Acyl-quinic acids from the root bark of Acanthopanax gracilistylus and their inhibitory effects on neutrophil elastase and cyclooxygenase-2 in vitro

Abstract

Eleven new acyl-quinic acids (AQAs) 1a–9, and 18 known AQAs 10–27 were isolated from the root bark of Acanthopanax gracilistylus W. W. Smith (Acanthopanacis Cortex). The planar structures of 1a–9 were determined based on their HR-ESIMS, IR, and NMR data. The absolute configurations of 1a–6 were identified by comparing the experimental and the calculated electronic circular dichroism (ECD) spectra. This is the first report of the isolation of AQAs from Acanthopanacis Cortex. Notably, 1a–6 were determined as unusual oxyneolignan-(−)-quinic acids heterodimers, representing a new class of natural products. The inhibitory activities of 1a–27 on neutrophil elastase (NE) and cyclooxygenase-2 (COX-2) were studied in vitro, and the results indicated they possessed significant inhibitory activities on COX-2. Among them, the IC50 values of 1a–9 were 0.63±0.014, 0.75±0.028, 0.15±0.023, 0.63±0.016, 0.30±0.013, 35.63±4.600, 8.70±1.241, 16.51±0.480, 0.69±0.049, 0.39±0.017, and 0.26±0.080 μM, respectively. This study represents the inaugural disclosure of the anti-COX-2 constituents found in Acanthopanacis Cortex, thereby furnishing valuable insights into the exploration of novel COX-2 inhibitors derived from natural reservoirs.