Coix: Chemical composition and health effects

Comparative study on the bioactive components and in vitro biological activities of three green seedlings

To explore functional food ingredients from green seedlings, the bioactive components (phenolic compounds and γ-aminobutyric acid) and antioxidant activities (DPPH radical scavenging ability, ABTS radical scavenging ability and reducing power) of three green seedlings, including coix seed seedling (CSS), highland barely seedling (HBS) and naked oats seedling (NOS) cultivars were respectively measured and deeply compared. Results indicated that CSS showed the highest contents of the total polyphenol (183.35 mg/100 g), total flavonoid (348.68 mg/100 g), and γ-aminobutyric acid (54.17 mg/100 g). As expected, CSS also exerted the highest level of antioxidant activity, followed by HBS and NOS. Moreover, CSS possessed the potential of stimulating immune responses, including promoting proliferation and strengthening phagocytosis function of RAW264.7 cells. Taken together, all results suggested that the three green seedlings, especially CSS could be used as natural ingredients for functional food.

Effects of fermentation with Lactobacillus plantarum NCU137 on nutritional, sensory and stability properties of Coix (Coix lachryma-jobi L.) seed

This study aimed to investigate the effect of fermentation with Lactobacillus plantarum NCU137 on the nutritional, sensory and stability properties of Coix (Coix lachryma-jobi L.) seed. The nutritional compounds, including free amino acid, free fatty acid, soluble dietary fiber and organic acids of fermented coix seed were significantly (p < 0.05) increased than those of non-fermented coix seed. The fermented coix seed exhibiting a special flavor, due to the production of acids, the decreased level of aldehydes and ketones, and the increased level of alcohols in the volatile compounds, whereas the amount of hazardous substance 2-pentylfuran was reduced and natural antiseptic hexanoic acid was produced. The increased viscosity together with the larger particle size and the reduced absolute ζ potential contribute to the stability of the fermented coix seed paste system. Therefore, fermentation with L. plantarum NCU137 could improve the nutritional, sensory and stability properties of coix seed.

Preparation of coix seed oil bioactive delivery systems based on homologous polysaccharides and proteins

Natural products belonging to a class of generally-recognized-as-safe biomaterials have exceptional biocompatibility and biodegradability and can be used as delivery vehicles for a variety of functional foods. Adlay (Coix lacryma-jobi), is a nutritious food, rich in various bioactive ingredients. Coix seed oil extract (CSO) is also bioactive but it is sensitive to oxidation. In this study, a bioactive delivery system based on homologous polysaccharides and proteins was developed to deliver coix seed oil. The results show that the CSO nanoparticles have high encapsulation efficiency, narrow particle size distribution, and good stability. Moreover, the fusion of the nanoparticles with the membrane enabled the transport of CSO through the Caco-2 cell monolayer and improved the intestinal permeability. These findings could provide useful information for designing homologous polysaccharide and protein-based delivery systems to increase the bioavailability of lipophilic nutraceuticals in the food industry.

Comprehensive evaluation of physicochemical properties and antioxidant activity of B. subtilis-fermented polished adlay subjected to different drying methods

The physicochemical properties and antioxidant activity of B. subtilis-fermented polished adlay (BPA) subjected to different drying methods (hot-air drying, HAD; infrared-radiation drying, IRD; vacuum drying, VD; microwave-vacuum drying, MVD; and freeze-vacuum drying, FVD) were evaluated in this study. Results showed FVD was ideal for maintaining the natural appearance and higher contents of proximate compositions, free fatty acids, tetramethylpyrazine (6.91 mg/g DW), coixol (0.62 mg/g DW), coixenolide (4.21% DW), coixan (35.10% DW), and triterpenoids (17.41 mg/g DW). The higher contents of total phenolics and flavonoids, stronger antioxidant activity, and higher color differences were observed in HAD and IRD samples. MVD displayed the shorter drying time, higher γ-aminobutyric acid content, and higher retention ratios of tetramethylpyrazine (75.54%), coixol (87.10%), coixenolide (98.57%), and coixan (99.11%). Pearson's correlation coefficient exhibited that the positive correlation between the contents of phenolics and flavonoids and the antioxidant activities of all dried BPA samples was observed (R 2 > 0.881, p < .05). Principal component analysis showed that the top three categories of comprehensive quality were FVD-, MVD-, and VD-treated BPA samples. In conclusion, MVD should be a potential preservation method to obtain high-quality dried BPA for short drying time and high comprehensive quality.

