Triagem de extratos vegetais e fúngicos de diferentes biomas para identificação de antagonistas do receptor P2X7

The purinergic receptor P2X7 is involved in important physiological and metabolic functions, but it also participates in pathology, especially when inflammatory in character. Despite the importance of P2X7, it has no specifi c antagonists yet available for use in clinical treatment of diseases related to the receptor's activation. Today, many drugs on the market have chemical structures related to natural products obtained from botanical species with traditional use in indigen ous medicine, forming the basis for studying natural products to obtain specific activity on cellular targets. This work focused primarily on the study of plant and fungal species extracts obtained from different biomes provided by LQPN of the Research Cen ter Rene Rachou - Fiocruz - MG, aiming to identify antagonists for the P2X7 receptor. The first step was to standardize a method that allowed the screening of approximately 60 extracts at the same time through the use of a plate spectrophotometer. Once stand ardized, the application of this methodology was promoted in the screening of 1800 extracts. Of these, only three extracts (8067, 8549 and 8568) showed antagonistic activity in the pre - established cut range [100 mg/mL], with inhibition profiles of 65%, 62% , and 61% respectively, on the P2X7R. Th e IC's50 of them were determinate in murine (2.1, 2.6, and 3.8 mg/mL) and human (0.69, 0.92, and 1.5 mg/mL) cell lines. Which an increased activity was possible to verify when they were tested in human cells. Consequ ent evaluation of action on physiological functions related to the activation of P2X7R revealed an inhibitory effect of these extracts on the release of IL - 1beta, NO, and ROS. The three tested compounds were able to inhibit these functions in a range betwe en 50% and 60%. To obtain a pharmacological characterization of these extracts on the P2X7 receptor, electrophysiological experiments were conducted, which characterized the dose - dependent inhibitory effects, exhibiting inhibitory current profiles of 76%, 47%, and 75%, respectively. In vitro cytotoxicity was also evaluated, using both cell strains, showing no significant toxicity after 24 hours of treatment at doses of up to four times that of the IC50; the results were similar to the untreated control. Aft er evaluating the antagonistic activity of these extracts in vitro, experiments using the in vivo models of ethanol - induced ulcers and inflammatory and neuropathic pain were performed. Previous studies correlate the activity of the P2X7R with the evolution of these pathologies. In the neuropathic pain protocol experiment, only two extracts showed analgesic activity (8067 and 8549) by inhibiting the pain stimulation by 68% and 66%, but in the context of inflammatory pain, the three tested extracts showed ana lgesic effects by inhibiting the stimulus by the following percentages: 8067 = 48 %, 8549 = 50%, and 8568 = 44%. The results of the ethanol - induced ulcer demonstrated an inhibitory effect on the ulcer’s development of 88%, 84%, and 51% by these extracts, a nd found that the extracts were more effective than BBG (reversible antagonist of this receptor) and the medicine used clinically (Lansoprazole), which inhibited the formation of ulcers by 43% and 46%, respect ively. The data set links to extracts with significant antagonist activity on the P2X7R, and potential to the development xix of new medicines of great interest to the pharmaceutical industry and important contributions to the knowledge of medicinal properties present in biodiversity