Résumé
Abstract The “bacuri” (Platonia insignis Mart., Clusiaceae) is a native tropical fruit from the Brazilian Amazon and Northeast Regions. Its seeds are used to treat inflammatory diseases, diarrhea and skin problems in traditional medical practices. Regarding its widespread medicinal uses, it is important to evaluate the biological and toxicological potential of this species. This way, the aim of this study was to investigate the in vitro cytotoxic and immunomodulatory effects of the hexanic extract of P. insignis seeds, as well as its in vivo acute oral toxicity. The biological evaluation was performed by the determination of cytotoxic (MTT and hemolysis assay) and immunomodulatory (phagocytic capacity, lysosomal volume and nitrite production) activities of EHSB in murine peritoneal macrophages. In addition, the oral acute toxicity was evaluated using female Wistar rats treated with EHSB (2.0 g/kg), in accordance with the OECD 423 Guideline. The EHSB showed low toxicity for macrophages in the MTT test (CC50 value: 90.03 µg/ml), as well as for erythrocytes, which caused only 2.5% hemolysis at the highest concentration. A strong immunomodulatory activity was observed by a markedly increase of the NO production, phagocytic ability and lysosomal volume. On the other hand, it was not observed deaths or changes in the clinical and behavioral parameters in the toxicological evaluation. This manner, the present study contributes to the knowledge about the immunomodulatory and toxicological properties of the P. insignis. This may provide perspectives for the evaluation and development of effective and safe phytomedicines created from the Brazilian local biodiversity.
Résumé
Administration of ethanol extract of stem bark from Z. rhoifolium (EEtOH-ZR) induced hypotension associated with a dual effect in heart rate in normotensive rats. This response was highlighted in spontaneously hypertensive rats (SHR). In rat superior mesenteric artery rings, the cumulative addition of EEtOH-ZR (0.1–750 µg/mL) on a phenylephrine-induced pre-contraction (10-5 M) promoted a vasorelaxant effect by a concentration-dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl-induced pre-contractions (80 mM). EEtOH-ZR attenuated contractions induced by cumulative addition of CaCl2 (10-6–3 × 10-2 M) in depolarizing medium without Ca2+ only at 500 or 750 µg/mL. Likewise, on S-(–)-Bay K 8644-induced pre-contractions (10-7 M), the EEtOH-ZR-induced vasorelaxant effect was attenuated. EEtOH-ZR (27, 81, 243 or 500 µg/mL) inhibited contractions induced by cumulative addition of phenylephrine (10-9 - 10-5 M) in endothelium-denuded preparations or by a single concentration (10-5 M) in a Ca2+-free medium. The involvement of K+ channels was evaluated by tetraethylammonium (3 mM); the EEtOH-ZR-induced vasorelaxation was not attenuated. Thus, calcium influx blockade through voltage-operated calcium channels (CaVL) and inhibition of calcium release from intracellular stores are probably underlying EEtOH-ZR-induced cardiovascular effects.