B lymphoma Ramos cells were used as the research object to explore the inhibitory effect of α-mangostin (α-Ma) on the proliferation of B lymphoma and explain its molecular mechanism.Firstly,the inhibitory effect of α-Ma on Ramos cells was investigated by the CCK-8 method.Then the effect of α-Ma on the morphology of Ramos cells was observed by inverted microscope imaging.DCFH-DA,JC-1,Annexin V-FITC/PI fluorescence dye,and flow cytometry were used to detect the effects of α-Ma on the level of reactive oxygen species,mitochondrial membrane potential,and apoptosis in Ramos cells.Western blot was used to detect the expression of apoptosis-related proteins and signal pathway proteins in Ramos cells treated with α-Ma.CCK-8 analysis showed that α-Ma inhibited the proliferation of Ramos cells in a concentration-dependent and time-dependent manner,and its IC₅₀ values at 24 h and 48 h were 14.84 μmol/L and 8.087 μmol/L,respectively.Inverted microscope imaging revealed that α-Ma reduced the number of Ramos cells and induced apoptosis-like changes in cell morphology.Flow cytometry analysis showed that α-Ma increased the level of reactive oxygen species,decreased the mitochondrial membrane potential,and induced apoptosis in Ramos cells.Western blot showed that α-Ma could down-regulation the expression of caspase-3/9 and up-regulate the expression of cleaved caspase-3/9,cleaved PARP,Bax,Bim,and p-p38 MAPK.In conclusion,α-Ma can inhibit the proliferation of B lymphoma Ramos cells,and the possible mechanism is that α-Ma activated ROS/p38 MAPK/Bax cascade reaction to induce apoptosis of B lymphoma cells.