Characterization of antioxidant phenolics in Syringa vulgaris L. flowers and fruits by HPLC-DAD-ESI-MS.

In this study the polyphenolic composition of lilac flowers and fruits was determined for the first time. For the identification of compounds accurate molecular mass and formula, acquired by LC and ESI-TOF-MS and fragmentation pattern given by LC-ESI/MS/MS analyses were used. Our chromatographic system in conjunction with tandem MS was found to be valuable in the rapid separation and determination of the multiple constituents in methanolic extracts of lilac flowers and fruits. Altogether 34 phenolics, including 18 secoiridoids, 7 phenylpropanoids, 4 flavonoids and 5 low molecular weight phenols were identified. As marker compounds two secoiridoids (oleuropein and nuzhenide), two phenylpropanoids (acteoside and echinacoside) and rutin were quantified by validated methods. As a result of quantitative analysis it was confirmed that flowers contain significant amount of phenylpropanoids (acteoside (2.48%), echinacoside (0.75%)) and oleuropein (0.95%), while in fruits secoiridoid oleuropein (1.09%) and nuzhenide (0.42%) are the major secondary metabolites. The radical scavenging activities of the extracts and the constituents were investigated by DPPH and ABTS assays. Both extracts show remarkable antioxidant activities. Our results clearly show that lilac flowers and fruits are inexpensive, readily available natural sources of phenolic compounds with pharmacologic and cosmetic perspectives. This article is protected by copyright. All rights reserved.