Chamomile infusions inhibit proteases involved in gastric inflammation

Chamomile, prepared with dried flowers from Matricaria recutita L., is one of the most commonly consumed herbal tea. The drug is used for the treatment of gastrointestinal complaints (minor spasms, epigastric distensions, gastritis and gastric inflammation). Several classes of bio-active compounds have been identified in the extracts of chamomile including phenolic acids, coumarins, and flavonoids such as the glycosides of apigenin, quercetin, patuletin, luteolin and several derivatives. Several studies showed that chamomile infusions possess a protective effect on gastritis and gastric ulcer, but the mechanisms involved in this effect are not completely established. Matrix metalloproteinases (MMPs) and neutrophils elastase (NE) are proteases that degrade extracellular matrix in physiological and pathological conditions. Since MMP-9 and NE are involved in gastric inflammation, the aim of this work was the evaluation of the effects of chamomile infusions of dried capitula (CFI) and sifted (SFI) flowers on MMP-9 and NE, and the identification of the compounds responsible for the observed effect. Each infusion was analyzed by LC-MS/MS in order to verify whether compositional differences affected biological activity. Analysis of CFI and SFI by LC-MS showed a complex profile. The compounds unequivocally identified by LC-MS/MS were the flavonoids apigenin-7-O-glucoside (api7glu), luteolin-7-O-glucoside (lut7glu), patuletin-7-O-glucoside (pat7glu) and hyperoside (hyp). Api7glu was more abundant in CFI than in SFI whereas the opposite was for lut7glu (5.2 µg/ml vs 8.1 µg/ml). Pat7glu was the most abundant in both the infusions, whereas Hyp was the lowest. CFI and SFI inhibited enzymatic activity of MMP-9 catalytic domain in a concentration-dependent manner. At 1500 microg/ml the inhibition was 28 % and 55 % for CFI and SFI, respectively. Api7glu and lut7glu (10 µM) showed an inhibitory activity of 40% and 30%, respectively, demonstrating their contribute to the effect of the infusions. The inhibitory effect of CFI and SFI was confirmed on MMP-9 released by human adenocarcinoma cells (AGS cells). CFI was able to inhibit MMP-9 secretion from AGS cells (85% at 1500 microg/ml). The inhibitory effect of the infusions on NE was also tested. Concentration-response curves were performed and IC50 of CFI and SFI on NE were 369.2 microg/ml and 536.7 microg/ml, respectively. The individual compounds that showed an inhibitory effect on NE activity were api7glu (IC50 74.3 microM), lut7glu (IC50 8.6 microM), pat7glu (IC50 10.4 microM), and chlorogenic acid (IC50 31.3 microM). In conclusion, the present study shows some biochemical mechanism of action for the effect of chamomile infusions and supports the use of chamomile in the treatment of gastrointestinal inflammation.