Nowadays, medicinal plants, and fruits and vegetables with antioxidant and antimicrobial activity are increasingly studied. In this review, the impact of the medicinal plant extracts on the immune system was discussed. The first part described the phenomenon of oxidative stress, followed by the mechanisms involved in the antioxidant activity and finally discussed on the evaluation of the antioxidant activity of plants and fruits. The second part revised the works that discuss about the antimicrobial activity of plants and fruits extracts, emphasizing in the factors that influence the evaluation of such characteristic. Finally, in the third part, studies on the effect of the plant extracts over the immune response were discussed, describing the results of the enhancer effects, as well as those of the suppressing ones. This work allowed us to discern the necessity of a wider research on the chemical composition of the natural extracts, in order to establish a correlation with the effects observed in health.

Festuca arundinacea Schreb. is a widely used type of forage due to its great ecological breadth and adaptability. An agricultural intervention that improves the selenium content in cultivated plants has been defined as bio-fortification, a complementary strategy to improve human and non-human animals’ nutrition. The advancement of science has led to an increased number of studies based on nanotechnologies, such as the development of nanoparticles (NPs) and their application in crop plants. Studies show that NPs have different physicochemical properties compared to bulk materials. The objectives of this study were (1) to determine the behavior of F. arundinacea Schreb. plants cultivated with Se nanoparticles, (2) to identify the specific behavior of the agronomic and productive variables of the F. arundinacea Schreb. plants, and (3) to quantify the production and quality of the forage produced from the plant (the bioactive compounds’ concentrations, antioxidant activity, and the concentration of selenium). Three different treatments of SeNPs were established (0, 1.5, 3.0, and 4.5 mg/mL). The effects of a foliar fertilization with SeNPs on the morphological parameters such as the root size, plant height, and biomass production were recorded, as well as the effects on the physicochemical parameters such as the crude protein (CP), lipids (L), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), carbohydrates (CH), the content of total phenols, total flavonoids, tannins, quantification of selenium and antioxidant activity 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Significant differences (p < 0.05) were found between treatments in all the response variables. The best results were obtained with foliar application treatments with 3.0 and 4.5 mg/mL with respect to the root size (12.79 and 15.59 cm) and plant height (26.18 and 29.34 cm). The F. arundinacea Schreb. plants fertilized with 4.5 mg/L had selenium contents of 0.3215, 0.3191, and 0.3218 mg/Kg MS; total phenols of 249.56, 280.02, and 274 mg EAG/100 g DM; and total flavonoids of 63.56, 64.96, and 61.16 mg QE/100 g DM. The foliar biofortified treatment with a concentration of 4.5 mg/mL Se NPs had the highest antioxidant capacities (284.26, 278.35, and 289.96 mg/AAE/100 g).

The objective of the present work was to optimize the extraction of phytochemicals from Hamelia patens Jacq. by ultrasound-assisted extraction. Taguchi L9 orthogonal array was used to evaluate the factors solid/liquid ratio (1:8, 1:12, and 1:16), extraction time (10, 20, and 30 min), and ethanol concentration (0, 35, and 70%). Total polyphenols were the response variable. Chromatographic fractionation using Amberlite XAD-16 was carried out and the total polyphenols, flavonoids, and condensed tannins were quantified. The redox potential, the reduction of the 2,2-diphenyl-1-picrylhydrazyl (DPPH), and the lipid oxidation inhibition were determined. Anti-bacterial activity was evaluated. The phytochemicals were identified by liquid chromatography coupled to mass spectrometry. Optimal extraction conditions were a solid/liquid ratio of 1:16, ethanol of 35%, and 10 min of ultrasound-assisted extraction. Maximum polyphenol content in the crude extract was 1689.976 ± 86.430 mg of gallic acid equivalents (GAE)/100 g of dried plant material. The purified fraction showed a total polyphenols content of 3552.84 ± 7.25 mg of GAE, flavonoids 1316.17 ± 0.27 mg of catechin equivalents, and condensed tannins 1694.87 ± 22.21 mg of procyanidin B1 equivalents, all per 100 g of purified fraction. Its redox potential was 553.93 ± 1.22 mV, reducing 63.08 ± 0.42% of DPPH radical and inhibiting 77.78 ± 2.78% of lipid oxidation. The polyphenols demonstrated antibacterial activity against Escherichia coli, Klebsiella pneumonia, and Enterococcus faecalis. The HPLC-ESI-MS analysis revealed the presence of coumarins, hydroxycinnamic acids, and flavonoids.

This study was aimed at evaluating the effect of a nanoemulsion containing the bioactive compounds of orange essential oil and xoconostle (Opuntia oligacantha C.F. Först) on maintaining and improving the quality of the shelf life of tomato fruits. The nanoemulsion was applied as a coating on the whole fruits during physiological maturity; the treatments were thus: Control 1 without coating (C1); Control 2 with food-grade mineral oil coating (C2); and nanoemulsions that were diluted with mineral oil at 2.5% (DN2.5), 5% (DN5), 10% (DN10), and 20% (DN20). Further, the following parameters were determined for 21 days: the percentage weight loss, firmness, colour, pH, titratable acidity, total soluble solids, ascorbic acid content, total phenols, flavonoids, tannins, antioxidant activities DPPH and ABTS, and the histological evaluation of the pericarp of the fruits. Significant differences (p < 0.05) were observed during the treatments; DN10 and DN20 obtained the best weight loss results (3.27 ± 0.31% and 3.71 ± 0.30%, respectively) compared with C1 and C2. The DN5 and DN20 textures exhibited the highest firmness (11.56 ± 0.33 and 11.89 ± 1.04 N, respectively). The antioxidant activity (DPPH on Day 21) was higher in the DN20 treatment (48.19 ± 0.95%) compared with in C1 (39.52 ± 0.30%) and C2 (38.14 ± 0.76%). Histological evaluation revealed that the nanoemulsion coating allowed a slower maturation of the cells in the pericarp of the fruits. The nanoemulsion, as a coat, improved the quality and valuable life of the tomato regarding its physicochemical and antioxidant properties, thus availing an effective alternative for conserving this fruit.

The need for encapsulation processes in compounds such as procyanidins (PCs) is related to their functional stability, which may limit their application in functional foods. The aim of this study was to evaluate the in vitro digestion of microencapsulated PCs from litchi peel and coffee pulp to determine concentration changes and antioxidant activity. The PCs were extracted, purified, encapsulated, and subjected to in vitro digestion and absorption. Phenolic acids, flavonoids, and PCs were characterized by UPLC-PDA-ESI-QqQ, identifying 27 compounds, including PCs with mean degrees of polymerization (mDP) of 1.2 and 1.7 for lychee and coffee. It was shown that the concentrations of encapsulated PCs were adequately retained during digestion (94.81 ± 4.83 and 90.74 ± 1.77%, lychee and coffee, respectively), with variation in their antioxidant capacity (68.33 ± 2.89 and 77.07 ± 4.59%); however, they showed better results than in their free form. Additionally, litchi PCs showed a higher absorption rate (100%) than coffee PCs (60%). These results allowed us to determine that encapsulation preserves the properties of the PCs and provides better conservation percentages than other studies, which could be a valuable addition to the functional ingredients market, offering greater value to these by-products.