Novel Antitumor L‐Arabinose Derivative of Indolocarbazole with High Affinity to DNA

Abstract

Novel indolocarbazole derivative 12-(alpha-L-arabinopyranosyl)indolo[2,3-alpha]pyrrolo[3,4-c]carbazole-5,7-dione (AIC) demonstrated high potency (at submicromolar concentrations) against the NCI panel of human tumor cell lines and transplanted tumors in vivo. In search of tentative targets for AIC, we found that the drug formed high affinity intercalative complexes with d(AT)(20), d(GC)(20) and calf thymus DNA (binding constants (1.6x10(6)) M(-1)< or =K(a)< or =(3.3x10(6)) M(-1)). The drug intercalated preferentially into GC pairs of the duplex. Importantly, the concentrations at which AIC formed the intercalative complexes with DNA (C< or =1 microM) were identical to the concentrations that triggered p53-dependent gene reporter transactivation, the replication block, the inhibition of topoisomerase I-mediated DNA relaxation and death of HCT116 human colon carcinoma cells. We conclude that the formation of high affinity intercalative complexes with DNA is an important factor for anticancer efficacy of AIC.

Solubility and Seeded Metastable Zone width of functional sugar L-arabinose

“…L-arabinose is the critical agent in the synthesis of antiviral drug clevudine (Choung et al, 2012) and telbivudine (Jia et al, 2014;Li et al, 2014), which are potent anti-hepatitis B (HBV) agents. It also has great usage in tumor therapy (Loessner et al, 2007;Jeong et al, 2014;Kaluzhny et al, 2009) and chemistry (Yamauchi & Kinoshita, 2001;EL-Farargy & Ghonium, 2008) and biology fields (Becker & Boles, 2003;Jeon et al, 2010). Although it has been known for a long time, the solubility and metastable zone width of L-arabinose in aqueous solution have not been reported before.…”

Novel Indolocarbazole Derivative 12-(α-L-arabinopyranosyl)indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7-dione Is a Preferred c-MycGuanine Quadruplex Ligand

“…The UV absorption spectra of free AIC showed two prominent bands at 285 nm and 318 nm and a weaker band at 425 nm [22]. The absorption near λ = 318 nm decreased upon binding of AIC to G-c- Myc , G-tel, and c- Myc duplex d(AGGGTGGGG) 2 :d(CCCCACCCT) 2 in Hanks' buffer at 20°C (Figure 2).…”

“…Studies of energy transfer and circular dichroism (CD) spectra were performed as described by Kaluzhny et al [22]. …”

“…However, the binding constants to the duplex and G-quadruplex DNAs of indolocarbazoles containing one carbohydrate substituent are relatively low ( K a ≤ 2 · 10 5  M −1 ) [18–20]. In contrast, we found the association constant to native double stranded DNA (dsDNA) of the novel indolocarbazole derivative, 12-( α - L -arabinopyranosyl)indolo[2,3- α ]pyrrolo[3,4- c ]carbazole-5,7-dione (AIC, Figure 1) to be substantially higher (1.6·10 6  M −1 ≤ K a ≤ 3.3·10 6  M −1 ) [21, 22]. AIC potently inhibited growth of 60 cultured human tumor cell lines (National Cancer Institute drug screening panel).…”

“…This compound demonstrated promising in vivo therapeutic efficacy against transplanted tumors. The concentrations of AIC required for the formation of intercalative complexes with dsDNA and the concentrations that induced tumor cell death were similar, suggesting that intercalation into DNA is an important factor of cytotoxicity of this indolocarbazole derivative [22]. …”