Hydroxytyrosol and two other polyphenols of olive tree, hydroxytyrosol acetate and 3,4-dihydroxyphenylglycol, are known for a wide range of beneficial activities in human health and prevention from diseases. The inability to isolate high, pure amounts of these natural compounds and the difficult and laborious procedures for the synthesis of them led us to describe herein an efficient, easy, cheap, and scaling up synthetic procedure, from catechol, via microwave irradiation.
Background:
Purine isosteres are often endowed with interesting pharmacological
properties, due to their involvement in cellular processes replacing the natural purines. Among
these compounds, pyrazolopyridines are under active investigation for potential anticancer properties.
Objective:
Based on previously discovered substituted pyrazolopyridines with promising antiproliferative
activity, we designed and synthesized new, suitably substituted analogues aiming to investigate
their potential activity and contribute to SAR studies of this class of bioactive compounds.
Methods:
The new compounds were synthesized using suitably substituted 2-amino-4-picolines,
which upon ring-closure provided substituted pyrazolo[3,4-c] pyridine-5-carbonitriles that served
as key intermediates for the preparation of the target 3,5,7 trisubstituted derivatives. The antiproliferative
activity of 31 new target derivatives was evaluated against three cancer cell lines (MIA
PaCa-2, PC-3 and SCOV3), whereas cell-cycle perturbations of exponentially growing PC-3 cells,
using three selected derivatives were also performed.
Results:
Eight compounds displayed IC50 values in the low μM range, allowing the extraction of
interesting SAR’s. Two of the most potent compounds against all cell lines share a common pattern,
by accumulating cells at the G0/G1 phase. From this project, a new carboxamidine-substituted
hit has emerged.
Conclusion:
Among the new compounds, those possessing the 3-phenylpyrazolo[3,4-c]pyridine
scaffold, proved to be worth investigating and the majority of them showed strong cytotoxic activity
against all cell lines, with IC50 values ranging from 0.87-4.3 µM. A carboxamidine analogue
that resulted from the synthetic procedure, proved to be highly active against the cancer cells and
could be considered as a useful lead for further optimization.
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