Polyploidy, a numerical alteration of the karyotype, is one of the most important mechanisms in plant speciation and diversification, but could also be detected among populations, the cytotypes. For example, Psidium cattleyanum, a polyploid complex, has chromosome numbers ranging from 2n=3x=33 to 2n=12x=132. Polyploidization causes an increase in DNA content, and both modifications may cause alteration in plant growth, physiology, and epigenetics. Based on this possibility, here we aim to verify the influence of the polyploidization on the production of P. cattleyanum essential oil chemotypes. Differences in the DNA contents, as a proxy to different ploidies, were observed and three distinct chemotypes were identified through the chromatographic profile analysis. The Psidium cattleyanum DNA content and qualitative and quantitative characteristics of the essential oils presented a positive relationship. Plants with higher DNA contents presented higher levels of oil production, which was mostly composed of hydrogenated sesquiterpenes, while plants with lower DNA contents produced lower amount of oil, which was mostly composed of hydrogenated monoterpenes. Based on the importance of essential oils, polyploid plants, which present higher DNA content, are recommended as possible matrices for the propagation of new plants with the potential to produce major compounds of agronomic and pharmacological interest.
The search for more environmental friendly herbicides, aiming at the control of agricultural pests, combinated with less harmfulness to human health and the environment has grown. An alternative used by researchers is the application of products of secondary plant metabolism, which are investigated due to their potential bioactivities. Thus, species belonging to the Myrtaceae family are potential in these studies, since this family is recognized for having high biological activity. A species belonging to this genus is Psidium cattleyanum, which has a medicinal effect and its fruits are used in human food. Thus, the objective of this research was to evaluate and compare the phyto-cyto-genotoxicity of aqueous and ethanolic leaf extracts of the specie P. cattleyanum, from plant bioassays, as well as to identify the main classes of compounds present in the extracts. For this, the extracts were prepared, characterized and biological tests were carried out by evaluating, in seeds and seedlings of lettuce and sorghum, the variables: percentage of germination, germination speed index, root growth and aerial growth; and in meristematic lettuce cells the variables: mitotic phases, mitotic index, nuclear alterations and chromosomal alterations. Flavones, flavonones, flavonols, flavononols, flavonoids, alkaloids, resins, xanthones and anthraquinone glycoside were characterized in the ethanolic extract. Both evaluated extracts, in the highest concentration, inhibited the initial plant development. All treatments caused alterations in the mitotic phases and inhibited mitotic index. In addition, the treatments promoted an increase in nuclear and chromosomal alterations. The mechanism of action presented was aneugenic, clastogenic and determined in epigenetic alterations. The ethanolic extract was more cytotoxic, since it had a more expressive effect at a lower concentration. Despite the cytotoxicity of the extracts under study, they promoted alterations at lower levels than the glyphosate positive control.
Natural products with biological activity, such as essential oils, can be used in the search for and development of ecological herbicides as an alternative to reduce the damage caused by synthetic herbicides. This work to aimed to determine the chemical composition and phytotoxic properties of the essential oils, at concentrations of 3000, 1500, 750, 375 and 187.5 µg/mL, of four cultivars of Psidium guajava (guava) evaluated on germination and root growth of plant models Lactuca sativa and Sorghum bicolor, as well as in the L. sativa cell cycle. Exposure to essential oils reduced germination and root growth in bioassays, especially at the highest concentration (3000 µg/mL). The essential oils interfered in the normal dynamics of the cell cycle of L. sativa at most concentrations, causing a decrease in the mitotic index and increasing of chromosomal alterations, evidencing aneugenic and clastogenic action. The biological activity of the oils was associated with the presence of sesquiterpenes and monoterpenes found here, such as caryophyllene oxide, (E) -caryophyllene, and limonene. Thus, the essential oils of cultivars of guava demonstrated the promising potential for use as natural herbicides.
The present investigation aimed to develop inclusion complexes (ICs) from Psidium gaudichaudianum (GAU) essential oil (EO) and its major compound β-caryophyllene (β-CAR), and to evaluate their herbicidal (against Lolium multiflorum and Bidens pilosa) and cytogenotoxic (on Lactuca sativa) activities. The ICs were obtained using 2-hydroxypropyl-β-cyclodextrin (HPβCD) and they were prepared to avoid or reduce the volatility and degradation of GAU EO and β-CAR. The ICs obtained showed a complexation efficiency of 91.5 and 83.9% for GAU EO and β-CAR, respectively. The IC of GAU EO at a concentration of 3000 µg mL−1 displayed a significant effect against weed species B. pilosa and L. multiflorum. However, the β-CAR IC at a concentration of 3000 µg mL−1 was effective only on L. multiflorum. In addition, the cytogenotoxic activity evaluation revealed that there was a reduction in the mitotic index and an increase in chromosomal abnormalities. The produced ICs were able to protect the EO and β-CAR from volatility and degradation, with a high thermal stability, and they also enabled the solubilization of the EO and β-CAR in water without the addition of an organic solvent. Therefore, it is possible to indicate the obtained products as potential candidates for commercial exploration since the ICs allow the complexed EO to exhibit a more stable chemical constitution than pure EO under storage conditions.
Essential oils are a source of promising bioactive compounds for the development of environmentally friendly herbicides. However, the low solubility, high volatility, and degradability make it impossible to apply essential oils under field conditions. Encapsulation in nanoemulsions and inclusion complexes can overcome these disadvantages by increasing the stability of these products. Recent studies have shown the ability of some protected essential oils to suppress weed development. This chapter reviews the processes of encapsulation and use of these essential oils. Inclusion complexes can be prepared using oligosaccharides such as cyclodextrins by the molecular inclusion method, while nanoemulsions can be obtained through low and high-energy methods. The development of nanoemulsions and inclusion complexes can increase the solubility and physicochemical stability of essential oils, providing stable formulations for use in agricultural fields.
As plantas do gênero Psidium (Myrtaceae) apresentam, dentre seus usos relevantes, atividades biológicas relacionadas aos seus compostos ativos, com destaque ao óleo essencial (OE) presente na folha. Os OEs extraídos das folhas de Psidium guajava, Psidium cattleyanum e Psidium gaudichaudianum possuem aplicações em larvas de Aedes aegypti, herbicida e citogenotóxica. Para ampliar as aplicações do OE, que é insolúvel em água e facilmente degradado por fatores externos, métodos de proteção podem ser utilizados para formar cápsulas ou complexos de inclusão (CIs). Um oligossacarídeo que pode ser utilizado para complexar o OE é a 2-hidroxipropil-β-ciclodextrina (HPβCD), que é derivada do amido. Para produzir os CIs, os métodos físicos como maceração (KN) e liofilização (FD) podem ser empregados. A fim de comprovar se os CIs foram preparados corretamente, técnicas analíticas podem ser utilizadas, como a espectroscopia na região do UV-Vis, FTIR, TGA, DLS e XRD. Os OEs e CIs de Psidium produzidos podem ser aplicados em larvas de Aedes aegypti, em plantas invasoras como Lolium multiflorum e Bidens pilosa e em células meristemáticas da raiz de Lactuca sativa, sendo verificado a influência na normalidade do ciclo celular. Considerando a importância dos óleos essenciais, dos complexos de inclusão e de suas potenciais aplicações, este capítulo aborda os assuntos mais relevantes numa revisão da literatura sobre esse assunto.
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