Purinergic agents of hydroalcoholic Agaricus brasiliensis extracts: identification, quantification and biological assays

In the present work the effects of an hydroalcoholic extract of Agaricus brasiliensis (formerly known as A. blazei) on metabolic parameters in the perfused rat liver have been examined with emphasis on its content on nucleotides and nucleosides, which act as purinergic agents. Several nucleosides and nucleotides were identified in the A. brasiliensis extract. Consistently, the extract is active on several liver functions in a relatively complex way. It increased perfusion pressure, oxygen consumption, glycogenolysis, glycolysis, ureogenesis, gluconeogenesis, and shifted the redox state of the cytosolic NAD-NADH couple toward a more reduced state. A significant part of these effects seems to be the result of purinergic action, as indicated mainly by experiments with inhibitors and antagonists: pressure changes, glycogenolysis control (glucose and lactate release) and the redox state changes. Another set of phenomena, namely the increased gluconeogenesis and ureogenesis and especially the ubiquitous stimulation of oxygen consumption, are more likely the consequence of metabolic transformation of several substrates contained within the extract, especially amino acids. The results of the present work have implications for both the consumer of A. brasiliensis as a functional and nutraceutic food and for the experimentator interested in the physiologic and pharmacologic effects of the mushroom. It seems apparent that consumption of A. brasiliensis represents not only the ingestion of metabolic precursors, but also the ingestion of substances that, even at low concentrations, can exert important signalling functions not only in the liver but in the organism as a whole.

Acknowledgements: Financial support: CNPq and Fundaçao Araucaria.