Search results for "I.5"
showing 10 items of 399 documents
Cytotoxic bufadienolides from the leaves of a medicinal plant Melianthus comosus collected in South Africa.
2020
Abstract From the leaves of South African medicinal plant Melianthus comosus, four previously undescribed bufadienolides, 16β-formyloxymelianthugenin (1), 2β-acetoxymelianthusigenin (2), 2β-hydroxy-3β,5β-di-O-acetylhellebrigenin (3), and 2β-acetoxy-5β-O-acetylhellebrigenin (4) were isolated together with two known bufadienolides. The structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy, high-resolution mass spectrometry, and other spectroscopic methods. The relative configurations were determined by single-crystal X-ray crystallography analysis and NOESY correlations. The isolated compounds displayed strong cytotoxicity against MCF-7 breast cancer cells, sensitive…
Cytotoxic 14-Membered Macrolides from a Mangrove-Derived Endophytic Fungus, Pestalotiopsis microspora.
2016
Seven new 14-membered macrolides, pestalotioprolides C (2), D-H (4-8), and 7-O-methylnigrosporolide (3), together with four known analogues, pestalotioprolide B (1), seiricuprolide (9), nigrosporolide (10), and 4,7-dihydroxy-13-tetradeca-2,5,8-trienolide (11), were isolated from the mangrove-derived endophytic fungus Pestalotiopsis microspora. Their structures were elucidated by analysis of NMR and MS data and by comparison with literature data. Single-crystal X-ray diffraction analysis was used to confirm the absolute configurations of 1, 2, and 10, while Mosher's method and the TDDFT-ECD approach were applied to determine the absolute configurations of 5 and 6. Compounds 3-6 showed signif…
Furoquinolines and dihydrooxazole alkaloids with cytotoxic activity from the stem bark of Araliopsis soyauxii.
2018
Abstract Two new furoquinoline alkaloids, maculine B (1) and kokusaginine B (2) and one new dihydrooxazole alkaloid, veprisazole (3), along with four known compounds namely, N13-methyl-3-methoxyrutaecarpine (4), flindersiamine (5), skimmianine (6) and tilianin (7) were isolated from the methanol extract of the stem bark of Araliopsis soyauxii Engl. by various chromatographic methods. Their structures were determined using spectrometry and spectroscopic techniques including NMR and MS. The cytotoxicity of the new compounds compared to that of doxorubicin, the reference anticancer compound, was determined on a panel of nine cancer cell lines including sensitive and drug resistant phenotypes. …
Rotenoids, Flavonoids, and Chalcones from the Root Bark of Millettia usaramensis.
2015
Five new compounds, 4-O-geranylisoliquiritigenin (1), 12-dihydrousararotenoid B (2), 12-dihydrousararotenoid C (3), 4'-O-geranyl-7-hydroxyflavanone (4), and 4'-O-geranyl-7-hydroxydihydroflavanol (5), along with 12 known natural products (6-17) were isolated from the CH2Cl2/MeOH (1:1) extract of the root bark of Millettia usaramensis ssp. usaramensis by chromatographic separation. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas their absolute configurations were established on the basis of chiroptical data and in some cases also by X-ray crystallography. The crude extract was moderately active (IC50 = 11.63 μg/mL) against the ER-negative…
Naphthalene Derivatives from the Roots of Pentas parvifolia and Pentas bussei
2016
The phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Pentas parvifolia led to the isolation of three new naphthalenes, parvinaphthols A (1), B (2), and C (3), two known anthraquinones, and five known naphthalene derivatives. Similar investigation of the roots of Pentas bussei afforded a new polycyclic naphthalene, busseihydroquinone E (4), a new 2,2'-binaphthralenyl-1,1'-dione, busseihydroquinone F (5), and five known naphthalenes. All purified metabolites were characterized by NMR and MS data analyses, whereas the absolute configurations of 3 and 4 were determined by single-crystal X-ray diffraction studies. The E-geometry of compound 5 was supported by DFT-base…
