MATERIALS AND METHODS: FT-IR, 1D and 2D NMR spectroscopy, and CHN microanalysis were used to elucidate the structures of the trimers. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction were used to study the transitional and phase properties of the trimers, which were length and spacer parity dependent. Trimers with short spacer length in the cholesteryl arm, m = 4 showed an interesting phase sequence of BP/N*-TGBA*-SmA*.
RESULTS AND DISCUSSION: The TGBA* phase was sensitive to spacer length as it was only observed in trimers with short ester linkage. For the long analogues, m = 9, characteristic visible reflection and a much simpler phase sequence with only N* and SmA* phases were observed.
CONCLUSION: The X-ray diffraction measurements revealed that layer periodicities of the SmA* phase were approximately half the estimated all-trans molecular length (d/L ≈ 0.44-0.52), thus suggesting that the molecules are either strongly intercalated or bent.
OBJECTIVE: It is of great interest to identify the oxidation products of sesamol that may be beneficial to humans. This study was undertaken to identify the oxidation products of sesamol and investigate their antioxidant and cytotoxic activities.
MATERIALS AND METHODS: Using the ferricyanide oxidation approach, four oxidation products of sesamol (2, 3, 20 & 21) have been identified. Structural elucidation of these compounds was established on the basis of their detailed NMR spectroscopic analysis, mass spectrometry and x-ray crystallography. Additionally, a formation mechanism of compound 20 was proposed based on high-resolution mass spectrometry-fragmentation method. The antioxidant activities of these compounds were determined by the DPPH, FRAP, and ABTS assays. The in vitro antiproliferative activity of these compounds was evaluated against a panel of human cancer cell lines as well as non-cancerous cells.
RESULTS: Two oxidation products of sesamol were found to contain an unusual methylenedioxy ring-opening skeleton, as evidenced by spectroscopic and x-ray crystallographic data. Among all compounds, 20 displayed impressive antiproliferative activities against a panel of human cancer cell lines yet remained non-toxic to noncancerous cells. The antioxidant activities of compound 20 are significantly weaker than sesamol as determined by the DPPH, FRAP, and ABTS assays.
CONCLUSION: The oxidation products of sesamol could be a valuable source of bioactive molecules. Compound 20 may be used as a potential lead molecule for cancer studies.
OBJECTIVE: For the tuning of surfactant properties, double click coupling of the antipode precursors was attempted. Failure of the CuAAC to provide the targeted product in combination with unexpected reaction outputs led to an investigation of the side reaction.
METHODS: The CuAAC-based coupling of sugar azide with propargyl building block in the presence of copper- (I) catalyst exclusively led to the mono-coupling product in a respectable yield of almost 80%. Besides the unexpected incomplete conversion, the loss of the remaining propargyl group, as indicated by both NMR and MS. On the other hand, application of substantial amounts of CuSO4 under reducing conditions in refluxing toluene/water furnished the alkyne dimer in a moderate yield of 43%, while no change of azide compound was noticed.
RESULTS: The Cu(I)-catalyst applied for azide-alkyne cycloadditions enables the homo-coupling of certain terminal alkynes at a higher temperature. Moreover, aromatic propargyl ethers may be cleaved to furnish the corresponding phenol. The copper-catalyzed coupling appeared highly sensitive towards the alkyne compound. Only selected derivatives of propargyl alcohol were successfully dimerized.
CONCLUSIONS: The observed failure of the Huisgen reaction for the synthesis of sugar-based surfactants may indicate non-recognized constrains of the reaction, which could affect its wide application in bioconjugation. The temperature requirement for the alternative dimerization of terminal alkynes renders this side reaction nonrelevant for typical click couplings, while narrow substrate diversity and moderate yield limit its synthetic application.
OBJECTIVE: Arene diazonium salts play an important role in organic synthesis as intermediate and a wide variety of aromatic compounds have been prepared using them. A serious drawback of arene diazonium salts is their instability in a dry state; therefore, they must be stored and handled carefully to avoid spontaneous explosion and other hazard events.
METHODS: The arene diazonium saccharin salts were prepared as active intermediates in situ through the reaction of various aryl amines with tert-butyl nitrite (TBN) in the presence of saccharin (Sac-H). Then, in situ obtained intermediates were used into the diazotization step without separation and purification in the current protocol.
RESULTS: A variety of aryl iodides were synthesized at a greener and low-cost method in the presence of TBN, Sac-H, glacial acetic acid, and TEAI.
CONCLUSION: In summary, a telescopic reaction is developed for the synthesis of aryl iodides. The current methodology is safe, cost-effective, broad substrate scope, and metal-free. All used reagents are commercially available and inert to moisture and air. Also, the saccharine and tetraethylammonium cation could be partially recovered from the reaction residue, which reduces waste generation, energy consumption, raw material, and waste disposal costs.
METHODS: The psoralen derivatives were produced through the condensation of seven different types of amine groups consisting of electron withdrawing groups and electron donating groups.
RESULTS: All the synthesised compounds were obtained with moderate to high yields. Structural characterization using ATR-FTIR, 1H NMR, 13C NMR, and HRMS has confirmed their structure. Moreover, in silico evaluation of the psoralen derivatives against the AChE enzyme was performed, and acetylcholinesterase inhibitory activity of psoralen derivatives was also conducted.
CONCLUSION: Results from molecular docking show the potential of compound 12e as AChE inhibitors due to its highest binding energy value. It was further supported by the anti-acetylcholinesterase activity of compound 12e, which has 91.69% inhibition, comparable to galantamine (94.12%). Furthermore, 100 ns run molecular dynamics (MD) simulation was used to refine docking results.