Anti-UV/HIV activity of Kampo medicines and constituent plant extracts

In order to search for new biological activities of Kampo medicines and their constituent plant extracts, we investigated whether they protect the cells from the cytotoxicity induced by UV irradiation and human immunodeficiency virus (HIV) infection.

Anti-UV/HIV activity (SI value) was evaluated as the ratio of the CC(50) (concentration that reduced the viable cell number by 50%) to the EC(50) (the concentration that increased the viability of UV-irradiated or HIV-infected cells to 50%): SI=CC(50)/EC(50). The content of glycyrrhizin in each sample was determined by high performance liquid chromatography (HPLC). Caspase-3/-7 activity was assayed by cleavage of poly ADP ribose polymerase using western blot analysis.

Among 25 plant extracts, Gardenia fruit had the highest anti-UV activity (SI≥8.0), followed by Glycyrrhiza (SI=4.3), Coptis rhizoma (SI=1.5), Cimicifuga rhizoma (SI>1.4), Saposhnikovia root (SI>1.3) and Japanese Gentian (SI>1.1). Among ten Kampo medicines, Unseiin and Hangesyashinto (SI>4.9) had the highest anti-UV activity, followed by Shosaikoto (SI>4.3), Saireito (SI>3.4), Rikkosan (SI>1.2) and Kikyoto (SI=1.1). Glycyrrhiza inhibited UV-induced caspase-3/-7 activation. Only Polyporus sclerotium (SI>4.4), Gardenia fruit (SI>2.7), Atractylodes lancea rhizoma (SI>1.9), Cnidium rhizoma (SI>1.5) and Japanese Angelica root (SI>1.1) exhibited some anti-HIV activity. There was no apparent correlation of their anti-UV/HIV activity and content of glycyrrhizin, a major component of Glycyrrhiza, which exhibited much higher anti-UV activity (SI=20.6) and some anti-HIV activity (SI>2.0).

The present study suggests the involvement of substances other than glycyrrhizin in the anti-UV/HIV activity of Kampo medicines and their constituent plant extracts.