| 1. |
- Erdelyi, Mate, 1975-
(författare)
-
Pterocarpans and isoflavones from the root bark of Millettia micans and of Millettia dura
- 2016
-
Ingår i: Phytochemistry Letters. - 1874-3900 .- 1876-7486. ; 21, s. 216-220-
-
Tidskriftsartikel (refereegranskat)abstract
- From the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia micans, a new pterocarpan, (6aR,11aR)-3-hydroxy-7,8,9-trimethoxypterocarpan (1), named micanspterocarpan, was isolated. Similar investigation of the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia dura gave a further new pterocarpan, (6aR,11aR)-8,9-methylenedioxy-3-prenyloxypterocarpan (2), named 3-O-prenylmaackiain, along with six known isoflavones (3-8) and a chalcone (9). All purified compounds were identified by NMR and MS, whereas the absolute configurations of the new pterocarpans were established by chriptical data analyses including quantum chemical ECD calculation. Among the isolated constituents, calopogonium isoflavone B (3) and isoerythrin A-4′-(3-methylbut-2-enyl) ether (4) showed marginal activities against the 3D7 and the Dd2 strains of Plasmodium falciparum (70–90% inhibition at 40 μM). Maximaisoflavone B (5) and 7,2′-dimethoxy-4′,5′-methylenedioxyisoflavone (7) were weakly cytotoxic (IC50 153.5 and 174.1 μM, respectively) against the MDA-MB-231 human breast cancer cell line. None of the tested compounds showed in-vitro translation inhibitory activity or toxicity against the HEK-293 human embryonic kidney cell line at 40 μM.
|
|
| 2. |
- Fred, Rikard G., et al.
(författare)
-
The human insulin mRNA is partly translated via a cap- and eIF4A-independent mechanism
- 2011
-
Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 412:4, s. 693-698
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whether cap-independent insulin mRNA translation occurs in human pancreatic islets at basal conditions, during stimulation at a high glucose concentration and at conditions of nitrosative stress. We also aimed at correlating cap-independent insulin mRNA translation with binding of the IRES trans-acting factor polypyrimidine tract binding protein (FTB) to the 5'-UTR of insulin mRNA. For this purpose, human islets were incubated for 2 h in the presence of low (1.67 mM) or high glucose (16.7 mM). Nitrosative stress was induced by addition of 1 mM DETA/NO and cap-dependent mRNA translation was inhibited with hippuristanol. Insulin biosynthesis rates were determined by radioactive labeling and immunoprecipitation. PTB affinity to insulin mRNA 5'-UTR was assessed by a magnetic micro bead pull-down procedure. We observed that in the presence of 1.67 mM glucose, approximately 70% of the insulin mRNA translation was inhibited by hippuristanol. Corresponding value from islets incubated at 16.7 mM glucose was 93%. DETA/NO treatment significantly decreased the translation of insulin by 85% in high glucose incubated islets, and by 50% at a low glucose concentration. The lowered insulin biosynthesis rates of DETA/NO-exposed islets were further suppressed by hippuristanol with 55% at 16.7 mM glucose but not at 1.67 mM glucose. Thus, hippuristanol-induced inhibition of insulin biosynthesis was less pronounced in DETA/NO-treated islets as compared to control islets. We observed also that PTB bound specifically to the insulin mRNA 5'-UTR in vitro, and that this binding corresponded well with rates of cap-independent insulin biosynthesis at the different conditions. In conclusion, our studies show that insulin biosynthesis is mainly cap-dependent at a high glucose concentration, but that the cap-independent biosynthesis of insulin can constitute as much as 40-100% of all insulin biosynthesis during conditions of nitrosative stress. These data suggest that the pancreatic beta-cell is able to uphold basal insulin synthesis at conditions of starvation and stress via a cap- and eIF4A-independent mechanism, possibly mediated by the binding of FIB to the 5'-UTR of the human insulin mRNA.
|
|
| 3. |
- Makungu, Marco, et al.
(författare)
-
Pterocarpans and isoflavones from the roots of Millettia micans and of Millettia dura
- 2016
-
Ingår i: Advances in Drug Discovery and Development. ; 1:1, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- From the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia micans, a new pterocarpan, (6aR,11aR)-7,8,9-trimethoxy-3-hydroxypterocarpan (1), named micanspterocarpan, was isolated. Similarinvestigation of the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia dura gave a further new pterocarpan,3-O-prenylmaackiain (2) along with six known isoflavones (3-8) and a chalcone (9). All purifiedcompounds were identified by NMR and MS, and the absolute configuration of 1 was established by quantumchemical CD calculation. The isolated constituents, calopogonium isoflavone B (3) and isoerythrin A-4'-(3-methylbut-2-enyl) ether (4) showed marginal activities against the 3D7 and the Dd2 strains of Plasmodiumfalciparum (70-90% inhibition at 40 M). Maximaisoflavone B (5) and 7,2'-dimethoxy-4',5'-methylenedioxyisoflavone (7) were weakly cytotoxic (IC50 153.5 and 174.1 uM, respectively) against theMDB-MB-231 human breast cancer cell line. None of the tested compounds showed toxicity against theHEK-293 human embryonic kidney cell line at 40 uM.
|
|
| 4. |
- Nyandoro, Stephen S., 1975, et al.
(författare)
-
Polyoxygenated Cyclohexenes and Other Constituents of Cleistochlamys kirkii Leaves
- 2017
-
Ingår i: Journal of natural products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:1, s. 114-125
-
Tidskriftsartikel (refereegranskat)abstract
- Thirteen new metabolites, including the polyoxygenated cyclohexene derivatives cleistodiendiol (1), cleistodienol B (3), cleistenechlorohydrins A (4) and B (5), cleistenediols A–F (6–11), cleistenonal (12), and the butenolide cleistanolate (13), 2,5-dihydroxybenzyl benzoate (cleistophenolide, 14), and eight known compounds (2, 15–21) were isolated from a MeOH extract of the leaves of Cleistochlamys kirkii. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of compounds 1, 17, and 19 were established by single-crystal X-ray diffraction. The configuration of the exocyclic double bond of compound 2 was revised based on comparison of its NMR spectroscopic features and optical rotation to those of 1, for which the configuration was determined by X-ray diffraction. Observation of the co-occurrence of cyclohexenoids and heptenolides in C. kirkii is of biogenetic and chemotaxonomic significance. Some of the isolated compounds showed activity against Plasmodium falciparum (3D7, Dd2), with IC50 values of 0.2–40 μM, and against HEK293 mammalian cells (IC50 2.7–3.6 μM). While the crude extract was inactive at 100 μg/mL against the MDA-MB-231 triple-negative breast cancer cell line, some of its isolated constituents demonstrated cytotoxic activity with IC50 values ranging from 0.03–8.2 μM. Compound 1 showed the most potent antiplasmodial (IC50 0.2 μM) and cytotoxic (IC50 0.03 μM, MDA-MB-231 cell line) activities. None of the compounds investigated exhibited translational inhibitory activity in vitro at 20 μM.
|
|
