Havachoobe (Onosma dichroanthum Boiss) Root Extract Decreases the Hepatitis B Virus Surface Antigen Secretion in the PLC/PRF/5 Cell Line

An overview of anti-Hepatitis B virus flavonoids and their mechanisms of action

Flavonoids, a diverse group of polyphenolic compounds found in various plant-based foods, have garnered attention for their potential in combating Hepatitis B Virus (HBV) infection. Flavonoids have demonstrated promising anti-HBV activities by interfering with multiple stages of the HBV life cycle, making them promising candidates for novel antiviral agents. Certain plant families, such as Theaceae, Asteraceae, Lamiaceae, and Gentianaceae, are of particular interest for their flavonoid-rich members with anti-HBV activities. Evidences, both in vitro and in vivo, supports the anti-HBV potential of flavonoids. These subsets of compound exert their anti-HBV effects through various mechanisms, including inhibiting viral entry, disrupting viral replication, modulating transcription factors, enhancing the immune response, and inducing autophagy. The antioxidant properties of flavonoids play a crucial role in modulating oxidative stress associated with HBV infection. Several flavonoids like epigallocatechin gallate (EGCG), proanthocyanidin (PAC), hexamethoxyflavone, wogonin, and baicalin have shown significant anti-HBV potential, holding promise as therapeutic agents. Synergistic effects between flavonoids and existing antiviral therapies offer a promising approach to enhance antiviral efficacy and reduce drug resistance. Challenges, including limited bioavailability, translation from preclinical studies to clinical practice, and understanding precise targets, need to be addressed. Future research should focus on clinical trials, combination therapies, and the development of flavonoid derivatives with improved bioavailability, and optimizing their effectiveness in managing chronic HBV infections.

In vitro wound healing potential of cyclohexane extract of Onosma dichroantha Boiss. based on bioassay-guided fractionation

Onosma dichroantha Boiss. is a biennial herb used in traditional medicine in Iran for healing wounds and burns. Our previous study demonstrated that cyclohexane extract of O. dichroantha Boiss. enhanced wound healing in vitro. The aim of the present study was to identify the active fractions and compounds responsible for this effect through bio-guided fractionation followed by three in vitro tests for anti-inflammation, proliferation, and migration (scratch test). Fractionation of the CE extract yielded six fractions (Fr. A to Fr. F). Fr. F showed the most remarkable wound healing activity in three assays. Fr. F was further fractionated into five subfractions (FF-SUB1 to FF-SUB5). FF-SUB1 and FF-SUB2 were selected for further purification based on their wound healing activity. The major components, F. F1 to F. F5, were isolated from these two subfractions and identified as acetylshikonin, deoxyshikonin, β, β-dimethylacrylshikonin, β-hydroxyisovalerylshikonin, and trans-anethole of the active subfractions. Bioassay-guided fractionation revealed that naphthoquinone derivatives, as an active component, are responsible for the wound healing properties of the fractions and subfractions of cyclohexane extract of O. dichroantha roots. The findings indicate that these fractions and subsections, as well as purified compounds, have a high potential for further investigation as an effective therapeutic agent in wound healing using in vivo models.

A fragment-based drug discovery developed on ciclopirox for inhibition of Hepatitis B virus core protein: An in silico study

The Hepatitis B virus (HBV) core protein is an attractive target for preventing capsid assembly and viral replication. Drug repurposing strategies have introduced several drugs targeting HBV core protein. This study used a fragment-based drug discovery (FBDD) approach to reconstruct a repurposed core protein inhibitor to some novel antiviral derivatives. Auto Core Fragment in silico Screening (ACFIS) server was used for deconstruction-reconstruction of Ciclopirox in complex with HBV core protein. The Ciclopirox derivatives were ranked based on their free energy of binding (ΔGB). A quantitative structure affinity relationship (QSAR) was established on the Ciclopirox derivatives. The model was validated by a Ciclopirox-property-matched decoy set. A principal component analysis (PCA) was also assessed to define the relationship of the predictive variable of the QSAR model. 24-derivatives with a ΔGB (-16.56±1.46 Kcal.mol-1) more than Ciclopirox was highlighted. A QSAR model with a predictive power of 88.99% (F-statistics = 9025.78, corrected df(25), Pr > F = 0.0001) was developed by four predictive descriptors (ATS1p, nCs, Hy, F08[C-C]). The model validation showed no predictive power for the decoy set (Q2 = 0). No significant correlation was observed between predictors. By directly attaching to the core protein carboxyl-terminal domain, Ciclopirox derivatives may be able to suppress HBV virus assembly and subsequent viral replication inhibition. Hydrophobic residue Phe23 is a critical amino acid in the ligand binding domain. These ligands share the same physicochemical properties that lead to the development of a robust QSAR mode. The same strategy may also be used for future drug discovery of viral inhibitors.

Digging for the discovery of SARS-CoV-2 nsp12 inhibitors: a pharmacophore-based and molecular dynamics simulation study

Aim: COVID-19 is a global health threat. Therapeutics are urgently needed to cure patients severely infected with COVID-19. Objective: to investigate potential candidates of nsp12 inhibitors by searching for druggable cavity pockets within the viral protein and drug discovery. Methods: A virtual screening of ZINC natural products on SARS-CoV-2 nsp12's druggable cavity was performed. A lead compound with the highest affinity to nsp12 was simulated dynamically for 10 ns. Results: ZINC03977803 was nominated as the lead compound. The results showed stable interaction between ZINC03977803 and nsp12 during 10 ns. Discussion: ZINC03977803 showed stable interaction with the catalytic subunit of SARS-CoV-2, nsp12. It could inhibit the SARS-CoV-2 life cycle by direct interaction with nsp12 and inhibit RdRp complex formation.