Interaction of Safranal and Picrocrocin with ctDNA and Their Preferential Mechanisms of Binding to GC- and AT-Rich Oligonucleotides

Abstract

Saffron (Crocus sativus L.) shows different biological properties, some of which relate to its special components including safranal (deglycosylated picrocrocin). In our previous study on the mechanism of saffron functions, interaction of saffron carotenoids with DNA and oligonucleotides was reported. The present study aimed to investigate the interaction of safranal with calf thymus DNA (ctDNA), oligo(GC)15, and oligo(AT)15 in comparison with picrocrocin. Circular dichroism (CD) and fluorometric results show the nonintercalative/minor groove binding of the mentioned ligands to ctDNA. The CD plots indicate that picrocrocin interacts with DNA and oligonucleotides at lower concentrations than safranal does, which is accompanied by B- to C-DNA transition. At higher concentrations, it induces more conformational changes, that is, unstacking of DNA and oligonucleotides bases, the same as saffron carotenoids. However, similar results are obtained for safranal interaction with ctDNA (56% AT) and oligo(AT)15, but after adding safranal (with a free aldehyde group) to oligo(GC)15, the CD spectra show some changes (two positive and a displaced negative peaks) that are characteristics of triple-helix DNA. Thus, the mechanism for B- to H-DNA transition, due to the interaction of safranal with GC-rich sequences, is presented here.

Spectroscopic Studies on the Interaction of Anti Cancer Rosemary With ctDNA

“…It indicated the irregular changes base-base interaction due to the un-stacking of DNA base. Such behavior has previously been reported for ingredients of saffron (6,7). As mentioned in the introduction, the rosemary extract contains different components such as carnosic acid, carnosol and rosmanol.…”

“…due to the B to C-form transition (7). Also, at higher concentrations of rosemary extract, positive and negative peaks come near to the zero point.…”

“…High molecular weight DNA was purified from calf thymus, as previously illustrated. The ctDNA (calf thymus DNA) concentrations were determined by an extinction coefficient of 6600 M -1 cm -1 at 260 nm and expressed in terms of base molarity (7). Titration of ctDNA (0.03 mg/mL) and buffer was carried out at various concentrations of rosemary extract (0 -16 mg/mL) and EtBr (ethidium bromide) source (0.008 mg/mL) for one minute in each addition.…”

“…These interactions can change DNA conformation and torsional tension, and also dissociate protein-DNA interactions lightly and may break DNA strands (1,2). There are various anticancer agents derived from herbs that interact with DNA such as mitoxantrone (3), curcumin (4), quercetin (5) and saffron metabolites (6,7).…”

44 Circular dichroism (CD) studies of the interaction between G-quadrulexes/I-motif with saffron secondary active metabolites

“…These structures may be stabilized or changed by binding to specific proteins or small molecules. In continuation of our previous studies on the interaction between crocin and crocetin, as the natural C20 carotenoids, and picrocrocin and safranal, as the natural monoterpene aldehydes, obtained from saffron and DNA (Bathaie et al, 2007;Hoshyar et al, 2008), herein, we report the in vitro effect of these saffron metabolites on the mentioned structures (Hoshyar et al, 2012). Circular dichroism (CD) data indicate that crocetin has higher affinity for these structures.…”