The electrochemical behaviour of the flavonoid naringenin (NGN) was investigated for the first time by cyclic voltammetry (CV), using a disposable electroactivated pencil graphite electrode (PGE*). In this electrochemical sensor, NGN is irreversibly oxidized, giving rise to two pH-dependent peaks due to mixed (diffusion- and adsorption-controlled) electrode processes involving the same number of electrons and protons, namely two and one, respectively. Exploiting these peaks, differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at PGE* in 0.05 mol L⁻¹ potassium hydrogen phthalate were applied for quantitative determination of NGN. The new proposed methods presented linear ranges covering more than three orders of magnitude (7.86 × 10⁻⁸ to 1.82 × 10⁻⁴ mol L⁻¹ NGN for DPV and 7.50 × 10⁻⁸ to 1.00 × 10⁻⁴ mol L⁻¹ NGN for SWV) and low limits of detection (LoD) and quantification (LoQ) (LoD = 3.06 × 10⁻⁸ mol L⁻¹, LoQ = 1.02 × 10⁻⁷ mol L⁻¹ NGN for DPV and LoD = 4.40 × 10⁻⁸ mol L⁻¹, LoQ = 1.11 × 10⁻⁷ mol L⁻¹ NGN for SWV), similar to or better than those reported in the literature. The developed voltammetric methods were applied with good results to determine the intermediate antioxidant power polyphenolics content expressed as mg naringenin equivalent per L grapefruit juice.

The present study evaluated three green extraction methods, accelerated solvent extraction (ASE), ultrasound-assisted extraction (UAE), and laser irradiation extraction (LE), for the polyphenolic compounds and vitamin C extraction of Cornus mas L. and Crataegus monogyna fruit extracts. The polyphenols and vitamin C of extracts were quantified using HPLC-DAD, and the total phenolic content, flavonoid content, antioxidant activity (DPPH and reducing power), and antidiabetic activity were also studied. The antidiabetic activity was examined by the inhibition of α-amylase and α-glucosidase, and in vitro on a beta TC cell line (β-TC-6). The results showed significant differentiation in the extraction yield between the methods used, with the ASE and LE presenting the highest values. The C. mas fruit extract obtained by ASE exhibited the best antioxidant activity, reaching an IC₅₀ value of 31.82 ± 0.10 µg/mL in the DPPH assay and 33.95 ± 0.20 µg/mL in the reducing power assay. The C. mas fruit extracts obtained by ASE and LE also have the highest inhibitory activity on enzymes associated with metabolic disorders: α-amylase (IC₅₀ = 0.44 ± 0.02 µg/mL for the extract obtained by ASE, and 0.11 ± 0.01 µg/mL for the extract obtained by LE at combined wavelengths of 1270 + 1550 nm) and α-glucosidase (IC₅₀ of 77.1 ± 3.1 µg/mL for the extract obtained by ASE, and 98.2 ± 4.7 µg/mL for the extract obtained by LE at combined wavelengths of 1270 + 1550 nm). The evaluation of in vitro antidiabetic activity demonstrated that the treatment with C. mas and C. monogyna fruit extracts obtained using ASE stimulated the insulin secretion of β-TC-6 cells, both under normal conditions and hyperglycemic conditions, as well. All results suggest that C. mas and C. monogyna fruit extracts are good sources of bioactive molecules with antioxidant and antidiabetic activity.

The purpose of this study was to extract the lipophilic fraction from one of the largest source of waste in the industrial sector, namely, the tomato residue from processing the fruit. In order to make this process more environmentally sustainable, this study used a green extraction protocol employing natural deep eutectic solvents (NADESs) combined with a less energy-consuming technology, the ultrasound-assisted extraction (UAE) method, to simultaneously recover carotenoids and tocopherol from dried powder tomato waste. Two NADESs, one hydrophilic and one hydrophobic, were prepared and compared to support high extraction efficiency and increase the stability of the extracted compounds. The optimal extraction parameters were identified as choline chloride:1,3-butanediol (1:5)-based NADES, a solid-to-liquid ratio of 1:20 (w/v), time of extraction 12 min, temperature 65 °C, radiation frequency 37 Hz, and an ultrasound power level of 70%. The extraction process was intensified and resulted in extracts rich in lycopene (215.13 ± 4.31 μg/g DW), β-carotene (206.95 ± 3.27 μg/g DW), and tocopherol (130.86 ± 8.97 μg/g DW) content, with the highest antioxidant capacity 93.84 ± 0.18 mM Trolox equivalent. Incorporating NADESs for the extraction of bioactive compounds offers numerous benefits, such as improved sustainability, enhanced extraction efficiency, better protection of sensitive compounds, and reduced environmental impact. These advantages make NADESs a promising alternative to traditional organic solvents, especially in industries that require natural, green, and efficient extraction processes for valuable bioactive molecules.

