Ethyl Acetate Extract from Romdoul (Sphaerocoryne affinis) Fruit Induced Apoptosis in Human Promyelocytic Leukemia Cells.

Background: Romdoul (Sphaerocoryne affinis) is a flowering plant of the Annonaceae family and has been used customarily in folk medicine. The bioactivities of this plant, especially the anti-cancer effect, however, remain surprisingly few.

Objective: this study aimed to elucidate the anti-leukemic effect of romdoul fruit extracts and their underlining mechanisms.

Methods: The extracts were prepared from fresh fruits and the phytochemical contents were evaluated by biochemical assays and HPLC method. The promising extract was identified via the inhibition of HL60 as well as normal NIH-3T3 cell densities utilizing MTT assay. The underline mechanism of the extract's effect was studied by accessing the treated HL60 cell population overtime (via MTT assay). The morphology of abnormal cells was examined by bright-field microscopic imaging. Hallmarks of apoptosis including nucleus characteristics and caspase 3 activation were analyzed by fluorescence imaging. The underline mechanisms of apoptosis and proliferation inhibition were accessed via RT-qPCR examination of involved genes.

Results: Our findings showed that the ethyl acetate extract of romdoul fruit (SA-EA) was found to be an exceptional anti-leukemic candidate (IC₅₀ was as low as 4.11 μg/mL). More interestingly, the treated HL60 cells expressed nuclear fragmentation and caspase 3 activation, indicating the effect could follow an apoptotic mechanism. Importantly, the transcription assessment of apoptotic and proliferative genes suggested that SA-EA might suppress the growth of HL60 cells and induce p21-dependent apoptotic pathway.

Conclusion: This study demonstrated one of the first scientific evidence for the anti-cancer activity of Sphaerocoryne affinis fruit-derived extract. Thus, our findings exhibited a novel and promising anti-leukemic candidate for future studies.