<b><i>Background:</i></b> Many efforts are currently focused on functional treatment of the hepatitis B virus (HBV). This can be done by suppressing the secretion of HBV surface antigen (HBsAg). Scientific communities are very interested in natural products in that respect. <b><i>Objective:</i></b> Use of root extract of Havachoobe (<i>Onosma dichroanthum BoissI</i>), a Northern Iranian native medical herb, for assessment of its anti-HBsAg secretion activity. <b><i>Methods:</i></b> Havachoobe had been bought at a nearby apothecary store. Plant root extract was obtained using a hydroalcoholic process. Cytotoxic activity of the extract was examined on PLC/PRF/5 cells using MTT assay. ELISA has been used to measure HBsAg in the treated cell line supernatants. In addition, real-time PCR analysis was performed to evaluate the expression of HBsAg before and after treatment of Onosma in vitro. <b><i>Results:</i></b> The results showed very low root extract cytotoxicity at concentrations under 8 μg/mL. Tissue culture infectious dose 50 was obtained at 63.78 μg/mL. In a dose-dependent and time-dependent manner, a significantly reduced HBsAg secretion was observed at a concentration of 8 ppm at 12 h post-treatment. The real-time PCR result showed relative decreased HBsAg expression at all doses at 12 h post-treatment time. <b><i>Discussion:</i></b> In this study, we first reported anti-HBsAg activity on an Iranian herbal medicine. Havachoobe root extract was shown to be able to inhibit HBsAg in a dose-dependent and time-dependent manner. We find the extract exerts its inhibitory effect of HBsAg by targeting transcription of HBsAg.

Background and objectives: Drug resistance in Staphylococcus aureus and Escherichia coli, as severe pathogenic bacteria, has become a health challenge. However, nanoparticles have been introduced as effective candidates for their eradication. In this study, we investigated presence of genes involved in conferring resistance to silver nanoparticles in S. aureus and E. coli isolates and evaluated its association with minimal inhibitory concentration (MIC) of the nanoparticles against these isolates. Methods: The MIC of silver nanoparticles against 121 clinical isolates of E. coli and 183 S. aureus isolates was assessed by broth microdilution assay. Presence and expression of the silver resistance genes (silE, silR/S) in the isolates were investigated by PCR and real-time PCR, respectively. Results: The silE gene was found in three (1.6%) S. aureus and four (3%) E. coli isolates. MIC of silver nanoparticles against S. aureus isolates with the silE gene was 1, 2 and 8 µg/ml. Moreover, the MIC of the nanoparticles against silEpositive E. coli isolates was 16 μg/ml in three cases and 8 μg/ml in one case. None of the S. aureus isolates contained the silR/S gene, but presence of both silE and silR/S was confirmed in two E. coli isolates. Real-time PCR showed no sil expression in the isolates containing the resistance genes. Conclusion: The frequency of the silver resistance genes among S. aureus and E. coli isolates is very low. There is no relationship between presence of the resistance genes and the MIC value of silver nanoparticles.

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