Abstract
It has been reported that extracts of the spike of Prunella vulgaris (PS) exhibit anti-HIV activity at the adsorption and reverse transcription stages. In this study, the actual activity of PS in cells, kinetic analysis of the inhibitory activity of PS against HIV reverse transcriptase and the feasibility of oral administration were examined. First, to clarify whether this extract shows anti-HIV activity in cells in vitro, the number of copies of proviral DNA in HIV-exposed cells was calculated. The number of copies was significantly decreased in cells cultured in the presence of PS extract, but not in the presence of dextran sulphate. The activity of PS extract in the cells was also assessed by the drug addition test, during and after HIV adsorption. PS extract and dextran sulphate suppressed HIV production to similar levels when added after HIV adsorption. However, only PS extract suppressed HIV production at the same concentration when the drugs were added during HIV adsorption. Presumably, the penetration of the PS extract into the cells was required for this activity. Secondly, fractionated PS inhibited HIV reverse transcription in a non-competitive manner. This fractionated PS kept anti-HIV activity, but inhibited HIV replication and adsorption to a lesser extent compared to dextran sulphate. Lastly, an active component(s) was detected in plasma in vivo, after injection into the intestine, which demonstrates the feasibility of oral administration dosing.