In some previous studies, we described the isolation of nine compounds from leaves of Derris urucu, a species found widely in the Amazon rainforest, identified as five stilbenes and four dihydroflavonols. In this work, three of these dihydroflavonols [urucuol A (1), urucuol B (2) and isotirumalin (3)] were evaluated to identify their potential as allelochemicals, and we are also reporting the isolation and structural determination of a new flavonoid [5,3'-dihydroxy-4'-methoxy-(7,6:5″,6″)-2″,2″-dimethylpyranoflavanone (4)]. We investigated the effects of the dihydroflavonols 1-3 on seed germination and radicle and hypocotyl growth of the weed Mimosa pudica, using solutions at 150 mg.L-1. Urucuol B, alone, was the substance with the greatest potential to inhibit seed germination (26%), while isotirumalin showed greater ability to reduce the development of the hypocotyl (25%), but none of the three substances showed the potential to inhibit radicle. When combined in pairs, the substances showed synergism for the development of root and hypocotyl and effects on seed germination that could be attributed to antagonism. When tested separately, the trend has become more intense effects on seed germination, while for the substances tested in pairs, the intensity of the effect was greater on development of weed.

Isotirumalin (Fig. 1) is a dihydroflavonol isolated from leaves of Derris urucu, a plant from Amazon region used as insecticide and ichthyotoxic agent, whose effects are attributed to the presence of rotenoids.1,2) Although, isotirumalin was previously described in Rhynchosia cyanosperma, its biological effects are still unknown.3) Consumption of flavonoids is directly related with reduced prevalence of cardiovascular diseases in humans.4) Several flavonoids have been described as vasodilator drugs, some with and others without an endothelium-dependent effect. 5,6) In the present work we aimed to investigate the vasorelaxant effect of isotirumalin. We describe here that isotirumalin is an endothelium-and nitric oxide (NO)-dependent vasodilator flavonoid. MATERIALS AND METHODS Materials Isotirumalin was obtained from leaves ofDerris urucu collected in forest reserve of EMBRAPAAmazônia Oriental in Belém, Pará State, Brazil. The isolation, purification and structural identification of pure isotirumalin (20 mg) have been described in previous work.1) Dioclein was synthesized as previously described.7) Phenylephrine, Nw-nitro-L-arginine-methyl-ester (L-NAME), S-nitroso-N-acetyl-DL-penicillamine (SNAP) were purchased from Sigma-Aldrich (St. Louis, MO, U.S.A.). Experiments with Rat AortaMale Wistar rats (200-250 g) from the Animal Care facilities (CEBIO) at UFMG were used. They were kept at 22-25°C in a 12 h light/dark cycle, and had free access to food and water. Animal experiments were performed according to the recommendations of the Brazilian Council for Animal Care.The descending thoracic aorta were prepared and mounted as previously described.8) The aortic rings were maintained at 37°C in Krebs-Henseleit solution, under a tension of 1 g and equilibrated for a period of 1 h before initiating experimental protocols. The presence of functional endothelium was assessed by the ability of acetylcholine (1 mM) to induce more than 70% relaxation of vessels pre-contracted with phenylephrine (0.1 mM). The endothelium was removed by a gentle rubbing of the lumen with a stainless steel wire and the removal was confirmed with absence of relaxation with acetylcholine (1 mM). The responses of the tissues were recorded using isometric transducers and amplifiers (World Precision Instruments, Inc., U.S.A.).Measurement of NO Production of NO induced by isotirumalin was measured simultaneously to vascular function experiments in organ bath system using carbon microsensors with a NO permeable membrane (ISO-NOPF100; World Precision Instruments Inc., U.S.A.) as previously described.9) Carbon microsensors were stabilized for 1 h in Krebs-Henseleit solution and then placed next to the lumen of the vessels before stimulus with isotirumalin (100 mM) and dioclein (10 mM). NO concentrations were determined by calibrations curves of known concentrations of SNAP (0.2 to 500 nM). Results are presented as NO concentrations (nM). Isotirumalin was added in single concentration once the response to phenylephrine (0.1 mM) had stabilized. Preparation...

