Isoliquiritigenin and naringenin are two active constituents of licorice to promote Treg induction and function.
(a) Structures of four major constituents from Gly1 fraction. (b) Naive CD4+ T cells were stimulated with Treg-inducing conditions in the absence or presence of isoliquiritigenin, naringenin, licoricidin, liquiritigenin. Foxp3+CD4+ Treg cells were analyzed by FACS. (c) CD4+CD25+ Treg cells untreated or treated with isoliquiritigenin were incubated with CFSE labelled CD4+CD25− conventional T cells. The suppression was assayed by FACS analysis for dilution of CFSE in gated Tconv cells. (d) Quantification of the result in (c). (e–g) C57BL/6 mice were orally administrated with isoliquiritigenin or naringenin for two weeks, colonic lamina propria Treg cells (e,f) and peripheral blood Treg cells (g) were monitored (n = 5 mice per group). Results are expressed as means ± SEM and are representative of more than three experiments. *P < 0.05, **P < 0.01 and ***P < 0.001, as determined by One-way ANOVA followed by Bonferroni’s test (b,f,g), or two-way ANOVA (d).