Sup[ina] Food? Health‐Promoting Potential of Grasses

Abstract

Part of living a healthy lifestyle is maintaining a healthy diet. Eating more fruits and veggies, choosing lean proteins, and resisting the temptation of the break room doughnuts. Some people will also look for foods know to contain high levels of antioxidants and other bioactive compounds. Bioactive compounds in food influence physiological or cellular activities in the organisms that consume that food. Research on this topic varies from identifying foods that contain these compounds to understanding the potential benefits and negative consequences of consuming bioactive compounds. For Vicki Schlegel, an Associate Professor at the University of Nebraska–Lincoln, investigating bioactive compounds in plants merges her training as an analytical chemist with her experience working in the pharmaceutical industry. The idea to look for bioactive compounds in grasses came from a former graduate student at the university, Casey Wenger. The reasoning was that plants within the grass family (Poaceae) are abundant, found across the globe, and are relatively easy to grow. Humans already grow plants in the grass family for food in the form of cereal grains like corn and wheat. However, fewer people consume the leaves of grasses. Wheatgrass is one example of a grass grown where the newly sprouted shoots are consumed as juice or a dried powder. “Grasses could be used for many health-promoting benefits, but research remains very severely limited on this highly abundant but under-utilized natural product,” Schlegel says. Prior and ongoing research by Schlegel and colleagues involves screening grasses, including non-cereal grasses, for bioactive compounds. In a study recently published in Crop Science (https://bit.ly/2wO9ftG), these researchers investigate two Poaceae species (supina bluegrass and bermudagrass) to identify and measure bioactive compounds, specifically phenols, at different growth stages. The grasses were grown from seed in a greenhouse and harvested at 3, 7, 14, and 21 days post-germination. The researchers measured antioxidant capacity using the oxygen radical absorbance capacity (ORAC) test, and phenols were quantified using high-performance liquid chromatography (HPLC) methods. Bioactive compounds were present in both bermudagrass and supina bluegrass, and these levels were observed to fluctuate with time since germination. For example, the total soluble free flavonoid (TSFF) levels in bermudagrass were observed to increase over time. Conversely, the TSFF levels in supina bluegrass were significantly greater on Days 3 and 21 compared with Days 7 and 14. In general, the levels of bioactive compounds are surprisingly high. Earlier work found the levels of total soluble free phenolics in bermudagrass and supina bluegrass were similar to the levels found in blueberries. However, Schlegel points out that “unlike fruit that can typically be harvested once annually, grasses provide a constantly renewable bioactive resource.” She says that the most important discovery was finding the compound catechin in supina bluegrass. Catechin is present in green tea and is a phenolic flavonoid shown to have anti-oxidative and anti-inflammatory properties, targeting cancer cells, and to reduce heart disease and obesity. The authors determined that catechin is abundant in supina at certain germination stages. This study also documents an important finding that the phenolic profile, which is both the types and levels of phenols present, varied over time. The differences in phenolic profile on different days was unexpected. Understanding what phenols are present and at what time following germination is important if turfgrasses are ever to be grown for health supplements. While we are a long way off from adding lawn clippings to our morning smoothie, the potential for grasses as a source of bioactive compounds is demonstrated by this work. Schlegel says that future research is needed to understand how to extract bioagents; explore how these phenols work in isolation and in combination with other compounds, like proteins and sugars; and determine the effects of germination and other growth conditions and farming practices on multiple grasses. View the full article, “Phenolic Content and Profile Alterations during Seedling Growth in Supina Bluegrass and Bermudagrass,” in the September–October 2018 issue of Crop Science: https://bit.ly/2wO9ftG.