Natural compounds have diverse structures and are present in different forms of life. Metabolites such as tannins, anthocyanins, and alkaloids, among others, serve as a defense mechanism in live organisms and are undoubtedly compounds of interest for the food, cosmetic, and pharmaceutical industries. Plants, bacteria, and insects represent sources of biomolecules with diverse activities, which are in many cases poorly studied. To use these molecules for different applications, it is essential to know their structure, concentrations, and biological activity potential. In vitro techniques that evaluate the biological activity of the molecules of interest have been developed since the 1950s. Currently, different methodologies have emerged to overcome some of the limitations of these traditional techniques, mainly via reductions in time and costs. These emerging technologies continue to appear due to the urgent need to expand the analysis capacity of a growing number of reported biomolecules. This review presents an updated summary of the conventional and relevant methods to evaluate the natural compounds’ biological activity in vitro.

The rise of antimicrobial resistance caused by inappropriate use of these agents in various settings has become a global health threat. Nanotechnology offers the potential for the synthesis of nanoparticles (NPs) with antimicrobial activity, such as iron oxide nanoparticles (IONPs). The use of IONPs is a promising way to overcome antimicrobial resistance or pathogenicity because of their ability to interact with several biological molecules and to inhibit microbial growth. In this review, we outline the pivotal findings over the past decade concerning methods for the green synthesis of IONPs using bacteria, fungi, plants, and organic waste. Subsequently, we delve into the primary challenges encountered in green synthesis utilizing diverse organisms and organic materials. Furthermore, we compile the most common methods employed for the characterization of these IONPs. To conclude, we highlight the applications of these IONPs as promising antibacterial, antifungal, antiparasitic, and antiviral agents.

Natural extracts have been and continue to be used to treat a wide range of medical conditions, from infectious diseases to cancer, based on their convenience and therapeutic potential. Natural products derived from microbes, plants, and animals offer a broad variety of molecules and chemical compounds. Natural products are not only one of the most important sources for innovative drug development for animal and human health, but they are also an inspiration for synthetic biology and chemistry scientists towards the discovery of new bioactive compounds and pharmaceuticals. This is particularly relevant in the current context, where antimicrobial resistance has risen as a global health problem. Thus, efforts are being directed toward studying natural compounds’ chemical composition and bioactive potential to generate drugs with better efficacy and lower toxicity than existing molecules. Currently, a wide range of methodologies are used to analyze the in vitro activity of natural extracts to determine their suitability as antimicrobial agents. Despite traditional technologies being the most employed, technological advances have contributed to the implementation of methods able to circumvent issues related to analysis capacity, time, sensitivity, and reproducibility. This review produces an updated analysis of the conventional and current methods to evaluate the antimicrobial activity of natural compounds.

Background: This review investigates the impact of bioactive molecules produced by probiotics on child health, focusing on their roles in modulating gut microbiota, enhancing immune function, and supporting overall development. Key metabolites, including short-chain fatty acids (SCFAs), bacteriocins, exopolysaccharides (EPSs), vitamins, and gamma-aminobutyric acid (GABA), are highlighted for their ability to maintain gut health, regulate inflammation, and support neurodevelopment. Objectives: The aim of this review is to examine the mechanisms of action and clinical evidence supporting the use of probiotics and postbiotics in pediatric healthcare, with a focus on promoting optimal growth, development, and overall health in children. Methods: The review synthesizes findings from clinical studies that investigate the effects of probiotics and their metabolites on pediatric health. The focus is on specific probiotics and their ability to influence gut health, immune responses, and developmental outcomes. Results: Clinical studies demonstrate that specific probiotics and their metabolites can reduce gastrointestinal disorders, enhance immune responses, and decrease the incidence of allergies and respiratory infections in pediatric populations. Additionally, postbiotics—bioactive compounds from probiotic fermentation—offer promising benefits, such as improved gut barrier function, reduced inflammation, and enhanced nutrient absorption, while presenting fewer safety concerns compared to live probiotics. Conclusions: By examining the mechanisms of action and clinical evidence, this review underscores the potential of integrating probiotics and postbiotics into pediatric healthcare strategies to promote optimal growth, development, and overall health in children.

Natural compounds have diverse structures and are present in different forms of life. Metabolites such as tannins, anthocyanins, and alkaloids, among others, serve as a defense mechanism in live organisms and are undoubtedly compounds of interest for the food, cosmetic and pharmaceutical industries. Plants, bacteria, and insects represent a source of biomolecules with diverse activities, poorly studied in many cases. To use these molecules for different applications, it is essential to know their structure, concentrations, and biological activity potential. In vitro techniques that evaluate the biological activity of the molecules of interest have been developed since the 1950s. Currently, different methodologies have emerged to overcome some of the limitations of these traditional techniques, mainly the reduction of time and costs. However, emerging technologies continue to appear due to the urgent need to expand the analysis capacity of a growing number of reported biomolecules and the lack of therapeutic options to treat various diseases. This review presents an updated summary of the conventional and current methods to evaluate natural compounds' biological activity, including a diagram that summarizes the minimum techniques essential for correctly assessing molecules with biological potential.

Edible flowers have been used since ancient times, but their potential for improving human health has not been explored. This study aimed to evaluate the profile of bioactive compounds (organic acids, phenolics, and carotenoids) and the antioxidant and antimicrobial activity of nine flower varieties with high concentrations of carotenoids or total phenolic compounds. Ninety-three edible flowers were analysed for physicochemical characteristics, total phenolic and carotenoid concentrations, and antioxidant activity (ABTS). Bioactive profiles were determined by rapid resolution liquid chromatography (RRLC), and antimicrobial activity was determined against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus mutans, and Candida albicans and Candida tropicalis. Chrysanthemum x hybrid orange, Helianthus annuus yellow, Tagetes patula orange, Canna indica red, and Hibiscus rosa-sinensis (orange1 and yellow) showed significant concentrations of total carotenoids. In contrast, Pelargonium hortorum orange2, Hibiscus rosa-sinensis red1, and Rosa x hybrid variety medium yellow showed high levels of total phenolics. The predominant compounds in these species were citric acid (991.4 mg/g DW in Hibiscus rosa-sinensis red1), 4-hydroxybenzoic acid (936.2 mg/100 g DW in P. hortorum orange2), kaempferol (971. 9 mg/100 g DW in T. patula orange), quercetin glucoside (958.8 in C. x hybrid), quercetin (919.3 mg/100 g DW in T. patula), α-carotene, and β-carotene in T. patula orange (989.5 and 601.2 mg/100 g DW, respectively). Regarding antimicrobial activity, T. patula orange and P. hortorum orange2 inhibited bacterial growth, while C. x hybrid orange and P. hortorum orange2 inhibited Candida albicans, and the latter inhibited Candida tropicalis. These results indicate the potential of edible flowers as a natural source of bioactive compounds and as a tool in the fight against antimicrobial resistance.