Search Results (41)

Colored rice (black, purple, red and brown) has been consumed in China for nearly 4000 years. Recent research has focused on exploring its nutritional and metabolomic profiles and associated health benefits. Due to the improvement in detection and quantification techniques for health-promoting compounds and their activities, the number of studies has increased significantly. In this regard, a timely and updated review of research on nutritional composition, phytochemistry, and metabolite content and composition can significantly enhance consumer awareness. Here, we present a detailed and up-to-date understanding and comparison of the nutritional and phytochemical (metabolite) composition of colored rice. While earlier literature reviews focus on either single type of colored rice or briefly present nutritional comparison or bioactivities, here we present more detailed nutrient profile comparison (carbohydrates, fats, proteins, amino acids, minerals, and vitamins), together with the most recent comparative data on phytochemicals/metabolites (flavonoids, anthocyanins, fatty acids, amino acids and derivatives, phenolic acids, organic acids, alkaloids, and others). We discuss how metabolomics has broadened the scope of research by providing an increasing number of detected compounds. Moreover, directions on the improvement in colored rice nutritional quality through breeding are also presented. Finally, we present the health-beneficial activities (antioxidant, anti-inflammatory, antimicrobial, hypoglycemic, neuroprotective, anti-aging, and antitumor activities) of different colored rice varieties, together with examples of the clinical trials, and discuss which bioactive substances are correlated with such activities. Full article

Pigmented rice, particularly the black and red varieties, is popular due to its better nutritional value. Anthocyanins and proanthocyanidins are two major flavonoid subcategories with broad physiological functions and therapeutic significance. However, pigment deposition is a complex process, and the molecular mechanism involved remains unknown. This review explores the metabolites responsible for the pigmentation in various rice tissues. Moreover, the current challenges, feasible strategies, and potential future directions in pigmented rice research are reported. Full article

As an agri-food by-product, the rice bran of pigmented rice, encompassing varieties such as red, black, and purple rice, has garnered increasing attention due to its richness in terms of bioactive compounds. Being mainly composed of the pericarp, aleuron, seed coat, and germ, the brown outer layer of the rice kernel offers potential health benefits and has applications in skincare. Human skin serves as the primary barrier against external threats, including pathogens, pollutants, and ultraviolet (UV) radiation. Notably, UV radiation accelerates the aging process and contributes to various skin issues. Recent trends suggest a heightened interest in incorporating pigmented rice into skincare regimens, motivated by its potential to mitigate oxidative stress, inflammation, and pigmentation, which are pivotal factors in skin aging and photodamage. With increasing consumer demand for natural and sustainable ingredients, pigmented rice has emerged as a promising candidate within the skincare and personal care sectors, effectively bridging the gap between nutrition and dermatological health. This review examines the applications of pigmented rice in skincare, with a particular focus on its bioactive components and potential mechanisms of action that contribute to skin health. The unique chemical composition of pigmented rice, which includes compounds such as anthocyanins, flavonoids, phenolic acids, and vitamin E, underlies its antioxidant, anti-inflammatory, and skin-protective properties. Despite the increasing recognition of its benefits, a comprehensive understanding of the underlying mechanisms remains limited, underscoring the necessity for further research to exploit the potential of pigmented rice in skincare applications fully. Full article

