Comparison of phenolics, flavonoids, and cellular antioxidant activities in ear sections of sweet corn (Zea mays L. saccharata Sturt)

Optimizing extraction conditions and isolation of bound phenolic compounds from corn silk (Stigma maydis) and their antioxidant effects

During the processing of maize, Stigma maydis, also known as corn silk, is normally discarded as waste. Phytochemical research was carried out on the S. maydis to use it as a valuable source of bioactive components. This research aimed to maximize the recovery of free and bound phenolic compounds from corn silk under optimal experimental conditions. Response surface design was operated to optimize the alkaline hydrolysis extraction of bound phytochemicals from corn silk based on total phenolic content and DPPH radical scavenging activity. The optimum conditions (i.e., NaOH concentration 2 M, digestion time 135 min, digestion temperature of 37.5°C, the solid-to-solvent ratio of 1:17.5, and acetone) were obtained. The optimum parameters were used to extract the corn silk. The structures of two compounds isolated from ethyl acetate extracts were then identified as friedelin (1) and (E)-4-(4-hydroxy-3-methoxyphenyl) but-3-en-2-one (2). The DPPH, H₂ O₂ , and ABTS % inhibition of the compounds is as follows: compound (1) 74.81%, 76.8%, 70.33% and compound (2) 70.37%, 56.70% and 57.46%, respectively. The current study has opened previously unexplored perspectives of the composition of bound compounds in corn silk and established the foundations for more effective processing and utilization of corn waste. PRACTICAL APPLICATION: Bound phenolic compounds from corn silk under optimal experimental conditions were obtained. Corn silk can be utilized as a type of medicinal herb as well as a source of inexpensive natural antioxidants.

Anti-cancerous effect of corn silk: a critical review on its mechanism of action and safety evaluation

Cancer is a broad collection of diseases that can begin in almost any organ or tissue of the body. Corn silk is the hair-like stigmata of female maize flowers which is generally discarded as waste from maize cultivation. The current study targets the anti-cancer potential of corn silk and its bioactive compounds namely, polyphenols, flavonoids, and sterols. The polyphenols and flavonoids like quercetin, rutin, apigenin and beta-sitosterol are a range of compounds from corn silk which were investigated for their anticancer effect. Corn silk showed apoptotic and antiproliferative effects in cancer cells through different signalling pathways, essentially the serine/threonine kinases (Akt)/lipid kinases (PI3Ks) pathway. The study revealed that corn silk compounds target immune cell responses, induce cell cytotoxicity, and upregulate the expression of proapoptotic genes p53, p21, caspase 9, and caspase 3 in certain cancer cell lines including HeLa cervical cancer cells, MCF-7 breast cancer cells, PANC-02 pancreatic cancer cells and Caco-2 colon cancer cells. Flavonoids derived from corn silk enhance T cell mediated immune response and decrease inflammatory factors. Corn silk bioactive compounds were found to reduce the side effects of cancer therapy. Antioxidants of corn silk, quercetin and rutin help in reducing the nephrotoxicity of chemotherapeutic drugs. The study also suggests that corn silk has anti-cancerous potential as it targets tumour suppression and inhibits metastasis A dose of 500 mg/kg body weight of corn silk has been found safe for human consumption. Corn silk extract can be used as a preventive or therapeutic step to cure cancer. The anti-cancer property, mechanism and role of corn silk in controlling cancer-related side effects have been critically reviewed providing new scope for the use of corn silk in cancer therapy.

Anti-Inflammatory Activity and Mechanism of Sweet Corn Extract on Il-1β-Induced Inflammation in a Human Retinal Pigment Epithelial Cell Line (ARPE-19)

Age-related macular degeneration (AMD) is an eye disease associated with aging. Development of AMD is related to degeneration and dysfunction of the retinal pigment epithelium (RPE) caused by low-grade chronic inflammation in aged RPE cells leading to visual loss and blindness. Sweet corn is a good source of lutein and zeaxanthin, which were reported to exert various biological activities, including anti-inflammatory activity. The present study aims to investigate the anti-inflammatory activity and mechanisms of SCE to inhibit the production of inflammatory biomarkers related to AMD development. Cells were pretreated with SCE for 1 h followed by stimulation with IL-1β for another 24 h. The results demonstrated that SCE attenuated IL-1β-induced production of IL-6, IL-8, and MCP-1 and the expression of ICAM-1 and iNOS in a dose-dependent manner. In addition, SCE suppressed the phosphorylation of ERK1/2, SAPK/JNK, p38, and NF-κB (p65) in IL-1β-stimulated ARPE-19 cells. These results proved that SCE protected ARPE-19 cells from IL-1β-induced inflammation by inhibiting inflammatory markers partly via suppressing the activation of MAPK and NF-κB signaling pathways. Overall, SCE is a potential agent for the prevention of AMD development, which should be further evaluated in animals.

