Bioactive caffeic acid esters from Glycyrrhiza glabra

Area of Science:

• Natural Product Chemistry
• Pharmacology
• Biochemistry

Background:

• Glycyrrhiza glabra (licorice) is traditionally used for its anti-ulcer properties.
• Flavonoids are known contributors to G. glabra's medicinal effects.
• The role of other G. glabra constituents, like caffeic acid derivatives, in its therapeutic actions requires further investigation.

Purpose of the Study:

• To isolate and characterize compounds from Glycyrrhiza glabra with potential biological activities.
• To evaluate the elastase inhibitory and antioxidant potential of isolated compounds.
• To explore the contribution of caffeic acid derivatives to the anti-ulcer effects of G. glabra.

Main Methods:

• Guided fractionation of Glycyrrhiza glabra extract using thin-layer chromatography bioautography.
• Isolation and structural elucidation of two caffeic acid derivative esters: eicosanyl caffeate and docosyl caffeate.
• Assay of elastase inhibitory activity using IC(50) values and antioxidant activity via DPPH and ABTS scavenging assays.

Main Results:

• Two compounds, eicosanyl caffeate (1) and docosyl caffeate (2), were successfully isolated.
• Both compounds demonstrated potent elastase inhibitory activity, with IC(50) values of 0.99 µg/mL and 1.4 µg/mL, respectively.
• Moderate antioxidant activity was observed for both compounds in DPPH and ABTS assays.

Conclusions:

• Caffeic acid derivative esters, specifically eicosanyl caffeate and docosyl caffeate, possess significant elastase inhibitory and antioxidant properties.
• These findings suggest that caffeic acid derivatives may play a role in the anti-ulcer effects of Glycyrrhiza glabra, complementing the known activity of flavonoids.
• Further research into these compounds could lead to novel therapeutic strategies for conditions involving elastase activity and oxidative stress.