The pigment content of rice leaves plays an important role in the growth and development of rice. The accurate and rapid assessment of the pigment content of leaves is of great significance for monitoring the growth status of rice. This study used the Analytical Spectra Device (ASD) FieldSpec 4 spectrometer to measure the leaf reflectance spectra of 4 rice varieties during the entire growth period under 4 nitrogen application rates and simultaneously measured the leaf pigment content. The leaf’s absorption spectra were calculated based on the physical process of spectral transmission. An examination was conducted on the variations in pigment composition among distinct rice cultivars, alongside a thorough dissection of the interrelations and distinctions between leaf reflectance spectra and absorption spectra. Based on the vegetation index proposed by previous researchers in order to invert pigment content, the absorption spectrum was used to replace the original reflectance data to optimize the vegetation index. The results showed that the chlorophyll and carotenoid contents of different rice varieties showed regular changes during the whole growth period, and that the leaf absorption spectra of different rice varieties showed more obvious differences than reflectance spectra. After replacing the reflectance of pigment absorptivity-sensitive bands (400 nm, 550 nm, 680 nm, and red-edge bands) with absorptivities that would optimize the vegetation index, the correlation between the vegetation index, which combines absorptivity and reflectivity, and the chlorophyll and carotenoid contents of 4 rice varieties during the whole growth period was significantly improved. The model’s validation results indicate that the pigment inversion model, based on the improved vegetation index using absorption spectra, outperforms the traditional vegetation index-based pigment inversion model. The results of this study demonstrate the potential application of absorption spectroscopy in the quantitative inversion of crop phenotypes. Full article

Pest infestations significantly impact rice production and threaten food security. Remote sensing offers a vital tool for the non-destructive, rapid detection of rice pests. Existing studies often focus on laboratory conditions at the leaf level, limiting their applicability for precise pesticide application. Therefore, this study aimed to develop a method for detecting rice pests (rice leaf folders) in paddy fields based on unmanned aerial vehicle (UAV) hyperspectral data. Firstly, a UAV imaging system collected hyperspectral images of rice plants in both the jointing and heading stages. A total of 222 field plots for investigating rice leaf folders was established during these two periods. Secondly, 23 vegetation indices were calculated as candidates for identifying rice pests. Then, hyperspectral data and field investigation data from the jointing stage were used to construct a machine learning (extreme gradient boosting, XGBoost) algorithm for detecting rice pests. The results showed that the XGBoost model exhibited the best performance when eight vegetation indices were considered as the selected input features for model construction: the Red-edge Normalized Difference Vegetation Index (red-edge NDVI), Structure Insensitive Pigment Index (SIPI), Enhanced Vegetation Index (EVI), Atmospherically Resistant Vegetation Index (ARVI), Soil-Adjusted Vegetation Index (SAVI), Red-edge Chlorophyll Index (CIred-edge), Pigment-Specific Simple Ratio₆₈₀ (PSSR₆₈₀), and Carotenoid Reflectance Index₇₀₀ (CPI₇₀₀). The training and testing accuracies reached 87.46% and 86%, respectively. Furthermore, the heading stage application confirmed the model’s feasibility. Thus, the XGBoost model with input features of eight vegetation indices provides an effective and reliable method for detecting rice leaf folders, supporting real-time, precise pesticide use in rice cultivation. Full article

Cereals have been a foundational component of human diets across different continents, with rice dominating in Asia, sorghum in Africa, wheat in Europe, and maize in America. Mexico, more accurately Mesoamerica, is recognized as the origin of maize (including pigmented maize), with its first ancestor traced back to Tehuacán, Puebla, Mexico. Pigmented maize owes its vibrant colors due to its anthocyanin (i.e., cyanidin-3-glucoside) contents, which contribute to the red, purple, or blue coloration and offer notable health benefits. The antioxidant properties of maize are crucial, given the role of oxidative stress in various diseases, and present a valuable resource for functional foods and nutraceuticals. Emerging studies underscore the prebiotic potential of anthocyanins, showing their ability to modulate gut microbiota positively. This review aims to explore the potential of pigmented maize in traditional Mexican beverage (such as pozol and tejuino) production, emphasizing the bioactive compounds (mainly anthocyanins) present and their health benefits while also considering new opportunities in the functional food industry. Full article

