Antifungal compounds from the root and root exudate of Zea mays

Zeaamine, a new amine from roots of Zea mays and its cytotoxic activity against CT26 and SW480 cell lines

A new amine, zeaamine (1), along with nine known compounds (2-10), were isolated from the roots of Zea mays. Among these, compound 2 was first isolated from this plant, and compound 3 was first isolated from the roots. In the current investigation, the cytotoxicity against CT26 and SW480 cells of the compounds were evaluated. Zeaamine (1) exhibited moderately affected CT26 and SW480 cells with IC50 values of 17.91 and 10.21 µM.

Two New Alkaloids from Roots of Zea mays and Their Cytotoxic Activity against Hep3B and SW480 Cells

Two undescribed alkaloids, along with seven known compounds, were isolated from the roots of Zea mays (RM). Their chemical structures were elucidated based on extensive analyses of HR-ESI-MS, 1D and 2D NMR, and CD spectra. Two new alkaloids exhibited moderate inhibition of Hep3B (IC50 values of 11.7±2.4 and 14.2±3.6 μM) and SW480 cells (IC50 values of 33.4±8.2 and 47.3±5.8 μM) compared to that of the positive control compound, Oxaliplatin, IC50 value of 8.4±1.7 and 45.8±5.6 μM, respectively.

By-Products of Zea mays L.: A Promising Source of Medicinal Properties with Phytochemistry and Pharmacological Activities: A Comprehensive Review

Zea mays (Z. mays) is one of the main cereal crops in the world, and it's by-products have exhibited medicinal properties to explore. This article intends to review the chemical compositions and pharmacological activities of by-products of Z. mays (corn silks, roots, bract, stems, bran, and leaves) which support the therapeutic potential in the treatment of different diseases, with emphasis on the natural occurring compounds and detailed pharmacological developments. Based on this review, 231 natural compounds are presented. Among them, flavonoids, terpenes, phenylpropanoids, and alkaloids are the most frequently reported. The by-products of Z. mays possess diuretic effects, hepatoprotective, anti-diabetic, antioxidant, neuroprotective, anti-inflammatory, anti-cancer, plant protection activity, and other activities. This article reviewed the phytochemistry and pharmacological activities of Z. mays for comprehensive quality control and the safety and effectiveness to enhance future application.

Structurally diverse specialized metabolites of maize and their extensive biological functions

Maize originated in southern Mexico and various hybrid varieties have been bred during domestication. All maize tissues are rich in specialized plant metabolites (SPMs), which allow the plants to resist the stresses of herbivores and pathogens or environmental factors. To date, a total of 95 terpenoids, 91 phenolics, 31 alkaloids, and 6 other types of compounds have been identified from maize. Certain volatile sesquiterpenes released by maize plants attract the natural enemies of maize herbivores and provide an indirect defensive function. Kauralexins and dolabralexins are the most abundant diterpenoids in maize and are known to regulate and stabilize the maize rhizosphere microbial community. Benzoxazinoids and benzoxazolinones are the main alkaloids in maize and are found in maize plants at the highest concentrations at the seedling stage. These two kinds of alkaloids directly resist herbivory and pathogenic infection. Phenolics enhance the cross-links between maize cell walls. Meanwhile, SPMs also regulate plant-plant relationships. In conclusion, SPMs in maize show a large diversity of chemical structures and broad-spectrum biological activities. We use these to provide ideas and information to enable the improvement of maize resistances through breeding and to promote the rapid development of the maize industry.

Potential Effect of DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on Alleviating the Autotoxic Coumarin Stress in Alfalfa (Medicago sativa) Seedlings

