Banca de QUALIFICAÇÃO: JANIELE ALVES EUGÊNIO RIBEIRO GALVÃO

Obtaining Aranto Extract (Kalanchoe laetviriens) with supercritical CO2 and Ethanol

Kalanchoe leatviriens, supercritical extraction, CO₂, ethanol, quercetin.

Aranto (Kalanchoe laetviriens) is an Africa’s native succulent plant, which is present on several continents. Easy to propagate, it contains bioactive compounds such as phenolic compounds and bufadienolides. Used as a natural remedy, there is still no unanimity regarding its pharmacological effectiveness. However, recent studies indicate that its components have anti-inflammatory, antitumor and analgesic activity. In this context, extraction with supercritical CO₂ appears as an alternative for obtaining these components, as it avoids the degradation of bioactives, in addition to being a quick extraction that allows for a purer extract. The use of co-solvent was necessary due to the viscosity of the extract and the established operating conditions, with ethanol being used in all experiments. The operational conditions of the tests were developed in the range of 80 to 140 bar pressure, 35 to 65° C temperature and a percentage of 5 to 15% Ethanol, with a fixed extraction time and previously defined bed granulometry, composing a 2³ factorial planning with triplicates at the central point. The extract was characterized in terms of antioxidant power analysis by scavenging the DPPH radical (2,2-diphenyl-1-picrylhydrazyl) and the content of phenolic compounds using the Folin-Ciocalteu spectrophotometric method. Quercetin was identified and quantified in the samples via HPLC (High Performance Liquid Chromatography). The mass yields obtained in the extractions ranged from 0.48 to 2.19%, with the best result being at 65 °C, 80 bar and 15% Ethanol. According to the statistical analysis of the yield results, the cosolvent concentration showed a significant effect. In Soxhlet extractions, a yield of 19.05% was found using dry aranto leaves and ethanol as solvent. However, using fresh leaves from the respective plant, a yield of 0.97% was observed, due to the moisture contente of 95.9%. Quercetin quantification results from samples ranged from 2.50 to 21.45 mg/L. The antioxidant content of the best supercritical extraction condition resulted in an EC50 value (effective concentration that reduces 50% of free radicals) of 22.86 µg/ml, while the sample from the conventional extraction of dried leaves with ethanol resulted in values of 114.26 µg/ml. Regarding the content of phenolic compounds, the best condition presented 65.73 mg GAE/g Extract (GAE – Gallic Acid Equivalents).