بحث وتحديد نواتج الأيض الثانوي للنبتتين Centaurea solstitialis ssp. schouwii (DC.) Q. et S. وSerratula cichoracea- الفعالية البيولوجية.

Abstract

This work is the assessment of two studies which we conductedon two plants belonging to Asteraceae family, Centaurea solstitialis ssp.schouwii (CD.) Q. et S. and Serratula cichoracea. The works carried out on Centaurea solstitialis ssp. schouwii (CD.) Q. et S.began with the maceration in 70% ethanol of the aerial parts collected in the flowering stage from the area of El Kala. After filtration,concentration and dilution in distilled water,theremaining solution was successively extracted with petroleum ether, CHCl3, EtOAcand n-BuOH to give the corresponding extracts.The antioxidant abilities of CHCl3, EtOAc and n-BuOH extracts were assessed using DPPH radical scavenging, and cupric ion reducing antioxidant capacity (CUPRAC).Butylhydroxyanisole (BHA), Butylhydroxytoluene (BHT) and α –Tocopherol were used as controls. The total phenolic and total flavonoid contents of the extracts were also determined. Concerning the antioxidant activity, the EtOAc extract was the most active followed by the n-BuOH extract in the two methods. However, none of the extracts exhibited higher activity than those of the antioxidant standards. The n-BuOH extract had the highest phenolic and flavonoid contents followed by EtOAc extract. These data allowed guiding the fractionation of EtOAc and n-BuOH extracts which was carried out by chromatography on silica gel60column. The obtained fractions, purified bychromatography on preparative normal silica gel plates led to the isolation of twosesquiterpene lactones with guaianolide skeleton-type one of which was new, we describe it for the first time in the literature. We also isolated 5 flavonoid glycosides.The structures of all the isolated compounds were established by the analyses of: the high resolution mass spectra recorded in ESI positive mode [HRESI-MS(+)], the results of UV-Vis spectral series , the 1D NMR (1H, 13C and DEPT) and 2D NMR (COSY, NOESY, HSQC and HMBC) spectra, the results of the acidic hydrolysis of the glycosylated compoundsand finallywith comparison of their spectroscopic data with those reported in the literature. Concerning the species Serratula cichoracea, the carried out work represents continuity of a study that we previously realized on the ethyl acetate extract obtained by a protocol similarto that indicated higher forCentaurea solstitialis ssp. schouwii (CD.) Q. et S., after fractionation of this extract on silica gel column, the study of one of the obtained fractionsallowed the isolation and the structural determination of two ecdysteroid diastereoisomers. One of these two compounds was new, we reported it for the first time in the literature. These works were the object of two international publications.