949 J. Indian Chem. Soc., Vol. 94, September 2017, pp. 949-958 Studies on the interaction and complexation of pyrrole compound with hemoglobin Sanjit Kumar Mahato* †a,b , Ajay Kumar Timiri c , Mrityunjoy Mahato* d , Arjun Maity b,e and Yogesh Kumar Walia a a Department of Chemistry, School of Basic and Applied Sciences, Career Point University, Hamirpur-176 041, Himachal Pradesh, India E-mail : sanjitmahato@gmail.com b Department of Chemical Engineering, College of Science, Engineering and Technology (CSET), University of South Africa (UNISA), South Africa c Department of Pharmaceutical Sciences & Technology, Birla Institute of Technology, Mesra, Ranchi-835 215, Jharkhand, India d Physics Division, Department of Basic Sciences and Social Sciences, School of Technology, North Eastern Hill University, Shillong-793 022, Meghalaya, India E-mail : mrityunjoyphy@gmail.com e DST/CSIR Innovation Centre, National Centre for Nanostructured Materials, CSIR Material Science and Manufacturing, Building-19B, PO Box 395, Pretoria-0001, South Africa † Currently Research Scientist at TCG Lifesciences Pvt. Ltd., Kolkata-700 091, India Manuscript received 23 June 2017, accepted 15 July 2017 Abstract : Alkaloids such as pyrrole, tetrapyrrole etc. are gaining intensive research importance due to its structural and conformational similarities with porphyrin and heme proteins as well as possess a great bio- logical significance to the living systems. Herein, we have reported a detail investigation into the nature of interaction and complexation of a pyrrole compound, methyl-4-(2-oxo-2-phenyl-ethyl)-5-phenyl-1 H-pyrrole-3- carboxylic acid methyl ester (PyS) with an important blood protein Hemoglobin (Hb). The spectroscopic and computer generated docking calculation have been applied in this study to understand the molecular interac- tion and complexation. Systematic concentration dependent studies of the Hb-PyS complex in solution phase using absorption, steady state/time resolved emission have been reported in this paper. A number of residues have been identified as the interaction zone for the PyS compound within the Hb protein such as heme group, tryptophan (Trp), tyrosine (Tyr) and amide group through  - interaction and hydrogen bonding as evident from simultaneous experimental and docking results. This study may contribute to the basic understanding of the biological and medicinal potential of the pyrrole based pure substituted alkaloid. Keywords : Hemoglobin, pyrrole compound, complexation, interaction studies, spectroscopy, docking. Introduction Alkaloids such as pyrrole, tetrapyrrole and their derivatives are having structural similarities with por- phyrin and heme proteins and due to its important biological significance, it is gaining intensive research thrust 1 . Especially after the discovery of the pyrrole based drug atorrastatin which are used for lowering blood cholesterol as well as prevention of events as- sociated with heart diseases 1,2 . Tetrapyrrole deriva- tives occur abundantly in many biological systems such as in heme protein (iron porphyrin), in photo- synthetic proteins as chlorophyll and porphyrin, and