In Vitro Evaluation of Blood and Water Enriched with Lactobacillus plantarum on the Anticancer Properties and Protein Concentrations of Saliva in Iranian Medicinal Leech (Hirudo orientalis)

Background and Objectives: The Iranian medicinal leech (Hirudo orientalis), an animal with high muscle contractility, has the ability to store blood in the stratum corneum, and after concentrating the blood, produces saliva rich in therapeutic enzymes. Unfavorable conditions of the digestive tract of leeches collected in the wild or farmed leeches with improper nutrition can sometimes affect their beneficial microbial population and reduce the amount and concentration of saliva produced, which is the main goal of leech growth and reproduction. The present study was conducted to evaluate the effects of consuming the probiotic Lactobacillus plantarum in two environments of water and blood consumed by leeches and to examine its results on the saliva of Iranian medical leeches.
Materials and Methods: In this study, the effect of feeding leeches with the probiotic Lactobacillus plantarum with different concentrations of 104, 106, 108 CFU/ml and a control group without any concentration of bacteria in the blood and water environment was investigated. The experiments were conducted with seven treatments and five replications and a completely randomized statistical design and in laboratory conditions. Saliva was extracted using menthol after 12 weeks of starvation (quarantine without food) on leeches and was examined by MTT test (to measure anticancer activity) and Bradford test (to measure protein).
Results:
The study showed a significant increase in the protein concentration of the saliva of the medicinal leech Orientalis in treatments containing 108 CFU/mL that used the aforementioned bacteria (P<0.05). Also, the saliva of leeches fed with high concentrations through blood showed the greatest effect of inhibiting the growth of MCF-7 cancer cells. In general, it can be stated that the probiotic improved the therapeutic quality of the saliva of cultured leeches.
Conclusion:
Increased salivation in medical leeches is a natural response to the type of leech feeding, which is caused by the presence of bioactive substances in their saliva. This saliva contains a combination of compounds that help leech nutrition and facilitate its therapeutic effects. Therefore, adding the probiotic Lactobacillus plantarum to the leeches' diet significantly improves the quality of the saliva produced (increasing the concentration of active proteins) and increases its anticancer properties. This could be an effective step in improving the effectiveness of farmed leeches in medical treatments.