Desenvolvimento de uma formulação com potencial biocida baseada no encapsulamento do óleo essencial da Piper callosum: avaliação da estabilidade a 25 °C e 35 °C utilizando diferentes conservantes

Abstract

The aim of this research was to develop a biocide containing Piper callosum essential oil encapsulated in polymeric nanoparticles based on gelatin and poly-ɛ-caprolactone (PCL) and the evaluation of its stability at 25 °C and 35 °C using different preservatives. Biodegradable polymeric nanoparticles that carry essential oil have been widely used in medicine, agriculture and food. However, there are few scientific evidences reporting stability tests with different preservatives at different temperatures. The GC/MS technique showed that safrole (64 %) is the main constituent of the EO of Piper callosum, followed by methyleugenol (7.94 %), α-pinene (7.12 %) and β-pinene (6, 62 %). The size of the unloaded nanoparticles (NP) was ± 180 nm, with a polydispersity index (PDI) of 0.17. The formulation at 25 °C containing EO and preservative NE exhibited sizes of ± 230 nm, with PDI of 0.20. The formulation under 35 °C presented size of ± 260 nm and PDI of 0.22. Through Fourier transform infrared spectroscopy (FTIR), it was possible to confirm the encapsulation efficiency (EE), when comparing the spectrum of the nanoparticles containing the bioactive to the sample spectrum of the essential oil of Piper callosum in natura. The peaks of the essential oil disappeared in the formulation containing the natural active. After 25 days evaluating the stability of the biocide, the samples containing the preservative NE did not show changes in the stability parameters. Therefore, these formulations were selected to continue the research. The formulations containing NE (25 ° and 35 °C) evaluated in an open system showed a white and fluid appearance, with a pleasant odor and without evidence of biological and physical-chemical influences that would interfere with its stability for 120 days. The turbidity at 25 °C and 35 °C showed an initial value of 20 NTU and a final value at 25 °C of 35 NTU, while at 35 °C the turbidity value was around 30 NTU. The EE for both temperatures started at 94 %, with a final value of 90 % at 25 °C and 91 % at 35 °C. After 240 days, the formulations at 25 °C and 35 °C, in closed systems, exhibited an unpleasant odor and color change, being discarded. The samples proved to be stable in all released media, with very similar values. However, it was noted that the formulation with the preservative NE (25 °C) released the bioactive more quickly. The stability data showed that the synthesis with the preservative NE is promising for future applications.