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Abstract: A phytochemical study on the most bioactive extract from Tectona grandis led to the isolation of two new norlignans, tectonoelin A and tectonoelin B, together with ten known compounds. The structures of the compounds were determined by a combination of 1D and 2D NMR techniques. This is the first time that this type of compound (C8–C8′ linkage norlignans) has been isolated from a dicotyledon. The general bioactivities of the isolated compounds have been studied using etiolated wheat coleoptiles. The activities showed that the isolated lignans and norlignans should be part of the defence mechanisms of this plant. [Copyright &y& Elsevier]

Abstract: The bioactive fractions of Tectona grandis have yielded seven apocarotenoids, two of which have been isolated for the first time as natural products (tectoionols A and B). The chemical structures were determined through 1D and 2D nuclear magnetic resonance experiments. The absolute configuration of tectoionol A was determined using a modified Mosher methodology. Some NMR assignments for the compounds 9(S)-4-oxo-7,8-dihydro-β-ionol and 3β-hydroxy-7,8-dihydro-β-ionone have been corrected on the basis of g-HSQC and g-HMBC experiments. The general bioactivities of isolated compounds have been studied using etiolated wheat coleoptiles. Those compounds that presented higher levels of activity were assayed on standard target species (Lactuca sativa, Lycopersicum esculentum, Lepidium sativum and Allium cepa). [Copyright &y& Elsevier]

Abstract Alzheimer's disease (AD) is a pathology characterized by the abnormal accumulation of amyloid-beta (Aβ) and hyperphosphorylated tau. Oxidative stress and neuroinflammation are also strongly related to this disease. The ability of two new glycosylated angucyclinones, streptocyclinones A and B (1 and 2), isolated from Streptomyces sp to improve AD hallmarks was evaluated. Compounds were able to protect SH-SY5Y neuroblastoma cells from H 2 O 2 -induced oxidative injury by activating the nuclear factor E2-related factor (Nrf2). Their capacity to modulate neuroinflammation was tested in lipopolysaccharide-activated BV2 microglial cells. Compounds reduced the release of pro-inflammatory factors, inhibited the activation of NFκB and mitogen activated kinases (MAPK), and induced the translocation of Nrf2 to the nucleus of microglial cells. A trans-well co-culture was established to determine the effect of microglia treated with streptocyclinones on the survival of SH-SY5Y cells. The cell viability of neuroblastoma cells increased when the compounds were added to BV2 cells. SH-SY5Y-TMHT441 cells were used to determine the effect of compounds on tau phosphorylation. Both compounds reduced tau hyperphophorylation by targeting MAPK kinases. Moreover, streptocyclinone B (2) was able to inhibit the activity of β-secretase 1 and decrease the release of reactive oxygen species in BV2 cells stimulated with Aβ. With the same co-culture trans-well system, the treatment of Aβ-stimulated microglia with compound 2 augmented the viability of SH-SY5Y-TMHT441 cells. The results presented in this work provide evidences of the multitarget activities displayed by these new Streptomyces compounds, making them good candidates for further studies in the treatment of AD. Graphical abstract Image 1 Highlights • Streptocyclinones protect SH-SY5Y cells from oxidative stress by activating Nrf2. • Compounds modulate neuroinflammation by NFκB and MAPKs inhibition and Nrf2 activation. • Tau hyperphosphorylation is reduced by compounds through inhibition of MAPK kinases. • Streptocyclinone B inhibits BACE1 and decreases ROS release in Aβ-activated BV2 cells. • Neuronal cells are protected by compounds in trans-well co-cultures with microglia. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to assess the phytotoxic potential of leaves of Myrcia tomentosa, as well as to isolate and identify the main bioactive compounds. The results for the coleoptile and phytotoxicity bioassays indicated the ethyl acetate extract for the phytochemistry study, owing to the high activity and the maintenance of the activity at lower concentrations. This extract was chromatographed and subjected to 1H NMR and 13C NMR. Two major active compounds were isolated from the ethyl acetate extract of leaves of M. tomentosa: avicularin and juglanin. The fractions where these compounds were isolated showed potent inhibition of coleoptile growth. This paper is the first report on the presence of the flavonoids avicularin and juglanin in species of Myrtaceae from Neotropical savanna and provides a basis for future studies on the bioprospecting of M. tomentosa. [Copyright &y& Elsevier]