Anti-hepatitis B virus activity of Boehmeria nivea leaf extracts in human HepG2.2.15 cells

Abstract

Boehmeria nivea (Linn.) Gaudich of the Urticaceae family is a perennial ratoon herbal plant, the root of which is used in traditional Chinese medicine and possesses a variety of pharmacological properties. The 20% ethanol Boehmeria nivea root extract was shown to exert an anti-hepatitis B virus (HBV) effect in vitro and in vivo; however, whether the Boehmeria nivea leaf (BNL) extract possesses similar properties has not been determined. In this study, we aimed to investigate the anti-HBV effects of the BNL extract in HepG2.2.15 cells transfected with human HBV DNA. Our results demonstrated that the secretion of HBsAg and HBeAg was reduced in HepG2.2.15 cells treated with the BNL extract, without any recorded cytotoxic effects. In addition, the chloroform fraction (CF) and ethyl acetate fraction (EAF) of BNL were shown to be more potent compared to the other fractions: CF (100 mg/l) inhibited the secretion of HBsAg by 94.00±1.78% [inhibitory concentration 50 (IC₅₀) = 20.92 mg/l] and that of HBeAg by 100.19±0.35% (IC₅₀=19.67 mg/l) after 9 days of treatment. Similarly, EAF (200 mg/l) inhibited the secretion of HBsAg by 89.95±2.26% (IC₅₀=39.90 mg/l) and that of HBeAg by 98.90±1.42% (IC₅₀=36.45 mg/l). Furthermore, we observed that the content of HBV DNA in the medium secreted by the HepG2.2.15 cells was significantly decreased under CF (100 mg/l) or EAF (200 mg/l) treatment. Thus, we concluded that the BNL extracts exhibited anti-HBV activity, with CF and EAF being the most potent among the fractions.

Keywords: Boehmeria nivea leaf; HBeAg; HBsAg; HepG2.2.15 cell; hepatitis B virus; hepatitis B virus DNA.

Figure 1

BNL extraction procedure. Dried BNL (7 kg) was extracted in a stepwise procedure. Finally, 27 g of petroleum ether, 35 g of chloroform, 25 g of ethyl acetate, 75 g of n-butanol and 34 g of aqueous extracts were harvested. BNL Boehmeria nivea leaf; PEF, petroleum ether fraction; CF, chloroform fraction; EAF, ethyl acetate fraction; nBF, n-butanol fraction; AF, aqueous fraction.

Figure 2

Effects of CF and EAF on HBV DNA in the medium secreted by HepG2.2.15 cells. A total of 1×10⁴ cells were seeded in 96-well plates and cultured for 24 h prior to the addition of CF or EAF. The medium was changed three times every 3 days and replaced with fresh medium containing the corresponding extracts. At different time points (3, 6 or 9 days), medium was collected and the HBV DNA content was measured. Under the same conditions, 3TC was used as a positive control. Con, control; CF, chloroform fraction; EAF, ethyl acetate fraction; HBV, hepatitis B virus; 3TC, 2′-3′deoxy-3′-thiocytidine.