A proprietary herbal extract titred in verbascoside and aucubin suppresses lipopolysaccharide-stimulated expressions of cyclooxygenase-2 in human neutrophils

Introduction
Bacterial lipopolysaccharide (LPS) initiates several major cellular responses that play a crucial role in the pathogenesis of inflammation, including activation of neutrophils and production of prostaglandin E2 (PGE2) by cyclooxygenase-2 (COX-2).

Material and methods
Recent years have witnessed a growing interest in natural compounds as promising alternatives to synthetic COX-2 inhibitors. In this study, we sought to investigate the effect of a proprietary herbal extract from Lippia citriodora and Plantago lanceolata, titred in verbascoside (≥ 5%) and aucubin (≥ 2%), against LPS-stimulated expressions of COX-2 in human neutrophils using both reverse transcription-polymerase chain reaction (RT-PCR) and a PGE2 immunoassay.

Results
Our main results indicated that: 1. The proprietary herbal extract titred in verbascoside and aucubin is not significantly cytotoxic as shown by the MTT assay; 2. The extract does not significantly inhibit COX-1, whereas it is able to suppress LPS-elicited COX-2 hyperexpression at the mRNA level in human neutrophils; and 3. The effect of the extract at 5% concentration was comparable to that elicited celecoxib 1%, although, in terms of absolute and relative reduction of COX-2 mRNA expression and production of PGE2 in human neutrophils, the drug significantly outperformed the extract.

Conclusions
In general, these results suggest that the proprietary herbal extract titred in verbascoside and aucubin is safe and may possess significant anti-inflammatory and analgesic effects by acting as a specific COX-2 inhibitor. Further studies are required to confirm the clinical efficacy of the extract.