The allelopathic theory has garnered considerable attention in the field of agricultural production for its efficient plant protection, rapid crop yield increase, and scientific establishment of the crop rotation system. To study the effects of the main maize allelochemical DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on the growth and development of alfalfa under autotoxic coumarin stress, we treated alfalfa seedlings with DIMBOA under coumarin stress and non-stress conditions in this study. Results show that 0.0342 mM coumarin significantly inhibited alfalfa seed germination percentage(Gp), germination potential(GP), radicle length, germ length, seeding height, and simple viability index (SVI), with decreases of 37.29%, 59.91%, 7.60%, 30.90%, 13.27%, and 45.70%, respectively. An amount of 0.6 mM DIMBOA could promote alfalfa seed Gp, GP, radicle length, germ length, seeding height, dry fresh ratio, and SVI, with increases of 12.38%, 23.91%, 48.69%, 48.65%, 48.68%, 295.12%, and 67.17%, respectively. However, the addition of DIMBOA under conditions of coumarin stress could effectively alleviate coumarin effects on alfalfa seedlings. Coumarin + DIMBOA treatment for 24 h mainly decreased reactive oxygen species (ROSs) and malondialdehyde (MDA) as well as soluble protein and soluble sugar, increasing some antioxidant enzyme activities and antioxidant content to alleviate the oxidative damage of alfalfa caused by coumarin stress. Administration of treatment for 72 h significantly promoted the morphological development of alfalfa seeding roots. Administration of treatment for 96 h significantly enhanced the photosynthetic capacity of alfalfa seedlings. The results of principal component analysis demonstrated that chlorophyll b(Chl b)and net photosynthetic rate(Pn) were the key indicators for coumarin + DIMBOA treatment to promote photosynthesis in alfalfa seedlings. Additionally, root length, mean root diameter, and root volume were the key indicators of root growth and development. Coumarin + DIMBOA treatment primarily increased catalase(CAT), peroxidase (POD), and ascorbate peroxidase (APX) activity and antioxidants(ASA) while reducing MDA and superoxide anion radical(O2•-). This study strongly suggested that DIMBOA can effectively improve the tolerance of alfalfa seedlings to coumarin stress through a combination of effects on root morphology, photosynthesis, and physiological indicators.

Plant-microbe interactions in the rhizosphere via a circular metabolic economy

Chemical exchange often serves as the first step in plant-microbe interactions and exchanges of various signals, nutrients, and metabolites continue throughout the interaction. Here, we highlight the role of metabolite exchanges and metabolic crosstalk in the microbiome-root-shoot-environment nexus. Roots secret a diverse set of metabolites; this assortment of root exudates, including secondary metabolites such as benzoxazinoids, coumarins, flavonoids, indolic compounds, and terpenes, shapes the rhizosphere microbiome. In turn, the rhizosphere microbiome affects plant growth and defense. These inter-kingdom chemical interactions are based on a metabolic circular economy, a seemingly wasteless system in which rhizosphere members exchange (i.e. consume, reuse, and redesign) metabolites. This review also describes the recently discovered phenomenon "Systemically Induced Root Exudation of Metabolites" in which the rhizosphere microbiome governs plant metabolism by inducing systemic responses that shift the metabolic profiles of root exudates. Metabolic exchange in the rhizosphere is based on chemical gradients that form specific microhabitats for microbial colonization and we describe recently developed high-resolution methods to study chemical interactions in the rhizosphere. Finally, we propose an action plan to advance the metabolic circular economy in the rhizosphere for sustainable solutions to the cumulative degradation of soil health in agricultural lands.

Nanocatalytic Interface to Decode the Phytovolatile Language for Latent Crop Diagnosis in Future Farms

Crop diseases cause the release of volatiles. Here, the use of an SnO₂-based chemoresistive sensor for early diagnosis has been attempted. Ionone is one of the signature volatiles released by the enzymatic and nonenzymatic cleavage of carotene at the latent stage of some biotic stresses. To our knowledge, this is the first attempt at sensing volatiles with multiple oxidation sites, i.e., ionone (4 oxidation sites), from the phytovolatile library, to derive stronger signals at minimum concentrations. Further, the sensitivity was enhanced on an interdigitated electrode by the addition of platinum as the dopant for a favorable space charge layer and for surface island formation for reactive interface sites. The mechanistic influence of oxygen vacancy formation was studied through detailed density functional theory (DFT) calculations and reactive oxygen-assisted enhanced binding through X-ray photoelectron spectroscopy (XPS) analysis.

Synthesis and activity of 3-oxo-α-ionone analogs as male attractants for the solanaceous fruit fly, Bactrocera latifrons (Diptera: Tephritidae)

A series of 3-oxygenated α-ionone analogs have been developed as highly specific male lures for the solanaceous fruit fly Bactrocera latifrons, a pest of solanaceous fruits. We compared the attractant and phagostimulant activities of analogs with or without (i) unsaturations at the 4,5- and/or 7,8-positions and (ii) oxygen moieties at the 3- and/or 9-positions of the ionone molecule. Since naturally occurring vomifoliol (V2) was found to induce a highly potent phagostimulant activity in B. latifrons males, related analogs including dehydrovomifoliol (V1), 6-hydroxy-α-ionone (U1), and 6-hydroxy-α-ionol (U2) were synthesized to evaluate their attractant and phagostimulant activities. Synthetic V1, V2, U1, and U2 exhibited low attractant activity, but their phagostimulant activity was relatively high. Optical isomers of 3-oxo-7,8-dihydro-α-ionone (P3) and V1 were prepared to examine the stereochemical specificity of attractants. (+)-(6R)-P3 and (+)-(6S)-V1 exhibited the corresponding activities, while their respective antipodal enantiomers were found entirely inactive.

