Fernando Cesar Martins Betim

Tagetes minuta L. is a naturalized species that is not endemic to the high-altitude fields of Santa Catarina in southern Brazil. In this study, we investigated the composition of the essential oil (EO) from the flowers of the plant and its larvicidal activity against Aedes aegypti. The EO was obtained by hydrodistillation using a Clevenger apparatus. The chemical composition was determined using gas chromatography coupled with mass spectrometry (GC-MS). The EO extraction yield was 4.9%, and the major compounds (Z)-tagetone, (Z)-β-ocimene, and dihydrotagetone were identified. The 24 h larvicidal activity was verified against that of L3 larvae of the Rockefeller strain of Ae. Aegypti. The EO showed larvicidal activity against Ae. aegypti, with LC₅₀ = 17.28 μg/mL^-1. The results indicate that the bioinsecticidal potential of T. minuta EO is promising for the development of research in the field of natural products.

The objective of this study was to assess the potential antioxidant, antimicrobial, and toxicological properties of crude extracts and fractions obtained from the leaves and stem of Psychotria fractistipula L.B. Sm., Klein & Delprete. The content of phenolic compounds varied significantly between samples (783.70–78.22 GAE mg/g), with the highest concentrations being in the ethyl acetate fraction of the leaves and stem (679.39 and 783.70 GAE mg/g, respectively). The latter yielded also the best IC₅₀ of the DPPH radical, which amounted to 9.48 and 4.75 µg/mL, respectively; whereas other samples ranged up to 156.64 µg/mL. Similarly, phosphomolybdenum activity varied between 90.17% and 16.00%, with the ethyl acetate fractions of the leaves and stem corresponding to 90.17% and 87.37%, respectively. Antimicrobial activity was elevated in the leaves crude extract (Staphylococcus aureus, 62.5 µg/mL), leaves ethyl acetate fraction (S. aureus, 31.25 µg/mL; Enterococcus faecalis, 62.4 µg/mL), and the stem ethyl acetate fraction (S. aureus, 31.25 µg/mL; Pseudomonas aeruginosa, 62.5 µg/mL). Hemolytic activity was high in the chloroform fractions of the leaves (1000 µg/mL) and stem (500 µg/mL). Larvicidal activity against Aedes aegypti was observed in the hexane fraction of the stem (LC₅₀, 297.44 µg/mL). The ethyl acetate fractions of the stem and leaves were toxic to Artemia salina, with LC₅₀ values of 277.91 and 933.89 µg/mL, respectively. These results indicate that P. fractistipula may constitute an unexplored source of natural antioxidants and antimicrobials with low toxicity.

Research with fungi in search of substances with potential biological activity is gaining more prominence since they are sustainable sources of new molecules. Diplodia pinea is a phytopathogenic fungus found in forest species, which has shown few reports of molecules with biological activity and may present promising biotechnological potential. Thus, the objective of this study was to detect substances produced by this fungus in a liquid medium, under stressful conditions. A metabolite was detected in the alcoholic fraction characterized by X-ray diffraction as D-mannitol. This is the first description of this monosaccharide produced by D. pinea.

The Ocotea genus exhibits a variety of pharmacological, antibacterial and antioxidant effects. The aim of the present study was to evaluate the antioxidant potential and antibacterial properties of the ethyl acetate fraction of Ocotea nutans leaves. Isolation and identification of the phenolic compounds from the fraction was also carried out. The isolated compounds were characterised by one- and two-dimensional nuclear magnetic resonance analysis and identified as vitexin (1) and isovitexin (2). The ethyl acetate fraction of Ocotea nutans leaves demonstrated considerable antioxidant potential. The observed minimum inhibitory concentration of 250 µg.mL⁻¹ was classified as a moderate antibacterial activity against Enterococcus faecalis. Findings from this study demonstrate the utility of this plant as a potential source of antioxidant and antibacterial agents. Graphical Abstract

