Berberine, a strong polyriboadenylic acid binding plant alkaloid: spectroscopic, viscometric, and thermodynamic study

• Published in: Bioorganic & medicinal chemistry Vol. 13; no. 1; pp. 165 - 174
• Main Authors: Yadav, Ram Chandra, Kumar, Gopinatha Suresh, Bhadra, Kakali, Giri, Prabal, Sinha, Rangana, Pal, Sumana, Maiti, Motilal
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 03.01.2005; Elsevier Science
• Subjects: Alkaloid–poly(A) complexation; Berberine; Berberine - chemical synthesis; Berberine - metabolism; Biological and medical sciences; Circular Dichroism; General pharmacology; Medical sciences; Nucleic Acid Denaturation; Osmolar Concentration; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Poly A - metabolism; Poly(A); Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Thermodynamics; Viscosity; Berberine; Poly(A); Alkaloid–poly(A) complexation; Viscosity; Pharmacognosy; Molecular interaction; Extract; Mechanism; Fluorescence spectrometry; Circular dichroism; Medicinal plant; Absorption spectrometry; Alkaloid; Gene; Medium effect; Ionic strength; Thermodynamic properties; Single stranded RNA; Ribonucleotide; Rheological properties
• ISSN: 0968-0896; 1464-3391
• DOI: 10.1016/j.bmc.2004.09.045

Berberine binds strongly to single stranded poly(rA) by mechanism of partial intercalation, leading to its usefulness for inhibition of gene expression in eukaryotic cells. The interaction of berberine with single stranded poly(rA) structure was investigated using a combination of spectrophotometric, spectrofluorimetric, circular dichroic, viscometric, and thermodynamic studies. The interaction process was characterized by typical hypochromic and bathochromic effects in the absorption spectrum of berberine, enhancement of fluorescence intensity of berberine, increase of viscosity, and perturbation of circular dichroic spectrum of single stranded poly(rA). Scatchard plot obtained from spectrophotometric analysis showed that berberine bound strongly to single stranded poly(rA) in a non-cooperative manner. In contrast, berberine does not show any significant effect (i) in its absorbance and fluorescence spectra on binding to double stranded poly(rA), (ii) alter the circular dichroic spectrum of double stranded poly(rA), or (iii) increase of viscosity of double stranded poly(rA) indicating that it does not bind at all to double stranded poly(rA) structure. Thermodynamic parameters indicated that the binding of the alkaloid to single stranded poly(rA) is an endothermic process and entropy driven. All these findings, taken together clearly support that berberine binds strongly to single stranded poly(rA) structure by a mechanism of partial intercalation leading to its use in gene regulation in eukaryotic cells.