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Maize is one of the most important crops for human and animal consumption and contains a chemical arsenal essential for survival: flavonoids. Moreover, flavonoids are well known for their beneficial effects on human health. In this review, we decided to organize the information about maize flavonoids into three sections. In the first section, we include updated information about the enzymatic pathway of maize flavonoids. We describe a total of twenty-one genes for the flavonoid pathway of maize. The first three genes participate in the general phenylpropanoid pathway. Four genes are common biosynthetic early genes for flavonoids, and fourteen are specific genes for the flavonoid subgroups, the anthocyanins, and flavone C-glycosides. The second section explains the tissue accumulation and regulation of flavonoids by environmental factors affecting the expression of the MYB-bHLH-WD40 (MBW) transcriptional complex. The study of transcription factors of the MBW complex is fundamental for understanding how the flavonoid profiles generate a palette of colors in the plant tissues. Finally, we also include an update of the biological activities of C3G, the major maize anthocyanin, including anticancer, antidiabetic, and antioxidant effects, among others. This review intends to disclose and integrate the existing knowledge regarding maize flavonoid pigmentation and its relevance in the human health sector.

Metabolomics is gaining consideration as a viable approach to diseases detection and even shows promising results in COVID-19 diagnosis. This work extends the study of the relationship between extractable sweat compounds and COVID-19 positive patients. Sweat samples were collected from 426 patients (126 positives and 300 negatives) recruited at Merida and Progreso (Yucatán, México) health centers. The composition of sweat was analyzed with a solid phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS) method. The PLS-DA, with specificity and sensitivity percentages greater than 80%, revealed significant differences between the DI-SPME profiles of infected and non-infected patients. Six key peaks used in the classification model were annotated as undecanal, methyl palmitoleate, palmitic acid, methyl oleate, squalene, and methyl cerotate, based on NIST17 spectral matches (> 90%) and interpretation aided by retention index (RI) data. Palmitic acid and Methyl oleate signals were elevated in COVID-positive patients,while undecanal, methyl palmitoleate, squalene and methyl cerotate were detected in lower amounts in COVID-positive patients. The identified set of compounds may serve as potential biomarkers for COVID-19 disease, not only in serologic assessments but also in the development of non-invasive diagnostic approaches, such as sweat-based or volatilome-based testing, as well as for monitoring disease progression and patient recovery.

Consistent with their reported abundance in soils, several Burkholderia sensu lato strains were isolated from the rhizosphere of maize plants cultivated at different sites in central México. Comparative analysis of their 16S rRNA gene sequences permitted their separation into three distinctive clades, which were further subdivided into six other clusters by their close resemblance to (1) Trinickia dinghuensis; (2) Paraburkholderia kirstenboschensis, P. graminis, P. dilworthii and P. rhynchosiae; (3) B. gladioli; (4) B. arboris; (5) B. contaminans, or (6) B. metallica representative species. Direct confrontation assays revealed that these strains inhibited the growth of pathogenic Fusarium oxysporum f. sp. radicis-lycopersici, and F. verticillioides within a roughly 3–55% inhibition range. The use of a DIESI-based non-targeted mass spectroscopy experimental strategy further indicated that this method is an option for rapid determination of the pathogen inhibitory capacity of Burkholderia sensu lato strains based solely on the analysis of their exometabolome. Furthermore, it showed that the highest anti-fungal activity observed in B. contaminans and B. arboris was associated with a distinctive abundance of certain m/z ions, some of which were identified as components of the ornbactin and pyochelin siderophores. These results highlight the chemical diversity of Burkholderia sensu lato bacteria and suggest that their capacity to inhibit the Fusarium-related infection of maize in suppressive soils is associated with siderophore synthesis.

