RESULTS

Interpretations of results:

According to the OECD 471:1997, there are several criteria for determing a positive results, such as
a concentration-related increase over the range tested and a reproducible increase at one or more
concenttaytions in the number of revertant colonies per plate in at least one strain with or without
metabolic activation system. Statistical methods can be used as an aid in evaluating the results; for
this assay a statistical test has been used for the evaluation of the obtained results between the
number of revertant colonies in presence of the tested product and the number of spontaneous
revertant colonies on solvent control plates. If the difference can be considered not statistically
significant, the test substance could be consider not mutagenic in this test.

Mutagenic activity:
No increase is observed in the number of spontaneous revertant colonies per plate in any strain in
both conditions, with and without metabolic activation system.

Genetic characteristics of the bacterial strains:
The verification of phenotypic demonstrated that the strains maintained the genetic properties.

Toxicity of the tested product:
The product shows toxic effect at 5% concentration against the TA98, TA100, TA1535 and TA1537
strains, in absence of enzymatic metabolic system (S9-) while, in presence of the activation system
(S9*) the cytotoxicity was not confirmed. This effect is related to the ability of the metabolic activation to altere the cytotoxicity of a substance. No cytoxic effect is shown respect the TA102 strain in presence/absence of the enzymatic metabolic system.

Negative and positive controls:
The number of spontaneous reverting colonies in the negative control plates did not exceed the validated limits, and all the positive controls caused a significant increase in the number of reverting colonies.

Statistical evaluation: 
Statistical significance was calculated using the One-way ANOVA followed by Šidák multiple comparisons as post-test. Results show a significant difference between positive and negative controls and no significant difference between negative controls and sample at the tested concentrations

 

Figure 5.1. MIC identification (in blue) and MBC identification (in red) between the three concentrations tested respect to control, after the incubation of the raw material with 106 CFU/ml of the selected strains Malassezia furfur (ATCC 14521), Propionibacterium acnes (ATCC 11827) and Staphylococcus epidermidis (ATCC 12228) incubation during the MIC assay.

 

Figure 5.1. MIC identification (in blue) and MBC identification (in red) between the three concentrations tested respect to control, after the incubation of the raw material with 106 CFU/ml of the selected strains Malassezia furfur (ATCC 14521), Propionibacterium acnes (ATCC 11827) and Staphylococcus epidermidis (ATCC 12228) incubation during the MIC assay.