title: Structure elucidation and DNA binding specificity of natural compounds from Cassia siamea leaves: A biophysical approach.
abstract: A novel isoflavone, 5,6,7-trimethoxy-3-(3',4',5'-trimethoxyphenyl)-4H-chromen-4-one (1) along with a known pyranocoumarin, Seselin (2) have been isolated from the ethanolic extract of the leaves of Cassia siamea (Family: Fabaceae). Compound 1 has been reported for the first time from any natural source and has not been synthesized so far. Their structures were elucidated on the basis of chemical and physical evidences viz. elemental analysis, UV, FT-IR, (1)H-NMR, (13)C-NMR and mass spectral analysis. Structure of compound (1) was further authenticated by single-crystal X-ray analysis and density functional theory (DFT) calculations. A multi-technique approach employing UV-Visible spectroscopy, fluorescence, KI quenching studies, competitive displacement assay, circular dichroism and viscosity studies have been utilized to probe the extent of interaction and possible binding modes of isolated compounds (1-2) with calf thymus DNA (CT-DNA). Both the compounds were found to interact with DNA via non-intercalative binding mode with moderate proficiencies. Groove binding was the major interaction mode in the case of compound 2 while compound 1 probably interacts with DNA through electrostatic interactions. These studies provide deeper insight in understanding of DNA-drug (natural products) interaction which could be helpful to improve their bioavailability for therapeutic purposes.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Aligarh Muslim University, Aligarh 202002, India. Electronic address: mehtab.organic2009@gmail.com.
authors.forename: Mehtab
authors.initials: M
authors.lastname: Parveen
authors.affiliation: Department of Chemistry, Faculty of Sciences, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Faheem
authors.initials: F
authors.lastname: Ahmad
authors.affiliation: Department of Chemistry, Faculty of Sciences, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Ali Mohammed
authors.initials: AM
authors.lastname: Malla
authors.affiliation: Department of Chemistry, Faculty of Sciences, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Mohd Sohrab
authors.initials: MS
authors.lastname: Khan
authors.affiliation: Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Sayeed Ur
authors.initials: SU
authors.lastname: Rehman
authors.affiliation: Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Tabish
authors.affiliation: CEMDRX Physics Department, University of Coimbra, 3004-516 Coimbra, Portugal.
authors.forename: Manuela Ramos
authors.initials: MR
authors.lastname: Silva
authors.affiliation: CEMDRX Physics Department, University of Coimbra, 3004-516 Coimbra, Portugal.
authors.forename: P S Pereira
authors.initials: PS
authors.lastname: Silva
mesh_terms: D001688:Biological Products / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001703:Biophysics; D002366:Cassia / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D001688:Biological Products; D004247:DNA
keywords: Cassia siamea; DFT calculation; DNA binding study; Isoflavone; X-ray analysis