engleski

Isolation and identification of quercetagetin 3'-methyl ether 7-O-beta-D-glukopyranoside, a flavonoid with antiphytoviral activity, from Centaurea rupestris L.

The flavonoid which revealed a strong antiphytoviral activity against tomato bushy stunt tombusvirus was isolated from methanolic extract of the inflorescence of Centaurea rupestris L. (Asteraceae) and its chemical structure was elucidated. The isolation was started by means of column (silica gel 60) and preparative thin layer (aluminium sheets, silica gel 60, F254) chromatography. Final purification was achived by preparative HPLC. Isolated flavonoid was submitted to LC-MS analyses which demonstrated that isolated flavonoid had a molecular weight of 494. The flavonoid was assigned molecular formula C22H22O13 and it was submitted to a range of homonuclear and heteronuclear 1H and 13C NMR experiments. The 1HNMR spectrum exhibited for ring B 3H ABX system at ƒÔ 7.00 (d, J = 8 Hz, H5'), 7.75 (dd, J = 8 and 2 Hz, H6' and 7.85 (d, J = 2 Hz, H2'). H8 occurred at ƒÔ 7.00, consistent with a 7-0-glucoside and differentiating the compound from 6- or 4' - O – glycoside. The anomeric proton appeared at ƒÔ 5.18, again suggesting 7-O- glycosilation and ruling out 3-glycosilation. Based on these spectral interpretation and comparasion with literature data, isolated flavonoid was identificated as quercetagetin 3' – methyl ether 7-O-ƒŇ-D glucopyranoside.

Centaurea rupestris; antiphytoviral activity; quercetagetin

nije evidentirano