The present study evaluated the antioxidant and antidiabetic properties of Medicago sativa and Solidago virgaurea extracts enriched in polyphenolic compounds. The extracts were obtained by accelerated solvent extraction (ASE) and laser irradiation. Then, microfiltration was used for purification, followed by nanofiltration used to concentrate the two extracts. The obtained extracts were analyzed to determine their antioxidant activity using DPPH radical scavenging and reducing power methods. The antidiabetic properties have been investigated in vitro on a murine insulinoma cell line (β-TC-6) by the inhibition of α-amylase and α-glucosidase. M. sativa obtained by laser irradiation and concentrated by nanofiltration showed the highest DPPH• scavenging (EC₅₀ = 105.2 ± 1.1 µg/mL) and reducing power activities (EC₅₀ = 40.98 ± 0.2 µg/mL). M. sativa extracts had higher inhibition on α-amylase (IC₅₀ = 23.9 ± 1.2 µg/mL for concentrated extract obtained after ASE, and 26.8 ± 1.1), while S. virgaurea had the highest α-glucosidase inhibition (9.3 ± 0.9 µg/mL for concentrated extract obtained after ASE, and 8.6 ± 0.7 µg/mL for concentrated extract obtained after laser extraction). The obtained results after evaluating in vitro the antidiabetic activity showed that the treatment with M. sativa and S. virgaurea polyphenolic-rich extracts stimulated the insulin secretion of β-TC-6 cells, both under normal conditions and under hyperglycemic conditions as well. This paper argues that M. sativa and S. virgaurea polyphenolic-rich extracts could be excellent natural sources with promising antidiabetic potential.

Until recently, the main antioxidant role among wine constituents was attributed to polyphenolic compounds, but once the presence of melatonin in wines was confirmed, an interesting new field of research opened up due to its possible synergistic effects with other antioxidants in the winemaking process, which may lead to a change in the profile of polyphenolic compounds and antioxidant activity. In order to investigate the evolution of active principles from the phenylpropanoid metabolism associated with the synergistic effects of melatonin, for the first time, a melatonin treatment was performed in the pre-stage of the different winemaking processes of Feteasca Neagra and Cabernet Sauvignon wines with different melatonin concentrations. After comparing the acquired results for the evolution of the polyphenolic compound profile and antioxidant activity of treated wines, we ascertained an increase in the antioxidant compound concentrations, especially in resveratrol, quercetin, and cyanidin-3-glucoside, directly proportional to the used melatonin concentration; an intensification in activity of PAL and C4H enzymes; and the modification in the expression of specific anthocyanin biosynthesis genes, especially UDP-D-glucose-flavonoid-3-O-glycosyltransferase. It was also shown that the application of melatonin in the pre-stage of the winemaking process can be successfully used to obtain red wines with increased antioxidant activity (almost 14%).

The extraction of bio-compounds from medicinal plants provides opportunities for using the plant extract for health benefits. Rosa canina L. is considered a “natural superfood”, and the valorization of its active compounds requires an extraction technique that ensures a suitable extraction yield while preserving the compounds’ activity. In our study, infrared laser irradiation (IRLIR) technology was used for the first time in the bioactive compound’s extraction from Rosa canina L. Different solvents (water–ethanol, hexane–ethanol) and different extraction times were tested to obtain a high extraction yield. Chromatographic and spectrophotometry methods were used to monitor the profile of bioactive compounds and the antioxidant activity of the extracts. The results obtained for IRLIR were compared with those obtained by accelerated solvent extraction (ASE), an advanced extraction method. The IRLIR technology proved to be a more reliable analytical tool for the extraction of (+)-catechin, gallic acid, and lutein. In addition, a richer extract formula was obtained by IRLIR extraction with respect to ASE, with the IRLIR process ensuring a short extraction time, low volume of the extraction solvent, low energy consumption, and a less expensive device.