Untargeted Metabolomics and in Vitro Functional Analysis Unravel the Intraspecific Bioactive Potential of Flowers from Underexplored Camellia Japonica Cultivars Facing Their Industrial Application

The Camellia genus comprises a vast array of underexplored medicinal plants that merit a systematic valorization to exploit their potential as natural sources of phytochemicals with associated health-promoting properties. In this work, flower extracts from eight poorly characterized Camellia japonica L. cultivars were subjected to polyphenol profiling through untargeted metabolomics combined with in vitro functional analysis. Anthocyanins, mostly represented by cyanidin 3-O-glycosides, flavones, and flavonols, were found as the major constituents of C. japonica flowers, together with hydroxycinnamic acids, tyrosols, alkylphenols, and stilbenes, which were detected for the first time in this species. The application of multivariate statistics revealed a flower color-dependent fingerprint of C. japonica cultivars, featuring anthocyanins and other flavonoids as metabolite markers associated with color-flowered cultivars with respect to white-flowered ones. The accumulation of anthocyanins, especially reported in ‘Eugenia de Montijo’ flowers, was highly correlated with the cytotoxic and anti-inflammatory properties of the derived extracts, including AGS, Caco-2, and MCF7 cancer cell lines. Moreover, the flavones accumulation reported in ‘Carolyn Tuttle’ extracts was also associated with high rates of free-radical scavenging activity, as well as a potent cytotoxicity against the Caco-2 cell line. In general, C. japonica anthocyanin-enriched flower extracts were revealed as promising candidates for the industrial production of polyphenols with associated biological activities of high interest for critical sectors in the food, pharmaceutical, and cosmetic industries.