Evaluation of the availability of delphinidin and cyanidin-3-O-sambubioside from Hibiscus sabdariffa and 6-gingerol from Zingiber officinale in colon using liquid chromatography and mass spectrometry detection

The in vivo biological activity of Hibiscus sabdariffa (H.s.) and Zingiber officinale (Z.o.) polyphenols is tightly related to their availability in the site of action. The availability of non-absorbed and intact polyphenols, or partially metabolized, in the colon, would perform, according to in vitro outcomes, a highly antioxidant activity and trapping effect towards toxic molecules (e.g., methylglyoxal), which are locally produced in the colon by the gut microbiota. The aim of this study was to evaluate the in vivo availability of three selected polyphenolic compounds of dried H.s calyces, and fresh Z.o. rhizomes in the Wistar rat colon by liquid chromatography coupled to photodiode array and mass spectrometry detection (HPLC–PDA/ESI–MS). The colon-available polyphenols were extracted through the initial solid–liquid faeces extraction by the employment of a solvent mixture (methanol:water, 60:40 v/v), followed by a solid-phase extraction (SPE) on a C18 cartridge. The main H.s. anthocyanins (cyanidin-3-O-sambubioside, C3S and delphinidin-3-O-sambubioside, D3S) and 6-gingerol of Z.o. were available in the intact form in the colon 12 h after the administration of concentrated aqueous extracts (6% and 4% w/v). 72.15% of the ingested C3S and 76.19% of D3S were available in the colon, in comparison to the low availability of 6-gingerol equal to 1.50%. The duration of these bioactive compounds availability in the colon was limited to 12 h. The anthocyanin and gingerol availability in the colon may favor their absorption into the enterocytes, contributing to the antioxidant potential and health effects.