The Ocotea puberula (Rich.) Nees (Lauraceae) (popular name is canela-guaiacá) is rich in secondary metabolites, among them, the alkaloids. Dicentrine is an alkaloid from O.puberula and have pharmacological actions such as anti-inflammatory, analgesic, anxiolytic and antimalarial. The objective of this work was to investigate the antioxidant and biological potential of the alkaloid dicentrine isolated from the galls of Ocotea puberula. To evaluate the antioxidant potential, the techniques of the formation of the phosphomolybdenum complex, Prussian blue and the reduction of DPPH• were used and the biological activity was evaluated using Artemia salina, sheep erythrocytes, Aedes aegypti larvae and two target species. The phosphomolybdenum method showed an antioxidant potential of 90.68% compared to rutin, 30.88% compared to BHT and 16.62% compared to ascorbic acid. By the DPPH• method it presented IC₅₀ = 943.11 µg.mL^-1, indicating low antioxidant potential. When evaluating dicentrine in Artemia salina, a low toxic potential and a non-hemolytic effect were verified in sheep erythrocytes. In the larvicidal activity in Aedes aegypti, dicentrin showed LC₅₀ = 23.62 µg.mL^-1. On Lactuca sativa, dicentrine did not influence germination, IVG and hypocotyl growth, but root growth was stimulated with 250 µg.mL^-1 and inhibited with 500 µg.mL^-1. On Allium cepa dicentrine with 25 and 100 µg.mL^-1 stimulated the germination percentage and the GVI. The growth of the Allium cepa root was not influenced, however, the coleoptile was stimulated with 25 µg.mL^-1 and inhibited with 50 µg.mL^-1. After evaluating the results presented in the chosen tests, it was observed that dicentrine has a larvicidal and allelopathic potential.

Inúmeros metabólitos primários e secundários provenientes de fungos tem-se destacado na pesquisa devido o potencial biológico de suas moléculas, com aplicação direta na área da saúde. A dengue é uma patologia transmitida por um vetor, o mosquito Aedes aegypti, e possui grande relevância epidemiológica em diversos países, incluindo o Brasil. Como estratégias do Ministério da Saúde para o combate e controle da dengue emprega-se o uso de inseticidas, eliminação de criadouros e campanhas de conscientização. O uso de compostos inseticidas tem mecanismo de ação sobre o mosquito A. aegypti e suas larvas. Neste contexto e levando em consideração que larvicidas de origem natural, em sua maior parte, não causam impactos tão severos ao meio ambiente e à saúde humana, o objetivo do presente trabalho foi testar a atividade larvicida de extratos obtidos do fungo Diplodia pinea, observar o rendimento destes extratos e realizar um screening químico qualitativo para observação de compostos secundários. Os extratos hexano e clorofórmio apresentaram atividade larvicida significativa com LC50 441.42 e LC50 90.49, respectivamente. A triagem de metabólitos indicou a presença para as classes esteroides, triterpenos e compostos fenólicos e o rendimento dos extratos foi de 1,67 a 47,33%. Estes resultados demonstram que os extratos obtidos a partir do fungo D.pinea apresentam potencial efeito larvicida e ausência de toxicidade frente à Artemia salina.

Panneerselvam et al.³ and Seetharaman et al.⁴ have reported that the overuse of conventional synthetic pesticides and larvicidal agents has influenced the emergence of resistant mosquito populations. The Brazilian flora, which is both extensive and diverse, is a natural asset possessing immense potential for secondary plant compounds, many of which can be utilized in the manufacture of agrochemicals. The search for novel compounds with larvicidal and insecticidal activities has gained further significance as the region is currently experiencing a dramatic increase in the incidence of insect-transmitted diseases.

Essential oils are an important natural source of pesticides and can be suitable used in ectoparasite control. The goal of this paper was to investigate the chemical composition of the volatile oils obtained from leaves and stems of Philodendron meridionale Buturi & Sakur by gas chromatography/mass spectrometry and to evaluate their insecticidal effect against Ctenocephalides felis Bouché adult insects and their cytotoxicity on human Jurkat leukemic T-cells by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazoluim bromide (MTT) reduction method. The main compound was ent-kaur-16-ene at concentrations of 20.78 and 22.46% for volatile oils from leaves and stems, respectively. These volatile oils provided insecticidal effect against C. felis with an average knockdown time of 9.61 and 7.35 min for fumigant test performed with the leaves and stems samples, respectively. Considering the topical application, these P. meridionale volatile oils extracted from leaves and stems demonstrated average knockdown values of 14.70 and 20.0 min, respectively. A very low cytotoxic effect of 9.48 and 11.32% was observed for P. meridionale volatile oils from leaves and stems even at the highest tested concentration of 400 μg.mL-1, respectively. Therefore, it is possible to propose a biological selectivity to the volatile oils under study, which guarantees, at the same time, effect against this insect with no evident damage to human biological system.