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Immunosuppressive effect of voacamine from Voacanga africana 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