Toxicity evaluation of Eleutherine plicata Herb. extracts and possible cell death mechanism.

Eleutherine plicata has been shown to be a promising medicinal plant, and its activity has been associated with naphthoquinones. The present study aimed at evaluating the cytotoxicity, genotoxicity, and oral toxicity of the ethanol extract (EEEp), dichloromethane fraction (FDMEp) of E. plicata, and isoeleutherin. For the cytotoxicity evaluation, the viability test (MTT) was used. Genotoxicity was accessed through the Comet assay (alkaline version), acute and subacute oral toxicities were also evaluated. The antioxidant capacity of the samples in the wells where the cells were treated with E. plicata was evaluated. Furthermore, the participation of caspase-8 in the possible mechanism of action of isoeleutherin, eleutherin, and eleutherol was also investigated through a docking study. FDMEp and isoeleutherin were cytotoxic, with higher rates of DNA fragmentation observed for FDMEp and isoeleutherin, and all samples displayed higher antioxidant potential than the control. In the acute oral toxicity test, EEEp, FDMEp, and isoeleutherin did not cause significant clinical changes. In the subacute toxicity assay, EEEp and FDMEp also did not cause clinical, hematological, or biochemical changes. The three compounds bound similarly to caspase-8. Despite the results of cytotoxicity, in vitro studies demonstrated that the use of EEEp appears to be safe and cell death may involve its binding to caspase-8.

Antioxidant activity of α and ß-amyrin isolated from Myrcianthes pungens leaves.

Brazil has a great variety of native plants which could be explored and among them guabiju (Myrcianthes pungens) stands out. Thus, this study consisted of isolating pentacyclic triterpenes, α and ß-amyrin from guajibu leaves, and determine the antioxidant activity.The leaves were dried, pulverized and submitted to a dynamic maceration process with ethanol 96° GL, concentrated to obtain crude leaf extract (CLE). CLE was eluted with dichloromethane until total depletion, resulting in a dichloromethane fraction (FRDicl) which was concentrated and analyzed by GC/MS and NMR. The result of the chemical analysis revealed the presence of pentacyclic triterpenes of oleanane (ß-amyrin), and ursane (α-amyrin) groups. The ß-carotene bleaching method revealed a high antioxidant activity for the CLE as well as for FRDicl. The antioxidant protection equivalent to the trolox was of 137 and 129%, respectively at 500 µg/mL. The antioxidant potential of FRDicl can be explained by the presence of α and ß-amyrins.

Phytochemical study guided by the myorelaxant activity of the crude extract, fractions and constituent from stem bark of Hymenaea courbaril L.

ETHNOPHARMACOLOGICAL RELEVANCE: Hymenaea courbaril L. (Caesalpinoideae) is used in Brazilian folk medicine to treat anemia, kidney problems, sore throat and other dysfunctions of the respiratory system, such as bronchitis and asthma, although such properties are yet to be scientifically validated. AIM OF THE STUDY: In order to give a scientific basis to support the traditional use of Hymenaea courbaril, this study was designed to evaluate antioxidant, myorelaxant and anti-inflammatory properties of the ethanol extract from stem bark and its fractions. The myorelaxant effect of astilbin, a flavonoid isolated from the bioactive ethyl acetate fraction (EAF), has also been evaluated. MATERIAL AND METHODS: In the present study ethanol extract from stem bark (EEHC) and fractions were analyzed using bioassay-guided fractionation. The following activities were investigated: antioxidant by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, myorelaxant on rat tracheal smooth muscle, and anti-inflammatory using ovalbumin-induced leukocytosis and airway hyperresponsiveness in rats. RESULTS: The results of the present investigation show that the whole extract of Hymenaea courbaril and some of its fractions strongly scavenged DPPH radical. The extract showed myorelaxant activity on rat trachea, being EAF its highest efficient fraction. Bio-guided study allowed the isolation of astilbin, a well-known flavonoid. The activity induced by this compound indicates that it may be partly responsible for the myorelaxant effect of EAF. EAF reduced contractions that depended on divalent cation inflow through voltage-operated Ca(2+) channels (VOCCs) or receptor-operated Ca(2+) channels (ROCCs), but it was more potent to inhibit VOCC- than ROCC-dependent contraction induced by Ca(2+) addition in ACh-enriched Ca(2+)-free medium. Oral pretreatment of antigen-challenged animals with EAF prevented airway hyperresponsiveness on KCl-induced contraction and reduced the number of total white cells, particularly eosinophils and neutrophils in bronchoalveolar lavage. CONCLUSIONS: This study provided scientific basis that Hymenaea courbaril presents potential antioxidant, myorelaxant and anti-inflammatory actions, which support its use in folk medicine to treat inflammatory airway diseases.