Aspectos botânicos, químicos, farmacológicos e terapêuticos do Hypericum perforatum L / Botanical, chemical, pharmacological and therapeutic aspects of Hypericum perforatum L

Estima-se que aproximadamente 25% das drogas prescritas em todo o mundo são oriundas de espécies vegetais. Dentre as plantas com alto potencial medicinal, se destaca o Hypericum perforatum L. (HP), planta herbácea perene, pertencente à família Hypericaceae. Extratos orgânicos e aquosos de HP têm sido utilizados na medicina popular e em testes pré-clínicos para o tratamento e prevenção de diversas doenças através de efeitos nefroprotetores, atividades antioxidante, antifúngica, ansiolítica, antiviral e cicatrizante. Estudos clínicos indicaram que esta espécie pode ser útil no tratamento de desordens originadas do sistema nervoso central, especialmente na depressão unipolar. HP contém, ao menos, dez classes de compostos biologicamente ativos, dentre eles antraquinonas/naftodiantronas, derivados de floroglucinol, flavonoides, biflavonas, xantonas, óleos voláteis, aminoácidos, vitamina C, cumarinas, taninos e carotenoides. Ao mesmo tempo em que os constituintes possuem relevantes efeitos farmacológicos, os mesmos podem prejudicar, por antagonismo farmacocinético (interação com algumas enzimas do citocromo), a eficácia de outros fármacos. Devido a relevante importância do HP como agente terapêutico, ressalta-se a importância do desenvolvimento de novos estudos com o intuito de elucidar questões ainda controversas acerca do extrato de HP, e.g., dose, melhor horário para colheita, padronização dos extratos, e possíveis efeitos tóxicos, podendo assim, definir claramente os riscos e benefícios da utilização desta planta.

It is estimated that approximately 25% of prescribed drugs are derived from plant species. Among the plants with high medicinal potential, it highlights the Hypericum perforatum L. (HP), perennial herbaceous plant belonging to the family Hypericaceae. Organic and aqueous extracts of HP have been used in folk medicine and in pre-clinical testing for the treatment and prevention of several diseases through effects nefroprotetores, antioxidant, antifungal, anxiolytic, wound healing and antiviral activities. Clinical studies indicated that this specie can be useful in the treatment of central nervous system disorders, especially to unipolar depression. HP contains at least ten classes of biologically active compounds, including anthraquinones/naftodiantronas, phloroglucinol derivatives, flavonoids, biflavones, xanthones, volatile oils, amino acids, vitamin C, coumarins, carotenoids and tannins. At the same time that the secondary metabolites have important pharmacological effects, they can impair the effectiveness of other drugs by pharmacokinetic antagonism.

Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest.

Habitat fragmentation, caused by the expansion of agriculture in natural areas, may be one of the strongest impacts humans have on the ecosystem. These changes can decrease the number of individuals in a population, leading to endogamy. In allogamous species, endogamy can have a negative effect on reproductive capacity. In this study, we analyzed the effects of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora L., a tree species native to the Atlantic Forest. We analyzed 4 populations, 3 of which were connected by forest corridors and 1 of which was isolated by agricultural fields on all sides. For microsporogenesis analysis, 9000 meiocytes representing all stages of meiosis were evaluated. To perform the pollen viability test, we evaluated 152,000 pollen grains. Microsporogenesis was stable in plants from populations that were connected by forest corridors (abnormalities, less than 6%), while microsporogenesis in plants from the isolated population showed a higher level of abnormalities (13-29%). Average pollen viability was found to be more than 93% in the non-isolated populations and 82.62% in the isolated population. The χ(2) test showed that, in the isolated population, the meiotic index was significantly lower than that in the non-isolated populations (P = 0.03). The analysis of variance for the percentage of viable pollen grains confirmed the significant difference between the isolated and non-isolated populations. Our data show that forest fragmentation has a direct effect on microsporogenesis and pollen viability in E. uniflora and can directly influence the reproductive capacity of isolated populations of this species.