Hibiscus moscheutos L. Flower Petals Extract Phenolic Profile and In Vitro Antimicrobial, Biofilm Formation,...

The flowers of Hibiscus moscheutos L. are among the largest within the genus, and the plant contains numerous nutrients and phytochemicals that perform various structural and regulatory functions in the human body upon consumption. However, these properties remain insufficiently explored. In this study, the phenolic composition and in vitro biological activity of an ethanolic extract from H. moscheutos petals were investigated. The total phenolic content was 219.52 mg/g (HPLC method), including phenolic acids (5.17 mg/g), flavanols (59.18 mg/g), flavonols (93.09 mg/g), and anthocyanins (62.08 mg/g). Many species of the genus Staphylococcus, as well as two probiotic strains of Lacticaseibacillus spp., were sensitive to the extract's effects (100 mg/mL), which appeared to be strain-dependent. The MIC values for Staphylococcus spp. ranged from 6.25 to 100.00 mg/mL, while for the two probiotic strains, they were 12.50 and 100.00 mg/mL, respectively. The extract did not show prebiotic activity. Nevertheless, it enhanced the biofilm-forming ability of both probiotic and pathogenic microbiota on abiotic (polystyrene) and biotic (mucin and gelatin) surfaces. The stimulation of Staphylococcus spp. biofilms is considered undesirable and may justify limiting the use of the extract, for example, in pharmaceutical or medical applications. At concentrations above 25 mg/mL, the extract reduced bacterial autoaggregation. It also exhibited low genotoxicity in the Ames test and demonstrated anti-inflammatory activity comparable to sodium diclofenac. Hibiscus petal extracts might represent a promising source of bioactive compounds for novel pharmaceutical, nutraceutical, and food applications; however, their potential requires further in-depth investigation.