The issue of chiral drug is now a major theme in the design, discovery and development of new drugs. It has
been shown for many pharmaceuticals that only one enantiomer contains the desired activity, and the synthesis of such
drug molecules in their optically pure form is becoming increasingly important. Mitsunobu reaction was carried out between
(R)- and (S)-3,4-dihydro-2H-1,5-benzoxathiepin-3-ol and purines under microwave irradiation. A contraction into a
six-membered ring takes place with concomitant inversion at the stereocentre with excellent enatiomeric excesses giving
rise to the homochiral 9-(2,3-dihydro-1,4-benzoxathiin-3-ylmethyl)-9H-purines. The anti-tumour activity of all enantiomers
is reported against the caspase-3-deficient MCF-7 and the wild type SKBR-3 human breast cancer cells. The most
active homochiral compound displays an IC50 of 1.85 μM and induces inhibition of the translation initiation factor eIF2α.
All homochiral compounds included in this study show different apoptotic effects between both enantiomers with levels
up to 99%. We have analyzed caspase-mediated apoptotic pathways on enantiomers and racemates. We have found a homochiral
derivative that activates the canonical intrinsic caspase-8/caspase-3 apoptotic pathway on the MCF-7 cells, and a
racemic compound that induces caspase-2 activation. Moreover, we demonstrate the involvement of caspase activation
during cell death induced by these compounds in SKBR-3 cells.
Keywords: Antitumour drugs, apoptosis, 1, 4-benzoxathiin, MCF-7and SKBR-3 breast cancer cell lines, eIF2α, enantiospecific
synthesis, neighbouring-group participation.
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