The anti‑hepatitis B virus activity of sea buckthorn is attributed to quercetin, kaempferol and isorhamnetin
Mohammad Khalid Parvez, Mohammed S. Al‐Dosari, Omer A. Basudan, Rashed N. Herqash
Abstract
The present study assessed the <em>in vitro</em> anti‑hepatitis B virus (HBV) effects of cold‑adapted sea buckthorn (<em>Hippophae rhamnoides</em>). Sea buckthorn leaf ethanol extracts subjected to chloroform (SB‑Chl), ethyl acetate (SB‑Eac), <em>n</em>‑butanol (SB‑But) and aqueous (SB‑Aqu) fractionation were first examined (MTT assay) for their toxic effects on HepG2 cells. While SB‑Chl (IC<sub>50</sub>, 32.58 µg/ml) exhibited high cytotoxicity, SB‑Eac, SB‑But SB‑Aqu were non‑toxic at up to 150 µg/ml. High performance liquid chromatography analysis led to the identification of the anti‑HBV active flavonols, quercetin (93.09 µg/g), kaempferol (44.19 µg/g) and isorhamnetin (138.75 µg/g) in the extract. The analysis of the anti‑HBV effects of SB‑Eac, SB‑But and SB‑Aqu (50 µg/ml, each) on HepG2.2.15 cells revealed the marked inhibition of HBsAg and HBeAg expression levels. At the concentration of 10 µg/ml, quercetin and kaempferol exerted potent inhibitory effects on HBsAg (60.5 and 62.3%, respectively) and HBeAg synthesis (64.4 and 60.2%, respectively), as compared to isorhamnetin (30.5 and 28.4%, respectively). The HBV‑polymerase inhibitor drug, lamivudine (2 µM), inhibited HBsAg and HBeAg expression by 87.4 and 83.5%, respectively. The data were in good agreement with a previous <em>in vitro</em> and <em>in silico</em> molecular docking analysis performed by the authors where quercetin, kaempferol and lamivudine had formed stable complexes with HBV‑polymerase binding‑pocket amino acids. On the whole, to the best of our knowledge, the present study provides the first report of the anti‑HBV therapeutic potential of sea buckthorn, attributed to quercetin, kaempferol and isorhamnetin.