ANTIVIRAL ACTIVITY OF FLAVONOID-DERIVED COMPOUNDS AGAINST HEPATITIS B VIRUS
T. Pollicino1*, C. Musolino1, A. Bitto2, G. Raimondo1, F. Squadrito2, D. Altavilla2
1Internal Medicine, 2Clinical, Experimental Medicine and Pharmacology, University Hospital of Messina, Messina, Italy. ****@****
Recent evidence has shown that flavonoids may exert antiviral activities (i.e., against HIV, HSV, influenza virus and HCV) by targeting virus entry, reverse transcription or gene expression.
Aim: To investigate whether Flavocoxid (containing the natural flavonoids, baicalin and catechin) exerts any antiviral activity against HBV and, if used in combination with Entecavir (ETV), it may act synergistically to completely inhibit HBV activities.
Methods: HepG2 cells were transfected with linear wild-type HBV genomes. HBV replicating cells were treated with different dosages of Flavocoxid to determine the drug inhibitory concentrations (IC50). Treatment with Flavocoxid or ETV or with drugs combination started 3 hours after transfection and was renewed every other day for 5 days. Total HBV replicative intermediates, viral transcripts and cccDNA levels were evaluated in untreated and treated HepG2 cells by quantitative real-time PCR, Southern and Northern blots experiments. To analyse the epigenetic modulation of HBV cccDNA the cccDNA-ChIP assay was applied to untreated and treated cells.
Results: The analysis of HBV replicative intermediates synthesized in the presence or absence of Flavocoxid enabled to determine that IC50 of this drug was 75 µg/mL. Five days of Flavocoxid treatment reduced viral RNA levels by 70% than in untreated cells. The ratio between the pregenome/C-mRNA and the preS/S mRNAs did not change during treatment, indicating that all these transcripts were similarly affected by Flavocoxid. This effect was paralleled by a decrease of HBsAg amounts in the supernatants. HBV replicative intermediates decreased to more than 80% of the initial level at 5 days post-treatment. Of note, a 30% reduction of cccDNA amounts was also observed. In cells treated with Flavocoxid and ETV combination therapy, the reduction of the levels of HBV replicative intermediates, transcripts and HBsAg was of about 85%, 90% and 75%, respectively, compared to control cells. In addition, HBV cccDNA was highly hypoacetylated in cells treated with combination therapy.
Conclusions: The results of our study demonstrate for the first time that Flavocoxid:
(a) is capable to inhibit HBV replication,
(b) exerts its antiviral activity against HBV at multiple levels and
(c) acts synergistically with ETV in a cell-based HBV replication system.
Assigned speakers:
A/Prof. Teresa Pollicino, University Hospital of Messina , Messina , Italy
Assigned in sessions:
25.04.2013, 09:00-18:00, Poster Session, P01-07a, Category 07a: Viral Hepatitis B & D: Experimental, Poster Area