB, and COX-2 in a dose-dependent manner.

Conclusions:

• The isolated limonoids from *Cortex Dictamni* possess significant anti-inflammatory activities.
• Specific compounds, including dictamlimonol D, fraxinellone, and dasylactone A, effectively modulate key inflammatory mediators.
• These findings provide a scientific basis for the traditional use of *Cortex Dictamni* in managing inflammatory conditions.