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Ethanol extracts of different parts of P. cincinnata were obtained by maceration. The total phenolic and flavonoid contents were evaluated. The antioxidant activities were determined by β-carotene-linoleic acid bleaching test, 2,2-diphenyl-1-picrylhydrazil (DPPH), and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging. The crude ethanol stem extract showed the highest amount of total polyphenols (45.53 mg gallic acid equivalent/g) while the highest total flavonoid contents (1.42 mg of quercetin equivalent/g) were observed in the leaf extract. The lowest IC 50 (25.65 μg/ml) by the DPPH method was observed for the stem extract. The ABTS method showed a significant antioxidant activity for all investigated extracts.The secondary metabolite composition of ethanol extracts was assessed by HPLC-DAD-MS/MS analysis, leading to the identification of fourteen secondary metabolites in P. cincinnata extracts. These results showed the potentiality of this species as a source of phenolic compounds and antioxidants.

Abstract. Polyanilines are reported to exhibit stabilizing effects in rubber mixtures submitted to gamma-irradiation and thermo-oxidative treatment. Such abilities may be explained by their action as radical scavengers. Since radical formation followed by main chain scission is a widely accepted mechanism for radiolytic degradation of PMMA, polyaniline is a promising additive for commercial plastics submitted to radiosterilization processing. In this work, we investigated the ability of polyaniline emeraldine salt nanofibers (PANF-HCl) in preventing radiation damage on PMMA matrix. Effects of gamma-irradiation on PMMA/PANF-HCl composites films were assessed by comparison of the variation of viscosityaverage molar mass (Mv) of PMMA at 25 kGy dose when compared to commercial PMMA films. Samples containing 0.15% PANF-HCl (wt/wt) retained 92% of the initial Mv after irradiation while control sample presented 42% of Mv retention. When exposed to 60-200 kGy doses, PANF-HCl embedded into PMMA matrix preserved their oxidation state but started to exhibit mild deprotonation. PANF-HCl nanofibers were characterized by Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS) and Scanning Electronic Microscopy (SEM). PMMA/PANF-HCl composites films were characterized by SEM and UV-VIS spectroscopy.

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Atividade Citotóxica de Constituintes Químicos e Óleo Essencial das Folhas de Leonotis nepetifolia (Lamiaceae) Resumo: O câncer é um problema de saúde que afeta grande parte da população mundial. Nesse contexto, vários grupos de pesquisa têm investigado moléculas com maior eficiência e menores efeitos colaterais. A espécie Leonotis nepetifolia é um arbusto pertencente à família Lamiaceae com atividade citotóxica relatada na literatura. Este trabalho descreve o isolamento dos compostos hentriacontano, palmitato de fitila, estigmasterol glicosídeo, 6,7-dimetoxi-5,3',4'-trihidroxiflavona, apigenina-7-O-glicosídeo e luteolina-7-O-glicosídeo a partir de extratos e a composição química do óleo essencial das folhas de espécimes brasileiras de L. nepetifolia, além das suas atividades citotóxicas in vitro. Os compostos foram identificados por uma série de métodos espectroscópicos e espectrométricos, principalmente RMN (1D e 2D) e CG-EM, bem como por comparação com dados da literatura. A atividade citotóxica de compostos isolados e óleo essencial foi realizada utilizando o ensaio de brometo de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazólio (MTT), contra linhagens de células tumorais HCT-116 (cólon humano) e SF-295 (glioblastoma). O álcool 1-octen-3-ol foi o composto majoritário do óleo essencial e os compostos hentriacontano, palmitato de fitila, estigmasterol glicosídeo, apigenina-7-O-glicosídeo e luteolina-7-O-glicosídeo foram descritos pela primeira vez nesta espécie. Todos os compostos testados e o óleo essencial apresentaram baixa atividade citotóxica para as linhagens celulares testadas, sugerindo que outros estudos fitoquímicos devam ser conduzidos para a descoberta de outros compostos responsáveis pela atividade citotóxica da espécie.

BackgroundLeonotis nepetifolia (Family Lamiaceae) is a medicinal plant from which the flavonoid cirsiliol with sedative, hypnotic, anti-inflammatory and cytotoxic activity has been extracted.MethodsSeedlings were cultivated under different levels of shade in native or fertilized modes. The content of cirsiliol was measured monthly by high-performance liquid chromatography and the total phenolic content by the Folin-Ciocalteu method. Monitoring of growth was carried out with the weekly measurement of height until the stabilization of growth.ResultsThe application of fertilizing and/or shading does not alter significantly the cirsiliol content. However, this content varies throughout the year, reaching the peak production in the summer, independently of the treatment applied. This same profile, with production in the summer, was also verified for phenolic compounds, reaching 58.15 ± 9.35 mg of equivalents of gallic acid per g of extract in the summer, content 1.84 times greater than the content verified in winter (31.56 ± 4.09 mg of gallic acid/g of extract). Although shading and fertilizing had no effect on cirsiliol content, the results also showed a positive influence on the height and biomass of the plant, which can causes a higher yield of extractable material.DiscussionBiotic and abiotic stresses are able to increase or decrease the production of secondary metabolites, including phenolic compounds in medicinal plants and, as the stress response is peculiar to each species, cultivation studies become necessary. The present study reports by the first time the influence of shading, fertilizing and seasons in cirsiliol content in L. nepetifolia. Among analyzed variables, the seasons showed a larger influence in expression of cirsiliol and among seasons, our results showed that the summer is the ideal season for collections. In summer, the photoperiod is larger than in other seasons of the year and due to that, the plants need greater protection against the long photoperiod. For this, the plants increase the production of phenolic compounds as observed in this study. Although they do not influence the production of cirsiliol, the shading and nutrients in soil favor growth and leaf area of several plants, explaining, thus, the higher height and biomass obtained.

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