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Immunosuppressive effect of voacamine from <i>Voacanga africana</i> Stapf based on SPRi experiment


Hong Xiang Li
Yan Qiu Wang
Jin Shuang Zhao
Li Xia Zhu
Wen Ying Huai
Rong Qiang Liu
Tian E. Zhang
Yun Deng

Abstract

Purpose: To investigate the affinity of a bis-indole alkaloid - voacamine from Voacanga Africana Stapf for IL-2Rα - and its immunosuppressive effect on concanavalin A-induced T cell proliferation and lipopolysaccharide -induced B cell proliferation in vitro.


Methods: Surface plasmon resonance imaging (SPRi) was used to screen the target protein of voacamine, while CCK-8 kit was used to evaluate cytotoxicity. Mitogen-induced proliferation assay was carried out to assess the inhibitory effect of voacamine on Con A-induced T cell proliferation and LPSinduced B cell proliferation. The binding characteristics of voacamine were investigated using a binding model with IL-2Rα constructed based on molecular docking simulation.


Results: Voacamine had a high-affinity for IL-2Rα with an equilibrium dissociation constant (KD) of 1.85×10-8 M. Cytotoxicity data showed that voacamine did not exhibit cytotoxicity at concentrations lower than 0.32 µM. However, it exerted significant immunosuppressive effect on B cells at a lower concentration, but had no influence on proliferation of T cells. Autodock results indicate that voacamine has a good interaction with the enzyme active site.


Conclusion: Voacamine and its analogues exert influence on the immune system.


Journal Identifiers


eISSN: 1596-9827
print ISSN: 1596-5996