6th International AIDS Conference


San Francisco, California, USA — June 20-23, 1990

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Inhibition of HTLV-I viral production by two plant compounds, baicalein and extracts of Phyllanthus urinaria.

Int Conf AIDS 1990 Jun 20-23; 6:330 (abstract no. 1064)
Baylor NW, Tao F, Ruscetti F; BCDP, PRI, NCI-FCRF, Frederick, MD. USA

OBJECTIVE: The effects of 2 plant compounds, baicalein (5,6,7 trihydroxyflavone) and a purified aqueous extract of Phyllanthus urinaria, on their ability to inhibit the production of HTLV-I in chronically infected cells were examined. Antiviral activity of both compounds has been previously reported (Ono, K. et. al., 1989. Biochem. Biophys. Res. Comm. 160: 982; Ven Kateswaran, P.S. et al., 1987. Proc. Natl. Acad. Sci. USA 84:274).

METHOD: HTLV-I infected producer T cell lines MT-2 and CS-1, and infected B lymphocytes HS-1 and CS-2 which express 3 logs less of HTLV-1 encoded protein, p19 (Longo, D,L., et al., 1984. Nature 310:505) were used. Viral production was tested by measuring HTLV-I p19 activity and HTLV-I LTR transactivation before and after 24-48 hour treatment with either baicalein or phyllanthus extract.

RESULTS: The majority (greater than 95%) of HTLV-I p19 production in chronically infected cells was abolished with ED50 concentrations of baicalein being 80 mug/ml and phyllanthus 133 mug/ml. Greater than 75% inhibition was observed at concentrations that produced little inhibition of total cellular protein synthesis or cellular DNA synthesis in infected cells, with no loss in cell viability. Transactivation of HTLV-I LTR was essentially normal after drug treatment.

CONCLUSION: These results indicate that baicalein and purified extracts of phyllanthus possess antireplicative potential against HTLV-I in vitro. The clinical potential of these two compounds in the therapy of HTLV-I adult T-cell leukemia remains to be determined by elucidating the mechanism(s) which underlies the observed selective anti-HTLV-I activity of these two compounds.

Keywords: AEGIS, Human T-lymphotropic virus 1, Deltaretrovirus, Leukemia-Lymphoma, T-Cell, Acute, HTLV-I-Associated, Deltaretrovirus Infections, Leukemia, T-Cell, Cell Line, T-Lymphocytes, Terminal Repeat Sequences, Trans-Activation (Genetics), B-Lymphocytes, Plants, Adult, In Vitro, virology, genetics, ICA6

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