Siderophores are iron-chelating secondary metabolites that can effectively control fungal diseases in several agronomically important crops. In the present study, the bacterium Burkholderia contaminans MSR2 was found to profusely accumulate siderophores when grown under iron-limiting conditions. Therefore, subsequent experimental procedures were performed to determine whether the siderophore-rich supernatants of B. contaminans MSR2 were effective against anthracnose disease caused by Colletotrichum gloeosporioides in post-harvest avocado fruits. Dual culture assays performed in vitro showed that B. contaminans MSR2 produced an approximate 25% reduction in the radial mycelial growth of C. gloeosporioides . Moreover, cell-free supernatants (CFSs) with a siderophore concentration of 58.08 mM deferoxamine mesylate equivalent caused a 78% reduction of C. gloeosporioides growth under in vitro conditions. In avocado fruits, siderophore-rich CFSs significantly reduced the severity and incidence of post-harvest anthracnose disease, similar to the effect produced by the Captan 4L fungicide (2-(trichloromethylsulfanyl)-3a,4,7,7a-tetrahydroisoindole-1,3-dione) at 2 g/L. Untargeted metabolomic analyses of B. contaminans CFSs obtained under iron-limited conditions revealed the predominant accumulation of the ornibactin C8 and pyochelin siderophores, in addition to numerous other antimicrobial compounds, including secondary siderophores and further biological compounds known to have fungitoxic activity. These results support the proposal that siderophore-rich bioactive CFSs from B. contaminans MSR2 can be effectively employed for biological control of post-harvest anthracnose in avocado fruits. Key points • B. contaminans MSR2 cell-free supernatants (CFSs) inhibited C. gloeosporioides’growth. • CFSs and Captan similarly reduced post-harvest anthracnose damage in avocado fruits. • Pyochelin, pyochelin-like, ornibactin C8, and tetrapeptide siderophores were prominent anti-anthracnose CFSs.

The massive arrival of Sargassum biomass on the Caribbean coast is a potential raw material source that needs an assessment of its quality and preservation state. Thus, the present study aimed to investigate how pelagic Sargassum changes its chemical composition due to sample transportation, morphotype ( S. natans  I,  S. natans  VIII, and  S. fluitans  III), and exposure to open-air conditions during two months of outdoor conditions using Fourier Transform Infra-Red (IR) spectroscopy and chemometric analysis. The results demonstrate that cold transportation to the lab before flash-freezing caused sample degradation, characterized by mannitol consumption and the formation of anaerobic metabolism products. Multivariate analyses showed that the IR spectral zone with differences between S. natans and S. fluitans were in the same IR spectral regions related to sample degradation. In the two flash-freezing treatments, S. fluitans had the highest IR peak absorbance of mannitol and a lower absorbance for the carboxylic acids IR peak. Between S. natans morphotypes, S. natans I had the highest modification caused by the cold transportation to the lab. The decomposition under prolonged time (up to eight weeks) in open-air conditions demonstrated an increased absorbance on the IR bands of carboxylic acids in the first four weeks. In the sixth and eighth weeks, the IR signals of calcium carbonate increased more than those from organic matter. This study provides a better understanding of the importance of preserving the collected samples and how the decomposition dynamics of Sargassum species may impact the extraction of key compounds, e.g., alginate and mannitol.

Different maize (Zea mays L.) varieties have been used for thousands of years as a healthy food source in Mesoamerica including pigmented maize. Maize ingestion could contribute to the reduction in the rate of non-communicable diseases and, in turn, to its function as an adjuvant in their management. These diseases are mainly associated with oxidative stress, which is characterized by a redox cell imbalance produced due to pro-oxidant molecules accumulation, inducing irreversible damages. Although the endogenous antioxidant defense system is efficient, exogenous antioxidants are necessary to help to prevent this damage. Bioactive compounds, like anthocyanins, contained in dietary plants exert a major activity against oxidative stress. Could the maize anthocyanins play a curative, preventive or complementary role in the treatment of chronic diseases? Here, we describe the occurrence of anthocyanins from pigmented maize and their chemical structures. Furthermore, the biosynthesis, bioavailability, and stability are also summarized. Finally, many in vitro and in vivo studies of maize anthocyanins are discussed that demonstrated their nutraceutical potential, antioxidant capacity, and other biological effects. Given the importance of the biological properties of maize anthocyanins, it is necessary to understand the current knowledge and propose further research or clinical studies which allows us to better elucidate the biological mechanism of maize anthocyanins derivatives of several varieties and processes of cooking and combination with other ingredients to enhance their nutritional and health benefits.