Molecular Search of New Active Drugs AgainstToxoplasma Gondii
1999
Molecular connectivity has been applied to the search of new compounds with activity against the protozoan Toxoplasma gondii, using a stepwise linear discriminant analysis (SLDA) which is able to classify a compound according its activity either as active or as inactive. Among the selected compounds, andrographolide and dibenzotiophene sulfone stand out, both with IC50 values lower than 1 microgram/ml, which are comparable to these of drugs such as sulfamethoxazole, pyrimethamine and trimethoprim, with IC50 values equal to 1.1, 0.04 and 2.31 micrograms/ml, respectively. These results confirm the usefulness of our topological approach for the selection and design of new-lead drugs active aga…
Receptor Binding Properties of the New and Specific Thromboxane Receptor Antagonist Bay U 3405
1992
Human platelet membranes were used to characterize the receptor binding properties of the specific thromboxane receptor antagonist 3H-SQ 29548 and the displacement of 3H-SQ 29548 from its binding site by the new thromboxane receptor antagonist Bay u 3405. The specific binding of 3H-SQ 29548 was saturable with an association rate constant of 1 x 10(-11) mol-1 min-1 and a dissociation rate constant of 0.032 min-1. Nonspecific binding of 3H-SQ 29548 was below 10%. When Scatchard plot analysis was performed on equilibrium saturation binding the kD was 69 nmol/l and the Bmax was calculated as 3.9 pmol/mg membrane protein. 3H-SQ 29548 was dose dependently displaced from its binding site by additi…
5 – 6 gadīgu bērnu tikumisko vērtību izpratnes veidošanās literāro darbu apguves procesā
2021
Kvalifikācijas darba tēma: ,,5 – 6 gadīgu bērnu tikumisko vērtību izpratnes veidošanās literāro darbu apguves procesā”. Darba autore: Agnese Raiska. Pētījuma mērķis: Pētīt 5 – 6 gadīgu bērnu tikumisko vērtību izpratnes veidošanos literāro darbu apguves procesā. Hipotēze: 5 –6 gadīgu bērnu tikumisko vērtību izpratnes veidošanās literāro darbu apguves procesā būs sekmīgāka ja: •skolotājs piedāvās daudzveidīgus tikumiskās vērtības atspoguļojošus literāros darbus; •literārie darbi tiks mērķtiecīgi pārrunāti. Darbs sastāv no divām daļām – teorētiskās un empīriskās daļas. Teorētiskajā daļā ir analizētas pedagogu (L. Priede, A. Špona, I. Freiberga, V. Hibnere, I. Žogota, L. Žukovs u.c.) atziņas pa…
Interactive effects of zearalenone and its metabolites on cytotoxicity and metabolization in ovarian CHO-K1 cells.
2014
Zearalenone (ZEA) is a non-steroidal estrogen mycotoxin with high binding affinity to estrogen receptors. ZEA is rapidly absorbed and metabolized in vivo to α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL). So, mixtures of them may be present in biological systems and suppose a hazard to animals and human health. The aims of this study were to determine the cytotoxic effects of ZEA and its metabolites, alone and in combination in ovarian (CHO-K1) cells during 24, 48 and 72h by the MTT assay; and to investigate the metabolism of the CHO-K1 cells on ZEA, and its conversion into α-ZOL and β-ZOL by CHO-K1 cell after 24 and 48h of exposure. The IC50 value obtained for individual mycotoxins range fr…
Fertility and Polarized Cell Growth Depends on eIF5A for Translation of Polyproline-Rich Formins in Saccharomyces cerevisiae
2014
eIF5A is an essential and evolutionary conserved translation elongation factor, which has recently been proposed to be required for the translation of proteins with consecutive prolines. The binding of eIF5A to ribosomes occurs upon its activation by hypusination, a modification that requires spermidine, an essential factor for mammalian fertility that also promotes yeast mating. We show that in response to pheromone, hypusinated eIF5A is required for shmoo formation, localization of polarisome components, induction of cell fusion proteins, and actin assembly in yeast. We also show that eIF5A is required for the translation of Bni1, a proline-rich formin involved in polarized growth during …