Rice Bran Metabolome Contains Amino Acids, Vitamins & Cofactors, and Phytochemicals with Medicinal and Nutritional Properties

Iman Zarei,Dustin G Brown,Nora Jean Nealon,Elizabeth P Ryan

doi:10.1186/s12284-017-0157-2

Abstract

BackgroundRice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Food metabolomics uses multiple chromatography and mass spectrometry platforms to detect and identify a diverse range of small molecules with high sensitivity and precision, and has not been completed for rice bran.ResultsThis study utilized global, non-targeted metabolomics to identify small molecules in rice bran, and conducted a comprehensive search of peer-reviewed literature to determine bioactive compounds. Three U.S. rice varieties (Calrose, Dixiebelle, and Neptune), that have been used for human dietary intervention trials, were assessed herein for bioactive compounds that have disease control and prevention properties. The profiling of rice bran by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography–mass spectrometry (GC–MS) identified 453 distinct phytochemicals, 209 of which were classified as amino acids, cofactors & vitamins, and secondary metabolites, and were further assessed for bioactivity. A scientific literature search revealed 65 compounds with health properties, 16 of which had not been previously identified in rice bran. This suite of amino acids, cofactors & vitamins, and secondary metabolites comprised 46% of the identified rice bran metabolome, which substantially enhanced our knowledge of health-promoting rice bran compounds provided during dietary supplementation.ConclusionRice bran metabolite profiling revealed a suite of biochemical molecules that can be further investigated and exploited for multiple nutritional therapies and medical food applications. These bioactive compounds may also be biomarkers of dietary rice bran intake. The medicinal compounds associated with rice bran can function as a network across metabolic pathways and this metabolite network may occur via additive and synergistic effects between compounds in the food matrix.

Highlights

Rice bran is a functional food that has shown protection against major chronic diseases in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals
The outer covering of the rice grain, contains a unique profile of phytochemicals with medicinal and nutritional properties that are beneficial to human health, some of which have been targeted for nutraceutical development for cancer (Henderson et al 2012; Verschoyle et al 2007), type 2 diabetes (Cheng et al 2010; de Munter et al 2007; Qureshi et al 2002), lipid metabolism regulation (Kuriyan et al 2005; Qureshi et al 1997; Shibata et al 2016; Wang et al 2015), immune regulatory processes (Wang et al 2015), and obesity (Ham et al 2015)
Non-Targeted Rice Bran Metabolomics The metabolite profile composition of rice bran revealed 453 metabolites with known identity that were clustered into the following metabolic pathways: amino acid

Summary

Introduction

Rice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Rice bran contains nonsaponifiable lipids (i.e. gamma oryzanol), vitamin E (e.g. tocopherols and tocotriols), polyphenols (e.g. ferulic acid caffeic acid and salicylic acid), and phytosterols (e.g. betasitosterol) (Henderson et al 2012) with reported health properties. Many of these compounds are available in the lipid fraction and known as rice bran oil Given the emphasis in previous studies on rice bran lipids (Forster et al 2013), this analysis focused on rice bran amino acids, cofactors & vitamins, and secondary metabolites that have medicinal and nutritional properties important to human health

Methods

Results

Discussion

Conclusion