Pigmented rice grains are important resources for health and nutritional perspectives. Thus, a thorough dissection of the variation of nutrients and bioactive metabolites in different colored rice is of global interest. This study applied LC–MS-based widely targeted metabolite profiling and unraveled the variability of metabolites and nutraceuticals in long grain/non-glutinous black (BR), red (RR), green (GR), and white rice (WR) grains. We identified and classified 1292 metabolites, including five flavonoid compounds specific to BR. The metabolite profiles of the four rice grains showed significant variation, with 275–543 differentially accumulated metabolites identified. Flavonoid (flavone, flavonol, and anthocyanin) and cofactor biosynthesis were the most differentially regulated pathways among the four rice types. Most bioactive flavonoids, anthocyanidins (glycosylated cyanidins and peonidins), phenolic acids, and lignans had the highest relative content in BR, followed by RR. Most alkaloids, amino acids and derivatives, lipids, and vitamins (B6, B3, B1, nicotinamide, and isonicotinic acid) had higher relative contents in GR than others. Procyanidins (B1, B2, and B3) had the highest relative content in RR. In addition, we identified 25 potential discriminatory biomarkers, including fagomine, which could be used to authenticate GR. Our results show that BR and RR are important materials for medicinal use, while GR is an excellent source of nutrients (amino acids and vitamins) and bioactive alkaloids. Moreover, they provide data resources for the science-based use of different colored rice varieties in diverse industries. Full article

The study investigates the structural and chemical properties of brown rice flour (WRF), black rice flour (BRF) and their mixtures in ratios of 25%, 50% and 75% to provide reference information for the gluten-free bakery industry. BRF contains higher concentrations of proteins, lipids, total minerals, crude fiber, total polyphenols, proanthocyanidins and flavonoids than WRF. A higher amylose content in BRF than in WRF resulted in flour mixtures with slower starch digestion and a lower glycemic response depending on the BRF ratio added. Differences in the chemical composition of WRF and BRF led to improved composition of the flour mixtures depending on the BRF ratio. The presence of anthocyanidins and phenolic acids in higher concentrations in the BRF resulted in a red–blue color shift within the flour mixtures. The deconvoluted FTIR spectra showed a higher proportion of α-helixes in the amide I band of BRF proteins, indicating their tighter folding. An analysis of the FTIR spectra revealed a more compact starch structure in BRF than in WRF. By processing reflection spectra, nine optically active compound groups were distinguished in rice flour, the proportion in BRF being 83.02% higher than in WRF. Due to co-pigmentation, the bathochromic shift to higher wavelengths was expressed by the proanthocyanins and phenolic acids associated with the wavelengths 380 nm to 590 nm and at 695 nm. Anthocyanins, protein–tannin complexes, methylated anthocyanins and acylated anthocyanins, associated with wavelengths 619, 644 and 668 nm, exhibited a hypsochromic effect by shifting the wavelengths to lower values. This research represents a first step in the development of rice-based products with increased nutritional value and a lower glycemic index. Full article

Red yeast rice dietary supplements have been proven to ameliorate hyperglycemia, but the mechanism was unclear. In this work, ankaflavin (AK) and monascin (MS), as typical pigments derived from red yeast rice, were found to exert noteworthy inhibitory ability against α-glucosidase, with an IC₅₀ of 126.5 ± 2.5 and 302.6 ± 2.5 μM, respectively, compared with acarbose (IC₅₀ = 341.3 ± 13.6 μM). They also exhibited mixed-type inhibition of α-glucosidase in vitro and caused fluorescence quenching through the static-quenching process. Molecular-docking studies indicated that AK and MS bind to amino acid residues outside the catalytic center, which induces structural changes in the enzyme, thus influencing its catalytic activity. The anti-glycation ability of Monascus-fermented products was evaluated, and they exhibited a high inhibition rate of 87.1% in fluorescent advanced glycation end-product formation at a concentration of 0.2 mg mL⁻¹, while aminoguanidine showed a rate of 75.7% at the same concentration. These results will be significant in broadening the application scope of Monascus pigments, especially AK and MS, in treating type 2 diabetes. Full article

