Composition of naturally occurring compounds decreases activity of Omicron and SARS-CoV-2 RdRp complex

Naturally-occurring compounds are acknowledged for their broad antiviral efficacy. Little is however known about their mutual cooperation. Here, we evaluated in vitro efficacy of the defined mixture of agents against the RdRp complex of the original SARS-CoV-2 and Omicron variant. This composition of vitamin C, N-acetylcysteine, resveratrol, theaflavin, curcumin, quercetin, naringenin, baicalin, and broccoli extract showed to inhibit activity of RdRp/nsp7/nsp8 both these variants. In vitro exposure of recombinant RdRp complex to individual compounds of this composition pointed to quercetin as the driving inhibitory compound. The outcome of this study supports the motion of antiviral efficacy of natural compounds against SARS-CoV-2 and Omicron and implies that their reciprocal or mutual interaction may augment antiviral action through simultaneous effect on different mechanisms. Consequently, this makes it more difficult for an infectious agent to evade all these mechanisms at the same time. Considering the urgency in finding effective prevention, but also side-effects free treatment of COVID-19 our results call for clinical affirmation of the benefits of this micronutrient combination in both preventive and therapeutic aspects. Whether observed effects can be achieved, by concentrations of the active agents used in these in vitro experiments, in in vivo or clinical setting warrants further study.