Aedes aegypti L. (Diptera: Culicidae) is an important transmitter of diseases in tropical countries and controlling the larvae of this mosquito helps to reduce cases of diseases such as dengue, zika and chikungunya. Thus, the present study aimed to evaluate the larvicidal potential of the essential oil (EO) of Ocimum basilicum var. minimum (L.) Alef. The EO was extracted by stem distillation and the chemical composition was characterized by gas chromatography coupled with mass spectrometry (GC/MS and GC-FID). The larvicidal activity of EO was evaluated against third instar Ae. aegypti following World Health Organization (WHO) standard protocol and the interaction of the major compounds with the acetylcholinesterase (AChE) was evaluated by molecular docking. The predominant class was oxygenated monoterpenes with a concentration of 81.69% and the major compounds were limonene (9.5%), 1,8-cineole (14.23%), linalool (24.51%) and methyl chavicol (37.41%). The O. basilicum var. minimum EO showed unprecedented activity against third instar Ae. aegypti larvae at a dose-dependent relationship with LC50 of 69.91 (µg/mL) and LC90 of 200.62 (µg/mL), and the major compounds were able to interact with AChE in the Molecular Docking assay, indicating an ecological alternative for mosquito larvae control.

Hancornia speciosa Gomes is a tree native to Brazil and has therapeutic potential for several diseases. Ethnopharmacological surveys have reported that the plant is used as a hypoglycemic agent and to lose weight. This study aimed to evaluate the effects of the aqueous extract from H. speciosa latex (LxHs) in a zebrafish model of diabetes. The extract was evaluated through high-performance thin-layer chromatography (HTPLC), nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FT-IR). We then tested treatments with LxHs (500, 1000, and 1500 mg/kg) by assessing blood glucose levels in alloxan-induced diabetic animals, and metformin was used as a control. The toxicity was evaluated through histopathology of the pancreas and biochemical assessment of serum levels of AST, ALT, creatinine, and urea. The extract was also assessed for acute toxicity through several parameters in embryos and adult animals. Finally, we performed in silico analysis through the SEA server and docking using the software GOLD. The phytochemical study showed the compounds cornoside, dihydrocornoide, and 1-O-methyl-myoinositol (bornesitol). The treatment with all doses of LxHs significantly decreased alloxan-induced hyperglycemia without any significant histological or biochemical abnormalities. No significant frequency of teratogenesis was observed in the embryos exposed to the extract, and no significant behavioral changes or deaths were observed in adult animals. In silico, the results showed a potential interaction between inositol and enzymes involved in carbohydrates’ metabolism. Overall, the results show a hypoglycemic activity of the extract in vivo, with no apparent toxicity. The computational studies suggest this could be at least partially due to the presence of bornesitol, since inositols can interact with carbohydrates’ enzymes.

A espécie Vatairea guianensis Aubl, tem grande importância e aplicação na medicina tradicional no tratamento de doenças causadas por fungos dermatofíticos, sendo uma espécie promissora de moléculas bioativas, como antioxidantes, antifúngica dentre outras. Neste contexto, o objetivo deste estudo foi realizar o estudo fitoquímico e testar a atividade citotóxica em linhagens tumorais. O fracionamento do extrato etanólico das folhas levaram ao isolamento e identificação estrutural de cinco metabólicos secundários pertencentes a classe das isoflavonas. Destacam-se dois: Vatairenona A (S1) e Vatairenona B (S2), que são novos produtos naturais. A elucidação estrutural foi realizada utilizando dados espectroscópicos de RMN 1D e 2D, e em comparação com os dados da literatura. A substância Lupiwighteona (S3) apresentou citotoxicidade seletiva nas linhas de mama (MCF-7) e melanoma (SK-MEL-19), com valores IC50 3,971 ± 0,153 e 4,677 ± 0,328 μM, sem causar hemólise em eritrócitos de camundongos, avaliada pelo método MTT in vitro. Os resultados são promissores, sendo o primeiro estudo do gênero Vatairea com atividade citotóxica de isoflavonas de produtos naturais.