Boronated oligonucleotides are potential candidates for boron neutron
capture therapy, antisense technology, and as tools in molecular biolo
gy. The biological properties of dodecathymidylic acids containing one
or more 5-(o-carboran-1-yl)-2'-deoxyuridine residues at different loc
ations within the oligonucleotide chain were studied. 5-(o-Carboran-1-
yl)-2'-deoxyuridine containing oligonucleotides manifested marked incr
eased lipophilicity and resistance to 3'- or 5'-phosphodiesterases com
pared to the corresponding unmodified oligomer. They were substrates f
or T4 polynucleotide kinase and primers for Escherichia coli polymeras
e I and human immunodeficiency virus type 1 reverse transcriptase but
not for human DNA polymerase alpha and beta. They also formed heterodu
plexes that were substrates for E. coli RNase H, an essential property
for antisense technology. These studies indicate that the carboranyl-
containing oligonucleotides have desirable properties that need to be
exploited further in the design of novel biopharmaceuticals.