No abstract

Leaves of Croton argyrophyllus contain essential oil with promising active components for the development of drugs and botanical insecticides. In this study, we evaluated the enzymatic pretreatment process to increase the extraction of essential oil from fresh and dried leaves of C. argyrophyllus. Pretreatment was carried out using a crude multienzymatic extract obtained via solid‐state fermentation of forage palm by Aspergillus niger, and the extraction was performed by hydrodistillation. A Doehlert matrix was used to optimize the enzymatic pretreatment variables temperature and enzymatic extract. The effect of pretreatment time was also investigated. At optimum experimental conditions, 41.34°C, 140 min, and 130.73 mL of enzyme in 369.27 mL of water, the essential oil yield from fresh leaves subjected to enzymatic pretreatment increased by 9.35% and that from dry leaves by 6.77%. Based on chromatographic analysis (GC–MS), no compound was degraded in the extraction process. Micromorphological analysis confirmed the rupture of the glandular trichomes, favoring essential oil release. Therefore, enzymatic pretreatment associated with hydrodistillation increased the essential oil yield and is a promising application to obtain essential oil for therapeutic purposes without altering its composition.

The objective of this work was to optimize the production and characterize α-amylase produced by Aspergillus niger through solid state fermentation, using leaf residues of C. linearifolius as substrate. For optimization, the incubation temperature, initial humidity and fermentation time were combined based on Doehlert experimental design. The highest productivity of the enzyme was 122.88 Ug-1, at 33oC, 70% humidity and 14 days of time. In the enzymatic characterization, the enzyme extract presented pH 5.0 and temperature 50oC, and α-amylase was thermostable up to 60oC, maintaining more than 90% of the activity. In evaluation of the effect of salt addition, sodium carbonate, calcium chloride, iron chloride, and cobalt chloride increased the enzymatic activity of α-amylase, while potassium and sodium from their chlorides served as enzyme inhibitors. The Km and Vmax values ​​found were 0.04 mg/mL and 46.95 µmol/min/mL, respectively, indicating that the substrate has affinity for α-amylase. Therefore, the results demonstrate that the residues of C. linearifolius can be used as a substrate for A. niger in the production of enzymatic extracts, such as α-amylase.