Coixol Suppresses NF-κB, MAPK Pathways and NLRP3 Inflammasome Activation in Lipopolysaccharide-Induced RAW 264.7 Cells

Coixol, a plant polyphenol extracted from coix (Coix lachryma-jobi L.var.ma-yuen Stapf), has not been investigated for its anti-inflammatory effect. In this study, using a lipopolysaccharide (LPS)-induced macrophage cell model, we observed that coixol can effectively reduce the expression of interleukin (IL)-1β, IL-6, IL-18, tumor necrosis factor (TNF)-α, nitric oxide (NO), inducible nitric oxide synthases (iNOS), and cyclooxygenase (COX)-2, but had no effect on the expression of the anti-inflammatory mediator IL-10. Furthermore, we found that coixol inhibits mitogen-activated protein kinases (MAPKs), nuclear transcription factor κ B (NF-κB) pathways, and NOD-like receptor protein (NLRP) 3 inflammasome activation. In conclusion, the present study demonstrates that coixol exerts certain anti-inflammatory effects by inhibiting the expression of pro-inflammatory mediators in vitro. The mechanism of this effect was in part related to its ability to inhibit the activation of NF-κB, MAPKs pathways, and NLRP3 inflammasome.

The Coix Genome Provides Insights into Panicoideae Evolution and Papery Hull Domestication

Coix is a grass crop domesticated as early as the Neolithic era. It is still widely cultivated for both highly nutritional food and medicinal use. However, the genetic study and breeding of this crop are hindered by the lack of a sequenced genome. Here, we report de novo sequencing and assembly of the 1619-Mb genome of Coix, and annotation of 75.39% repeats and 39 629 protein-coding genes. Comparative genomics analysis showed that Coix is more closely related to sorghum than maize, but intriguingly only Coix and maize had a recent genome duplication event, which was not detected in sorghum. We further constructed a genetic map and mapped several important traits, especially the strength of hull. Selection of papery hull (thin: easy dehulling) from the stony hull (thick: difficult dehulling) in wild progenitors was a key step in Coix domestication. The papery hull makes seed easier to process and germinate. Anatomic and global transcriptome analysis revealed that the papery hull is a result of inhibition of cell division and wall biogenesis. We also successfully demonstrated that seed hull pressure resistance is controlled by two major quantitative trait loci (QTLs), which are associated with hull thickness and color, respectively. The two QTLs were further fine mapped within intervals of 250 kb and 146 kb, respectively. These resources provide a platform for evolutionary studies and will facilitate molecular breeding of this important crop.

Effect of polysaccharides from adlay seed on anti-diabetic and gut microbiota

Diabetes is a chronic metabolic disease characterized by elevated blood glucose levels due to insulin resistance and β-cell dysfunction. This study aims to examine the effects of polysaccharides from adlay seeds (PAS) on hyperglycemia and gut microbiota in streptozocin (STZ)-induced diabetic mice. The administration of PAS in diabetic mice caused a significant decrease in the glucose level and serum levels of glycosylated hemoglobin (HbA1c). Similarly, PAS also showed decreased total cholesterol (TC) and triglyceride (TG) concentrations. Furthermore, a significant increase in the concentrations of glucagon-like peptide 1 (GLP-1) was observed. Unexpectedly, PAS reduced the concentrations of anti-amyloid beta (Aβ1-42) protein. Also, histopathological examination showed that PAS contributed to the reduction of STZ-lesioned pancreatic cells. Metformin treatment significantly reduced the diversity of the gut microbiota, while PAS treatment altered the diversity and composition of the microbiota. Collectively, our findings demonstrate that the hypoglycemic effects of PAS in type-2 diabetic mice (T2D) may be associated with the regulation of the intestinal microbiota and its metabolic pathways.

