AUTHOR=Salinas Ibáñez Ángel Gabriel , Vallés Diego , Adaro Mauricio , Barberis Sonia , Vega Alba E. 

TITLE=Antimicrobial Effect of a Proteolytic Enzyme From the Fruits of Solanum granuloso-leprosum (Dunal) Against Helicobacter pylori

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.699955

DOI=10.3389/fnut.2021.699955

ISSN=2296-861X

ABSTRACT=<p><italic>Helicobacter pylori</italic> is a gram-negative, helix-shaped, and microaerophilic bacteria that colonizes the human gastric mucosa, causing chronic infections, gastritis, peptic ulcer, lymphomas associated with lymphoid mucosa tissue, and gastric cancer. <italic>H. pylori</italic> is considered a Type 1 human carcinogen by WHO. The prevalence of the infection is estimated in more than half of the world population. Treatment of <italic>H. pylori</italic> infection includes antibiotics and proton pump inhibitors, but the increasing antibiotic resistance promotes the research of novel, more effective, and natural antibacterial compounds. The aim of this work was to study the effect of the partially purified proteolytic extract (RAP) of the fruits from <italic>Solanum granuloso-leprosum</italic> (Dunal), a South American native plant, and a purified fraction named <italic>granulosain</italic> I, against <italic>H. pylori</italic>, to obtain natural food additives for the production of anti-<italic>H. pylori</italic> functional foods. Furthermore, granulosain I and RAP could be used as natural adjuncts to conventional therapies. Granulosain I and RAP antibacterial activity was evaluated as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against <italic>H. pylori</italic> NCTC 11638 (reference strain) and twelve <italic>H. pylori</italic> wild strains, using a microdilution plating technique (Clinical and Laboratory Standards Institute). All the strains tested were susceptible to granulosain I with MIC from 156.25 to 312.5 μg/mL and MBC from 312.5 to 625 μg/mL, respectively. Besides, all the strains tested were susceptible to the RAP with MIC from 312.5 to 625 μg/mL and MBC from 625 to 1,250 μg/mL, respectively. The effect of granulosain I and RAP on the transcription of <italic>H. pylori</italic> genes encoding pathogenic factors, <italic>omp</italic>18, <italic>ure</italic>A, and <italic>fla</italic>A, with respect to a housekeeping gene (<italic>16S</italic> rRNA), was evaluated by RT-PCR technique. The band intensity between pathogenic factors and control gene was correlated under treated or untreated conditions, using the ImageJ program. Granulosain I and RAP significantly decreased the expression of pathogenic factors: <italic>omp</italic>18, <italic>ure</italic>A, and <italic>fla</italic>A. The combined inhibitory effect of granulosain I or RAP and an antibiotic such as, amoxicillin (AML, 10 μg), clarithromycin (CLA, 15 μg), levofloxacin (LEV, 5 μg), and metronidazole (MTZ, 5 μg) was evaluated, using the agar diffusion technique. Granulosain I and RAP showed significant synergistic effect on AML, CLA, and LEV, but no significant effect on MTZ was observed. Besides, granulosain I and RAP did not show toxicological effects at the concentrations studied. Finally, granulosain I and RAP could be used as safe natural food additives and as adjuvants for conventional therapies against <italic>H. pylori</italic>.</p>