Carolina de Oliveira Bernardes

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by 1H NMR, 13C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL-1. Most of the tested compounds presented MIC values ≤220 μg mL-1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

Chemotype diversity of Psidium guajava L.

The essential oil of Psidium guajava L. has been studied for pharmacological and industrial purposes, without considering the plants genotype regarding the heterogeneity of its composition. The present study aimed to characterize the chemotype diversity of the essential oil extracted from the leaves of 22 genotypes of P. guajava grown in two different environments in the state of Espírito Santo, Brazil, and to identify the different chemical markers present in these plants. Essential oil from the leaves of the P. guajava genotypes was extracted by hydrodistillation, and its chemical composition was analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Thirty-three compounds were identified, comprising 87.5-99.0% of the total composition, with a prevalence of sesquiterpenes in all samples. The major compounds identified consisted of (E)-trans-Caryophyllene, α-Humulene, trans-Nerolidol, β-Bisabolene, β-Bisabolol, and Hinesol, the first of which was identified as a possible chemical marker for the species. Multivariate factor analysis of the chemical composition of P. guajava oil identified three chemotypes: Commercial - PAL, SEC, PS, PET, C7, C11, and C17MI, characterized by high levels of β-Selinene, α-Selinene, Hinesol, and 14-hydroxy-epi-(E)-caryophyllene, with β-Selinene and α-Selinene as the chemical markers; C10 and C13, exhibiting high levels of Elemol, trans-Nerolidol, trans-β-Eudesmol, and (2Z, 6Z)-Farnesol, which were indicated as chemical markers, and Cortibel - C1, C2, C3, C4, C5, C6, C8, C9, C12, C14, C15, C16, C17LI, which retained high levels of α-Cedrene, cis-α-Bergamotene, α-Humulene, Humulene epoxide, epi-α-Cadinol, β-Bisabolol, and α-Bisabolol, with β-Bisabolol and α-Bisabolol as the chemical markers. The use of guava genotypes with different chemotypes, that are agronomically favorable to fruit production and essential oil exploitation adds value to the crop and renders it more sustainable. Given guava crops produce large amounts of leaf biomass, resulting from successive prunings, the extraction of their essential oil, which retains commercially valuable compounds, can be feasible.

Transferability of Psidium microsatellite loci in Myrteae (Myrtaceae): a phylogenetic signal

Myrteae is the most diverse tribe, in number of species and genera, of the family Myrtaceae, representing half of the family’s biodiversity. Analysis of universal cross-transferable genetic markers across genera/species is essential and may significantly contribute towards the better understanding of species systematics and evolution. In the present study, a total of 133 sequence-tagged microsatellite markers from Psidium guajava L. were evaluated for transferability to forty-four species of the tribe Myrteae, which represent nine different genera of the family Myrtaceae (Myrciaria, Plinia, Pimenta, Acca, Campomanesia, Psidium, Eugenia, Syzygium, and Eucalyptus). Cross-transferable simple sequence repeat (SSR) markers were employed to evaluate the phylogenetic relationships between them. The results indicated a high level of congruence with earlier reports regarding genetic divergence and taxa clustering. An analysis to optimize the number of SSR markers was also performed, revealing that even a small amount is capable of determining the systematic positions of different genera/species of the Myrteae tribe.

INTERFERÊNCIA DA RADIAÇÃO SOLAR NA CULTURA DO RABANETE

Podem ocorrer diferencas nas caracteristicas fisiologicas, bioquimicas, anatomicas e de crescimento de uma planta quando esta for submetida a modificacoes nos niveis de luminosidade ao qual esta adaptada. A resposta da planta as diferentes condicoes de intensidade luminosa e importante para determinar o seu potencial de crescimento e ocorrencia e, tambem, avaliar a sua capacidade competitiva em diferentes condicoes ambientais. O objetivo deste trabalho foi avaliar as caracteristicas de plantas de rabanete submetidas a diferentes niveis de luminosidade. O experimento foi conduzido em casa de vegetacao e o delineamento experimental utilizado foi de blocos ao acaso com sete repeticoes. Os tratamentos foram compostos por quatro intensidades de radiacao solar (100%, 70%, 50% e 30% de luminosidade). A reducao de intensidade de luz para 70%, 50% e 30% foi obtida com o uso de tela sombrites de 30%, 50% e 70%, respectivamente. Foram avaliados os teores de clorofila A, B e total, numero de folhas, area foliar, massa da materia fresca e seca da parte aerea e sistema radicular. Conclui-se que os niveis de sombreamento de 30%, 50% e 70% prolongaram o ciclo de desenvolvimento da cultura e promoveram a reducao no tamanho e na massa das raizes tuberosas.

Carrot seed germination in different conditions of salinity and temperature

El exito en el proceso de la germinacion depende del agua que ingresa a traves de los tejidos que rodean la semilla. La presencia de sal reduce el gradiente entre el suelo y la superficie de la semilla, lo que limita la absorcion del agua por la semilla. El objetivo de la investigacion fue evaluar el efecto de la salinidad y la temperatura sobre la germinacion de semillas de zanahoria. El potencial osmotico utilizado en las soluciones fue 0,0 (control); - 0,4; -0,8; -1,2, -1,6 y 2,0 Mpa, obtenidas con el uso de NaCl, y las temperaturas utilizadas fueron 15 °C 20 °C 25 °C 35 °C 15-35 °C y 25- 35 °C. En las evaluaciones, se utilizo un lote comercial de Brasilia. En las evaluaciones de semillas de zanahoria cv se midieron porcentaje de germinacion, indice de velocidad de germinacion, peso fresco y seco de las plantulas. Las medias fueron sometidos a analisis de regresion. En el ensayo, la germinacion se redujo en 35 °C en potencial osmotico mayor que -0,8 MPa. Las temperaturas de 20 °C y 25 °C son mas favorables para la germinacion y la tasa de germinacion de las condiciones ensayadas.