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Binding of Bioactive Phytochemical Piperine with Human Serum Binding of Bioactive PhytochemicalStudy with Human Serum Albumin: Albumin: A Spectrofluorometric Piperine A Spectrofluorometric Study
Dodda Venkatanna Suresh,1 Honsigere G. Mahesha,2 A. G. Appu Rao,2 Krishnapura Srinivasan1

Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore 570 020,Karnataka, India Department of Protein Chemistry and Technology, Central Food Technological Research Institute, Mysore 570 020, Karnataka, India Received 27 November 2006; revised 22 March 2007; accepted 23 March 2007 Published online 3 April 2007 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/bip.20735


Piperine, the bioactive alkaloid compound of the spice blackpepper (Piper nigrum) exhibits a wide range of beneficial physiological and pharmacological activities. Being essentially water-insoluble, piperine is presumed to be assisted by serum albumin for its transport in blood. In this study, the binding of piperine to serum albumin was examined by employing steady state and time resolved fluorescence techniques. Binding constant for the interaction ofpiperine with human serum albumin, which was invariant with temperature in the range of 17–478C, was found to be 0.5 3 105MÀ1, having stoichiometry of 1:1. At 278C, the van’t Hoff enthalpy DH8 was zero; DS8 and DG8 were found to be 21.4 cal molÀ1 KÀ1 and À6.42 kcal molÀ1. The binding constant increased with the increase of ionic strength from 0.1 to 1.0M of sodium chloride. The decrease of Stern–Volmerconstant with increase of temperature suggested that the fluorescence quenching is static. Piperine fluorescence showed a blue shift upon binding to serum albumin, which reverted with the addition of ligands — triiodobenzoic acid and hemin. The distance between piperine and tryptophan after binding was found to be
Correspondence to: Dr. K. Srinivasan; e-mail: ksri.cftri@gmail.com

¨ 2.79 nm byForster type resonance energy transfer calculations. The steady state and time resolved fluorescence measurements suggest the binding of piperine to the subdomain IB of serum albumin. These observations are significant in understanding the transport of piperine in blood under physiological conditions. # 2007 Wiley Periodicals, Inc. Biopolymers 86: 265–275, 2007. Keywords: interaction studies;piperine; serum albumin; steady state fluorescence; time resolved fluorescence This article was originally published online as an accepted preprint. The ‘‘Published Online’’date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com



C V 2007

Wiley Periodicals, Inc.

he alkaloid piperine(1-piperoyl piperidine) is the major bite factor of the spice black pepper (Piper nigrum), which is widely used in foods (Figure 1). Piperine has been endowed with several health beneficial physiological and pharmacological properties. Among these, the most important is its ability to enhance bioavailability of therapeutic drugs and phytonutrients.1,2 Piperine enhances the bioavailability of theseconcomitantly administered compounds by virtue of inhibiting the drug metabolizing enzymes, thus retarding their clearance from the body.3,4 It is also evident that enhancement of bioavailability of these compounds by piperine is partly attributable to an increased absorption, facilitated by alterations in the intestinal epithelial membrane lipid dynamics and permeation

Biopolymers Volume 86 /Number 4



Suresh et al.


Structure of piperine.

characteristics.5 Dietary piperine stimulates the digestive enzymes of pancreas and significantly reduces the gastrointestinal food transit time.6 Piperine has been demonstrated to protect against oxidative damage by inhibiting or quenching free radicals and reactive oxygen species.7 Piperine has been found to possess...
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