Determination of In Vitro and In Vivo Activities of Plant Carotenoid Cleavage Oxygenases

Carotenoid cleavage products, apocarotenoids, are biologically active compounds exerting important functions as chromophore, hormones, signaling molecules, volatiles, and pigments. Apocarotenoids are generally synthesized by the carotenoid cleavage dioxygenases (CCDs) that comprise a ubiquitous family of enzymes. The activity of plant CCDs was unraveled more than 20 years ago, with the characterization of the maize VP14, the first identified CCD. The protocol developed to determine the activity of this enzyme in vitro is still being used, with minor modifications. In addition, in vivo procedures have been developed during these years, mainly based on the exploitation of Escherichia coli cells engineered to produce specific carotenoid substrates. Further, technological developments have led to significant improvements, contributing to a more efficient detection of the reaction products. This chapter provides an updated set of detailed protocols suitable for the in vitro and in vivo characterization of the activities of CCDs, starting from well-established methods.

Priming maize resistance by its neighbors: activating 1,4-benzoxazine-3-ones synthesis and defense gene expression to alleviate leaf disease

Plant disease can be effectively suppressed in intercropping systems. Our previous study demonstrated that neighboring maize plants can restrict the spread of soil-borne pathogens of pepper plants by secreting defense compounds into the soil. However, whether maize plant can receive benefits from its neighboring pepper plants in an intercropping system is little attention. We examined the effects of maize roots treated with elicitors from the pepper pathogen Phytophthora capsici and pepper root exudates on the synthesis of 1,4-benzoxazine-3-ones (BXs), the expression of defense-related genes in maize, and their ability to alleviate the severity of southern corn leaf blight (SCLB) caused by Bipolaris maydis. We found that SCLB was significantly reduced after the above treatments. The contents of 1,4-benzoxazine-3-ones (BXs: DIBOA, DIMBOA, and MBOA) and the expression levels of BX synthesis and defense genes in maize roots and shoots were up-regulated. DIMBOA and MBOA effectively inhibited the mycelium growth of Bipolaris maydis at physiological concentrations in maize shoots. Further studies suggested that the defense related pathways or genes in maize roots and shoots were activated by elicitors from the P. capsici or pepper root exudates. In conclusion, maize increased the levels of BXs and defense gene expression both in roots and shoots after being triggered by root exudates and pathogen from neighboring pepper plants, eventually enhancing its resistance.

A Prospective Randomized Double-Blind Study Evaluating UP165 and S-Adenosyl-l-Methionine on Depression, Anxiety and Psychological Well-Being

The primary objective of this pilot clinical trial was to evaluate the effects of UP165 (derived from Zea mays L., commonly known as corn) over time. The secondary objective was the comparison for outcomes versusS-adenosyl-methionine (SAM-e). Subjects with mild depression or anxiety were given the Beck Depression Inventory second edition (BDI-II), the Beck Anxiety Inventory (BAI), and the Schwartz Outcome Scale (SOS-10). Forty-two subjects (21–65 years old) were randomized to eight-weeks of supplementation with UP165 or SAM-e with questionnaires being administered at randomization, week four and eight. Those receiving UP165 achieved significant reduction from baseline at weeks four and eight, respectively for the BDI-II, as well as a trend for reduction in BAI at week four and significance at week eight. There was a trend for improvement on the SOS at week four and significance at week eight. SAM-e demonstrated a trend for improvement on the BDI-II by week eight over the UP165 with no differences between the two for the BAI or the SOS. Overall, this study indicates that there may be benefit to UP165 for mood enhancement in those with mild depression or anxiety. Randomized placebo comparator trials appear warranted.

Anti-Fungal Sesquiterpenoid from the Root Exudate ofSolanum abutiloides

The Solanum abutiloides plant is highly resistant to soil-borne pathogens such as Fusarium oxysporum f. sp. melongenae, Verticillium dahliae, and Ralstonia solanacearum. This species is utilized as a mating source of resistant cultivars and is also used as a rootstock. The root exudate of Solanum abutiloides was extracted from a soil system composed of charcoal and vermiculite. Anti-fungal activity was found in the extract, and an active ingredient was isolated. The chemical structure of the active compound was determined to be 3-beta-acetoxysolavetivone, a new sesquiterpenoid. The anti-fungal activity of 3-beta-acetoxysolavetivone examined by the inhibition of spore germination of Fusarium oxysporum was close to that of lubimin, and higher than that of solavetivone.

