Phytochemicals levels and biological activities in Hibiscus sabdariffa L. were enhanced using microbial fermentation

Hibiscus sabdariffa L. calyx, a common and important crop, has been extensively applied in the food, cosmetic or pharmaceutical industries worldwide. In this study, the extract of Hibiscus sabdariffa L. calyx (eHS) was used for microbial fermentation to amend its phytochemical constituents and improve the biological activity of eHS. After fermentation in eHS contained medium, antioxidant activity such as 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH) and nitric oxide (NO) scavenging activity and total phenolic and flavonoid contents were significantly increased when the various fermentation starters were used especially on Galactomyces geotrichum inoculation. Additionally, 1% of eHS addition and static culture method were determined after optimization of fermentation conditions. High performance liquid chromatography (HPLC) and enzymatic activity analysis also demonstrated that the increased levels of phenolic compounds, flavonoids, anthocyanin and its aglycone derivatives mainly caused the improved biological activities of fermented eHS. This is the first report to apply eHS to microbial fermentation to improve the biological functionalities of fermented eHS.