engleski

Permanent positive charge strongly influences DNA/RNA binding and antiproliferative activity of urea-phenanthridinium conjugates

An introduction of the permanent positive charge by methylation of heterocyclic nitrogen on a series of previously studied bis-urea phenanthridine derivatives substantially changed their interactions with DNA and RNA as well as biological activity. At variance to non-methylated analogues, novel methylated derivatives interacted with DNA/RNA not only at pH 5 but also at pH 7, and some compounds switched DNA binding mode from minor groove binding (non-methylated derivatives) to intercalation (novel, methylated derivatives). Moreover, selective ds-RNA over ds-DNA thermal stabilisation of previously observed non-methylated derivatives was reversed for novel, methylated derivatives. The variation of linker length connecting two urea-phenanthridinium conjugates regulated their binding modes toward double stranded polynucleotides. All novel compounds were able to distinguish between polynucleotides of A-T(U) and G-C basepair composition by specific fluorescence change. Moreover, the introduction of permanent positive charge on the phenanthridinium moiety resulted in significantly higher biological potency in respect to non-methylated analogues.

urea-phenanthridinium ; DNA ; RNA ; fluorescence selectivity ; intercalation ; antiproliferative activity

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