Sambucus nigra cell suspension cultures inhibit SARS-CoV-2 cytopathic effects and display selective antibacterial activity

In vitro cultivation of Sambucus nigra cell suspensions might offer a sustainable source of health-relevant secondary metabolites, yet it remains unclear whether in vitro biomass reproduces the bioactivity of native fruits. We assessed antiviral and antimicrobial activities of S. nigra cell suspensions, tested strategies to enhance these activities using elevated light intensity and flg22 elicitation, and evaluated the impact of scale-up. Biosynthetic gene expression was quantified by qRT-PCR, and flavonoid and anthocyanin levels by colorimetric quantification methods. Elevated light was associated with a modest, non-significant upward trend in flavonoid levels and a pronounced increase in pigment accumulation, accompanied by upregulation of biosynthetic genes, whereas flg22 did not induce flavonoid accumulation and transiently reduced anthocyanins with minimal transcriptional responses. Scale-up lowered metabolite yields, though high light partially restored pigments at the expense of biomass. Cell culture extracts selectively inhibited Pseudomonas aeruginosa and, under optimized light, suppressed SARS-CoV-2 cytopathic effects comparably to native extracts, demonstrating the potential of S. nigra cell cultures as a renewable source of bioactive compounds.