Phytochemical analysis, antioxidant activity and in vitro ocular irritation of Hibiscus rosa-sinensis L. extracts

Hibiscus ssp. is a source of phytochemicals, mainly anthocyanins, widely known for its medicinal properties. The aim of this study was to develop a microwave-assisted extraction (MAE) method to extract bioactive compounds from yellow and red petals of Hibiscus rosa-sinensis L. (HRS) and evaluate their antioxidant and eye irritation potential. For MAE, the effect of microwave power, irradiation time, solvent concentration and solvent volume was tested. The antioxidant activity and eye irritation potential were evaluated. The extracts were analyzed by LC-DAD-ESI-IT-MS/MS. The acidified aqueous extraction was the best choice for the recovery of anthocyanins, while hydroethanolic was best extractor solvent to recovery flavonol and flavanols. MAE extracts showed efficient recovery: total phenolic content (28.4 and 23.2 mg GAE/g), total flavonoids content (44.8 and 34.5 mg RE/g),total anthocyanins content (4.1 and 16.3 mg Cy-3-glu/100 g) and extraction yields (29.5 and 23.2 %) and remarkable antioxidant activity (IC50=12.35 and 15.76 mg L-1) for yellow and red petal extracts, respectively. Main compounds were cyanidin-3-sophoroside and cyanidin-3,5-diglucoside, besides catechin, epicatechin and rutin. The extracts were classified as non-irritating ingredients. The data revealed HRS as a source of bioactive compounds and significant variations in phytochemical content among yellow and red petals of HRS.