عنوان المقالة:methods in labelling of flavonoid glycosides and phenolic acids in medicinal plants: Sempervivum tectorum L. and Corylus avellana: flavonoids and phenollics extracts
In recent years a number of medicinal plants have been proved to offer an alternative to synthetic drugs in preventing and treating diseases. Quality control of standardized herb extracts is an essential part of investigations regarding safety, efficacy and therapeutical reproducibility. However, it is not an easy task, because medicinal plant extracts or preparations comprising several herbs are complex mixtures of numerous different compounds among which a substantial proportion is unknown. This applies particularly to extracts containing plant phenolics, since these are present in plant material in great structural variability. Characterization of quality includes phytochemical screening of medicinal plants with the objectives of authentication and relevation of diagnostic compounds to avoid adulteration.
In order to develop modern evidence-based phytomedicines or registered herbal extracts, standardization is a crucial step. It comprises identification and determination of the active substances in a herbal remedy, as well as development of validated methods for comprehensive chemical characterization and quantification of the main compounds. However, pharmacological effects often can not be attributed to a certain active substance, but a sort of constituents contribute to them or a synergistic effect between compounds exists.
For all these phytoanalytical challenges provides mass spectrometry (MS) coupled to high-performance liquid chromatography (HPLC) an adequat tool. Mass spectrometry offers great selectivity and sensitivity and with the separative power of high-performance liquid chromatography enables simultaneous structural analysis of compounds present in complex matrices.
Evaluation of two taditional medicinal plants, Sempervivum tectorum L. and Corylus avellana L. has been chosen as scope of our work. Mainly kaempferol glycosides have been reported for Sempervivum tectorum, however, its phytochemical characterization is incomplete. Its flavonoid profile has been studied only at the aglycone level, although glycosyl substitution can have a great impact on bioavailability of compounds. Phenolics in kernels of Corylus avellana have been studied extensively, nevertheless data regarding leaves are less detailed.
د محمد محمود محمد عبد الفتاح | DR MOHAMMAD MAHMOUD MOHAMMAD ADEL FATAH | 9779