OBJECTIVETo investigate the effect of Euphorbia fischeriana extract on latent HIV reactivation and the pathway involved in this process and discuss the value of Euphorbia fischeriana extract in eliminating HIV.

METHODSFresh tissues of Euphorbia fischeriana root were crushed into powder after quick freezing with liquid nitrogen and extracted with acetone followed by a three-day vacuum freeze-drying for dehydration of the extract. The extract (EFE) was separated using RP-C18 column with high-performance liquid chromatography (HPLC) and identified with mass spectrometry (MS). The activity of reactivated latent HIV was analyzed by fluorescence-activated cell sorting in a J-Lat 10.6 cell model treated with EFE (50 µg/mL) for 24 h, using TNF-α (10 ng/mL) as the positive control. The effect of a NF-κB pathway inhibitor (Bay 11-7082) on EFE activity was tested. The changes in P65 expression in the cell nuclei within 2 h and HIV protein p24 expression within 24 h were analyzed by Western blotting in cells treated with EFE.

RESULTSEFE was obtained by one-step acetone extraction, and the concentration of prostratin in the extract was around 0.53 mmol/L. About 50% of the cells showed HIV reactivation after treatment with 50 µg/mL EFE for 24 h accompanied by a significantly increased p24 expression. The activity of EFE in reactivating latent HIV was inhibited by Bay 11-7082 in a concentration-dependent manner, and p65 accumulation was detected in the cell nuclei within 2 h.

CONCLUSIONEFE we obtained contains the active compounds of prostratin and its analogues and shows a strong capacity to reactivate latent HIV through classical NF-κB pathway.