Metabolomics based inferences to unravel phenolic compound diversity in cereals and its implications for human gut health

Background

Scope and approach

Key findings and conclusion

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Phenolic compounds are critical in avoiding metabolic disorders associated with oxidative stress.

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Breeding cereal crops to enrich phenolic compounds in grains contributes to personalized nutrition.

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A diet rich in cereal phenolics likely to increase human gut health, thereby lowering the risk of non-communicable illness.

Synchronous Efficient Reduction of Cr (VI) and Removal of Total Chromium by Corn Extract / Fe (III) System

In this study, a cost-effective and environmentally friendly composite system for the remediation of Cr (VI)-polluted groundwater was developed. The system of simultaneous reduction of Cr (VI) and precipitation of Cr (III) was innovatively constructed, using corncob extract as electron donor and Fe (III) as strengthening reagent. In the process of the total chromium removal, the addition of alkaline substances was not required, when pH ≤ 4 it showed an optimal reduction of Cr (VI). In addition, the removal rate of total chromium reached 88% within 120 min. To understand the mechanism of this system, we characterized the corn extract and particulate matter before and after the reaction. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry suggested that alcohols, phenols, and aldehydes provided the electrons that were required to reduce Cr (VI). As an electron shuttle, Fe (III) improved the efficiency of electron transfer, and Fe (II) and nano-zerovalent iron (nZVI) particles were formed during this process. X-ray diffraction and transmission electron microscopy analyses showed that FeOCl was formed under the action of the plant extract and adsorbed Cr (III), thus reducing total chromium. Both nZVI and FeOCl were covered with a layer of paste cap, which maintained the stability of their physical and chemical properties. The regulation of pH during the repair process was not required, and the cost of the process was significantly reduced. Therefore, this technology provides a new strategy for the in situ remediation of Cr (VI) pollution in groundwater.

Towards Functional Insect Feeds: Agri-Food By-Products Enriched with Post-Distillation Residues of Medicinal Aromatic Plants in Tenebrio molitor (Coleoptera: Tenebrionidae) Breeding

Sustainability, circular economy and alternative production systems are urgent imperatives for humanity and animal husbandry. Unless wasted, agri-food by-products can offer a promising source of high value. We evaluated the effect of rice bran (RB), corncob (CC), potato peels (PP), solid biogas residues (BR), and olive-oil processing residuals (OR), as alternative substrates to wheat bran (WB as control), on the growth and nutritional value of Tenebrio molitor during its breeding for animal feeds and/or human consumption. Innovation-wise, we further investigated the substrate supplementation (0, 10, 20%) with post-distillation residues of Mediterranean aromatic-medicinal plants (MAPs: lavender, Greek oregano, rosemary, olive; 1:1:1:1 ratio). Tenebrio molitor larvae (TML) were reared in all the studied substrates, and TML and diets’ proximate and fatty acid compositions as well as total phenol and flavonoid content and antioxidant potential were assessed using standard procedures. After statistical analysis of correlations, we observed that CC promoted oviposition and progeny survival; larval weight and dry matter were positively affected mainly by dietary energy and fat content; number of TML and/or larval weight increased using 10% MAPs inclusion in WB, RB and OR or RB, OR, BR and PP, respectively, which did not affect protein content; TML fatty acid composition decreased the content of saturated ones and increased that of mono-unsaturated ones; MAPs residues had an apparent favorable impact on total phenolic content and antioxidant activity of each substrate, with RB displaying the highest capacity and content. These findings indicate that alternative substrates can be exploited and their enrichment with natural phenolics is able to influence T. molitor growth, offering highly beneficial and nutritional value.

