Novel CYP11A1-Derived Vitamin D and Lumisterol Biometabolites for the Management of COVID-19

Abstract

Vitamin D deficiency is associated with a higher risk of SARS-CoV-2 infection and poor outcomes of the COVID-19 disease. However, a satisfactory mechanism explaining the vitamin D protective effects is missing. Based on the anti-inflammatory and anti-oxidative properties of classical and novel (CYP11A1-derived) vitamin D and lumisterol hydroxymetabolites, we have proposed that they would attenuate the self-amplifying damage in lungs and other organs through mechanisms initiated by interactions with corresponding nuclear receptors. These include the VDR mediated inhibition of NFκβ, inverse agonism on RORγ and the inhibition of ROS through activation of NRF2-dependent pathways. In addition, the non-receptor mediated actions of vitamin D and related lumisterol hydroxymetabolites would include interactions with the active sites of SARS-CoV-2 transcription machinery enzymes (M^pro;main protease and RdRp;RNA dependent RNA polymerase). Furthermore, these metabolites could interfere with the binding of SARS-CoV-2 RBD with ACE2 by interacting with ACE2 and TMPRSS2. These interactions can cause the conformational and dynamical motion changes in TMPRSS2, which would affect TMPRSS2 to prime SARS-CoV-2 spike proteins. Therefore, novel, CYP11A1-derived, active forms of vitamin D and lumisterol can restrain COVID-19 through both nuclear receptor-dependent and independent mechanisms, which identify them as excellent candidates for antiviral drug research and for the educated use of their precursors as nutrients or supplements in the prevention and attenuation of the COVID-19 disease.

Keywords: ACE2; Mpro; RdRp; SARS-CoV-2; anti-inflammatory; lumisterol; vitamin D.

Figure 1

Possible mechanisms by which vitamin D can counteract the COVID-19 illness. In panel (A) it is proposed that the novel hydroxyderivatives of vitamin D3, in similar manner as 1,25(OH)₂D3, inhibit cytokine storm and oxidative stress, with net attenuating effect on ARDS and multiorgan failure induced by COVID-19. Panel (B) proposes a mechanism of action of canonical and non-canonical vitamin D-hydroxyderivatives. Vitamin D signaling in mononuclear cells involves the activation of the VDR or inverse agonism on RORγ with downstream inhibition of inflammatory genes and the suppression of oxidative stress through the activation of NRF2. VDR, vitamin D receptor; RXR, retinoid X receptor; ROR, retinoic acid orphan receptor, RORE, ROR response element; ARE, antioxidant response element; VDRE, vitamin D response element; NRF2, transcription factor NF-E2-related factor 2. Panel (C) shows how different routes of vitamin D delivery impact vitamin D hydroxylation/activation patterns. Reprinted with permission from the publisher [86].

Figure 2

The binding pattern of identified compounds with SARS-CoV-2 M^pro. (A) structural representation of the protein in complex with selected sterols and secosteroids. (B) selected compounds blocking the binding pocket and making significant interactions with the functionally important residues of SARS-CoV-2 M^pro. (C) surface representation of conserved substrate-binding pocket of SARS-CoV-2 M^pro in complex with selected compounds. (D) zoomed view of the substrate-binding pocket of SARS-CoV-2 M^pro in complex with selected compounds. Reprinted with permission from the publisher [74].

Figure 3

Enzyme inhibition by the selected sterols and secosteroids. (A) the M^pro enzyme inhibition by the selected metabolites at concentration of 2 × 10⁻⁷ M. The inhibition percentages were calculated using the formula: % inhibition = 100 × [1(X Minimum)/(Maximum–Minimum)]. Minimum = negative control without any enzyme (0% enzyme activity); Maximum = positive control with enzyme and substrate (100% enzyme activity). The test sets included enzymes, substrates, and the test compounds, and excitation at a wavelength of 360 nm and the detection of emission at a wavelength of 460 nm was observed for change in enzyme activity. The statistical significance of differences was evaluated by one-way ANOVA; *** p< 0.001 and **** p < 0.0001 for all conditions relative to ethanol blank, n = 3. (B) the RdRp enzyme activity inhibition by selected sterols and secosteroids. The inhibition percentages were calculated using the formula: % inhibition = 100 × [1 − (X-Minimum)/(Maximum–Minimum)]. Minimum = negative control without any enzyme (0% enzyme activity); Maximum = positive control with enzyme and substrate (100% enzyme activity). The statistical significance of differences was evaluated by one-way ANOVA; *** p < 0.001 and **** p < 0.0001 for all conditions relative to the ethanol blank, n = 3. RdRp, RNA-dependent RNA polymerase. Reprinted with permission from the publisher [74].

Figure 4

The binding pattern of identified sterols and secosteroids with SARS-CoV-2 RdRp. (A) structural representation of the protein in complex with selected compounds. (B) active site residues of the RdRp-binding pocket making significant interactions with each of the identified compounds. (C) surface view of the RdRp active site with the electrostatic potential from red (negative) to blue (positive) in complex with selected compounds. RdRp, RNAdependent RNA polymerase. Reprinted with permission from the publisher [74].