- Design and synthesis of calindol derivatives as potent and selective calcium sensing receptor agonists
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We report the first comprehensive structure-activity study of calindol (4, (R)-N-[(1H-indol-2-yl)methyl]-1-(1-naphthyl)ethanamine), a positive allosteric modulator, or calcimimetic, of the calcium sensing receptor (CaSR). While replacement of the naphthyl moiety of calindol by other aromatic groups (phenyl, biphenyl) was largely detrimental to calcimimetic activity, incorporation of substituents on the 4, 5 or 7 position of the indole portion of calindol was found to provide either equipotent derivatives compared to calindol (e.g., 4-phenyl, 4-hydroxy, 5-hydroxycalindol 44, 52, 53) or, in the case of 7-nitrocalindol (51), a 6-fold more active calcimimetic displaying an EC50 of 20 nM. Unlike calindol, the more active CaSR calcimimetics were shown not to act as antagonists of the closely related GPRC6A receptor, suggesting a more selective profile for these new analogues.
- Kiefer, Lionel,Beaumard, Floriane,Gorojankina, Tatiana,Faure, Hélène,Ruat, Martial,Dodd, Robert H.
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- CBI analogues of the duocarmycins and CC-1065
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An extensive series of CBI analogues of the duocarmycins and CC-1065 exploring substituent effects within the first indole DNA binding subunit is detailed. In general, substitution at the indole C5 position led to cytotoxic potency enhancements that can be ≧1000-fold providing simplified analogues containing a single DNA binding subunit that are more potent (IC50=2-3 pM) than CBI-TMI, duocarmycin SA, or CC-1065. The increases in cytotoxicity correlate well with accompanying increases in the rate and efficiency of DNA alkylation. This effect is more pronounced with the CBI versus DSA or CPI based analogues. Moreover, this effect is largely insensitive to the electronic character of the C5 substituent but is sensitive to the size, rigid length, and shape (sp, sp2, sp3 hybridization) of this substituent consistent with expectation that the impact is due simply to its presence.
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