Avaliação do extrato fermentado e bioativo da biomassa de Spirulina platensis como potencial prebiótico cutâneo

Abstract

Spirulina sp. is a cyanobacterium constituent of one of the most studied and produced microalgae genres due to its high nutritional value, rich in proteins, fatty acids, vitamins and minerals. Also, it exerts therapeutic effects for its composition in bioactive compounds, including on skin, on which it performs many benefits. Moreover, its constitution contributes for its intestinal prebiotic effect. This characteristic allows its exploration in another microbiota types, as cutaneous one. Among diverse extraction methods, fermentation is a technique that has been applied to improve biological activity of different types of substrates. The aim of this work is to evaluate if the bioactive extract of S. platensis produced by fermentation has potential prebiotic action on skin. The optimization of the fermentation was done by central composite rotational design using the factors time, inoculum volume and temperature. To obtain a bioactive extract, dependent variables chosen were the content of total phenolic compounds (TPC) and antioxidant activity, determined by Folin-Ciocalteu method and the inhibition of DPPH radical, respectively. From the best stipulated conditions, its efficiency against the extraction without L. acidophilus inoculation was verified. The change of bioactivity in the process was evaluated along 48 hours in sterilized (S) and non-sterilized (NS), with (I) and without inoculum. At the beginning and end of extraction the microbial load was determined by plate count method. Cutaneous prebiotic potential was analyzed through the influence of the extracts (2,5%) in 4 and 24 hours in the growth of the respective probiotic and pathogen bacteria: Staphylococcus epidermidis and S. aureus. With exception of the temperature for DPPH inhibition, all the factors showed to be significative (p<0,05) to the both answers. The generated mathematical models with low R² showed to be inaccurate to predict the fermentation behavior. Through response surfaces, it was verified the low influence of temperature and inoculum, being time the most significative. In 40 hours of extraction with 15% of inoculum in 37 ºC, it was found L. acidophilus action does not improve extract bioactivity, with TPC and DPPH inhibition 14,13 ad 40,10% lower, respectively. In 48 hours of extraction, it was observed the gradual improve of bioactivity in SI, NS and NSI, with NS showing the best results. In SI was evident the improve was due to L. acidophilus monoculture. All the extracts inhibited Staphylococcus strains in 4 hours. After 24 hours the effect decreased. Only NS showed greater inhibition to S. aureus in relation to S. epidermidis in both times (reduction in log CFU/mL of 5.15 vs. 4.08 (4 h) and 1.97 vs. 0.64 (24 h), presenting advantage in prebiotic action. It was concluded the addition of L. acidophilus to S. platensis extraction does not improve its bioactivity with non-sterilized biomass, as well as it does not exert cutaneous prebiotic effect. Still, S. platensis extract noninoculated could be better explored to this purpose.