Deuteration of the farnesyl terminal methyl groups of δ-tocotrienol and its effects on the metabolic stability and ability of inducing G-CSF production.
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ABSTRACT:
SUBMITTER: Liu X
PROVIDER: S-EPMC7433030 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Previous studies have demonstrated the anticancer activities of tocotrienol on several types of cancer, but its effects on chondrosarcoma have never been investigated. Therefore, this study aims to determine the anticancer properties of annatto tocotrienol (AnTT), γ-tocotrienol (γ-T3) and δ-tocotrienol (δ-T3) on human chondrosarcoma SW1353 cells. Firstly, the MTT assay was performed to determine the half-maximal inhibitory concentration (IC50) of tocotrienol on SW1353 cells after 24 h treatment. The mode of cell death, cell cycle analysis and microscopic observation of tocotrienol-treated SW1353 cells were then conducted according to the respective IC50 values. Subsequently, RNAs were isolated from tocotrienol-treated cells and subjected to RNA sequencing and transcriptomic analysis. Differentially expressed genes were identified and then verified with a quantitative PCR. The current study demonstrated that AnTT, γ-T3 and δ-T3 induced G1 arrest on SW1353 cells in the early phase of treatment (24 h) which progressed to apoptosis upon 48 h of treatment. Furthermore, tocotrienol-treated SW1353 cells also demonstrated large cytoplasmic vacuolation. The subsequent transcriptomic analysis revealed upregulated signalling pathways in endoplasmic reticulum stress, unfolded protein response, autophagy and transcription upon tocotrienol treatment. In addition, several cell proliferation and cancer-related pathways, such as Hippo signalling pathway and Wnt signalling pathway were also significantly downregulated upon treatment. In conclusion, AnTT, γ-T3 and δ-T3 possess promising anticancer properties against chondrosarcoma cells and further study is required to confirm their effectiveness as adjuvant therapy for chondrosarcoma.
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Project description:1. delta-Tocotrienol (8-methyltocotrienol) was isolated from the latex of Hevea brasiliensis. This new member of the tocopherol family is a pale-yellow oil at room temperature. 2. The properties of delta-tocotrienol are very similar to those of delta-tocopherol and the small differences can be explained by the change in side chain. 3. The ultraviolet and infrared spectra of delta-tocotrienol were determined and a conversion factor for use with the Emmerie-Engel reaction was worked out. Details are given for the chromatography of delta-tocotrienol on thin layers (adsorption and partition) and reversed-phase paper, and the nitroso derivatives were formed. 4. An ethyl carbonate ester of delta-tocotrienol was prepared and compared with a similar ester of delta-tocopherol. 5. Hydroxymethylation of delta-tocotrienol followed by reduction gave beta-tocotrienol as a major product.
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Project description:Eleven farnesyl diphosphate analogues, which contained omega-azide or alkyne substituents suitable for bioorthogonal Staudinger and Huisgen [3 + 2] cycloaddition coupling reactions, were synthesized. The analogues were evaluated as substrates for the alkylation of peptide cosubstrates by yeast protein farnesyl transferase. Five of the diphosphates were good alternative substrates for farnesyl diphosphate (FPP). Steady-state kinetic constants were measured for the active compounds, and the products were characterized by HPLC and LC-MS. Two of the analogues gave steady-state kinetic parameters (kcat and Km) very similar to those of the natural substrate.
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Project description:Gamma and delta tocotrienols are isomers of Vitamin E with established potency in pre-clinical anti-cancer research. This single-dose, randomized, crossover study aimed to compare the safety and bioavailability of a new formulation of Gamma Delta Tocotrienol (GDT) in comparison with the existing Tocotrienol-rich Fraction (TRF) in terms of gamma and delta isomers in healthy volunteers. Subjects were given either two 300 mg GDT (450 mg ?-T3 and 150 mg ?-T3) capsules or four 200 mg TRF (451.2 mg ?-T3 &102.72 mg ?-T3) capsules and blood samples were taken at several time points over 24 hours. Plasma tocotrienol concentrations were determined using HPLC method. The 90% CI for gamma and delta tocotrienols for the ratio of log-transformation of GDT/TRF for Cmax and AUC0-? (values were anti-logged and expressed as a percentage) were beyond the bioequivalence limits (106.21-195.46, 154.11-195.93 and 52.35-99.66, 74.82-89.44 respectively). The Wilcoxon Signed Rank Test for Tmax did not show any significant difference between GDT and TRF for both isomers (p > 0.05). No adverse events were reported during the entire period of study. GDT was found not bioequivalent to TRF, in terms of AUC and Cmax. Gamma tocotrienol in GDT showed superior bioavailability whilst delta tocotrienol showed less bioavailability compared to TRF.
