Two new cyclic hexapeptoids incorporating N-carboxyethylglycine and N-methoxyethylglycine residues are able to efficiently bind Gd(3+). Their thermodynamic stabilities and relaxivities have been assessed by (1)H-relaxometric investigations.
The interaction between 13-phenylalkyl and 13-diphenylalkyl berberine derivatives (NAX) and human telomeric DNA G4 structures has been investigated by both spectroscopic and crystallographic methods. NAX042 and NAX053 are the best compounds improving the performance of the natural precursor berberine. This finding is in agreement with the X-ray diffraction result for the NAX053-Tel12 adduct, showing the ligand which interacts via π-stacking, sandwiched at the interface of two symmetry-related quadruplex units, with its benzhydryl group contributing to the overall stability of the adduct by means of additional π-stacking interactions with the DNA residues. The berberine derivatives were also investigated for their cytotoxic activity towards a panel of human cancer cell lines. Compounds NAX042 and NAX053 affect the viability of cancer cell lines in a dose-dependent manner.
The natural alkaloid berberine has been recently described as a promising anticancer drug. In order to improve its efficacy and bioavailability, several derivatives have been designed and synthesized and found to be even more potent than the lead compound. Among the series of berberine derivatives we have produced, five compounds were identified to be able to heavily affect the proliferation of human HCT116 and SW613-B3 colon carcinoma cell lines. Remarkably, these active compounds exhibit high fluorescence emission property and ability to induce autophagy.
A new series of 13-pyridinealkyl berberine analogues was synthesized and their DNA binding efficacy studied by employing spectroscopic, calorimetric and molecular modeling techniques.
A series of 13-diphenylalkyl berberine derivatives were designed and synthesized, and their base specificity and energetics of DNA binding were evaluated using one natural and two synthetic DNA polynucleotides.Biophysical evaluation demonstrated that the addition of the diphenylalkyl chain at the 13-position of berberine significantly improved the binding ability to DNA. The binding clearly revealed the high preference of the analogues to the alternating AT sequences compared to the alternating GC sequences.The binding affinity was enhanced with the increase in chain length up to a critical length of (CH 2 ) 3 in all the cases, after which the binding affinity decreased. Analogue BR4 had the best affinity for DNA, which corresponds to a length of (CH 2 ) 3 . The results also suggested the adenine-thymine (AT) base specificity of these berberine analogues and that the length of the side chain at the 13-position of the isoquinoline chromophore is critical in modulating the binding affinity. Scheme 1 Synthesis of (a) 13-diphenylmethylberberine (BR1): (i) NaBH 4 , Py, rt, 1 h; (ii) Ph 2 CHBr, CH 3 CN, NaI, 90 C, 12 h, then (iii) NaBH 4 , EtOH, 0 C to rt, 12 h; (iv) N-chlorosuccinimide, CHCl 3 , rt, 12 h; and (b) higher 13-diphenylalkylberberine (BR2-BR6): (v) Ph 2 CH(CH 2 ) 0-4 CHO, 80% aq. EtOH, AcOH, 85 C, 6 h, then (vi) 2 M HCl, rt, 2 h.
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