In vitro and in vivo activity of Chios mastic gum extracts and constituents against Helicobacter pylori
Sotirios Paraschos, Prokopios Magiatis, Sofia Mitakou*, Kalliopi Petraki, Antonios Kalliaropoulos, Petros Maragkoudakis, Andreas Mentis, Dionyssios Sgouras*, and Alexios-Leandros Skaltsounis
Laboratory of Pharmacognosy and Natural Products Chemistry, Department of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece; Laboratory of Medical Microbiology, Hellenic Pasteur Institute, 127 Vassilisis Sofias Avenue, Athens 11521, Greece
The extracts and pure major constituents of Chios mastic gum (resin of Pistacia lentiscus var. chia) were tested for their activity against Helicobacter pylori. A total mastic extract without polymer (TMEWP) was prepared after removal of the contained insoluble polymer in order to ameliorate solubility and enhance in vivo activity. Administration of TMEWP to H. pylori SS1-infected mice over the period of 3 months with an average dose of 0.75 mg/day led to an approximately 30-fold reduction in the H. pylori colonization (1.5 logCFU/g of tissue). However, no attenuation in the H. pylori-associated chronic inflammatory infiltration and the activity of chronic gastritis was observed. To further characterize potential active mastic constituents, the TMEWP was separated into an acidic and a neutral fraction. Both were extensively characterized by NMR and MS spectroscopy to elucidate the structure of the components contained within each fraction. After chromatographic separation, the acid fraction gave the major triterpenic acids, while the neutral fraction gave several triterpenic alcohols and aldehydes. Mastic extracts and isolated pure triterpenic acids were tested for in vitro activity against a panel of 11 H. pylori clinical strains. The acid fraction was found to be the most active extract (MBC 0.139 mg/ml) and the most active pure compound was isomasticadienolic acid (MBC 0.202 mg/ml, 0.443 mM). Our results show that administration of TMEWP may be effective in reducing H. pylori colonization and that the major triterpenic acids in the acid extract may be responsible for such an activity.