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Project description:Cell death is a vital event in life. Infections and injuries cause lytic cell death, which gives rise to danger signals that can further induce cell death, inflammation, and tissue damage. The mevalonate (MVA) pathway is an essential, highly conserved and dynamic metabolic pathway. Here, we discover that farnesyl pyrophosphate (FPP), a metabolic intermediate of the MVA pathway, functions as a newly identified danger signal to trigger acute cell death leading to neuron loss in stroke. Harboring both a hydrophobic 15-carbon isoprenyl chain and a heavily charged pyrophosphate head, FPP leads to acute cell death independent of its downstream metabolic pathways. Mechanistically, extracellular calcium influx and the cation channel transient receptor potential melastatin 2 (TRPM2) exhibit essential roles in FPP-induced cell death. FPP activates TRPM2 opening for ion influx. Furthermore, in terms of a mouse model constructing by middle cerebral artery occlusion (MCAO), FPP accumulates in the brain, which indicates the function of the FPP and TRPM2 danger signal axis in ischemic injury. Overall, our data have revealed a novel function of the MVA pathway intermediate metabolite FPP as a danger signal via transient receptor potential cation channels.
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Project description:Vitamin E consists of tocopherols and tocotrienols, in which α-tocotrienol is the most potent neuroprotective form that is also effective in protecting against stroke in rodents. As neuroprotective agents alone are insufficient to protect against stroke, we sought to test the effects of tocotrienol on the cerebrovascular circulation during ischemic stroke using a preclinical model that enables fluoroscopy-guided angiography. Mongrel canines (mean weight=26.3±3.2 kg) were supplemented with tocotrienol-enriched (TE) supplement (200 mg b.i.d, n=11) or vehicle placebo (n=9) for 10 weeks before inducing transient middle cerebral artery (MCA) occlusion. Magnetic resonance imaging was performed 1 hour and 24 hours post reperfusion to assess stroke-induced lesion volume. Tocotrienol-enriched supplementation significantly attenuated ischemic stroke-induced lesion volume (P<0.005). Furthermore, TE prevented loss of white matter fiber tract connectivity after stroke as evident by probabilistic tractography. Post hoc analysis of cerebral angiograms during MCA occlusion revealed that TE-supplemented canines had improved cerebrovascular collateral circulation to the ischemic MCA territory (P<0.05). Tocotrienol-enriched supplementation induced arteriogenic tissue inhibitor of metalloprotease 1 and subsequently attenuated the activity of matrix metalloproteinase-2. Outcomes of the current preclinical trial set the stage for a clinical trial testing the effects of TE in patients who have suffered from transient ischemic attack and are therefore at a high risk for stroke.
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Project description:H/D exchange at formyl groups represents the straightforward approach to C-1 deuterated aldehydes. This transformation has been recently realized by transition metal and NHC carbene catalysis. Mechanistically, all these processes involve an ionic pathway. Herein we report a distinct photoredox catalytic, visible light mediated neutral radical approach. Selective control of highly reactive acyl radical in the energy barrier surmountable, reversible reaction enables driving the formation of deuterated products when an excess of D2O is employed. The power of the H/D exchange process has been demonstrated for not only aromatic aldehydes, but also aliphatic substrates, which have been difficult in transitional metal catalyzed H/D exchange reactions, and for selective late-stage deuterium incorporation into complex structures with uniformly high deuteration level (>90%).
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Project description:BACKGROUND: Hepatitis delta virus (HDV) is a defected RNA virus and requires its encoded large antigen (LDAg) to interact with helper viral proteins (HBsAgs) during assembly. Recently, a study demonstrated a direct binding of the LDAg C-terminus from genotype I HDV to the clathrin heavy chain (CHC), which suggests that this interaction might facilitate HDV assembly. If LDAg binding to clathrin is essential to HDV life cycle, a clathrin box sequence at the C-terminus of LDAg should be conserved across all HDV. However, the C-terminal sequence of LDAg is variable among 43 HDV isolates. RESULTS: Based on the presence and location of clathrin box at the C-terminus of LDAg from 43 isolates of HDV, we classified them into three groups. Group 1 (13 isolates) and 2 (26 isolates) contain a clathrin box located at amino acids 199-203 and 206-210, respectively, as found in genotype I and genotype II. Group 3 (4 isolates) contains no clathrin box as found in genotype III. CHC binding by three different LDAg (genotype I to III) was then tested by in vivo and in vitro experiments. Transfection of plasmids which encode fusion proteins of EGFP and full-length of LDAg from three genotypes into HuH-7 cells, a human hepatoma cell line, was performed. GFP-pull down assays showed that a full-length of CHC was co-precipitated by EGFP-LDI, -LDII and -LDIII but not by EGFP. Further in vitro studies showed a full-length or fragment (amino acids 1 to 107) of CHC can be pull-down by 13-amino-acid peptides of LDAg from three genotypes of HDV. CONCLUSION: Both in vivo and in vitro studies showed that CHC can bind to various sequences of LDAg from the three major genotypes of HDV. We therefore suggest that the clathrin-LDAg interaction is essential to the HDV life-cycle and that sequences binding to clathrin are evolutionarily selected, but nonetheless show the diversity across different HDV genotypes.
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