Phytochemical screening and free radical scavenging activity of Citrullus colocynthis seeds extracts.

Objective: To study the phytochemical screening of different extracts from Citrullus colocynthis (C. colocynthis ) seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.

Methods: Phytochemical screening, total content of polyphenols and flavonoids of C.

Effects of D-mannoheptulose upon D-glucose metabolism in tumoral pancreatic islet cells.

D-[3H]mannoheptulose was recently reported to be poorly taken up by tumoral pancreatic islet cells of the RINm5F and INS-1 lines. We have now investigated the effects of D-mannoheptulose upon D-glucose metabolism in these two cell lines. D-mannoheptulose (1.

Pancreatic fate of D-[3H] mannoheptulose.

D-Mannoheptulose was recently postulated to be transported into cells by GLUT2. The validity of such an hypothesis was assessed by comparing the uptake of tritiated D-mannoheptulose by pancreatic islets versus pieces of pancreas and, in the latter case, by comparing results obtained in control rats versus animals injected with streptozotocin (STZ). The uptake of D-[3H] mannoheptulose by islets represents a time-related and temperature-sensitive process, inhibited by cytochalasin B and enhanced by D-glucose.

Uptake of D-mannoheptulose by rat erythrocytes, hepatocytes and parotid cells.

D-[3H]mannoheptulose (or D-[1-14C] mannoheptulose) net uptake was measured in rat erythrocytes, parotid cells and hepatocytes. In the erythrocytes and parotid cells, the intracellular distribution space of the heptose (0.1 mM) represented only about 1 and 13%, respectively, of the intracellular 3HOH space.

Uptake of D-mannoheptulose by normal and tumoral pancreatic islet cells.

D-mannoheptulose was recently proposed as a possible tool to label preferentially insulin-producing cells in the pancreatic gland. In the present study, D-[3H]-mannoheptulose uptake by rat pancreatic islets or dispersed islet cells was found to represent a time-related and temperature-sensitive process inhibited by cytochalasin B. This mould metabolite also inhibited the efflux of D-[3H]-mannoheptulose from prelabelled islets.