The extraction of PHI was extracted, identified, and characterized (Fig.
1A, FigS1 to S5). In the present study, we found that PHI exhibits
immunosuppressive activity in vitro . PHI was analyzed to
establish appropriate levels for subsequent use that showed minimal
signs of cytotoxicity on both murine splenocytes (Fig. 1B) and
THP-1cells over a 24h time course growing in cultures (Fig. 1C).
Fig. 1. Phillygenin exhibited favorable immunosuppressive
activity in vitro. (A) Chemical structure of PHI. (B) The cell
viability of splenic lymphocytes with PHI treatment and
IC50 on ConA or LPS-induced lymphocyte proliferation.
(C) The cell viability of THP-1 with PHI treatment. (D) Cytokine
secretion levels in LPS-induced THP-1 culture. (E) The gene expression
level of cytokine in LPS-induced THP-1.
Specifically, the CC50 of PHI on murine splenocytes was found to be
35.43 μg/mL, and it also exerted ideal immunosuppressive effects on
ConA- and LPS-induced lymphocyte proliferation, with IC50 values of
4.357 and 1.539 μg/mL, respectively (Fig. 1B). Furthermore, the
anti-inflammatory activity of PHI on PMA-induced human macrophages THP-1
was also confirmed. The ELISA assay indicated that PHI could effectively
inhibit the secretion of IL-6 and TNF-α induced by LPS (Fig. 1D). On the
genetic level, PHI was found to effectively inhibit expressions of
IL-1β, IL-6, and TNF-α. Taken together, these results indicate that PHI
is a promising candidate for immunosuppressive therapy in vitro(Fig. 1E).