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.

Chlorophyll and total phenolic contents, antioxidant activities and consumer acceptance test of processed grass drinks.

The processed drinks produced from grass of three varieties of rice (Jasmine, Sukhothai 1 and Sukhothai 2) and one each from wheat and barley grasses were analyzed for chlorophyll and total phenolic contents, and antioxidant activities [ABTS radical cation decolorisation assay and ferric reducing/antioxidative power (FRAP) assay]. The consumer acceptance of all the drinks was also evaluated. One serving size (200 mL) of these contained 82-958 µg of chlorophyll, 5.60-26.14 mg Gallic acid equivalent for total phenolic content and their antioxidant activities, ABTS and FRAP values were 17.88-35.18 mg Vitamin C equivalent and 5.66-23.70 mg FeSO4 equivalent, respectively. The overall consumer acceptability of drinks was significantly correlated to their aroma intensity and consumer preference on aroma and flavor. Jasmine and Sukhothai 1 rice grass drinks were most preferred, however, one subgroup preferred grass drink from Sukhothai 1 rice, while the second subgroup preferred the drinks from Sukhothai 2 rice and Jasmine rice. Wheat and barley grass drinks were not preferred by both subgroups.