Impact of a novel sugarcane straw extract-based ingredient on skin microbiota via a new preclinical in vitro model

During cosmetic product development, the impact on the skin microbiota needs to be evaluated, as it plays an important role in skin health. Clinical studies are frequently used to assess cosmetic effects, but are expensive, time-consuming and require finished ingredients, which may be a limiting factor. Thus, this study had two main objectives, the development of a preclinical in vitro model for the evaluation of the effect of cosmetic ingredients on the skin microbiota, and its use to evaluate a novel sugarcane straw extract-based ingredient. In the development of the preclinical in vitro model, the microbiota incubation time and atmospheric conditions were optimized. The model was validated using a benchmark ingredient with reported in vivo effects on skin microbiota. Then, the new sugarcane straw extract-based ingredient was tested in the model, using skin microbiota samples from 12 healthy female volunteers. The impact on microbial groups was analyzed using qPCR and next-generation sequencing. The best conditions for the in vitro model were 24 h incubation under aerobic conditions. Furthermore, the results obtained with the benchmark ingredient agreed with those obtained in vivo, thus validating our model. Sugarcane straw extract-based ingredient was found to have no effect on community α-diversity, however it appears to affect S. epidermidis. In conclusion, the developed model can be used as a tool to assess the impact of novel cosmetic ingredients on skin microbiota. Also, the novel ingredient seems to have an impact on commensal S. epidermidis.