Antimicrobial effect of a proteolytic enzyme from the fruits of Solanum granuloso leprosum (dunal) against Helicobacter pylori

A. G. SALINAS IBAÑEZ,; D. VALLES; M ADARO; S. BARBERIS; A. E. VEGA.

Frontiers in Nutrition

Frontiers

Año: 2021 vol. 8 p. 1 - 13

Helicobacter pylori is a gram-negative, helix-shaped, and microaerophilic bacteria thatcolonizes the human gastric mucosa, causing chronic infections, gastritis, peptic ulcer,lymphomas associated with lymphoid mucosa tissue, and gastric cancer. H. pylori isconsidered a Type 1 human carcinogen by WHO. The prevalence of the infection isestimated in more than half of the world population. Treatment of H. pylori infectionincludes antibiotics and proton pump inhibitors, but the increasing antibiotic resistancepromotes 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 Solanum granuloso-leprosum (Dunal), a South American nativeplant, and a purified fraction named granulosain I, against H. pylori, to obtain natural foodadditives for the production of anti-H. pylori functional foods. Furthermore, granulosainI and RAP could be used as natural adjuncts to conventional therapies. Granulosain Iand RAP antibacterial activity was evaluated as minimum inhibitory concentration (MIC)and minimum bactericidal concentration (MBC) against H. pylori NCTC 11638 (referencestrain) and twelve H. pylori wild strains, using a microdilution plating technique (Clinicaland Laboratory Standards Institute). All the strains tested were susceptible to granulosainI with MIC from 156.25 to 312.5μg/mL and MBC from 312.5 to 625μg/mL, respectively.Besides, all the strains tested were susceptible to the RAP with MIC from 312.5 to625μg/mL and MBC from 625 to 1,250μg/mL, respectively. The effect of granulosainI and RAP on the transcription of H. pylori genes encoding pathogenic factors, omp18,ureA, and flaA, with respect to a housekeeping gene (16S rRNA), was evaluated byRT-PCR technique. The band intensity between pathogenic factors and control gene wascorrelated under treated or untreated conditions, using the ImageJ program. GranulosainI and RAP significantly decreased the expression of pathogenic factors: omp18, ureA,and flaA. The combined inhibitory effect of granulosain I or RAP and an antibioticsuch as, amoxicillin (AML, 10 μg), clarithromycin (CLA, 15 μg), levofloxacin (LEV, 5μg), 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, butno significant effect on MTZ was observed. Besides, granulosain I and RAP did not showtoxicological effects at the concentrations studied. Finally, granulosain I and RAP could beused as safe natural food additives and as adjuvants for conventional therapies againstH. pylori.