Bioactive compounds in Layacha brown rice (Oryza sativa L.) improve immune responses in mice via activation of transcription factor Nrf2

Dysregulated or weak immunity is caused by ageing, chemo-radiotherapy, COVID-19, infections, steroids, pollutants and toxins. Bioactive foods are required for boosting immunity. In the present study, nine rice (Oryza sativa L.) varieties were selected from the repository of 23,250 Indian germplasm accessions. The immunomodulatory effects of these rice varieties were assessed in vitro and in vivo. Layacha-rice-methanolic-extract (Larimex) significantly enhanced innate (>20%) and adaptive (>10%) immune responses evinced from higher bacterial phagocytosis by macrophages, increased mitogen-induced T-cell proliferation (11%) and scavenged reactive oxygen species (ROS) (70–80%). Larimex activated transcription factor Nrf2 and its downstream genes Nqo1, Ho1 and Txnrd1 in immune cells. Larimex significantly improved immune responses (>20%) only in cells from wild type but not Nrf2 knock-out mice indicating its causal role in boosting immunity. Untargeted metabolomics of Layacha rice showed preponderance of metabolic pathways and bioactive compounds, which activate Nrf2 in mammalian cells. Layacha rice can be a suitable food for boosting immunity.

Molecular dynamic simulations reveal anti-SARS-CoV-2 activity of mitocurcumin by potentially blocking innate immune evasion proteins NSP3 and NSP16.

The coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is affecting human life in an unprecedented manner and has become a global public health emergency. Identification of novel inhibitors of viral infection/replication is the utmost priority to curtail COVID-19 progression. A pre-requisite for such inhibitors is good bioavailability, non-toxicity and serum stability. Computational studies have shown that curcumin can be a candidate inhibitor of certain SARS-CoV-2 proteins; however, poor bio-availability of curcumin limits its possible therapeutic application. To circumvent this limitation, we have used mitocurcumin (MC), a triphenyl phosphonium conjugated curcumin derivative, to study the ability to inhibit SARS-CoV-2 infection using molecular docking and molecular dynamics (MD) simulation. MC is serum stable and several fold more potent as compared to curcumin. Molecular docking studies revealed that MC can bind at active site of SARS-CoV-2 ADP Ribose Phosphatase (NSP3) and SARS-CoV-2 methyltransferase (NSP10-NSP16 complex) with a high binding energy of - 10.3 kcal/mol and - 10.4 kcal/mol, respectively. MD simulation (100 ns) studies revealed that binding of MC to NSP3 and NSP16 resulted in a stable complex. MC interacted with critical residues of NSP3 macro-domain and NSP10-NSP16 complex and occupied their active sites. NSP3 is known to suppress host immune responses whereas NSP10-NSP16 complex is known to prevent immune recognition of viral mRNA. Our study suggests that MC can potentially inhibit the activity of NSP3 and NSP10-NSP16 complex, resulting in compromised viral immune evasion mechanism, and thereby accentuate the innate immune mediated clearance of viral load.