Antibacterial Activity of Grape Extracts on cagA-Positive and -Negative Helicobacter pylori Clinical Isolates

Abstract

There is considerable interest in alternative/adjuvant approaches for the eradication of Helicobacter pylori using biologically active compounds, especially antioxidants from plants. In the present work, we tested the antioxidant and antimicrobialactivities of hydro-alcoholic extracts from Colorino, Sangiovese and Cabernet Sauvignon grape cultivars against H. pylori G21 (cagA-negative, cagA-) and 10K, (cagA-positive, cagA+) clinical isolates. we determined the minimum bactericidalconcentration (MBC) by incubating strain suspensions in Brucella broth with fetal bovine serum and samples at different concentrations in a final volume of 100 μl in amicroaerobic atmosphere. After incubation, subcultures were carried out on Brucella agar plates which were incubated for 3-5 days in a microaerobic environment. The lowest concentration in broth, where the subculture on agar showed complete absenceof growth, was considered the MBC.

The Colorino extract showed the highest antibacterial activity against G21 strain(MBC=1.35 mg/mL), while Sangiovese and Carbernet MBCs were 4.0 mg/mL ca. H.pylori 10K was only susceptible to Colorino after 48 hours (MBC = 3.57 mg/mL). Resveratrol exhibited the highest antibacterial activity. Interestingly, the most pathogenic strain (10K) was less susceptible to both the grape extracts and the isolated com-pounds. These results suggest that the administration of grape extracts and wine constituents, in addition to antibiotics, might be useful in the treatment of H. pylori infection. Should the reduced susceptibility of 10K strain be extended to all the cagA+ H. pylori isolates, which are endowed with cancer promoter activity, this bservation may help explain why the organisms expressing CagA are more closely associated with atrophic gastritis and gastric carcinoma development.

Keywords:

• Antimicrobial activity
• antioxidant activity
• grape extracts
• Helicobacter pylori