Chemical Constituents and Anti-gastric Ulcer Activity of Essential Oils of Alpinia officinarum (Zingiberaceae), Cyperus rotundus (Cyperaceae), and their Herbal Pair.

The essential oil (EO) of the herbal pair (HP), Alpinia officinarum-Cyperus rotundus (HP G-X) has been conventionally used in traditional Chinese medicine (TCM) for 'warming the stomach' and relieving pain. However, its pharmacologically active compounds, as well as the mechanism of its anti-gastric ulcer properties remain unclear. In this study, the EOs obtained from HP G-X and its corresponding single herbs were analyzed using GC/MS. A total of 74, 56, and 85 compounds were detected in A. officinarum (GLJ), C. rotundus (XF), and HP G-X, accounting for 93.2 %, 89.5 %, and 92.0 % of the total content, respectively. GLJ mainly contains 1,8-cineol (22.0 %) and α-terpineol (11.8 %), whereas cyperenone (22.4 %) and cyperene (12.3 %) were the major constituents in XF. These four compounds were also detected in the HP G-X with relatively high composition as 11.8 %, 5.5 %, 11.8 %, and 10.6 %, respectively. Although no new compounds were detected in HP G-X, the relative concentration of some compounds increased, while others decreased or even disappeared. HP G-X showed the lowest toxicity (TC50 >800 μg/mL) against human gastric mucosal epithelial cells (GES-1) and had the best protective effect against ethanol-induced GES-1 cell damage compared to the individual herbs. In vitro studies demonstrated that HP G-X and the corresponding single herbs significantly reduced IL-6, TNF-α, and COX-2. In addition, in vivo investigations indicated that HP G-X can protect the gastric mucosa of mice from ethanol-induced damage by inhibiting the inflammatory reaction and providing analgesia. It can also inhibit the expression of NF-κBp65, COX-2, and TRPV1 protein, reduce the concentrations of IL-6 and TNF-α, and relieve heat-induced pain. This study further substantiated the traditional application of HP G-X against gastric ulcers through both in vivo and in vitro investigations.