Red rice, a variety of pigmented grain, serves dual purposes as both a food and medicinal resource. In recent years, we have witnessed an increasing interest in the dermatological benefits of fermented rice extracts, particularly their whitening and hydrating effects. However, data on the skincare advantages derived from fermenting red rice with Aspergillus oryzae remain sparse. This study utilized red rice as a substrate for fermentation by Aspergillus oryzae, producing a substance known as red rice Aspergillus oryzae fermentation (RRFA). We conducted a preliminary analysis of RRFA’s composition followed by an evaluation of its skincare potential through various in vitro tests. Our objective was to develop a safe and highly effective skincare component for potential cosmetic applications. RRFA’s constituents were assessed using high-performance liquid chromatography (HPLC), Kjeldahl nitrogen determination, the phenol-sulfuric acid method, and enzyme-linked immunosorbent assay (ELISA). We employed human dermal fibroblasts (FB) to assess RRFA’s anti-aging and antioxidative properties, immortalized keratinocytes (HaCaT cells) and 3D epidermal models to examine its moisturizing and reparative capabilities, and human primary melanocytes (MCs) to study its effects on skin lightening. Our findings revealed that RRFA encompasses several bioactive compounds beneficial for skin health. RRFA can significantly promote the proliferation of FB cells. And it markedly enhances the mRNA expression of ECM-related anti-aging genes and reduces reactive oxygen species production. Furthermore, RRFA significantly boosts the expression of Aquaporin 3 (AQP3), Filaggrin (FLG), and Hyaluronan Synthase 1 (HAS1) mRNA, alongside elevating moisture levels in a 3D epidermal model. Increases were also observed in the mRNA expression of Claudin 1 (CLDN1), Involucrin (IVL), and Zonula Occludens-1 (ZO-1) in keratinocytes. Additionally, RRFA demonstrated an inhibitory effect on melanin synthesis. Collectively, RRFA contains diverse ingredients which are beneficial for skin health and showcases multifaceted skincare effects in terms of anti-aging, antioxidant, moisturizing, repairing, and whitening capabilities in vitro, highlighting its potential for future cosmetic applications. Full article

Red rice has achieved a lot of visibility due to its greater amounts of bioactive compounds compared to traditional white rice. The increased recognition of red rice by the industry is a consequence of the expansion of its study in the field of research. The red color of its grains is characteristic of the presence of proanthocyanidins, which is associated with health benefits such as reducing the risk of chronic diseases. In addition, red rice is gluten-free and hypoallergenic, which makes it suitable for celiac or gluten-intolerant patients. However, the contents of phytochemicals can vary with the influence of the adaptability of genotypes to the environment, cultivation practices, abiotic stresses, and industrial processing. In this scenario, one of the challenges is to increase the diversity of red rice products while having a minimum impact on the content of bioactive compounds, mainly flavonoids and phenolic acids. In this review, a complete overview of the importance of pigmented red rice is presented, including the effects of different genotypes, the growth environment, and industrial processing on the bioactive compounds, mainly flavonoids and phenolic acids, in red rice, and the health benefits of its products are described. Studies cited in this review article were found by searching through the Web of Science database from 2013 to 2023. After a detailed and up-to-date search, 36 studies were included in this review article. Full article

Villosiclava virens (anamorph: Ustilaginoidea virens) is the pathogen of rice false smut (RFS), which is a destructive rice fungal disease. The albino strain LN02 is a natural white-phenotype mutant of V. virens due to its incapability to produce toxic ustilaginoidins. In this study, three strains including the normal strain P1, albino strain LN02, and complemented strain uvpks1^C-1 of the LN02 strain were employed to investigate the activation of the ustilaginoidin biosynthesis gene uvpks1 in the albino strain LN02 to influence sporulation, conidia germination, pigment production, stress responses, and the inhibition of rice seed germination. The activation of the ustilaginoidin biosynthesis gene uvpks1 increased fungal tolerances to NaCl-induced osmotic stress, Congo-red-induced cell wall stress, SDS-induced cell membrane stress, and H₂O₂-induced oxidative stress. The activation of uvpks1 also increased sporulation, conidia germination, pigment production, and the inhibition of rice seed germination. In addition, the activation of uvpks1 was able to increase the mycelial growth of the V. virens albino strain LN02 at 23 °C and a pH from 5.5 to 7.5. The findings help in understanding the effects of the activation of uvpks1 in albino strain LN02 on development, pigment production, stress responses, and the inhibition of rice seed germination by controlling ustilaginoidin biosynthesis. Full article

