Synthesis and anticancer activity of a series of norcantharidin analogues.
Cantharidin (1) and norcantharidin (2) display high levels of anticancer activity against a broad range of tumour cell lines. Synthetic manipulation of norcantharidin yields (3S,3aR,4S,7R,7aS)-3-hydroxyhexahydro-4,7-epoxyisobenzofuran-1(3H)-one (3), which also displays a high level of anticancer activity against tumour cells but interestingly, shows selectivity towards HT29 (colon; GI(50) = 14 μM) and SJ-G2 (glioblastoma; GI(50) = 15 μM) cell lines. Substitution at the hydroxyl group of the cyclic lactone within (3) produces a diasteromeric pair of products that have no difference in cytotoxicity over the cell lines tested. Incorporation of an isopropyl tail at this position (16) produced the most promising compound of this series to date, with strong selectivity towards HT29 (colon; GI(50) = 19 μM) and SJ-G2 (glioblastoma; GI(50) = 21 μM) cell lines but completely void of any activity against the remaining tumour cell lines (GI(50) > 100 μM), as per the parent molecule. We also discovered that the introduction of a terminal phosphate moiety (28) at the same position produced a different trend in cytotoxicity with strong activity in BE2-C (neuroblastoma; GI(50) = 9 μM) cells; suggestive of an alternate mode of action.
Chemistry, Centre for Chemical Biology, School of Environmental & Life Sciences, University of Newcastle, University Drive, Callaghan NSW 2308, Australia.
Mark
M
Tarleton
Jayne
J
Gilbert
Jennette A
JA
Sakoff
Adam
A
McCluskey
D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D060326:Chemistry Techniques, Synthetic; D006801:Humans; D020128:Inhibitory Concentration 50
D000970:Antineoplastic Agents; D019086:Bridged Bicyclo Compounds, Heterocyclic; C069741:norcantharidin