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

Suthaya Phimphilai,Pimpisid Koonyosying,Chaiyavat Chaiyasut,Nuntouchaporn Hutachok,Rufus Daw,Somdet Srichairatanakool,Vanli Prasartthong-Osoth,Tanyaluk Kampoun

doi:10.3390/molecules26226887

Suthaya Phimphilai, Pimpisid Koonyosying + Show 6 more

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https://doi.org/10.3390/molecules26226887

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Abstract

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.

Highlights

Known endogenous antioxidant sources are superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), glutathione reductase, glutathione (GSH) and their reducing equivalents, while exogenous sources include vitamin C, vitamin E, vitaminA, β-carotene, selenium and dietary polyphenols [1]
We found that 2,2-diphenyl-1-picrylhydrazyl radical (DPPH ) generation was inhibited by ST1-rice grass extract (RGE) and Trolox treatments in a dose-dependent manner with concentrations at 50% inhibition (IC50 ) values of 0.15 mg/mL and 0.01 mg/mL, respectively (Figure 2)
The results indicate that the body weight (BW) of the rats treated with DI and Sukhothai-1 rice grass extract drink (ST1-RGE)

Summary

Introduction

Known endogenous antioxidant sources are superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), glutathione reductase, glutathione (GSH) and their reducing equivalents, while exogenous sources include vitamin C, vitamin E, vitaminA, β-carotene, selenium and dietary polyphenols [1]. Certain polyphenols, including catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG) and epigallocatechin-3-gallate (EGCG), are found in the form of secondary metabolites in numerous plants [4] They are known to exert antioxidative and free-radicals scavenging properties due to the aromatic hydroxyl groups present at the two phenolic rings [5]. Green tea-derived EGCG and ECG exhibited iron-chelating properties by lowering levels of iron overload and oxidative stress in β-thalassemic mice [8]. These molecules could pass through the cell membrane with a significant degree of efficacy by acting as a powerful antioxidant and chelator source [9]

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