Maria Mozarina Beserra Almeida

Ocorrência e atividade biológica de quassinóides da última década

Quassinoids, the bitter principles of the Simaroubaceae family, are a group of structurally complex and highly oxygenated degraded triterpenes. They are divided into five groups according to their basic skeleton, C-18, C-19, C-20, C-22 and C-25. In recent years, attention has been focused on quassinoids because several of them have shown promising biological activities. This paper features a review of some characteristics of these compounds, updating known information with discoveries from the last decade and covering chemical structures, basic skeletons, occurrence in genus and species, besides detailed studies of biological activities such as antitumor, antimalarial, phytotoxic, antifeedant, insecticidal, anti-inflammatory and antiulcer.

Estudo químico e biológico de Tephrosia toxicaria Pers.

The ethanol extracts from leaves, stems, pods and roots were assayed against the 3rd instar Aedes aegypti larvae and the highest activity was observed in the roots extracts (LC50 47.86 ppm). This extract was submitted to partition with hexane, chloroform, ethyl acetate and methanol. The respective fractions were bioassayed and the best larvicidal activities were identified in the hexane (LC50 23.99 ppm) and chloroform (LC50 13.80 ppm) fractions. Antioxidant activity (DDPH method) was observed in the ethanol extract (IC50 276 µg/mL) from roots of T. toxicaria. Fractions from this extract were also tested and the highest antioxidant activity (IC50 89 µg/mL) was found in the methanol fraction. The flavonoids iso-obovatin (1), obovatin (2), 6a,12a-dehydro-β-toxicarol (3), 6a,12a-dehydro-α-toxicarol (4) and α-toxicarol (5) were isolated and bioassayed against A. aegypti. The flavonoid 5 showed the best larvicidal activity (LC50 24.55 ppm). The antioxidant activity of 2 was investigated and showed IC50 3.370 µg/mL. The antioxidant and larvicidal activities of Tephrosia toxicaria are reported for the first time.

Determinação de nutrientes minerais em plantas medicinais

The use of vegetables has become widely spread as nourishment, medicinal and cosmetic purposes in recent years. Due to the importance of the analytical study of this class of plants, and considering the growing interest about their inorganic composition that can be represented by the significant number of publications during the last years, the present work intended to analyze the occurrence of some minerals in ten herbs of popular therapeutic use that play important roles in the human metabolism. The studied samples were treated by two different methods: 1) dry ashing followed by acid treatment and 2) as tea by infusion of leaves in boiling water. Next, the metals were quantitatively determined by atomic absorption spectrophotometry (Ca, Mg, Mn and Zn), molecular absorption spectrophotometry (Al and Fe) or flame photometry (K and Na). By comparing the results found in this work with those of the daily recommended values by RDA and WHO, studies are suggested with respect to the use of Chenopodium ambrosioides L. as an alternative source of Na, K, Mg and Zn. Likewise, Ageratum conyzoides L. could be a complementary source of Ca, Mg and Fe in the human diet. Although Lippia alba (Mill.) N. E. Brown and Justicia gendarussa L. have presented high Ca levels, caution should be recommended to some extent concerning the use of this vegetable in view of its significant Al levels.

Avaliação de macro e microminerais em frutas tropicais cultivadas no nordeste brasileiro

Brazil has great importance in the fruits market; however, data on the composition of Brazilian tropical fruits, mainly of those produced in the Northeast region, is scarce. In the present study, it was determined the macro- and micro-minerals of 11 tropical fruits cultivated in the Northeast of Brazil: pineapple, sweetsop, soursop, jackfruit, papaya, mangaba, murici, sapodilla, ciruela, tamarind, and umbu. The samples were dehydrated and mineralized in HNO3/HClO4 (3:1) solution. The minerals Ca, Mg, Mn, Zn, Fe, Co, Se and Ni were analyzed by atomic absorption spectrophotometry; Na and K by flame photometry; and P by the colorimetric method. The results indicated that tamarind is a rich source of all minerals available, especially of Mg, Cu and K, in addition to being a good source of Ca, P, Fe, and Se. Among the minerals evaluated in this study, K presented the highest content, followed by Ca and Mg. Sweetsop, soursop, sapodilla, and murici are good sources of two or more minerals. High correlations were obtained between K and the minerals P, Co, and Fe and between Co and Fe. Therefore, the consumption of the studied tropical fruits is suggested as an assistant to the reposition of mineral nutrients.

Alcaloides iboga de Peschiera affinis (Apocynaceae) - Atribuição inequívoca dos deslocamentos químicos dos átomos de hidrogênio e carbono: atividade antioxidante

Six known alkaloids iboga type and the triterpen α- and β-amyrin acetate were isolated from the roots and stems of Peschiera affinis. Their structures were characterized on the basis of spectral data mainly NMR and mass spectra. 1D and 2D NMR spectra were also used to unequivocal 1H and 13C chemical shift assignments of alkaloids. The ethanolic extract of roots, alkaloidic and no-alkaloidic fractions and iso-voacristine hydroxyindolenine and voacangine were evaluated for their antioxidative properties using an autographic assay based on β-carotene bleaching on TLC plates, and also spectrophotometric detection by reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical.

Estudo mineral de plantas medicinais

Determinations of Ca, Cu, Fe, Mg, Mn and Zn were evaluated in five different samples of medicinal plant leaves. Atomic absorption spectrometry was applied to the metals quantification. Except for Fe in Artemisia vulgaris L, significant levels of these elements were found in all investigated plant as compared to other vegetables which are abundant concerning that mineral content.