Sweet Corn Research around the World 2015–2020

Modern sweet corn is distinguished from other vegetable corns by the presence of one or more recessive alleles within the maize endosperm starch synthesis pathway. This results in reduced starch content and increased sugar concentration when consumed fresh. Fresh sweet corn originated in the USA and has since been introduced in countries around the World with increasing popularity as a favored vegetable choice. Several reviews have been published recently on endosperm genetics, breeding, and physiology that focus on the basic biology and uses in the US. However, new questions concerning sustainability, environmental care, and climate change, along with the introduction of sweet corn in other countries have produced a variety of new uses and research activities. This review is a summary of the sweet corn research published during the five years preceding 2021.

Preservation of Antioxidant Properties of Endemic Dark Corn Using Solar Energy for Nixtamalization

A comparative study of two corn nixtamalization processes is presented, one in the traditional way of the Michoacan region of Mexico, and the other using solar devices. The corn selected for the process was a nontransgenic endemic dark corn. For the nixtamalization process, a solar concentration oven was used; this process using the solar device is simple and affordable for communities. For characterization, the properties of the antioxidant content of dark corn were analyzed for both processes, and the highest concentration of antioxidants between the two varieties of corn was obtained. The antioxidant capacity in the two varieties of black corn was quantified and determined, and the anthocyanin pigments were extracted with methanol. The total anthocyanin content (CAT) was evaluated by the pH difference method, and the antioxidant capacity by the DPPH method. In the solar nixtamalization process, a higher content of CAT anthocyanins and antioxidant capacity were obtained. Therefore, the solar energy process was proposed as a sustainable energy option, and we concluded that black corn nixtamalized with a solar oven had high antioxidant levels and could be used as a nutritious food.

Optimization of ultrasound-assisted extraction of anthocyanins and bioactive compounds from butterfly pea petals using Taguchi method and Grey relational analysis

Ultrasound-assisted extraction (UAE) was used to extract anthocyanins, antioxidants and phenolic compounds from butterfly pea petals, as an alternative to traditional methods. Taguchi method with three factors: extraction time (30, 45, 60 min), temperature (40, 60, 80 °C) and liquid-solid ratio (5, 7.5, 10 mL distilled water/mg butterfly pea) was used to obtain the high extraction yield. Grey relational analysis was employed to convert multi-response problem into single response optimization. The high extraction efficiency could be achieved at optimal parameter condition using 45 min of extraction time, 40 °C and 10 ml distilled water/mg butterfly pea. Liquid-solid ratio exhibited the highest contribution for anthocyanin and total phenolic content. A high temperature of ultrasonication resulted in a negative effect on antioxidant capacity and total phenolic content. The findings from this study indicated that the UAE process optimization would be an efficient and sustainable method for the preparation of bioactive compounds from medical plants with saving of reaction time and cost in which extraction yields of antioxidant capacity and total phenolic content were also increased. The color response analysis results suggested that the gelatin film incorporated with butterfly pea extract can be potentially used as pH-indicator for detecting food spoilage for intelligent packaging.

Prediction of Sweet Corn Seed Germination Based on Hyperspectral Image Technology and Multivariate Data Regression

Vigor identification in sweet corn seeds is important for seed germination, crop yield, and quality. In this study, hyperspectral image (HSI) technology integrated with germination tests was applied for feature association analysis and germination performance prediction of sweet corn seeds. In this study, 89 sweet corn seeds (73 for training and the other 16 for testing) were studied and hyperspectral imaging at the spectral range of 400-1000 nm was applied as a nondestructive and accurate technique to identify seed vigor. The root length and seedling length which represent the seed vigor were measured, and principal component regression (PCR), partial least squares (PLS), and kernel principal component regression (KPCR) were used to establish the regression relationship between the hyperspectral feature of seeds and the germination results. Specifically, the relevant characteristic band associated with seed vigor based on the highest correlation coefficient (HCC) was constructed for optimal wavelength selection. The hyperspectral data features were selected by genetic algorithm (GA), successive projections algorithm (SPA), and HCC. The results indicated that the hyperspectral data features obtained based on the HCC method have better prediction results on the seedling length and root length than SPA and GA. By comparing the regression results of KPCR, PCR, and PLS, it can be concluded that the hyperspectral method can predict the root length with a correlation coefficient of 0.7805. The prediction results of different feature selection and regression algorithms for the seedling length were up to 0.6074. The results indicated that, based on hyperspectral technology, the prediction of seedling root length was better than that of seed length.