Evaluation of licorice (Glycyrrhiza glabra L.) as a novel microgreen from the anti-inflammatory potential of polyphenols

Literature on microgreens, an emerging new functional food crop, remains limited. Further study on microgreens as a promising dietary component for potential use in diet-based disease prevention is, therefore, essential. Given that the anti-inflammatory and anti-oxidant properties of mature licorice root material are well-documented, the objective of the present, preliminary study was to present licorice (Glycyrrhiza glabra L.) as a novel, edible fresh-food microgreen candidate. The effect of leaf, stem and root polyphenol extracts of 20-day old licorice microgreen seedlings on cell proliferation and viability of Caco-2 cells (simulating the intestinal epithelium), after pro-inflammatory induction of lipopolysaccharide (LPS), was examined and then compared to the polyphenol, flavonoid and anti-radical activities of the respective tissue extracts. Root extracts contained a two-fold less polyphenol (including flavonoid) content compared to leaf extracts, but with a five-fold lower anti-radical scavenging activity. Only the root extracts provided functional protection in terms of preserving cell proliferation and viability of LPS-treated Caco-2 cells. Some protection was also afforded by the stems, but the young leaf material offered no anti-inflammatory protection. Results point to a differing composition of anti-inflammatory polyphenols between the root and leaf, suggesting that the protective efficacy of the root extracts (and to some degree, the stem extracts) resides in inhibiting the pro-inflammatory cascade and resultant cytotoxic effects as opposed to a direct anti-radical scavenging activity. Potential use of licorice as a microgreen is promising, but will necessitate further study.