Study of the phytochemical composition and biological activities of rhamnus alaternus and retama sphaerocarpa

Abstract

Rhamnus alaternus L (Rhamnaceae) commonly known as M‟lilez and Retama sphaerocarpa (Retama) known as R‟tem are two medicinal plants growing in the Mediterranean Basin including Algeria. The aim of this study was to evaluate the phytochemical composition by HPLC-MS and GC-MS and to study the biological activities of extracts (methanolic, aqueous and traditional) prepared from different parts of these two plants. For R.alaternus results the flavonoid investigation showed that the composition of the plant is dominated with the presence of flavonols derivatives (quercetin, kaempferol and rhamnetin derivatives). The extracts showed a good antioxidant/free radical scavenger activity, hence in FRAP and ORAC tests the results of the bark methanolic extract were (1.71±0.07 Fe2+/g; 6.55±0.03 mmol TE/g, respectively), Furthermore, the bark methanolic extract was the best in cytotoxicity test because it reduced significantly the proliferation of U937 cancer cells (6.39 µg/ml), and oppositely produced less PBMC cell death (220.35 µg/ml), PE Annexin V test showed that R.alaternus methanolic extract induce apoptosis to U937 cancer cells in a dose dependent manner. Regarding R sphaerocarpa results the isoflavones (daidzein, genistein, Glycitein derivatives) dominated the composition of the extracts and the alkaloids study showed that R. sphaerocarpa stems methanolic extract contains quinolizidine alkaloids; the main components were cytisine and retamine. In another hand a good antioxidant activity was found, hence in FRAP and ORAC the results of the fruits methanolic extract were (0.65±0.05 Fe2+/g; 7.31± 0.07mmol TE/g, respectively). All the extracts of R. sphaerocarpa showed a good activity in advanced glycation end-products (AGEs) formation assay; the methanolic extract of the stems was the most active (IC50= 9.36%), this extract was tested for acute toxicity and was found to be slightly toxic (LD50 =2488.86 mg/kg). It was used also for antidiabetic activity in rats and showed at the end of the experiment at the dose 50 mg/kg a significant decrease in feed and water intake, blood glucose level (75±3.60 mg/dl), plasma triglycerides and cholesterol levels of diabetic rats (48.66±4.72 mg/dl, 89.00±3.00mg/dl, respectively). Similarly the hematological parameters studied were improved and the effect was not dose dependent. As a conclusion R. alaternus and R. sphaerocarpa especially bark and stems (respectively) can be regarded as good sources of bioactive compounds.