The application of green methods in the synthesis of nanoparticles using plants is a cost-effective and eco-friendly approach. Zinc oxide nanoparticles are of great importance due to their versatile properties. The conditions of synthesis strongly influence the characteristics and functionality of the nanoparticles. The present work studied the biological, green synthesis of zinc oxide nanoparticles (ZnONPs) in the presence of different concentrations of ethanolic extract of Larrea tridentata (10, 20, and 30 mg/mL). The time of the formation of nanoparticles was evaluated at different temperatures and pH values of the reaction medium. The formation of ZnONPs was confirmed by ultraviolet-visible (UV-Vis) and Fourier transform infrared spectroscopies (FT-IR), as well as scanning electron microscopy (SEM). X-ray diffraction analysis (XDR) determined the crystallographic structure of the nanoparticles. Obtained ZnONPs had a size range of 18 to 40 nm. The temperature, reaction time, and pH significantly influenced the nanoparticles’ morphology, size, and aggregation. The impact of chosen ZnONPs was tested on the germination of serrano chili seeds (Capsicum annuum). At 100 ppm, the nanoparticles improved germination percentage, vigor, and seedlings’ growth parameters.

Zinc oxide nanoparticles have gained attention in the last decades due to their versatile applications; in agriculture, they have been used for their multiple benefits. In this study, the effects of zinc oxide nanoparticles, obtained via chemical and biological synthesis and of 70–80 nm in size, on the germination and seedling growth of Capsicum annuum and Solanum lycopersicum seed were determined. The physiological parameters, photosynthetic pigments, the content of total phenols, total flavonoids, as well as the antioxidant capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH), and the enzymatic activity of catalase, peroxidase, and polyphenol oxidase were evaluated. The results indicated that treatment with zinc oxide nanoparticles obtained via green synthesis improved seed germination rate, while chemically synthesized nanoparticles at higher concentrations decreased germination percentage. In general, the parameters of enzymatic and nonenzymatic antioxidants in treated plants showed significant differences with respect to the control. However, the treatments with the bionanoparticles resulted in more beneficial parameters. Zinc oxide nanoparticles obtained via green synthesis are more effective in generating bioactive compounds and activating the enzyme defense system due to being more biocompatible.

The medicinal plants of the desert can be a potential source of natural bioactive compounds with applications in health and food preservation. This work aimed to investigate the phenolic content and antioxidant potential of twenty-three plants from the arid zone of Viesca, Mexico. The antioxidant potential was determined by three methods (ABTS, FRAP, and DPPH). Two extraction methods and three different concentration levels (1:10 mg/mL, 1:25 mg/mL, and 1:50 mg/mL) were evaluated. According to the results, Turnera diffusa (Damiana), Gutierrezia sarothrae (Hierba de San Nicolas), and Leucophyllum frutescens (Cenizo) present the largest content of phenolic compounds and high antioxidant activity. The highest values of antioxidant activity were achieved using a solid/liquid ratio of 1:50 g/mL for T. diffusa and G. sarothrae and 1:25 mg/mL for L. frutescens. The maceration method was the most suitable for extracting antioxidant compounds from T. diffusa and L. frutescens, while ultrasound-assisted extraction was more efficient for G. sarothrae. The HPLC-MS analysis showed the presence of important phenolic compounds. This study shows for the first time that three plants that naturally grow in Viesca have great potential as a source of natural antioxidant compounds.

Background: The immune system is able to recognize substances that originate from inside or outside the body and are potentially harmful. Foreign substances that bind to immune system components exhibit antigenicity and are defined as antigens. The antigens exhibiting immunogenicity can induce innate or adaptive immune responses and give rise to humoral or cell-mediated immunity. The antigens exhibiting mitogenicity can cross-link cell membrane receptors on B and T lymphocytes leading to cell proliferation. All antigens vary greatly in physicochemical features such as biochemical nature, structural complexity, molecular size, foreignness, solubility, and so on. Objective:: Thus, this review aims to describe the molecular bases of protein-antigenicity and those molecular bases that lead to an immune response, lymphocyte proliferation, or unresponsiveness. Conclusion: The epitopes of an antigen are located in surface areas; they are about 880-3,300 Da in size. They are protein, carbohydrate, or lipid in nature. Soluble antigens are smaller than 1 nm and are endocytosed less efficiently than particulate antigens. The more the structural complexity of an antigen increases, the more the antigenicity increases due to the number and variety of epitopes. The smallest immunogens are about 4,000-10,000 Da in size. The more phylogenetically distant immunogens are from the immunogen-recipient, the more immunogenicity increases. Antigens that are immunogens can trigger an innate or adaptive immune response. The innate response is induced by antigens that are pathogen-associated molecular patterns. Exogenous antigens, T Dependent or T Independent, induce humoral immunogenicity. TD protein-antigens require two epitopes, one sequential and one conformational to induce antibodies, whereas, TI non-protein-antigens require only one conformational epitope to induce low-affinity antibodies. Endogenous protein antigens require only one sequential epitope to induce cell-mediated immunogenicity.

Biofortification is the process of developing a crop with bioavailable micronutrients in its edible parts. This has been done using nanofertilizers, since they can be used to feed plants in a gradual and controlled manner. Therefore, the aim of this work was to evaluate the effect of foliar application of ZnO NPs in different concentrations on the commercial and phytochemical quality of the basil (Ocimum basilicum L.) crop, as it is one of the most important aromatic plants used for chemical and pharmacological properties. Four concentrations of ZnO NPs (5, 10, 15 and 20 mg L^-1) and a control treatment under a completely randomized design, were evaluated. The results show statistical differences in morphological parameters (leaf and stem fresh weight, height, number of leaves, leaf area and dry weight) with a slight tendency to increase on the treated basil plants mainly at concentration of 20 mg L^-1. The highest chlorophyll content (5.54 µg g^-1 FW) was obtained for the control treatment, whereas the lowest one (4.14 µg g^-1 FW) was observed for the 20 mg L^-1 treatment. However, carotenoid content in the leaves was markedly higher than the control, the control had the concentration of 0.84 µg g^-1 FW, while the treatment with 20 mg L^-1 ZnO NPs registered a value of 1.08 µg g^-1 FW. The highest total phenolic, flavonoid, antioxidant capacity and vitamin C content was obtained for 20 mg L^-1 ZnO NPs. Finally, basil plants treated with ZnO NPs could stimulate enzymatic activity, as demonstrated in this study. Detailed studies are suggested to understand the mechanism of action of nanoscale materials.