Aqueous extracts of Lamiaceae potently inhibit HIV-1 replication in C8166 T-cells, in the ex vivo human tonsil histoculture, and in monocyte-derived macrophages. The anti-HIVNL4-3 activity and cytotoxicity of aqueous peppermint extract was assessed in (A) C8166 T-cells or (B) human lymphoid aggregate cultures (HLAC) from tonsil in principle as described in the legend to Fig. 1. Each experiment was performed in triplicate, and 2–4 independent experiments were performed (see Table 1). Shown are arithmetic means ± SD from one experiment. (C) HIV-1YU-2 replication kinetics in monocyte-derived macrophages under conditions of continuous extract exposure. HIV-1YU-2 stocks were exposed to the indicated concentrations of lemon balm extract for 1 h at 37°C. Primary macrophages were challenged overnight with the virus-extract suspension, washed the following day, and then cells were continuously cultured in medium containing the indicated concentrations of extract. HIV-1 replication was monitored at days 1, 7, 12, and 16 post infection by p24 ELISA. (D) Relative levels of HIV-1 replication at the endpoint (day 16 post infection) relative to untreated controls with the IC50 indicated. (E) Viability. In parallel, monocyte-derived macrophages were exposed to the identical extract concentrations over the 16 day-period and then analyzed in a standard MTT assay. Shown are arithmetic means ± standard deviations relative to untreated controls (set to 100%) from one donor.