Abstract

Background: Forskolin, a polyhydroxylated labdone diterpene possesses various medicinal properties in the treatment of chronic diseases, in humans. The present study aimed to evaluate the interaction and binding affinity between forskolin and HSA by in silico method and spectral analysis.

Methods: The in silico study for screening the interaction of forskolin with HSA protein was carried out using AutoDock Vina software. The evaluation and characterization of the HSA–forskolin complex formation was achieved by spectroscopic methods–UV absorption, HPLC and FTIR analysis.

Results: The in silico studies revealed that forskolin mainly binds on site II A and III A of HSA, with binding score -7.4 kcal mol-1and formations of hydrogen bonds with amino acid residues Asn 295, Arg 218 and Pro 447. The UV spectral analysis revealed the λ max for forskolin at 210 nm, for HSA at 220 & 280 nm, and for HSA bound forskolin at 215 nm indicating the formation of HSA-forskolin complex. A new peak was observed at retention time 0.787 min by HPLC analysis. The Bmax was found to be at 34 ± 0.12 mg protein and Kd value was 5.3x10-11 ± 0.03 M indicating interaction of forskolin with HSA. The FTIR analysis demonstrated shifting of amide I groups from 1600, 1640 to 1596, 1636 cm−1 respectively further establishing the binding of forskolin to HSA.

Conclusion: The study demonstrates the binding of forskolin to HSA and formation of HSA-forskolin complex. We further hypothesize the imperative role of HSA in the pharmacokinetics of forskolin.

Keywords: Forskolin; human serum albumin; HSA-forskolin complex; forskolin binding.

Graphical Abstract