Differential Antioxidant Compounds and Activities in Seedlings of Two Rice Cultivars Under Chilling Treatment

Metabolic Profiling of Oryza sativa L. Triggered by Chilling Stress Using Ultraperformance Liquid Chromatography Coupled with Quadrupole/Time-of-Flight Mass Spectrometry (UPLC-QTOF-MS) with Transcriptome Analysis

Low temperature, a major abiotic stress, often causes molecular changes in crops, which leads to metabolic disturbances and probably affects crop yield. In this study, chilling stress induced distinct metabolic profiles associated with transcriptome regulation, exhibiting great metabolic differences between Qiutianxiaoting (japonica) and 93-11 (indica). In total, 41 and 58 differential metabolites were screened and identified in Qiutianxiaoting and 93-11, respectively. Five key metabolites were screened in response to chilling stress, which were involved or related to different metabolic pathways. Moreover, starch and sucrose metabolism, aminoacyl-tRNA biosynthesis, and phenylpropanoid biosynthesis were significantly enriched in Qiutianxiaoting to maintain cellular homeostasis. Aminoacyl-tRNA biosynthesis and antioxidation metabolism were significantly enriched in 93-11, but disorders of the metabolome and transcriptome occurred at recovery stage. The results could provide some useful information for in-depth understanding of cold-resistant mechanisms, as well as reference for the selection and breeding of rice varieties.

Secrets of Flavonoid Synthesis in Mushroom Cells

Flavonoids are chemical compounds that occur widely across the plant kingdom. They are considered valuable food additives with pro-health properties, and their sources have also been identified in other kingdoms. Especially interesting is the ability of edible mushrooms to synthesize flavonoids. Mushrooms are usually defined as a group of fungal species capable of producing macroscopic fruiting bodies, and there are many articles considering the content of flavonoids in this group of fungi. Whereas the synthesis of flavonoids was revealed in mycelial cells, the ability of mushroom fruiting bodies to produce flavonoids does not seem to be clearly resolved. This article, as an overview of the latest key scientific findings on flavonoids in mushrooms, outlines and organizes the current state of knowledge on the ability of mushroom fruiting bodies to synthesize this important group of compounds for vital processes. Putting the puzzle of the current state of knowledge on flavonoid biosynthesis in mushroom cells together, we propose a universal scheme of studies to unambiguously decide whether the fruiting bodies of individual mushrooms are capable of synthesizing flavonoids.

Enhancement Methods of Antioxidant Capacity in Rice Bran: A Review

Rice (Oryza sativa L.) is a primary food that is widely consumed throughout the world, especially in Asian countries. The two main subspecies of rice are japonica and indica which are different in physical characteristics. In general, both indica and japonica rice consist of three types of grain colors, namely white, red, and black. Furthermore, rice and rice by-products contain secondary metabolites such as phenolic compounds, flavonoids, and tocopherols that have bioactivities such as antioxidants, antimicrobial, cancer chemopreventive, antidiabetic, and hypolipidemic agents. The existence of health benefits in rice bran, especially as antioxidants, gives rice bran the opportunity to be used as a functional food. Most of the bioactive compounds in plants are found in bound form with cell wall components such as cellulose and lignin. The process of releasing bonds between bioactive components and cell wall components in rice bran can increase the antioxidant capacity. Fermentation and treatment with enzymes were able to increase the total phenolic content, total flavonoids, tocotrienols, tocopherols, and γ-oryzanol in rice bran.

Identifying Chemical Composition, Safety and Bioactivity of Thai Rice Grass Extract Drink in Cells and Animals

Rice grass has been reported to contain bioactive compounds that possess antioxidant and free-radical scavenging activities. We aimed to assess rice grass extract (RGE) drink by determining catechin content, free-radical scavenging and iron-binding properties, as well as toxicity in cells and animals. Young rice grass (Sukhothai-1 strain) was dried, extracted with hot water and lyophilized in a vacuum chamber. The resulting extract was reconstituted with deionized water (260 mg/40 mL) and served as Sukhothai-1 rice grass extract drink (ST1-RGE). HPLC results revealed at least eight phenolic compounds, for which the major catechins were catechin, epicatechin and epigallocatechin-3-gallate (EGCG) (2.71-3.57, 0.98-1.85 and 25.47-27.55 mg/40 mL serving, respectively). Elements (As, Cu, Pb, Sn and Zn) and aflatoxin (B1, B2, G1 and G2) contents did not exceed the relevant limits when compared with WHO guideline values. Importantly, ST1-RGE drink exerted radical-scavenging, iron-chelating and anti-lipid peroxidation properties in aqueous and biological environments in a concentration-dependent manner. The drink was not toxic to cells and animals. Thus, Sukhothai-1 rice grass product is an edible drink that is rich in catechins, particularly EGCG, and exhibited antioxidant, free radical scavenging and iron-binding/chelating properties. The product represents a functional drink that is capable of alleviating conditions of oxidative stress and iron overload.

Primary and Phenolic Metabolites Analyses, In Vitro Health-Relevant Bioactivity and Physical Characteristics of Purple Corn (Zea mays L.) Grown at Two Andean Geographical Locations

Purple corn (Zea mays L.) is native to the Andean region, but limited research has been performed about the potential metabolic variability when grown under Andean environmental conditions. This study was aimed at evaluating the phenolic and primary polar metabolites composition of purple corn (kernels and cobs) grown at two Peruvian Andean locations (lowland and highland) using targeted UHPLC (ultra-high-performance liquid chromatography) and untargeted GC-MS (gas chromatography mass spectrometry) metabolomic platforms, respectively. Changes in the physical characteristics and the in vitro bioactivity were also determined. Purple corn from the highland zone showed higher contents of ash, crude fiber, total phenolic contents, DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant capacity, and α-amylase inhibitory activity in kernels, whereas increased levels of flavonoids (anthocyanins and quercetin derivatives) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] antioxidant capacity were observed in cobs in comparison to lowland samples. No effect of the Andean location was found on the α-glucosidase inhibitory activity relevant for hyperglycemia management, while yield-linked physical characteristics were high in purple corn grown at the lowland zone. Polar primary metabolites related to the carbohydrate (monosaccharides, sucrose, and d-sorbitol), amino acid (valine and alanine), and tricarboxylic acid cycle (succinic, fumaric, and aconitic acid) metabolism were higher in highland purple corn (cob and kernel) likely due to abiotic stress factors from the highland environment. This study provides the foundation for further breeding improvements at Andean locations.