Activity-Guided Characterization of COX-2 Inhibitory Compounds in Waltheria indica L. Extracts

Area of Science:

• Phytochemistry
• Pharmacology
• Medicinal Chemistry

Background:

• Inflammation is a critical biological response involving Prostaglandin E2 (PGE-2) and Cyclooxygenase-2 (COX-2).
• Targeting COX-2 is a key strategy for managing inflammatory conditions.
• Waltheria indica L. is a traditional plant with known COX-2 inhibitory effects, but its active compounds were unidentified.

Purpose of the Study:

• To characterize the specific compounds in Waltheria indica responsible for COX-2 inhibition.
• To develop predictive models for quantifying COX-2 inhibitory activity without biological assays.
• To guide the targeted development of anti-inflammatory extracts from Waltheria indica.

Main Methods:

• Fractionation of Waltheria indica extract using centrifugal partition chromatography (CPC).
• In vitro COX-2 inhibition assay (fluorometric).
• Compound identification via high-resolution mass spectrometry (HPLC-MS/MS).
• Development and validation of mathematical prediction models.

Main Results:

• Alpha-linolenic acid, linoleic acid, and oleic acid were identified for the first time in Waltheria indica leaf extracts and contribute up to 41% of COX-2 inhibition.
• Steroidal and triterpenoid saponins also contribute to the observed COX-2 inhibitory activity.
• Two predictive models demonstrated high accuracy (RMSE = 1.6%) in quantifying COX-2 inhibition based on compound content.

Conclusions:

• Fatty acids (linoleic acid > alpha-linolenic acid) and saponins (steroidal > triterpenoid) are the primary contributors to COX-2 inhibition in Waltheria indica.
• The identified compounds and predictive models facilitate optimized extraction for potent anti-inflammatory Waltheria indica products.
• This research provides a foundation for developing targeted phytomedicines for inflammatory conditions.