Genome Assembly and Annotation of Soft-Shelled Adlay (Coix lacryma-jobi Variety ma-yuen), a Cereal and Medicinal Crop in the Poaceae Family

Coix lacryma-jobi, also called adlay or Job's tears, is an annual herbal plant belonging to the Poaceae family that has been cultivated as a cereal and medicinal crop in Asia. Despite its importance, however, genomic resources for better understanding this plant species at the molecular level and informing improved breeding strategies remain limited. To address this, we generated a draft genome of the C. lacryma-jobi variety ma-yuen (soft-shelled adlay) Korean cultivar, Johyun, by de novo assembly, using PacBio and Illumina sequencing data. A total of 3,362 scaffold sequences, 1.28 Gb in length, were assembled, representing 82.1% of the estimated genome size (1.56 Gb). Genome completeness was confirmed by the presence of 91.4% of the BUSCO angiosperm genes and mapping ratio of 98.3% of Illumina paired-end reads. We found that approximately 77.0% of the genome is occupied by repeat sequences, most of which are Gypsy and Copia-type retrotransposons, and evidence-based genome annotation predicts 39,574 protein-coding genes, 85.5% of which were functionally annotated. We further predict that soft-shelled adlay diverged from a common ancestor with sorghum 9.0-11.2 MYA. Transcriptome profiling revealed 3,988 genes that are differentially expressed in seeds relative to other tissues, of which 1,470 genes were strongly up-regulated in seeds and the most enriched Gene Ontology terms were assigned to carbohydrate and protein metabolism. In addition, we identified 76 storage protein genes including 18 seed-specific coixin genes and 13 candidate genes involved in biosynthesis of benzoxazinoids (BXs) including coixol, a unique BX compound found in C. lacryma-jobi species. The characterization of those genes can further our understanding of unique traits of soft-shelled adlay, such as high seed protein content and medicinal compound biosynthesis. Taken together, our genome sequence data will provide a valuable resource for molecular breeding and pharmacological study of this plant species.

Physicochemical and Morphological Properties of Extruded Adlay (Coix lachryma-jobi L) Flour

The effects of extrusion treatment on the structure and properties of adlay (Job’s tears) were investigated. Adlay flour was extruded through a twin-screw extruder with different parameters, including barrel temperature (80–160°C), moisture content (19–27%), and screw speed (170–330 rpm). The results showed that although the expansion index increased with increasing temperature, an increase in moisture content significantly decreased the EI (p<0.05). Extrusion improved the water solubility index and water absorption index of adlay flour (p<0.05). Furthermore, analysis of the gelating properties revealed that the structure and function of adlay flour had radically changed. After extrusion, the viscosity of the adlay flour decreased (peak viscosity decreased by more than 1000 cP), and its fluidity increased. The rheological data were modeled by the Herschel–Bulkley model. X-ray diffraction experiments showed that extrusion contributed to a decrease in relative crystallinity. Scanning electron microscopy revealed that extrusion damaged the basic structure of adlay flour, causing holes and pits on the extrudate surface. Compared to the native adlay flour, the extrusion resulted in significantly changing the pasting, gelating, thermal, rheological, and morphological properties of adlay flour. In conclusion, the extrusion can alter adlay characteristics, but it is necessary to choose appropriate conditions to attain the desired properties.

Coix lacryma-jobi chymotrypsin inhibitor displays antifungal activity

A novel chymotrypsin inhibitor, named ClCI, was purified from coix seed (Coix lacryma-jobi L.) by aqueous two-phase extraction, chymotrypsin-Sepharose 4B affinity chromatography and centrifugal ultrafiltration. ClCI was a 7.9 kDa competitive inhibitor with pI 6.54. The inhibition constants (K_i) for bovine pancreatic chymotrypsin and bacterial subtilisin were 1.27 × 10^-10 M and 1.57 × 10^-9 M respectively. ClCI had no inhibitory activity against bovine trypsin and porcine elastase. ClCI had wide pH stability and good heat resistance. It can maintain >90% inhibition activity against chymotrypsin at 20-80 °C for 1 h. The primary structure of ClCI was highly similar (57%-92%) to those of several inhibitors belonging to the Gramineae crop potato protease inhibitor- I superfamily and showed the typical sequence motif of the protease inhibitor of the seed storage protein group. ClCI (12.5 mg) inhibited mycelial growth of the phytopathogenic fungi Mycosphaerella melonis, Helminthosporium turcicum, Alternaria solani, Phytophthora capsici, Isariopsis griseola, and Colletotrichum gloeosporioides, and caused 89% inhibition of the proteases from spore germination of plant-pathogenic fungi. The results of the present study indicate that ClCI had biotechnological potential as an alternative agent to combat the important phytopathogenic fungi.