This study sought to evaluate starch from black and red rice modified by heat–moisture, investigating the extraction yield, starch and amylose content, color, and phenolic compounds. The water and oil absorption capacity, whole milk and zero lactose absorption index, syneresis index, and texture were also analyzed. Microstructural analysis included Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The heat–moisture treatment (HMT) reduced the extraction yield and the starch and amylose content, with native black rice starch having the highest values for these parameters. The modification also affected the color and phenolic compounds of the starch, making it darker and changing its appearance. The modification improved the absorption of water, oil, and milk, reducing syneresis and increasing stability during storage. The starch surface was altered, especially for modified black rice starch, with larger agglomerates. The type of starch also changed from A to Vh, with lower relative crystallinity. The textural properties of modified red rice starch were also significantly altered. The HMT proved to be a viable and economical option to modify the analyzed parameters, influencing the texture and physicochemical properties of pigmented rice starch, expanding its applications, and improving its stability during storage at temperatures above 100 °C. Full article

Unfavorable environmental conditions and climate change impose stress on plants, causing yield losses worldwide. The Indonesian pigmented rice (Oryza sativa L.) cultivars Cempo Ireng Pendek (black rice) and Merah Kalimantan Selatan (red rice) are becoming popular functional foods due to their high anthocyanin contents and have great potential for widespread cultivation. However, their ability to grow on marginal, high-salinity lands is limited. In this study, we investigated whether seed halopriming enhances salt tolerance in the two pigmented rice cultivars. The non-pigmented cultivars IR64, a salt-stress-sensitive cultivar, and INPARI 35, a salt tolerant, were used as control. We pre-treated seeds with a halopriming solution before germination and then exposed the plants to a salt stress of 150 mM NaCl at 21 days after germination using a hydroponic system in a greenhouse. Halopriming was able to mitigate the negative effects of salinity on plant growth, including suppressing reactive oxygen species accumulation, increasing the membrane stability index (up to two-fold), and maintaining photosynthetic pigment contents. Halopriming had different effects on the accumulation of proline, in different rice varieties: the proline content increased in IR64 and Cempo Ireng Pendek but decreased in INPARI 35 and Merah Kalimantan Selatan. Halopriming also had disparate effects in the expression of stress-related genes: OsMYB91 expression was positively correlated with salt treatment, whereas OsWRKY42 and OsWRKY70 expression was negatively correlated with this treatment. These findings highlighted the potential benefits of halopriming in salt-affected agro-ecosystems. Full article

Weeds that infest crops are a primary factor limiting agricultural productivity worldwide. Weedy rice, also called red rice, has experienced independent evolutionary events through gene flow from wild rice relatives and de-domestication from cultivated rice. Each evolutionary event supplied/equipped weedy rice with competitive abilities that allowed it to thrive with cultivated rice and severely reduce yields in rice fields. Understanding how competitiveness evolves is important not only for noxious agricultural weed management but also for the transfer of weedy rice traits to cultivated rice. Molecular studies of weedy rice using simple sequence repeat (SSR), restriction fragment length polymorphism (RFLP), and whole-genome sequence have shown great genetic variations in weedy rice populations globally. These variations are evident both at the whole-genome and at the single-allele level, including Sh4 (shattering), Hd1 (heading and flowering), and Rc (pericarp pigmentation). The goal of this review is to describe the genetic diversity of current weedy rice germplasm and the significance of weedy rice germplasm as a novel source of disease resistance. Understanding these variations, especially at an allelic level, is also crucial as individual loci that control important traits can be of great target to rice breeders. Full article