Studies of the Interaction between BSA and a Plumeran Indole Alkaloid Isolated from the Stem Bark of Aspidosperma cylindrocarpon (Apocynaceae)

• Published in: Journal of the Brazilian Chemical Society Vol. 28; no. 7; pp. 1229 - 1236
• Main Authors: Chaves, Otávio, Teixeira, Flávia, Guimarães, Heloisa, Braz‑Filho, Raimundo, Vieira, Ivo José, Sant’Anna, Carlos Mauricio, Netto-Ferreira, José Carlos, Cesarin-Sobrinho, Dari, Ferreira, Aurélio
• Format: Journal Article
• Language: English
• Published: Sociedade Brasileira de Química 01.07.2017
• Subjects: CHEMISTRY, MULTIDISCIPLINARY; molecular docking; circular dichroism; Aspidosperma cylindrocarpon; bovine serum albumin; fluorescence quenching
• ISSN: 0103-5053; 1678-4790
• DOI: 10.21577/0103-5053.20160285

Binding between bovine serum albumin (BSA) and a plumeran indole alkaloid (PIA) isolated from the stem bark of Aspidosperma cylindrocarpon (Apocynaceae) was studied by spectroscopic techniques (UV-Vis absorption, circular dichroism, steady state and time-resolved fluorescence), combined with molecular docking. Steady state and time resolved fluorescence data revealed that PIA can quench the BSA fluorescence via a static mechanism: energy transfer from BSA to PIA occurs with high probability. The binding is strong (Kb ca. 105-106 L mol-1), spontaneous (ΔG° ca. -35.7 kJ mol-1 at 310 K) and entropy-driven (ΔS° = 0.146 kJ mol-1 K-1). There is just one main binding site (n ca. 1) for the BSA:PIA interaction and the α-helix content of the albumin does not suffer significant perturbation upon PIA binding. Molecular docking results suggest site I as the main binding site to PIA, which is able to interact with the Trp-212, Arg-217, Val-342 and Pro-446 residues.