Analysis of Fungi on Coix (Coix lacryma-jobi) Seed and the Effect of Its Aqueous Extract on the Growth of Aspergillus flavus

Coix (Coix lacryma-jobi) seeds are susceptible to fungal infections, making their surface fungi complex and diverse. Some fungi can produce mycotoxins under suitable conditions, and fungal growth is closely related to the production of mycotoxins. In this study, the surface fungi of coix seed were identified by Illumina HiSeq high-throughput sequencing. Simultaneously, the fungi cultured by the plate method were identified by microscopy and DNA barcoding; finally, the species of fungi were identified accurately and reliably by combining three methods. The aqueous extract of coix seed was cocultured with Aspergillus flavus spores, and the relationship between the aqueous extract and the growth of A. flavus was studied with the dry weight of mycelium as an indicator. The results showed that there were 89 genera and 96 species of fungi on coix seed, which were mainly distributed in Ascomycota (81.48%) and Basidiomycota (4.08%), and Xeromyces (8.50%), Gibberella (7.25%), and Aspergillus (4.74%) were the predominant genera. Four fungi were isolated from coix seed by plate culture and identified as Aspergillus fumigatus, A. flavus, Aspergillus oryzae, and Rhizopus oryzae by microscopy and DNA barcoding. The aqueous extract of coix seed at low concentrations has a promoting effect on the growth of A. flavus. When the concentration is 3.125%, the promotion effect is the most pronounced, and the promotion rate is 29.17%. These results reveal the diversity of fungi on the coix seed, which can provide a reference for the prevention and control of harmful fungi on coix seed.

Preparation, characterization and anti-diabetic activity of polysaccharides from adlay seed

Coix (Coix lachryma-jobi L.), commonly known as adlay, is a traditional Chinese medicine for thousands of years. A new water-soluble polysaccharide with anti-diabetic activity was extracted and purified from the adlay seed (PAS). The structure and physicochemical properties of PAS were determined by Fourier transform infrared spectrometer (FT-IR) and scanning electron microscopy (SEM). Structural analysis indicated that PAS had a porous surface and relatively loose distribution. After intragastric administered PAS for 4 weeks, biochemical analysis demonstrated dose dependent anti-diabetic activity. These results showed that PAS decreased blood glucose and insulin levels. In addition, mice fed the PAS showed significantly reduced the plasma levels of amyloid β₄₂ and glycated hemoglobin (HbA1c), while the expression of glucagon-like peptide-1 (GLP-1) was markedly increased. Our study introduced a new polysaccharide PAS with unique anti-diabetic activity, which can be used as a potential dietary supplement or functional food.

Transcriptome and proteome analyses of the molecular mechanisms associated with coix seed nutritional quality in the process of breeding

In present study, the content of main nutrients in wild coix seed were significantly higher than cultivated coix seed. Transcriptome and proteome were combined to provide new insight of the molecular mechanisms linked to nutritional quality of wild coix seed and cultivated coix seed by RNA sequencing and isobaric tags for relative and absolute quantification techniques. A total of 20,039 genes and 471 proteins exhibited differential expression level in cultivated coix seed when compared with wild coix seed. These genes and proteins revealed that the pathway of flavonoids biosynthesis, starch and sucrose metabolism, lipid metabolism and amino acid metabolism were linked to nutritional quality of coix seed. Our results provided transcriptomics and proteomics information with respect to the molecular mechanisms of nutritional changes of coix seed, identified key genes and proteins that associated with the metabolism and accumulation of nutrients, and helped clarify the mechanisms of nutrient differences.

Physiological and proteomic analyses of coix seed aging during storage

Although a series of physio-biochemical changes of coix seed occur during the storage, the underlying mechanism remains unknown. The present study aimed to investigate the aging mechanism of coix seed during storage. Proteome patterns of coix seed stored for 1-month, 5-month and 10-month at room temperature were compared using 2-dimensional gel electrophoresis (2-DE) and mass spectra. Thirty-one differentially expressed proteins (DEPs) were detected, which involved seven pathways including starch and sucrose metabolism, carbon metabolism, RNA transport, proteasome, protein processing in endoplasmic reticulum, ribosome, and RNA degradation. Sucrose synthase 1 was associated with sucrose metabolism and affected the sucrose content during the storage. Increased ambient temperature enhanced respiration of coix after 5-month storage, and overexpression of aconitate hydratase 2 promoted the generation of energy. In addition, the proteins involved in the antioxidant system and resistance stimulus of coix seed were mostly up-regulated during storage.