Carotenoids and their cleavage products: biosynthesis and functions

This review focuses on plant carotenoids, but it also includes progress made on microbial and animal carotenoid metabolism to better understand the functions and the evolution of these structurally diverse compounds with a common backbone. Plants have evolved isogenes for specific key steps of carotenoid biosynthesis with differential expression profiles, whose characteristic features will be compared. Perhaps the most exciting progress has been made in studies of carotenoid cleavage products (apocarotenoids) with an ever-expanding variety of novel functions being discovered. This review therefore covers structural, molecular genetic and functional aspects of carotenoids and apocarotenoids alike. Apocarotenoids are specifically tailored from carotenoids by a family of oxidative cleavage enzymes, but whether there are contributions to their generation from chemical oxidation, photooxidation or other mechanisms is largely unknown. Control of carotenoid homeostasis is discussed in the context of biosynthetic and degradative reactions but also in the context of subcellular environments for deposition and sequestration within and outside of plastids. Other aspects of carotenoid research, including metabolic engineering and synthetic biology approaches, will only be covered briefly.

Apocarotenoids: hormones, mycorrhizal metabolites and aroma volatiles

Apocarotenoids are tailored from carotenoids by oxidative enzymes [carotenoid cleavage oxygenases (CCOs)], cleaving specific double bonds of the polyene chain. The cleavage products can act as hormones, signaling compounds, chromophores and scent/aroma constituents. Recent advances were the identification of strigolactones as apocarotenoids and the description of their novel role as shoot branching inhibitor hormones. Strigolactones are also involved in plant signaling to both harmful (parasitic weeds) and beneficial [arbuscular mycorrhizal (AM) fungi] rhizosphere residents. This review describes the progress in the characterization of CCOs, termed CCDs and NCEDs, in plants. It highlights the importance of sequential cleavage reactions of C(40) carotenoid precursors, the apocarotenoid cleavage oxygenase (ACO) nature of several CCOs and the topic of compartmentation. Work on the biosynthesis of abundant C(13) cyclohexenone and C(14) mycorradicin apocarotenoids in mycorrhizal roots has revealed a new role of CCD1 as an ACO of C(27) apocarotenoid intermediates, following their predicted export from plastid to cytosol. Manipulation of the AM-induced apocarotenoid pathway further suggests novel roles of C(13) apocarotenoids in controlling arbuscule turnover in the AM symbiosis. CCD7 has been established as a biosynthetic crosspoint, controlling both strigolactone and AM-induced C(13) apocarotenoid biosynthesis. Interdependence of the two apocarotenoid pathways may thus play a role in AM-mediated reduction of parasitic weed infestations. Potential scenarios of C(13) scent/aroma volatile biogenesis are discussed, including the novel mechanism revealed from mycorrhizal roots. The recent progress in apocarotenoid research opens up new perspectives for fundamental work, but has also great application potential for the horticulture, food and fragrance industries.

Accumulation of apocarotenoids in mycorrhizal roots of Ornithogalum umbellatum

Colonization of roots of Ornithogalum umbellatum by the arbuscular mycorrhizal fungus Glomus intraradices induced the accumulation of different types of apocarotenoids. In addition to the mycorrhiza-specific occurrence of cyclohexenone derivatives and the "yellow pigment" described earlier, free mycorradicin and numerous mycorradicin derivatives were detected in a complex apocarotenoid mixture for the first time. From the accumulation pattern of the mycorradicin derivatives their possible integration into the continuously accumulating "yellow pigment" is suggested. Structure analyses of the cyclohexenone derivatives by MS and NMR revealed that they are mono-, di- and branched triglycosides of blumenol C, 13-hydroxyblumenol C, and 13-nor-5-carboxy-blumenol C, some of which contain terminal rhamnose as sugar moiety.

Isoprenoid metabolism and plastid reorganization in arbuscular mycorrhizal roots

Plant root-colonizing arbuscular mycorrhizal (AM) fungi activate the methylerythritol phosphate pathway, carotenoid biosynthesis and oxidative carotenoid cleavage in roots, leading to C13 and C14 apocarotenoids, that is, cyclohexenone and mycorradicin derivatives. Mycorradicin causes the characteristic yellow coloration of many AM roots accumulating within a complex mixture of unknown components. The accumulating C13 cyclohexenones exhibit various ring substitutions and different glycosyl moieties. Transcript levels of the first two enzymes of the MEP pathway, 1-deoxy-D-xylulose 5-phosphate synthase and 1-deoxy-D-xylulose 5-phosphate reductoisomerase, and of the carotenoid pathway, phytoene desaturase and zeta-carotene desaturase, along with a carotenoid-cleaving dioxygenase, are markedly increased in AM roots. This correlates with proliferation and reorganization of root plastids. These results allow at this point only speculation about the significance of apocarotenoid accumulation: participation in the production of signaling molecules and control of fungal colonization or protection against soil-borne pathogens; protection of root cells against oxidative damage of membranes by reactive oxygen species; and promotion of the symbiotic interactions between plant roots and AM fungi.