Transcriptional suppression of the HIV promoter by natural compounds

Tannins and lignins are natural compounds contained in plants such as tea leaves. Previously, we demonstrated that tannic acid represses 12-o-tetra-decanoyl phorbol-13-acetate (TPA)-induced human immunodeficiency virus (HIV) promoter activity. Furthermore, we demonstrated that a 30-bp element located just downstream of the NF-κB element in the HIV promoter responds negatively to tannic acid. However, the kinds of molecules responsible for this suppressive effect have remained unknown, because tannic acid is a mixture of various galloylglucoses. Here, we examined structure-defined natural compounds for HIV promoter-suppressive effects. We found that ellagitannins suppress TPA-induced HIV promoter activity to the same extent as tannic acid. 3-Phenylcoumarins, isoflavone and chalcones have more suppressive effects than ellagitannins. On the other hand, other flavonoids and acetogenins have no suppressive effect. 3-Phenylcoumarins and chalcones showed no suppressive effect on the cytomegalovirus (CMV) promoter, suggesting that they act specifically on the HIV promoter. These results suggest that 3-phenylcoumarin or chalcone compounds could be used to develop novel anti-HIV drugs with an action targeted at HIV promoter activity.