Aloe emodin isolated from Cassiae semen upregulates IFITM1 to suppress hepatitis B virus replication via the interferon signaling pathway

The seeds of Cassia obtusifolia L. or Cassia tora L., known as Cassiae semen (juemingzi in Chinese), has been traditionally utilized for its hepatoprotective, lipid-lowering, anti-inflammatory, and immunomodulatory properties. However, their effects on hepatitis B virus (HBV), which causes chronic Infection leading to liver cirrhosis and hepatocellular carcinoma, remain largely unexplored. In this study, we prepared Cassiae semen water extract (CWE) and evaluated its impact on HBV replication using HepAD38 cells. Our results showed that CWE suppressed HBV replication in a concentration-dependent manner. To identify the bioactive components, several compounds derived from Cassiae semen, including cassiaside C, rubrofusarin-6-O-β-gentiobioside, aurantioobtusin, and aloe emodin, were tested for their anti-HBV activity. Among them, aloe emodin exhibited the most potent anti-HBV activity. Further mechanistic investigations indicated that the Antiviral effects of CWE and aloe emodin were associated with the interferon (IFN) signaling pathway. Treatment with both CWE and aloe emodin markedly upregulated the expression of type I IFN and the IFN-stimulated gene (ISG) IFITM1. Knockout of IFITM1 expression significantly weakened the anti-HBV activity of CWE and aloe emodin, demonstrating that the IFN-IFITM1 axis serves as a key pathway mediating the inhibitory effects of Cassiae semen on HBV replication. Collectively, our findings demonstrate for the first time that Cassiae semen extract and its bioactive constituent aloe emodin exert potent anti-HBV efficacy by modulating the interferon signaling pathway, thereby highlighting their potential as novel therapeutic agents for the treatment of chronic hepatitis B.IMPORTANCECHB caused by HBV is a major global health threat, often progressing to liver cirrhosis and hepatocellular carcinoma, with limited effective therapies. Cassiae semen, a widely used food-medicine homology herb in traditional Chinese medicine, is known for hepatoprotective properties, but its anti-HBV potential remains unexploited. This study identifies aloe emodin as the key bioactive component of Cassiae semen water extract that suppresses HBV replication via activating the host interferon-IFITM1 pathway with low cytotoxicity. These findings not only uncover a novel natural anti-HBV agent but also bridge traditional herbal medicine with modern Antiviral drug development, offering a promising, safe candidate for HBV-associated disease treatment.