ABSTRACT
Objective: To investigate the anti-HIV-1 activity and mechanism of pine cone extracts from Pinus kesiya var. langbianensis in vitro. Methods: The cytotoxicity of pine cone extract from P. kesiya var. langbianensis was examined by MTT assay; Syncytium formation inhibition assay, p24 assay, and the HIV-1-induced MT-4 cell death assay were used to evaluate the anti-HIV-1 activity of pine cone extract from P. kesiya var. langbianensis. HIV DNA species detection assay, cell fusion assays, and time of addition assay were used to determine the mechanisms of the extracts. Results: Pine cone extract from P. kesiya var. langbianensis named SMS-F showed the good inhibition on HIV-1 in C8166 cells with TI value above 436.46 and 558.61, respectively. HIV-1 DNA species detection showed that ssDNA and late-RT were lower in the SMS-F treated group than those in the control group. The result implied that the mechanism of SMS-F might target the early stage of HIV-1 replication. SMS-F blocked the cell to cell fusion with EC50 value 71.03 μg/mL and could not inhibit the replication of HIV-1 after entering the cell, which confirmed SMS-F targeting the HIV entry stage. Conclusion: Pine cone extract from P. kesiya var. langbianensis shows the good inhibition on HIV-1 targeting the viral entry stage.