Extraction of polyphenols from sea buckthorn leaves using microwave-assisted extraction (MAE) is described. The influence of different parameters on the extraction process (reactor type, stirring rate, extraction time, temperature, ethanol/water ratio) was studied. The polyphenolic extracts were analyzed in order to determine the total phenolic content (TPC) either by the Folin–Ciocalteu method or by differential pulse voltammetry (DPV), and the concentration of the main polyphenolic compounds by high-performance liquid chromatography (HPLC). The specific microwave energy was also determined. MAE resulted in a shorter extraction time (7.5 versus 30 min for the conventional method). The best results for MAE were obtained at a temperature of 90°C, using a solvent/plant ratio of 20/1 and 50% ethanol in the extraction solvent. The highest values of antioxidant capacity were obtained for polyphenolic extracts resulted from microwave extraction.

As a renewable and sustainable resource, lignocellulosic biomass serves as a crucial raw material for the production of biofuels, biochemicals, and various value-added products. This paper aims to develop and optimize a mild alkaline treatment of sawdust assisted by ultrasound, along with enzymatic hydrolysis of the pretreated material. The alkaline sonochemical pretreatment emerged as the optimal approach to enhance the susceptibility of cellulose to subsequent enzymatic hydrolysis to improve the yield of reducing sugars. A comparative study was performed using various ultrasonic applicators (horn and bath) and conventional assisted alkaline pretreatment. The ultrasonic-assisted pretreatment revealed a higher delignification of 68% (horn) and 57% (bath) compared with conventional pretreatment. Processes were optimized using a statistical analysis based on a 2³ factorial design. The ratios between sawdust and alkaline solution (R_SL = 0.5–1.5 g/100 mL), US amplitude (A = 20–60%), and working temperature (t = 30–50 °C) were selected as process factors. The optimal operating conditions to maximize the reducing sugar yield (138.15 mg GE/g_substrate) were found as follows: a solid/liquid ratio of R_SL,opt = 1.25 g/100 mL, US amplitude of A_opt = 60%, and pretreatment temperature of t_opt = 50 °C. The overall outcomes clearly confirmed the intensification of delignification by ultrasound-assisted alkaline pretreatment.

This work is focused on the study of the esterification parameters for the ultrasound assisted synthesis of isoamyl acetate catalyzed by lipase Lipozyme 435 in a continuous loop reactor. Investigating the influence of different parameters shows that a higher concentration of ester (462 mg/g mixture) can be obtained at a temperature of 50 °C, flow rate 0.16 mL/min. The best ultrasonication conditions are: sonication applied continuously for a short time (20 min), ultrasound power 32 mW and amplitude 20%. The enzyme can be successfully reused tree times without loss of enzyme activity. Reaction kinetics for isoamyl acetate ultrasound assisted production showed that satisfactory reaction concentration (close to the equilibrium concentrations) could be reached in short reaction times (2 h). Ultrasound assisted enzymatic esterification is consequently a cleaner and a faster process.

In this study, microwave assisted a hydrodistillation process (MWHD) of essential oils from lavender (Lavandula angustifolia Miller) was investigated. In order to examine any potential differences in essential oil extraction, the lavender flowers underwent enzymatic pretreatment. A 2³ factorial design of experiments, combined with statistical methods of data analysis were used to optimize enzymatic pretreatment and to evaluate the influence of major variables (enzyme concentration, temperature and pH) on the performance of the microwave assisted extraction. Under optimal conditions, an extraction yield of 24 mg oil g⁻¹ substrate was achieved (an increase by approximately 25% in comparison with the classic extraction conditions of conventional hydrodistillation). The main compounds of the essential oils obtained were analyzed and identified by gas chromatography coupled to mass spectrometry (GC-MS). Analyzing the data obtained indicated that the content of main compounds (linalool and linalyl acetate − 73%) was greater than that obtained by conventional extraction (67%).

The extraction of essential oils (EOs) and polyphenols from rosemary and thyme has been done using an integrated process: microwave hydro-diffusion and gravity (MHG) for EOs and microwave-assisted extraction (MAE) for polyphenols. The innovative installation based on the MHG principle allows uniform microwave irradiation field due to a mechanical stirring and experiments done at low pressure. The results of quantitative analysis of the EOs extracted by MHG after 10 min were similar with those obtained by traditional methods (conventional hydro-distillation (CHD) and microwave-assisted hydro-distillation (MHD)) after 150 and 105 min, respectively. The specific energy for MHG was 5–15 times lower compared with these classical methods. The MHG extraction of EOs is also an effective method for plant material pretreatment before polyphenol extraction. Total phenolic content increased from 35 to 55 mg GAE/g DM for rosemary and from 23 to 38 mg GAE/g DM for thyme.

The aim of this study was to establish the best ultrasound assisted extraction (UAE) conditions of saponins from Hedera helix L. leaves and to evaluate the in vitro biocompatibility of the extracts richest in saponins. Different parameters, such as extraction time, temperature, ultrasound power, solvent to plant material ratio, and solvent concentration, were investigated. The most efficient extraction conditions were a temperature of 50 °C, an ultrasound amplitude of 40%, an extraction time of 60 min, a plant material to solvent ratio of 1:20 (w:v), and 80% ethanol as solvent. In vitro cytotoxicity of the extracts richest in saponins and their influence on the DNA content of L929 (NCTC) fibroblasts were tested. Until 200 µg/mL, the studied extracts were cytocompatible with L929 fibroblast cell lines at 48 h of treatment. These in vitro cell culture results provide useful information for further applications of Hedera helix extracts in a pharmaceutical field.