Glycosyl flavonoid profile, in vivo antidiabetic and in vitro antioxidant properties of Linaria reflexa Desf.

Aerial parts of Linaria reflexa, used in North African folk medicine for treating certain skin diseases, were investigated by HPLC-DAD-ESI/MS technique able to identify the glycosyl flavonoids pectolinarin (1), isolinariin A (2), isolinariin B (3), linariin (4), isolinariin D (5) and isolinariin E (6) as the most abundant components in both hydroalcoholic (HAE) and ultrasound-assisted (UAE) extracts profiles. Metabolite 5, isolated and fully characterised by extensive nuclear magnetic resonance (NMR) analysis, has been very recently reported from L. japonica together with the compound 6. Good antioxidant activities (DPPH radical scavenging, β-carotene bleaching and reducing power assays) were observed for the extracts. The remarkable antidiabetic activity displayed by UAE (300 mg/kg) has yielded the most marked decrease in blood glucose levels of the alloxan diabetic rats (-72.09%), greater than the effects by the drug glybenclamide (-63.29%). This study reports the first correlation of antidiabetic activity of Linaria sp. extracts with their chemical composition.