Phytochemicals with potential anti-obesity properties

Incidence of obesity has reached an alarming rate worldwide. Obesity is the most prevalent nutritional disease and a major public health problem both in developed and undeveloped countries increasing the risk of metabolic disorders, chronic and cardiovascular diseases. It has been shown that obesity is associated with a chronic inflammatory status in adipose tissue and activation of oxidative stress. In addition, it involves a disfunctional intestinal barrier inducing alteration in its permeability. Plants provide a major dietary source of phytochemicals with anti-obesity potential since many of them, having antioxidant properties, should be able to relieve oxidative stress resulting from inflammation. In continuation of our studies on plants as a supply of valuable compounds with anti-obesity potential, we have investigated by a classical electrophysiology approach the effects of selected plant extracts on Model Planar Lipid Membranes (PLMs) made up of dioleoyl-phosphatidylserine:dioleoyl-phosphatidylethanolamine:palmitoyl-oleoylphosphatidylcholine (27:27:18, w:w:w), a surrogate of intestinal membranes. In particular, the hydroalcholic (70% EtOH) extract from the dry tunics of A. cepa var. Tropea was effective in forming channel-like pathways in the lipid bilayer. Electrophysiological data demonstrated that the extract was able to interact with the PLMs forming stable pores. This effect was also detectable with quercetin, the main component of the extract, that was able to interact with the PLMs and form stable pores in the ranges of applied voltages from 60 to 20 mV and from -60 to -20mV. The conductance values seemed to be inversely dependent on applied voltage thus suggesting that quercetin like the whole extract of A.cepa forms aqueous ion pathways thus modulating membrane permeability. Very interestingly, glycosylation of the molecule resulted in loss of activity.