ABSTRACT
The novel coronavirus (SARS-CoV-2) has caused large-scale global outbreaks and mainly mediates host cell entry through the interaction of its spike (S) protein with the human angiotensin-converting enzyme-2 (ACE-2) receptor. As there is no effective treatment for SARS-CoV-2 to date, it is imperative to explore the efficacy of new compounds that possess potential antiviral activity. In this study, we assessed the potential binding interaction of the beneficial components of Chaga mushroom, a natural anti-inflammatory and immune booster with that of the SARS-CoV-2 receptor-binding domain (RBD) using molecular docking, MD simulation, and phylogenetic analysis. Beta glycan, betulinic acid, and galactomannan constituents of Chaga mushroom exhibited strong binding interaction (-7.4 to -8.6 kcal/mol) forming multivalent hydrogen and non-polar bonds with the viral S1-carboxy-terminal domain of the RBD. Specifically, the best interacting sites for beta glycan comprised ASN-440, SER 373, TRP-436, ASN-343, and ARG 509 with average binding energy of -8.4 kcal/mol. The best interacting sites of galactomannan included ASN-437, SER 373, TRP-436, ASN-343, and ALA 344 with a mean binding energy of -7.4 kcal/mol; and the best interacting sites of betulinic acid were ASN-437, SER 373, TRP-436, PHE 342, ARG 509, and ALA 344 that strongly interacted with the S-protein (ΔG = -8.1 kcal/mol). The docking results were also compared with an S-protein binding analog, NAG and depicted similar binding affinities compared with that of the ligands (-8.67 kcal/mol). In addition, phylogenetic analysis using global isolates depicted that the current SARS-CoV-2 isolates possessed a furin cleavage site (NSPRRA) in the RBD, which was absent in the previous isolates that indicated increased efficacy of the present virus for enhanced infection through increased interaction with ACE-2. The results showed that Chaga could be an effective natural antiviral that can supplement the current anti-SARS-CoV-2 drugs.
ABSTRACT
[This corrects the article DOI: 10.1016/j.heliyon.2021.e06003.].
ABSTRACT
Chaga mushroom is one of the promising beneficial mushrooms thriving in the colder parts of Northern hemisphere. Chaga polysaccharides (IOP) have been reported to enhance immune response and alleviate oxidative stress during development. However, the effects of IOP on the genotoxicity in model organisms are yet to be clarified. In this study, IOP was extracted using hot water extraction method, followed by GC analysis. Zebrafish embryos (12 h post fertilization, hpf) were exposed to transient UVB (12 J/m2/s, 305-310nm) for 10 s using a UV hybridisation chamber, followed by IOP treatment (2.5 mg/mL) at 24 hpf for up to 7 days post fertilization (dpf). The genotoxic effects were assessed using acridine orange staining, alkaline comet assay, and qRT-PCR for screening DNA repair genes. Significant reduction in DNA damage and amelioration of the deformed structures in the IOP-treated zebrafish exposed to UVB (p < 0.05) was observed at 5 dpf and thereafter. The relative mRNA expressions of XRCC-5, XRCC-6, RAD51, and GADD45 were significantly upregulated, whereas p53 and BAX were downregulated in IOP-treated UVB-exposed zebrafish compared to UVB-exposed zebrafish. ELISA analysis revealed significantly decreased expression of XRCC5 and RAD51 in UVB-exposed compared to IOP-treated UVB-exposed and control zebrafish (7 dpf). However, p53 and BAX levels were high in UVB-exposed zebrafish, indicating higher apoptosis. Pathway analysis demonstrated coordinated regulation of DNA repair genes; p53 playing a pivotal role in regulating the expression of BAX, thereby promoting apoptosis in UVB-exposed zebrafish. Overall, IOP treatment ameliorated the genotoxic effects in UVB-exposed zebrafish by enhanced expression of DNA repair genes, which assisted in normal development. The study delineated the efficacy of IOP in mitigating UV-induced DNA damage in zebrafish.
ABSTRACT
Chaga (Inonotus obliquus) mushroom is considered as one of the most powerful antioxidants across the world. Though the therapeutic effects of Chaga components are well characterized in vitro, the in vivo developmental effects are not elucidated in detail. In this study, we assessed the in vivo developmental effects of Chaga polysaccharides in zebrafish, along with revealing the effects on cell cycle and apoptosis. Chaga mushroom polysaccharides comprised xylulose, rhamnose, mannose, glucose, inositol, and galactose, in addition to phenolic compounds; zebrafish embryos exhibited normal embryonic development upon transient exposure to Chaga extract (24 hours). Most embryos (>90%) were found to be healthy even at high concentrations (5 mg/mL). In addition, staining with the DNA binding dye, acridine orange showed that Chaga polysaccharides alleviated oxidative stress. Flow cytometric analysis using H2DCFDA that specifically binds to cells with fragmented DNA showed significantly reduced levels of intracellular reactive oxygen species (ROS) (p < 0.05), which in turn reduced apoptosis in the developing embryos. Cell cycle analysis by measuring the DNA content using flow cytometry revealed that Chaga polysaccharides moderately arrested the cells at G1 stage, thereby inhibiting cell proliferation that can be further explored in cancer studies. Overall, transient exposure of Chaga polysaccharide extract reduced intracellular ROS and assisted in the normal development of zebrafish.